diff --git a/java/res/values-th/donottranslate.xml b/java/res/values-th/donottranslate.xml
new file mode 100644
index 0000000..aeeebed
--- /dev/null
+++ b/java/res/values-th/donottranslate.xml
@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/*
+**
+** Copyright 2013, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
+    <!-- Whether this language uses spaces -->
+    <bool name="current_language_has_spaces">false</bool>
+</resources>
diff --git a/java/res/values/donottranslate.xml b/java/res/values/donottranslate.xml
index e352f08..8983536 100644
--- a/java/res/values/donottranslate.xml
+++ b/java/res/values/donottranslate.xml
@@ -18,6 +18,8 @@
 */
 -->
 <resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
+    <!-- TODO: these settings depend on the language. They should be put either in the dictionary
+         header, or in the subtype maybe? -->
     <!-- Symbols that are suggested between words -->
     <string name="suggested_punctuations">!,?,\\,,:,;,\",(,),\',-,/,@,_</string>
     <!-- Symbols that are normally preceded by a space (used to add an auto-space before these) -->
@@ -29,6 +31,8 @@
     <string name="symbols_word_separators">"&#x0009;&#x0020;\n"()[]{}*&amp;&lt;&gt;+=|.,;:!?/_\"</string>
     <!-- Word connectors -->
     <string name="symbols_word_connectors">\'-</string>
+    <!-- Whether this language uses spaces -->
+    <bool name="current_language_has_spaces">true</bool>
 
     <!--  Always show the suggestion strip -->
     <string name="prefs_suggestion_visibility_show_value">0</string>
diff --git a/java/src/com/android/inputmethod/accessibility/AccessibilityEntityProvider.java b/java/src/com/android/inputmethod/accessibility/AccessibilityEntityProvider.java
index 77f3234..8ce1263 100644
--- a/java/src/com/android/inputmethod/accessibility/AccessibilityEntityProvider.java
+++ b/java/src/com/android/inputmethod/accessibility/AccessibilityEntityProvider.java
@@ -172,7 +172,7 @@
             return null;
         }
         final String keyDescription = getKeyDescription(key);
-        final Rect boundsInParent = key.mHitBox;
+        final Rect boundsInParent = key.getHitBox();
 
         // Calculate the key's in-screen bounds.
         mTempBoundsInScreen.set(boundsInParent);
@@ -208,8 +208,8 @@
      * @param key The key to press.
      */
     void simulateKeyPress(final Key key) {
-        final int x = key.mHitBox.centerX();
-        final int y = key.mHitBox.centerY();
+        final int x = key.getHitBox().centerX();
+        final int y = key.getHitBox().centerY();
         final long downTime = SystemClock.uptimeMillis();
         final MotionEvent downEvent = MotionEvent.obtain(
                 downTime, downTime, MotionEvent.ACTION_DOWN, x, y, 0);
@@ -325,6 +325,6 @@
         // The key x- and y-coordinates are stable between layout changes.
         // Generate an identifier by bit-shifting the x-coordinate to the
         // left-half of the integer and OR'ing with the y-coordinate.
-        return ((0xFFFF & key.mX) << (Integer.SIZE / 2)) | (0xFFFF & key.mY);
+        return ((0xFFFF & key.getX()) << (Integer.SIZE / 2)) | (0xFFFF & key.getY());
     }
 }
diff --git a/java/src/com/android/inputmethod/accessibility/KeyCodeDescriptionMapper.java b/java/src/com/android/inputmethod/accessibility/KeyCodeDescriptionMapper.java
index 41f5b9a..58624a2 100644
--- a/java/src/com/android/inputmethod/accessibility/KeyCodeDescriptionMapper.java
+++ b/java/src/com/android/inputmethod/accessibility/KeyCodeDescriptionMapper.java
@@ -97,7 +97,7 @@
      */
     public String getDescriptionForKey(final Context context, final Keyboard keyboard,
             final Key key, final boolean shouldObscure) {
-        final int code = key.mCode;
+        final int code = key.getCode();
 
         if (code == Constants.CODE_SWITCH_ALPHA_SYMBOL) {
             final String description = getDescriptionForSwitchAlphaSymbol(context, keyboard);
@@ -116,8 +116,8 @@
             return getDescriptionForActionKey(context, keyboard, key);
         }
 
-        if (!TextUtils.isEmpty(key.mLabel)) {
-            final String label = key.mLabel.toString().trim();
+        if (!TextUtils.isEmpty(key.getLabel())) {
+            final String label = key.getLabel().trim();
 
             // First, attempt to map the label to a pre-defined description.
             if (mKeyLabelMap.containsKey(label)) {
@@ -126,7 +126,7 @@
         }
 
         // Just attempt to speak the description.
-        if (key.mCode != Constants.CODE_UNSPECIFIED) {
+        if (key.getCode() != Constants.CODE_UNSPECIFIED) {
             return getDescriptionForKeyCode(context, keyboard, key, shouldObscure);
         }
         return null;
@@ -215,8 +215,8 @@
         final int resId;
 
         // Always use the label, if available.
-        if (!TextUtils.isEmpty(key.mLabel)) {
-            return key.mLabel.toString().trim();
+        if (!TextUtils.isEmpty(key.getLabel())) {
+            return key.getLabel().trim();
         }
 
         // Otherwise, use the action ID.
@@ -267,7 +267,7 @@
      */
     private String getDescriptionForKeyCode(final Context context, final Keyboard keyboard,
             final Key key, final boolean shouldObscure) {
-        final int code = key.mCode;
+        final int code = key.getCode();
 
         // If the key description should be obscured, now is the time to do it.
         final boolean isDefinedNonCtrl = Character.isDefined(code) && !Character.isISOControl(code);
@@ -280,8 +280,8 @@
         if (isDefinedNonCtrl) {
             return Character.toString((char) code);
         }
-        if (!TextUtils.isEmpty(key.mLabel)) {
-            return key.mLabel;
+        if (!TextUtils.isEmpty(key.getLabel())) {
+            return key.getLabel();
         }
         return context.getString(R.string.spoken_description_unknown, code);
     }
diff --git a/java/src/com/android/inputmethod/keyboard/Key.java b/java/src/com/android/inputmethod/keyboard/Key.java
index 16c79eb..143c6e8 100644
--- a/java/src/com/android/inputmethod/keyboard/Key.java
+++ b/java/src/com/android/inputmethod/keyboard/Key.java
@@ -58,12 +58,12 @@
     /**
      * The key code (unicode or custom code) that this key generates.
      */
-    public final int mCode;
+    private final int mCode;
 
     /** Label to display */
-    public final String mLabel;
+    private final String mLabel;
     /** Hint label to display on the key in conjunction with the label */
-    public final String mHintLabel;
+    private final String mHintLabel;
     /** Flags of the label */
     private final int mLabelFlags;
     private static final int LABEL_FLAGS_ALIGN_LEFT = 0x01;
@@ -95,18 +95,18 @@
     private final int mIconId;
 
     /** Width of the key, not including the gap */
-    public final int mWidth;
+    private final int mWidth;
     /** Height of the key, not including the gap */
-    public final int mHeight;
+    private final int mHeight;
     /** X coordinate of the key in the keyboard layout */
-    public final int mX;
+    private final int mX;
     /** Y coordinate of the key in the keyboard layout */
-    public final int mY;
+    private final int mY;
     /** Hit bounding box of the key */
-    public final Rect mHitBox = new Rect();
+    private final Rect mHitBox = new Rect();
 
     /** More keys. It is guaranteed that this is null or an array of one or more elements */
-    public final MoreKeySpec[] mMoreKeys;
+    private final MoreKeySpec[] mMoreKeys;
     /** More keys column number and flags */
     private final int mMoreKeysColumnAndFlags;
     private static final int MORE_KEYS_COLUMN_MASK = 0x000000ff;
@@ -121,7 +121,7 @@
     private static final String MORE_KEYS_NO_PANEL_AUTO_MORE_KEY = "!noPanelAutoMoreKey!";
 
     /** Background type that represents different key background visual than normal one. */
-    public final int mBackgroundType;
+    private final int mBackgroundType;
     public static final int BACKGROUND_TYPE_EMPTY = 0;
     public static final int BACKGROUND_TYPE_NORMAL = 1;
     public static final int BACKGROUND_TYPE_FUNCTIONAL = 2;
@@ -135,7 +135,7 @@
     private static final int ACTION_FLAGS_ALT_CODE_WHILE_TYPING = 0x04;
     private static final int ACTION_FLAGS_ENABLE_LONG_PRESS = 0x08;
 
-    public final KeyVisualAttributes mKeyVisualAttributes;
+    private final KeyVisualAttributes mKeyVisualAttributes;
 
     private final OptionalAttributes mOptionalAttributes;
 
@@ -151,7 +151,7 @@
         public final int mVisualInsetsLeft;
         public final int mVisualInsetsRight;
 
-        public OptionalAttributes(final String outputText, final int altCode,
+        private OptionalAttributes(final String outputText, final int altCode,
                 final int disabledIconId, final int previewIconId,
                 final int visualInsetsLeft, final int visualInsetsRight) {
             mOutputText = outputText;
@@ -161,6 +161,18 @@
             mVisualInsetsLeft = visualInsetsLeft;
             mVisualInsetsRight = visualInsetsRight;
         }
+
+        public static OptionalAttributes newInstance(final String outputText, final int altCode,
+                final int disabledIconId, final int previewIconId,
+                final int visualInsetsLeft, final int visualInsetsRight) {
+            if (outputText == null && altCode == CODE_UNSPECIFIED
+                    && disabledIconId == ICON_UNDEFINED && previewIconId == ICON_UNDEFINED
+                    && visualInsetsLeft == 0 && visualInsetsRight == 0) {
+                return null;
+            }
+            return new OptionalAttributes(outputText, altCode, disabledIconId, previewIconId,
+                    visualInsetsLeft, visualInsetsRight);
+        }
     }
 
     private final int mHashCode;
@@ -194,12 +206,9 @@
         mMoreKeys = null;
         mMoreKeysColumnAndFlags = 0;
         mLabel = label;
-        if (outputText == null) {
-            mOptionalAttributes = null;
-        } else {
-            mOptionalAttributes = new OptionalAttributes(outputText, CODE_UNSPECIFIED,
-                    ICON_UNDEFINED, ICON_UNDEFINED, 0, 0);
-        }
+        mOptionalAttributes = OptionalAttributes.newInstance(outputText, CODE_UNSPECIFIED,
+                ICON_UNDEFINED, ICON_UNDEFINED,
+                0 /* visualInsetsLeft */, 0 /* visualInsetsRight */);
         mCode = code;
         mEnabled = (code != CODE_UNSPECIFIED);
         mIconId = iconId;
@@ -225,7 +234,7 @@
     public Key(final Resources res, final KeyboardParams params, final KeyboardRow row,
             final XmlPullParser parser) throws XmlPullParserException {
         final float horizontalGap = isSpacer() ? 0 : params.mHorizontalGap;
-        final int rowHeight = row.mRowHeight;
+        final int rowHeight = row.getRowHeight();
         mHeight = rowHeight - params.mVerticalGap;
 
         final TypedArray keyAttr = res.obtainAttributes(Xml.asAttributeSet(parser),
@@ -260,11 +269,11 @@
         final int previewIconId = KeySpecParser.getIconId(style.getString(keyAttr,
                 R.styleable.Keyboard_Key_keyIconPreview));
 
-        mLabelFlags = style.getFlag(keyAttr, R.styleable.Keyboard_Key_keyLabelFlags)
+        mLabelFlags = style.getFlags(keyAttr, R.styleable.Keyboard_Key_keyLabelFlags)
                 | row.getDefaultKeyLabelFlags();
         final boolean needsToUpperCase = needsToUpperCase(mLabelFlags, params.mId.mElementId);
         final Locale locale = params.mId.mLocale;
-        int actionFlags = style.getFlag(keyAttr, R.styleable.Keyboard_Key_keyActionFlags);
+        int actionFlags = style.getFlags(keyAttr, R.styleable.Keyboard_Key_keyActionFlags);
         String[] moreKeys = style.getStringArray(keyAttr, R.styleable.Keyboard_Key_moreKeys);
 
         int moreKeysColumn = style.getInt(keyAttr,
@@ -360,15 +369,8 @@
                 KeySpecParser.parseCode(style.getString(keyAttr,
                 R.styleable.Keyboard_Key_altCode), params.mCodesSet, CODE_UNSPECIFIED),
                 needsToUpperCase, locale);
-        if (outputText == null && altCode == CODE_UNSPECIFIED
-                && disabledIconId == ICON_UNDEFINED && previewIconId == ICON_UNDEFINED
-                && visualInsetsLeft == 0 && visualInsetsRight == 0) {
-            mOptionalAttributes = null;
-        } else {
-            mOptionalAttributes = new OptionalAttributes(outputText, altCode,
-                    disabledIconId, previewIconId,
-                    visualInsetsLeft, visualInsetsRight);
-        }
+        mOptionalAttributes = OptionalAttributes.newInstance(outputText, altCode,
+                disabledIconId, previewIconId, visualInsetsLeft, visualInsetsRight);
         mKeyVisualAttributes = KeyVisualAttributes.newInstance(keyAttr);
         keyAttr.recycle();
         mHashCode = computeHashCode(this);
@@ -377,6 +379,35 @@
         }
     }
 
+    /**
+     * Copy constructor.
+     *
+     * @param key the original key.
+     */
+    protected Key(final Key key) {
+        // Final attributes.
+        mCode = key.mCode;
+        mLabel = key.mLabel;
+        mHintLabel = key.mHintLabel;
+        mLabelFlags = key.mLabelFlags;
+        mIconId = key.mIconId;
+        mWidth = key.mWidth;
+        mHeight = key.mHeight;
+        mX = key.mX;
+        mY = key.mY;
+        mHitBox.set(key.mHitBox);
+        mMoreKeys = key.mMoreKeys;
+        mMoreKeysColumnAndFlags = key.mMoreKeysColumnAndFlags;
+        mBackgroundType = key.mBackgroundType;
+        mActionFlags = key.mActionFlags;
+        mKeyVisualAttributes = key.mKeyVisualAttributes;
+        mOptionalAttributes = key.mOptionalAttributes;
+        mHashCode = key.mHashCode;
+        // Key state.
+        mPressed = key.mPressed;
+        mEnabled = key.mEnabled;
+    }
+
     private static boolean needsToUpperCase(final int labelFlags, final int keyboardElementId) {
         if ((labelFlags & LABEL_FLAGS_PRESERVE_CASE) != 0) return false;
         switch (keyboardElementId) {
@@ -476,6 +507,22 @@
         }
     }
 
+    public int getCode() {
+        return mCode;
+    }
+
+    public String getLabel() {
+        return mLabel;
+    }
+
+    public String getHintLabel() {
+        return mHintLabel;
+    }
+
+    public MoreKeySpec[] getMoreKeys() {
+        return mMoreKeys;
+    }
+
     public void markAsLeftEdge(final KeyboardParams params) {
         mHitBox.left = params.mLeftPadding;
     }
@@ -522,6 +569,10 @@
                 && (mLabelFlags & LABEL_FLAGS_SHIFTED_LETTER_ACTIVATED) == 0;
     }
 
+    public KeyVisualAttributes getVisualAttributes() {
+        return mKeyVisualAttributes;
+    }
+
     public final Typeface selectTypeface(final KeyDrawParams params) {
         // TODO: Handle "bold" here too?
         if ((mLabelFlags & LABEL_FLAGS_FONT_NORMAL) != 0) {
@@ -696,6 +747,22 @@
                 ? iconSet.getIconDrawable(previewIconId) : iconSet.getIconDrawable(mIconId);
     }
 
+    public int getWidth() {
+        return mWidth;
+    }
+
+    public int getHeight() {
+        return mHeight;
+    }
+
+    public int getX() {
+        return mX;
+    }
+
+    public int getY() {
+        return mY;
+    }
+
     public final int getDrawX() {
         final OptionalAttributes attrs = mOptionalAttributes;
         return (attrs == null) ? mX : mX + attrs.mVisualInsetsLeft;
@@ -733,6 +800,10 @@
         mEnabled = enabled;
     }
 
+    public Rect getHitBox() {
+        return mHitBox;
+    }
+
     /**
      * Detects if a point falls on this key.
      * @param x the x-coordinate of the point
diff --git a/java/src/com/android/inputmethod/keyboard/KeyDetector.java b/java/src/com/android/inputmethod/keyboard/KeyDetector.java
index 17e707f..befb6fa 100644
--- a/java/src/com/android/inputmethod/keyboard/KeyDetector.java
+++ b/java/src/com/android/inputmethod/keyboard/KeyDetector.java
@@ -108,8 +108,9 @@
             if (distance > minDistance) {
                 continue;
             }
-            // To take care of hitbox overlaps, we compare mCode here too.
-            if (primaryKey == null || distance < minDistance || key.mCode > primaryKey.mCode) {
+            // To take care of hitbox overlaps, we compare key's code here too.
+            if (primaryKey == null || distance < minDistance
+                    || key.getCode() > primaryKey.getCode()) {
                 minDistance = distance;
                 primaryKey = key;
             }
@@ -118,7 +119,7 @@
     }
 
     public static String printableCode(Key key) {
-        return key != null ? Constants.printableCode(key.mCode) : "none";
+        return key != null ? Constants.printableCode(key.getCode()) : "none";
     }
 
     public static String printableCodes(int[] codes) {
diff --git a/java/src/com/android/inputmethod/keyboard/Keyboard.java b/java/src/com/android/inputmethod/keyboard/Keyboard.java
index fefac96..c40ddea 100644
--- a/java/src/com/android/inputmethod/keyboard/Keyboard.java
+++ b/java/src/com/android/inputmethod/keyboard/Keyboard.java
@@ -131,7 +131,7 @@
             }
 
             for (final Key key : mKeys) {
-                if (key.mCode == code) {
+                if (key.getCode() == code) {
                     mKeyCache.put(code, key);
                     return key;
                 }
@@ -148,7 +148,7 @@
 
         for (final Key key : mKeys) {
             if (key == aKey) {
-                mKeyCache.put(key.mCode, key);
+                mKeyCache.put(key.getCode(), key);
                 return true;
             }
         }
diff --git a/java/src/com/android/inputmethod/keyboard/KeyboardLayoutSet.java b/java/src/com/android/inputmethod/keyboard/KeyboardLayoutSet.java
index bccf8fb..711de63 100644
--- a/java/src/com/android/inputmethod/keyboard/KeyboardLayoutSet.java
+++ b/java/src/com/android/inputmethod/keyboard/KeyboardLayoutSet.java
@@ -162,7 +162,8 @@
         final KeyboardId id = new KeyboardId(keyboardLayoutSetElementId, mParams);
         try {
             return getKeyboard(elementParams, id);
-        } catch (RuntimeException e) {
+        } catch (final RuntimeException e) {
+            Log.e(TAG, "Can't create keyboard: " + id, e);
             throw new KeyboardLayoutSetException(e, id);
         }
     }
diff --git a/java/src/com/android/inputmethod/keyboard/KeyboardView.java b/java/src/com/android/inputmethod/keyboard/KeyboardView.java
index 28eb585..d049a86 100644
--- a/java/src/com/android/inputmethod/keyboard/KeyboardView.java
+++ b/java/src/com/android/inputmethod/keyboard/KeyboardView.java
@@ -265,9 +265,9 @@
             mClipRegion.setEmpty();
             for (final Key key : mInvalidatedKeys) {
                 if (mKeyboard.hasKey(key)) {
-                    final int x = key.mX + getPaddingLeft();
-                    final int y = key.mY + getPaddingTop();
-                    mWorkingRect.set(x, y, x + key.mWidth, y + key.mHeight);
+                    final int x = key.getX() + getPaddingLeft();
+                    final int y = key.getY() + getPaddingTop();
+                    mWorkingRect.set(x, y, x + key.getWidth(), y + key.getHeight());
                     mClipRegion.union(mWorkingRect);
                 }
             }
@@ -310,11 +310,11 @@
 
     private void onDrawKey(final Key key, final Canvas canvas, final Paint paint) {
         final int keyDrawX = key.getDrawX() + getPaddingLeft();
-        final int keyDrawY = key.mY + getPaddingTop();
+        final int keyDrawY = key.getY() + getPaddingTop();
         canvas.translate(keyDrawX, keyDrawY);
 
         final int keyHeight = mKeyboard.mMostCommonKeyHeight - mKeyboard.mVerticalGap;
-        final KeyVisualAttributes attr = key.mKeyVisualAttributes;
+        final KeyVisualAttributes attr = key.getVisualAttributes();
         final KeyDrawParams params = mKeyDrawParams.mayCloneAndUpdateParams(keyHeight, attr);
         params.mAnimAlpha = Constants.Color.ALPHA_OPAQUE;
 
@@ -330,7 +330,7 @@
     protected void onDrawKeyBackground(final Key key, final Canvas canvas) {
         final Rect padding = mKeyBackgroundPadding;
         final int bgWidth = key.getDrawWidth() + padding.left + padding.right;
-        final int bgHeight = key.mHeight + padding.top + padding.bottom;
+        final int bgHeight = key.getHeight() + padding.top + padding.bottom;
         final int bgX = -padding.left;
         final int bgY = -padding.top;
         final int[] drawableState = key.getCurrentDrawableState();
@@ -352,7 +352,7 @@
     protected void onDrawKeyTopVisuals(final Key key, final Canvas canvas, final Paint paint,
             final KeyDrawParams params) {
         final int keyWidth = key.getDrawWidth();
-        final int keyHeight = key.mHeight;
+        final int keyHeight = key.getHeight();
         final float centerX = keyWidth * 0.5f;
         final float centerY = keyHeight * 0.5f;
 
@@ -363,8 +363,8 @@
         // Draw key label.
         final Drawable icon = key.getIcon(mKeyboard.mIconsSet, params.mAnimAlpha);
         float positionX = centerX;
-        if (key.mLabel != null) {
-            final String label = key.mLabel;
+        final String label = key.getLabel();
+        if (label != null) {
             paint.setTypeface(key.selectTypeface(params));
             paint.setTextSize(key.selectTextSize(params));
             final float labelCharHeight = TypefaceUtils.getCharHeight(
@@ -441,8 +441,8 @@
         }
 
         // Draw hint label.
-        if (key.mHintLabel != null) {
-            final String hintLabel = key.mHintLabel;
+        final String hintLabel = key.getHintLabel();
+        if (hintLabel != null) {
             paint.setTextSize(key.selectHintTextSize(params));
             paint.setColor(key.selectHintTextColor(params));
             blendAlpha(paint, params.mAnimAlpha);
@@ -481,7 +481,7 @@
         }
 
         // Draw key icon.
-        if (key.mLabel == null && icon != null) {
+        if (label == null && icon != null) {
             final int iconWidth = Math.min(icon.getIntrinsicWidth(), keyWidth);
             final int iconHeight = icon.getIntrinsicHeight();
             final int iconX, alignX;
@@ -505,7 +505,7 @@
             }
         }
 
-        if (key.hasPopupHint() && key.mMoreKeys != null) {
+        if (key.hasPopupHint() && key.getMoreKeys() != null) {
             drawKeyPopupHint(key, canvas, paint, params);
         }
     }
@@ -514,7 +514,7 @@
     protected void drawKeyPopupHint(final Key key, final Canvas canvas, final Paint paint,
             final KeyDrawParams params) {
         final int keyWidth = key.getDrawWidth();
-        final int keyHeight = key.mHeight;
+        final int keyHeight = key.getHeight();
 
         paint.setTypeface(params.mTypeface);
         paint.setTextSize(params.mHintLetterSize);
@@ -602,9 +602,9 @@
         if (mInvalidateAllKeys) return;
         if (key == null) return;
         mInvalidatedKeys.add(key);
-        final int x = key.mX + getPaddingLeft();
-        final int y = key.mY + getPaddingTop();
-        invalidate(x, y, x + key.mWidth, y + key.mHeight);
+        final int x = key.getX() + getPaddingLeft();
+        final int y = key.getY() + getPaddingTop();
+        invalidate(x, y, x + key.getWidth(), y + key.getHeight());
     }
 
     @Override
diff --git a/java/src/com/android/inputmethod/keyboard/MainKeyboardView.java b/java/src/com/android/inputmethod/keyboard/MainKeyboardView.java
index f3d0ead..e4a8f4c 100644
--- a/java/src/com/android/inputmethod/keyboard/MainKeyboardView.java
+++ b/java/src/com/android/inputmethod/keyboard/MainKeyboardView.java
@@ -237,7 +237,7 @@
                 return;
             }
             sendMessageDelayed(
-                    obtainMessage(MSG_REPEAT_KEY, key.mCode, repeatCount, tracker), delay);
+                    obtainMessage(MSG_REPEAT_KEY, key.getCode(), repeatCount, tracker), delay);
         }
 
         public void cancelKeyRepeatTimer() {
@@ -298,7 +298,7 @@
             final MainKeyboardView keyboardView = getOuterInstance();
 
             // When user hits the space or the enter key, just cancel the while-typing timer.
-            final int typedCode = typedKey.mCode;
+            final int typedCode = typedKey.getCode();
             if (typedCode == Constants.CODE_SPACE || typedCode == Constants.CODE_ENTER) {
                 if (isTyping) {
                     startWhileTypingFadeinAnimation(keyboardView);
@@ -638,7 +638,6 @@
         mKeyPreviewLingerTimeout = delay;
     }
 
-
     private void locatePreviewPlacerView() {
         if (mPreviewPlacerView.getParent() != null) {
             return;
@@ -807,11 +806,11 @@
         }
         // The key preview is placed vertically above the top edge of the parent key with an
         // arbitrary offset.
-        final int previewY = key.mY - previewHeight + mKeyPreviewOffset
+        final int previewY = key.getY() - previewHeight + mKeyPreviewOffset
                 + CoordinateUtils.y(mOriginCoords);
 
         if (background != null) {
-            final int hasMoreKeys = (key.mMoreKeys != null) ? STATE_HAS_MOREKEYS : STATE_NORMAL;
+            final int hasMoreKeys = (key.getMoreKeys() != null) ? STATE_HAS_MOREKEYS : STATE_NORMAL;
             background.setState(KEY_PREVIEW_BACKGROUND_STATE_TABLE[statePosition][hasMoreKeys]);
             background.setAlpha(PREVIEW_ALPHA);
         }
@@ -903,7 +902,7 @@
     }
 
     private MoreKeysPanel onCreateMoreKeysPanel(final Key key, final Context context) {
-        if (key.mMoreKeys == null) {
+        if (key.getMoreKeys() == null) {
             return null;
         }
         Keyboard moreKeysKeyboard = mMoreKeysKeyboardCache.get(key);
@@ -938,7 +937,7 @@
         }
         final KeyboardActionListener listener = mKeyboardActionListener;
         if (key.hasNoPanelAutoMoreKey()) {
-            final int moreKeyCode = key.mMoreKeys[0].mCode;
+            final int moreKeyCode = key.getMoreKeys()[0].mCode;
             tracker.onLongPressed();
             listener.onPressKey(moreKeyCode, 0 /* repeatCount */, true /* isSinglePointer */);
             listener.onCodeInput(moreKeyCode,
@@ -946,7 +945,7 @@
             listener.onReleaseKey(moreKeyCode, false /* withSliding */);
             return;
         }
-        final int code = key.mCode;
+        final int code = key.getCode();
         if (code == Constants.CODE_SPACE || code == Constants.CODE_LANGUAGE_SWITCH) {
             // Long pressing the space key invokes IME switcher dialog.
             if (listener.onCustomRequest(Constants.CUSTOM_CODE_SHOW_INPUT_METHOD_PICKER)) {
@@ -972,13 +971,13 @@
         // keys keyboard is placed at the touch point of the parent key.
         final int pointX = (mConfigShowMoreKeysKeyboardAtTouchedPoint && !keyPreviewEnabled)
                 ? CoordinateUtils.x(lastCoords)
-                : key.mX + key.mWidth / 2;
+                : key.getX() + key.getWidth() / 2;
         // The more keys keyboard is usually vertically aligned with the top edge of the parent key
         // (plus vertical gap). If the key preview is enabled, the more keys keyboard is vertically
         // aligned with the bottom edge of the visible part of the key preview.
         // {@code mPreviewVisibleOffset} has been set appropriately in
         // {@link KeyboardView#showKeyPreview(PointerTracker)}.
-        final int pointY = key.mY + mKeyPreviewDrawParams.mPreviewVisibleOffset;
+        final int pointY = key.getY() + mKeyPreviewDrawParams.mPreviewVisibleOffset;
         moreKeysPanel.showMoreKeysPanel(this, this, pointX, pointY, mKeyboardActionListener);
         tracker.onShowMoreKeysPanel(moreKeysPanel);
     }
@@ -1174,13 +1173,14 @@
         if (key.altCodeWhileTyping() && key.isEnabled()) {
             params.mAnimAlpha = mAltCodeKeyWhileTypingAnimAlpha;
         }
-        if (key.mCode == Constants.CODE_SPACE) {
+        final int code = key.getCode();
+        if (code == Constants.CODE_SPACE) {
             drawSpacebar(key, canvas, paint);
             // Whether space key needs to show the "..." popup hint for special purposes
             if (key.isLongPressEnabled() && mHasMultipleEnabledIMEsOrSubtypes) {
                 drawKeyPopupHint(key, canvas, paint, params);
             }
-        } else if (key.mCode == Constants.CODE_LANGUAGE_SWITCH) {
+        } else if (code == Constants.CODE_LANGUAGE_SWITCH) {
             super.onDrawKeyTopVisuals(key, canvas, paint, params);
             drawKeyPopupHint(key, canvas, paint, params);
         } else {
@@ -1228,8 +1228,8 @@
     }
 
     private void drawSpacebar(final Key key, final Canvas canvas, final Paint paint) {
-        final int width = key.mWidth;
-        final int height = key.mHeight;
+        final int width = key.getWidth();
+        final int height = key.getHeight();
 
         // If input language are explicitly selected.
         if (mNeedsToDisplayLanguage) {
diff --git a/java/src/com/android/inputmethod/keyboard/MoreKeysKeyboard.java b/java/src/com/android/inputmethod/keyboard/MoreKeysKeyboard.java
index 3fd29dc..8256d46 100644
--- a/java/src/com/android/inputmethod/keyboard/MoreKeysKeyboard.java
+++ b/java/src/com/android/inputmethod/keyboard/MoreKeysKeyboard.java
@@ -276,6 +276,7 @@
             mParams.mVerticalGap = parentKeyboard.mVerticalGap / 2;
             mParentKey = parentKey;
 
+            final MoreKeySpec[] moreKeys = parentKey.getMoreKeys();
             final int width, height;
             // {@link KeyPreviewDrawParams#mPreviewVisibleWidth} should have been set at
             // {@link MainKeyboardView#showKeyPreview(PointerTracker}, though there may be
@@ -283,7 +284,7 @@
             // zero-division error at
             // {@link MoreKeysKeyboardParams#setParameters(int,int,int,int,int,int,boolean,int)}.
             final boolean singleMoreKeyWithPreview = parentKeyboardView.isKeyPreviewPopupEnabled()
-                    && !parentKey.noKeyPreview() && parentKey.mMoreKeys.length == 1
+                    && !parentKey.noKeyPreview() && moreKeys.length == 1
                     && keyPreviewDrawParams.mPreviewVisibleWidth > 0;
             if (singleMoreKeyWithPreview) {
                 // Use pre-computed width and height if this more keys keyboard has only one key to
@@ -312,8 +313,8 @@
                 mDivider = null;
                 dividerWidth = 0;
             }
-            mParams.setParameters(parentKey.mMoreKeys.length, parentKey.getMoreKeysColumn(),
-                    width, height, parentKey.mX + parentKey.mWidth / 2,
+            mParams.setParameters(moreKeys.length, parentKey.getMoreKeysColumn(),
+                    width, height, parentKey.getX() + parentKey.getWidth() / 2,
                     parentKeyboard.mId.mWidth, parentKey.isFixedColumnOrderMoreKeys(),
                     dividerWidth);
         }
@@ -321,7 +322,7 @@
         private static int getMaxKeyWidth(final Key parentKey, final int minKeyWidth,
                 final float padding, final Paint paint) {
             int maxWidth = minKeyWidth;
-            for (final MoreKeySpec spec : parentKey.mMoreKeys) {
+            for (final MoreKeySpec spec : parentKey.getMoreKeys()) {
                 final String label = spec.mLabel;
                 // If the label is single letter, minKeyWidth is enough to hold the label.
                 if (label != null && StringUtils.codePointCount(label) > 1) {
@@ -336,7 +337,7 @@
         public MoreKeysKeyboard build() {
             final MoreKeysKeyboardParams params = mParams;
             final int moreKeyFlags = mParentKey.getMoreKeyLabelFlags();
-            final MoreKeySpec[] moreKeys = mParentKey.mMoreKeys;
+            final MoreKeySpec[] moreKeys = mParentKey.getMoreKeys();
             for (int n = 0; n < moreKeys.length; n++) {
                 final MoreKeySpec moreKeySpec = moreKeys[n];
                 final int row = n / params.mNumColumns;
diff --git a/java/src/com/android/inputmethod/keyboard/MoreKeysKeyboardView.java b/java/src/com/android/inputmethod/keyboard/MoreKeysKeyboardView.java
index f00f5a9..973128d 100644
--- a/java/src/com/android/inputmethod/keyboard/MoreKeysKeyboardView.java
+++ b/java/src/com/android/inputmethod/keyboard/MoreKeysKeyboardView.java
@@ -127,7 +127,7 @@
     public void onUpEvent(final int x, final int y, final int pointerId, final long eventTime) {
         if (mCurrentKey != null && mActivePointerId == pointerId) {
             updateReleaseKeyGraphics(mCurrentKey);
-            onCodeInput(mCurrentKey.mCode, x, y);
+            onCodeInput(mCurrentKey.getCode(), x, y);
             mCurrentKey = null;
         }
     }
diff --git a/java/src/com/android/inputmethod/keyboard/PointerTracker.java b/java/src/com/android/inputmethod/keyboard/PointerTracker.java
index 5387ddb..d4d0d87 100644
--- a/java/src/com/android/inputmethod/keyboard/PointerTracker.java
+++ b/java/src/com/android/inputmethod/keyboard/PointerTracker.java
@@ -510,7 +510,7 @@
             return false;
         }
         if (key.isEnabled()) {
-            mListener.onPressKey(key.mCode, repeatCount, getActivePointerTrackerCount() == 1);
+            mListener.onPressKey(key.getCode(), repeatCount, getActivePointerTrackerCount() == 1);
             final boolean keyboardLayoutHasBeenChanged = mKeyboardLayoutHasBeenChanged;
             mKeyboardLayoutHasBeenChanged = false;
             mTimerProxy.startTypingStateTimer(key);
@@ -776,7 +776,7 @@
         if (sInGesture || !mGestureStrokeWithPreviewPoints.isStartOfAGesture()) {
             return;
         }
-        if (key == null || !Character.isLetter(key.mCode)) {
+        if (key == null || !Character.isLetter(key.getCode())) {
             return;
         }
         if (DEBUG_LISTENER) {
@@ -1075,8 +1075,8 @@
                     + " phantom sudden move event (distance=%d) is translated to "
                     + "up[%d,%d,%s]/down[%d,%d,%s] events", mPointerId,
                     getDistance(x, y, lastX, lastY),
-                    lastX, lastY, Constants.printableCode(oldKey.mCode),
-                    x, y, Constants.printableCode(key.mCode)));
+                    lastX, lastY, Constants.printableCode(oldKey.getCode()),
+                    x, y, Constants.printableCode(key.getCode())));
         }
         // TODO: This should be moved to outside of this nested if-clause?
         if (ProductionFlag.USES_DEVELOPMENT_ONLY_DIAGNOSTICS) {
@@ -1098,8 +1098,8 @@
                     + " bogus down-move-up event (raidus=%.2f key diagonal) is "
                     + " translated to up[%d,%d,%s]/down[%d,%d,%s] events",
                     mPointerId, radiusRatio,
-                    lastX, lastY, Constants.printableCode(oldKey.mCode),
-                    x, y, Constants.printableCode(key.mCode)));
+                    lastX, lastY, Constants.printableCode(oldKey.getCode()),
+                    x, y, Constants.printableCode(key.getCode())));
         }
         onUpEventInternal(x, y, eventTime);
         onDownEventInternal(x, y, eventTime);
@@ -1107,7 +1107,7 @@
 
     private void processSildeOutFromOldKey(final Key oldKey) {
         setReleasedKeyGraphics(oldKey);
-        callListenerOnRelease(oldKey, oldKey.mCode, true /* withSliding */);
+        callListenerOnRelease(oldKey, oldKey.getCode(), true /* withSliding */);
         startSlidingKeyInput(oldKey);
         mTimerProxy.cancelKeyTimers();
     }
@@ -1263,7 +1263,7 @@
 
         if (sInGesture) {
             if (currentKey != null) {
-                callListenerOnRelease(currentKey, currentKey.mCode, true /* withSliding */);
+                callListenerOnRelease(currentKey, currentKey.getCode(), true /* withSliding */);
             }
             mayEndBatchInput(eventTime);
             return;
@@ -1376,9 +1376,9 @@
         // doesn't have its more keys. (e.g. spacebar, globe key)
         // We always need to start the long press timer if the key has its more keys regardless of
         // whether or not we are in the sliding input mode.
-        if (mIsInSlidingKeyInput && key.mMoreKeys == null) return;
+        if (mIsInSlidingKeyInput && key.getMoreKeys() == null) return;
         final int delay;
-        switch (key.mCode) {
+        switch (key.getCode()) {
         case Constants.CODE_SHIFT:
             delay = sParams.mLongPressShiftLockTimeout;
             break;
@@ -1401,7 +1401,7 @@
             return;
         }
 
-        final int code = key.mCode;
+        final int code = key.getCode();
         callListenerOnCodeInput(key, code, x, y, eventTime);
         callListenerOnRelease(key, code, false /* withSliding */);
     }
@@ -1412,14 +1412,14 @@
         if (!key.isRepeatable()) return;
         // Don't start key repeat when we are in sliding input mode.
         if (mIsInSlidingKeyInput) return;
-        detectAndSendKey(key, key.mX, key.mY, SystemClock.uptimeMillis());
+        detectAndSendKey(key, key.getX(), key.getY(), SystemClock.uptimeMillis());
         final int startRepeatCount = 1;
         mTimerProxy.startKeyRepeatTimer(this, startRepeatCount, sParams.mKeyRepeatStartTimeout);
     }
 
     public void onKeyRepeat(final int code, final int repeatCount) {
         final Key key = getKey();
-        if (key == null || key.mCode != code) {
+        if (key == null || key.getCode() != code) {
             return;
         }
         final int nextRepeatCount = repeatCount + 1;
diff --git a/java/src/com/android/inputmethod/keyboard/ProximityInfo.java b/java/src/com/android/inputmethod/keyboard/ProximityInfo.java
index 9b0a33c..c0c02f1 100644
--- a/java/src/com/android/inputmethod/keyboard/ProximityInfo.java
+++ b/java/src/com/android/inputmethod/keyboard/ProximityInfo.java
@@ -96,7 +96,7 @@
 
     private static boolean needsProximityInfo(final Key key) {
         // Don't include special keys into ProximityInfo.
-        return key.mCode >= Constants.CODE_SPACE;
+        return key.getCode() >= Constants.CODE_SPACE;
     }
 
     private static int getProximityInfoKeysCount(final Key[] keys) {
@@ -122,7 +122,7 @@
                 if (!needsProximityInfo(neighborKey)) {
                     continue;
                 }
-                proximityCharsArray[infoIndex] = neighborKey.mCode;
+                proximityCharsArray[infoIndex] = neighborKey.getCode();
                 infoIndex++;
             }
         }
@@ -159,11 +159,11 @@
             if (!needsProximityInfo(key)) {
                 continue;
             }
-            keyXCoordinates[infoIndex] = key.mX;
-            keyYCoordinates[infoIndex] = key.mY;
-            keyWidths[infoIndex] = key.mWidth;
-            keyHeights[infoIndex] = key.mHeight;
-            keyCharCodes[infoIndex] = key.mCode;
+            keyXCoordinates[infoIndex] = key.getX();
+            keyYCoordinates[infoIndex] = key.getY();
+            keyWidths[infoIndex] = key.getWidth();
+            keyHeights[infoIndex] = key.getHeight();
+            keyCharCodes[infoIndex] = key.getCode();
             infoIndex++;
         }
 
@@ -183,7 +183,7 @@
                 if (!needsProximityInfo(key)) {
                     continue;
                 }
-                final Rect hitBox = key.mHitBox;
+                final Rect hitBox = key.getHitBox();
                 sweetSpotCenterXs[infoIndex] = hitBox.exactCenterX();
                 sweetSpotCenterYs[infoIndex] = hitBox.exactCenterY();
                 sweetSpotRadii[infoIndex] = defaultRadius;
@@ -204,7 +204,7 @@
                             "  [%2d] row=%d x/y/r=%7.2f/%7.2f/%5.2f %s code=%s", infoIndex, row,
                             sweetSpotCenterXs[infoIndex], sweetSpotCenterYs[infoIndex],
                             sweetSpotRadii[infoIndex], (row < rows ? "correct" : "default"),
-                            Constants.printableCode(key.mCode)));
+                            Constants.printableCode(key.getCode())));
                 }
                 infoIndex++;
             }
@@ -322,19 +322,21 @@
   have to align this on the center of the key. Hence, we don't need a separate value for
   bottomPixelWithinThreshold and call this yEnd right away.
 */
-            final int topPixelWithinThreshold = key.mY - threshold;
+            final int keyX = key.getX();
+            final int keyY = key.getY();
+            final int topPixelWithinThreshold = keyY - threshold;
             final int yDeltaToGrid = topPixelWithinThreshold % mCellHeight;
             final int yMiddleOfTopCell = topPixelWithinThreshold - yDeltaToGrid + halfCellHeight;
             final int yStart = Math.max(halfCellHeight,
                     yMiddleOfTopCell + (yDeltaToGrid <= halfCellHeight ? 0 : mCellHeight));
-            final int yEnd = Math.min(fullGridHeight, key.mY + key.mHeight + threshold);
+            final int yEnd = Math.min(fullGridHeight, keyY + key.getHeight() + threshold);
 
-            final int leftPixelWithinThreshold = key.mX - threshold;
+            final int leftPixelWithinThreshold = keyX - threshold;
             final int xDeltaToGrid = leftPixelWithinThreshold % mCellWidth;
             final int xMiddleOfLeftCell = leftPixelWithinThreshold - xDeltaToGrid + halfCellWidth;
             final int xStart = Math.max(halfCellWidth,
                     xMiddleOfLeftCell + (xDeltaToGrid <= halfCellWidth ? 0 : mCellWidth));
-            final int xEnd = Math.min(fullGridWidth, key.mX + key.mWidth + threshold);
+            final int xEnd = Math.min(fullGridWidth, keyX + key.getWidth() + threshold);
 
             int baseIndexOfCurrentRow = (yStart / mCellHeight) * mGridWidth + (xStart / mCellWidth);
             for (int centerY = yStart; centerY <= yEnd; centerY += mCellHeight) {
@@ -372,7 +374,7 @@
             if (index >= destLength) {
                 break;
             }
-            final int code = key.mCode;
+            final int code = key.getCode();
             if (code <= Constants.CODE_SPACE) {
                 break;
             }
diff --git a/java/src/com/android/inputmethod/keyboard/internal/KeyStyle.java b/java/src/com/android/inputmethod/keyboard/internal/KeyStyle.java
index f650569..e6a6743 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/KeyStyle.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/KeyStyle.java
@@ -24,7 +24,7 @@
     public abstract String[] getStringArray(TypedArray a, int index);
     public abstract String getString(TypedArray a, int index);
     public abstract int getInt(TypedArray a, int index, int defaultValue);
-    public abstract int getFlag(TypedArray a, int index);
+    public abstract int getFlags(TypedArray a, int index);
 
     protected KeyStyle(final KeyboardTextsSet textsSet) {
         mTextsSet = textsSet;
diff --git a/java/src/com/android/inputmethod/keyboard/internal/KeyStylesSet.java b/java/src/com/android/inputmethod/keyboard/internal/KeyStylesSet.java
index 6aab3e7..b21ea3f 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/KeyStylesSet.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/KeyStylesSet.java
@@ -66,7 +66,7 @@
         }
 
         @Override
-        public int getFlag(final TypedArray a, final int index) {
+        public int getFlags(final TypedArray a, final int index) {
             return a.getInt(index, 0);
         }
     }
@@ -123,14 +123,11 @@
         }
 
         @Override
-        public int getFlag(final TypedArray a, final int index) {
-            int flags = a.getInt(index, 0);
-            final Object value = mStyleAttributes.get(index);
-            if (value != null) {
-                flags |= (Integer)value;
-            }
+        public int getFlags(final TypedArray a, final int index) {
+            final Integer value = (Integer)mStyleAttributes.get(index);
+            final int flags = a.getInt(index, (value != null) ? value : 0);
             final KeyStyle parentStyle = mStyles.get(mParentStyleName);
-            return flags | parentStyle.getFlag(a, index);
+            return flags | parentStyle.getFlags(a, index);
         }
 
         public void readKeyAttributes(final TypedArray keyAttr) {
@@ -142,13 +139,13 @@
             readString(keyAttr, R.styleable.Keyboard_Key_keyHintLabel);
             readStringArray(keyAttr, R.styleable.Keyboard_Key_moreKeys);
             readStringArray(keyAttr, R.styleable.Keyboard_Key_additionalMoreKeys);
-            readFlag(keyAttr, R.styleable.Keyboard_Key_keyLabelFlags);
+            readFlags(keyAttr, R.styleable.Keyboard_Key_keyLabelFlags);
             readString(keyAttr, R.styleable.Keyboard_Key_keyIcon);
             readString(keyAttr, R.styleable.Keyboard_Key_keyIconDisabled);
             readString(keyAttr, R.styleable.Keyboard_Key_keyIconPreview);
             readInt(keyAttr, R.styleable.Keyboard_Key_maxMoreKeysColumn);
             readInt(keyAttr, R.styleable.Keyboard_Key_backgroundType);
-            readFlag(keyAttr, R.styleable.Keyboard_Key_keyActionFlags);
+            readFlags(keyAttr, R.styleable.Keyboard_Key_keyActionFlags);
         }
 
         private void readString(final TypedArray a, final int index) {
@@ -163,7 +160,7 @@
             }
         }
 
-        private void readFlag(final TypedArray a, final int index) {
+        private void readFlags(final TypedArray a, final int index) {
             if (a.hasValue(index)) {
                 final Integer value = (Integer)mStyleAttributes.get(index);
                 mStyleAttributes.put(index, a.getInt(index, 0) | (value != null ? value : 0));
diff --git a/java/src/com/android/inputmethod/keyboard/internal/KeyboardBuilder.java b/java/src/com/android/inputmethod/keyboard/internal/KeyboardBuilder.java
index b34d7c4..65eb171 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/KeyboardBuilder.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/KeyboardBuilder.java
@@ -218,20 +218,18 @@
                     parseKeyboardAttributes(parser);
                     startKeyboard();
                     parseKeyboardContent(parser, false);
-                    break;
-                } else {
-                    throw new XmlParseUtils.IllegalStartTag(parser, tag, TAG_KEYBOARD);
+                    return;
                 }
+                throw new XmlParseUtils.IllegalStartTag(parser, tag, TAG_KEYBOARD);
             }
         }
     }
 
     private void parseKeyboardAttributes(final XmlPullParser parser) {
+        final AttributeSet attr = Xml.asAttributeSet(parser);
         final TypedArray keyboardAttr = mContext.obtainStyledAttributes(
-                Xml.asAttributeSet(parser), R.styleable.Keyboard, R.attr.keyboardStyle,
-                R.style.Keyboard);
-        final TypedArray keyAttr = mResources.obtainAttributes(Xml.asAttributeSet(parser),
-                R.styleable.Keyboard_Key);
+                attr, R.styleable.Keyboard, R.attr.keyboardStyle, R.style.Keyboard);
+        final TypedArray keyAttr = mResources.obtainAttributes(attr, R.styleable.Keyboard_Key);
         try {
             final KeyboardParams params = mParams;
             final int height = params.mId.mHeight;
@@ -328,31 +326,30 @@
                 if (DEBUG) endTag("</%s>", tag);
                 if (TAG_KEYBOARD.equals(tag)) {
                     endKeyboard();
-                    break;
-                } else if (TAG_CASE.equals(tag) || TAG_DEFAULT.equals(tag)
-                        || TAG_MERGE.equals(tag)) {
-                    break;
-                } else {
-                    throw new XmlParseUtils.IllegalEndTag(parser, tag, TAG_ROW);
+                    return;
                 }
+                if (TAG_CASE.equals(tag) || TAG_DEFAULT.equals(tag) || TAG_MERGE.equals(tag)) {
+                    return;
+                }
+                throw new XmlParseUtils.IllegalEndTag(parser, tag, TAG_ROW);
             }
         }
     }
 
     private KeyboardRow parseRowAttributes(final XmlPullParser parser)
             throws XmlPullParserException {
-        final TypedArray a = mResources.obtainAttributes(Xml.asAttributeSet(parser),
-                R.styleable.Keyboard);
+        final AttributeSet attr = Xml.asAttributeSet(parser);
+        final TypedArray keyboardAttr = mResources.obtainAttributes(attr, R.styleable.Keyboard);
         try {
-            if (a.hasValue(R.styleable.Keyboard_horizontalGap)) {
+            if (keyboardAttr.hasValue(R.styleable.Keyboard_horizontalGap)) {
                 throw new XmlParseUtils.IllegalAttribute(parser, TAG_ROW, "horizontalGap");
             }
-            if (a.hasValue(R.styleable.Keyboard_verticalGap)) {
+            if (keyboardAttr.hasValue(R.styleable.Keyboard_verticalGap)) {
                 throw new XmlParseUtils.IllegalAttribute(parser, TAG_ROW, "verticalGap");
             }
             return new KeyboardRow(mResources, mParams, parser, mCurrentY);
         } finally {
-            a.recycle();
+            keyboardAttr.recycle();
         }
     }
 
@@ -382,13 +379,12 @@
                     if (!skip) {
                         endRow(row);
                     }
-                    break;
-                } else if (TAG_CASE.equals(tag) || TAG_DEFAULT.equals(tag)
-                        || TAG_MERGE.equals(tag)) {
-                    break;
-                } else {
-                    throw new XmlParseUtils.IllegalEndTag(parser, tag, TAG_ROW);
+                    return;
                 }
+                if (TAG_CASE.equals(tag) || TAG_DEFAULT.equals(tag) || TAG_MERGE.equals(tag)) {
+                    return;
+                }
+                throw new XmlParseUtils.IllegalEndTag(parser, tag, TAG_ROW);
             }
         }
     }
@@ -397,19 +393,16 @@
             throws XmlPullParserException, IOException {
         if (skip) {
             XmlParseUtils.checkEndTag(TAG_KEY, parser);
-            if (DEBUG) {
-                startEndTag("<%s /> skipped", TAG_KEY);
-            }
-        } else {
-            final Key key = new Key(mResources, mParams, row, parser);
-            if (DEBUG) {
-                startEndTag("<%s%s %s moreKeys=%s />", TAG_KEY,
-                        (key.isEnabled() ? "" : " disabled"), key,
-                        Arrays.toString(key.mMoreKeys));
-            }
-            XmlParseUtils.checkEndTag(TAG_KEY, parser);
-            endKey(key);
+            if (DEBUG) startEndTag("<%s /> skipped", TAG_KEY);
+            return;
         }
+        final Key key = new Key(mResources, mParams, row, parser);
+        if (DEBUG) {
+            startEndTag("<%s%s %s moreKeys=%s />", TAG_KEY, (key.isEnabled() ? "" : " disabled"),
+                    key, Arrays.toString(key.getMoreKeys()));
+        }
+        XmlParseUtils.checkEndTag(TAG_KEY, parser);
+        endKey(key);
     }
 
     private void parseSpacer(final XmlPullParser parser, final KeyboardRow row, final boolean skip)
@@ -417,12 +410,12 @@
         if (skip) {
             XmlParseUtils.checkEndTag(TAG_SPACER, parser);
             if (DEBUG) startEndTag("<%s /> skipped", TAG_SPACER);
-        } else {
-            final Key.Spacer spacer = new Key.Spacer(mResources, mParams, row, parser);
-            if (DEBUG) startEndTag("<%s />", TAG_SPACER);
-            XmlParseUtils.checkEndTag(TAG_SPACER, parser);
-            endKey(spacer);
+            return;
         }
+        final Key.Spacer spacer = new Key.Spacer(mResources, mParams, row, parser);
+        if (DEBUG) startEndTag("<%s />", TAG_SPACER);
+        XmlParseUtils.checkEndTag(TAG_SPACER, parser);
+        endKey(spacer);
     }
 
     private void parseIncludeKeyboardContent(final XmlPullParser parser, final boolean skip)
@@ -440,66 +433,63 @@
         if (skip) {
             XmlParseUtils.checkEndTag(TAG_INCLUDE, parser);
             if (DEBUG) startEndTag("</%s> skipped", TAG_INCLUDE);
-        } else {
-            final AttributeSet attr = Xml.asAttributeSet(parser);
-            final TypedArray keyboardAttr = mResources.obtainAttributes(attr,
-                    R.styleable.Keyboard_Include);
-            final TypedArray keyAttr = mResources.obtainAttributes(attr,
-                    R.styleable.Keyboard_Key);
-            int keyboardLayout = 0;
-            float savedDefaultKeyWidth = 0;
-            int savedDefaultKeyLabelFlags = 0;
-            int savedDefaultBackgroundType = Key.BACKGROUND_TYPE_NORMAL;
-            try {
-                XmlParseUtils.checkAttributeExists(keyboardAttr,
-                        R.styleable.Keyboard_Include_keyboardLayout, "keyboardLayout",
-                        TAG_INCLUDE, parser);
-                keyboardLayout = keyboardAttr.getResourceId(
-                        R.styleable.Keyboard_Include_keyboardLayout, 0);
-                if (row != null) {
-                    if (keyAttr.hasValue(R.styleable.Keyboard_Key_keyXPos)) {
-                        // Override current x coordinate.
-                        row.setXPos(row.getKeyX(keyAttr));
-                    }
-                    // TODO: Remove this if-clause and do the same as backgroundType below.
-                    savedDefaultKeyWidth = row.getDefaultKeyWidth();
-                    if (keyAttr.hasValue(R.styleable.Keyboard_Key_keyWidth)) {
-                        // Override default key width.
-                        row.setDefaultKeyWidth(row.getKeyWidth(keyAttr));
-                    }
-                    savedDefaultKeyLabelFlags = row.getDefaultKeyLabelFlags();
-                    // Bitwise-or default keyLabelFlag if exists.
-                    row.setDefaultKeyLabelFlags(keyAttr.getInt(
-                            R.styleable.Keyboard_Key_keyLabelFlags, 0)
-                            | savedDefaultKeyLabelFlags);
-                    savedDefaultBackgroundType = row.getDefaultBackgroundType();
-                    // Override default backgroundType if exists.
-                    row.setDefaultBackgroundType(keyAttr.getInt(
-                            R.styleable.Keyboard_Key_backgroundType,
-                            savedDefaultBackgroundType));
+            return;
+        }
+        final AttributeSet attr = Xml.asAttributeSet(parser);
+        final TypedArray keyboardAttr = mResources.obtainAttributes(
+                attr, R.styleable.Keyboard_Include);
+        final TypedArray keyAttr = mResources.obtainAttributes(attr, R.styleable.Keyboard_Key);
+        int keyboardLayout = 0;
+        float savedDefaultKeyWidth = 0;
+        int savedDefaultKeyLabelFlags = 0;
+        int savedDefaultBackgroundType = Key.BACKGROUND_TYPE_NORMAL;
+        try {
+            XmlParseUtils.checkAttributeExists(
+                    keyboardAttr, R.styleable.Keyboard_Include_keyboardLayout, "keyboardLayout",
+                    TAG_INCLUDE, parser);
+            keyboardLayout = keyboardAttr.getResourceId(
+                    R.styleable.Keyboard_Include_keyboardLayout, 0);
+            if (row != null) {
+                if (keyAttr.hasValue(R.styleable.Keyboard_Key_keyXPos)) {
+                    // Override current x coordinate.
+                    row.setXPos(row.getKeyX(keyAttr));
                 }
-            } finally {
-                keyboardAttr.recycle();
-                keyAttr.recycle();
+                // TODO: Remove this if-clause and do the same as backgroundType below.
+                savedDefaultKeyWidth = row.getDefaultKeyWidth();
+                if (keyAttr.hasValue(R.styleable.Keyboard_Key_keyWidth)) {
+                    // Override default key width.
+                    row.setDefaultKeyWidth(row.getKeyWidth(keyAttr));
+                }
+                savedDefaultKeyLabelFlags = row.getDefaultKeyLabelFlags();
+                // Bitwise-or default keyLabelFlag if exists.
+                row.setDefaultKeyLabelFlags(keyAttr.getInt(
+                        R.styleable.Keyboard_Key_keyLabelFlags, 0) | savedDefaultKeyLabelFlags);
+                savedDefaultBackgroundType = row.getDefaultBackgroundType();
+                // Override default backgroundType if exists.
+                row.setDefaultBackgroundType(keyAttr.getInt(
+                        R.styleable.Keyboard_Key_backgroundType, savedDefaultBackgroundType));
             }
+        } finally {
+            keyboardAttr.recycle();
+            keyAttr.recycle();
+        }
 
-            XmlParseUtils.checkEndTag(TAG_INCLUDE, parser);
-            if (DEBUG) {
-                startEndTag("<%s keyboardLayout=%s />",TAG_INCLUDE,
-                        mResources.getResourceEntryName(keyboardLayout));
+        XmlParseUtils.checkEndTag(TAG_INCLUDE, parser);
+        if (DEBUG) {
+            startEndTag("<%s keyboardLayout=%s />",TAG_INCLUDE,
+                    mResources.getResourceEntryName(keyboardLayout));
+        }
+        final XmlResourceParser parserForInclude = mResources.getXml(keyboardLayout);
+        try {
+            parseMerge(parserForInclude, row, skip);
+        } finally {
+            if (row != null) {
+                // Restore default keyWidth, keyLabelFlags, and backgroundType.
+                row.setDefaultKeyWidth(savedDefaultKeyWidth);
+                row.setDefaultKeyLabelFlags(savedDefaultKeyLabelFlags);
+                row.setDefaultBackgroundType(savedDefaultBackgroundType);
             }
-            final XmlResourceParser parserForInclude = mResources.getXml(keyboardLayout);
-            try {
-                parseMerge(parserForInclude, row, skip);
-            } finally {
-                if (row != null) {
-                    // Restore default keyWidth, keyLabelFlags, and backgroundType.
-                    row.setDefaultKeyWidth(savedDefaultKeyWidth);
-                    row.setDefaultKeyLabelFlags(savedDefaultKeyLabelFlags);
-                    row.setDefaultBackgroundType(savedDefaultBackgroundType);
-                }
-                parserForInclude.close();
-            }
+            parserForInclude.close();
         }
     }
 
@@ -516,11 +506,10 @@
                     } else {
                         parseRowContent(parser, row, skip);
                     }
-                    break;
-                } else {
-                    throw new XmlParseUtils.ParseException(
-                            "Included keyboard layout must have <merge> root element", parser);
+                    return;
                 }
+                throw new XmlParseUtils.ParseException(
+                        "Included keyboard layout must have <merge> root element", parser);
             }
         }
     }
@@ -554,10 +543,9 @@
                 final String tag = parser.getName();
                 if (TAG_SWITCH.equals(tag)) {
                     if (DEBUG) endTag("</%s>", TAG_SWITCH);
-                    break;
-                } else {
-                    throw new XmlParseUtils.IllegalEndTag(parser, tag, TAG_SWITCH);
+                    return;
                 }
+                throw new XmlParseUtils.IllegalEndTag(parser, tag, TAG_SWITCH);
             }
         }
     }
@@ -580,40 +568,40 @@
         if (id == null) {
             return true;
         }
-        final TypedArray a = mResources.obtainAttributes(Xml.asAttributeSet(parser),
-                R.styleable.Keyboard_Case);
+        final AttributeSet attr = Xml.asAttributeSet(parser);
+        final TypedArray caseAttr = mResources.obtainAttributes(attr, R.styleable.Keyboard_Case);
         try {
-            final boolean keyboardLayoutSetElementMatched = matchTypedValue(a,
+            final boolean keyboardLayoutSetElementMatched = matchTypedValue(caseAttr,
                     R.styleable.Keyboard_Case_keyboardLayoutSetElement, id.mElementId,
                     KeyboardId.elementIdToName(id.mElementId));
-            final boolean modeMatched = matchTypedValue(a,
+            final boolean modeMatched = matchTypedValue(caseAttr,
                     R.styleable.Keyboard_Case_mode, id.mMode, KeyboardId.modeName(id.mMode));
-            final boolean navigateNextMatched = matchBoolean(a,
+            final boolean navigateNextMatched = matchBoolean(caseAttr,
                     R.styleable.Keyboard_Case_navigateNext, id.navigateNext());
-            final boolean navigatePreviousMatched = matchBoolean(a,
+            final boolean navigatePreviousMatched = matchBoolean(caseAttr,
                     R.styleable.Keyboard_Case_navigatePrevious, id.navigatePrevious());
-            final boolean passwordInputMatched = matchBoolean(a,
+            final boolean passwordInputMatched = matchBoolean(caseAttr,
                     R.styleable.Keyboard_Case_passwordInput, id.passwordInput());
-            final boolean clobberSettingsKeyMatched = matchBoolean(a,
+            final boolean clobberSettingsKeyMatched = matchBoolean(caseAttr,
                     R.styleable.Keyboard_Case_clobberSettingsKey, id.mClobberSettingsKey);
-            final boolean shortcutKeyEnabledMatched = matchBoolean(a,
+            final boolean shortcutKeyEnabledMatched = matchBoolean(caseAttr,
                     R.styleable.Keyboard_Case_shortcutKeyEnabled, id.mShortcutKeyEnabled);
-            final boolean shortcutKeyOnSymbolsMatched = matchBoolean(a,
+            final boolean shortcutKeyOnSymbolsMatched = matchBoolean(caseAttr,
                     R.styleable.Keyboard_Case_shortcutKeyOnSymbols, id.mShortcutKeyOnSymbols);
-            final boolean hasShortcutKeyMatched = matchBoolean(a,
+            final boolean hasShortcutKeyMatched = matchBoolean(caseAttr,
                     R.styleable.Keyboard_Case_hasShortcutKey, id.mHasShortcutKey);
-            final boolean languageSwitchKeyEnabledMatched = matchBoolean(a,
+            final boolean languageSwitchKeyEnabledMatched = matchBoolean(caseAttr,
                     R.styleable.Keyboard_Case_languageSwitchKeyEnabled,
                     id.mLanguageSwitchKeyEnabled);
-            final boolean isMultiLineMatched = matchBoolean(a,
+            final boolean isMultiLineMatched = matchBoolean(caseAttr,
                     R.styleable.Keyboard_Case_isMultiLine, id.isMultiLine());
-            final boolean imeActionMatched = matchInteger(a,
+            final boolean imeActionMatched = matchInteger(caseAttr,
                     R.styleable.Keyboard_Case_imeAction, id.imeAction());
-            final boolean localeCodeMatched = matchString(a,
+            final boolean localeCodeMatched = matchString(caseAttr,
                     R.styleable.Keyboard_Case_localeCode, id.mLocale.toString());
-            final boolean languageCodeMatched = matchString(a,
+            final boolean languageCodeMatched = matchString(caseAttr,
                     R.styleable.Keyboard_Case_languageCode, id.mLocale.getLanguage());
-            final boolean countryCodeMatched = matchString(a,
+            final boolean countryCodeMatched = matchString(caseAttr,
                     R.styleable.Keyboard_Case_countryCode, id.mLocale.getCountry());
             final boolean selected = keyboardLayoutSetElementMatched && modeMatched
                     && navigateNextMatched && navigatePreviousMatched && passwordInputMatched
@@ -624,42 +612,42 @@
 
             if (DEBUG) {
                 startTag("<%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s>%s", TAG_CASE,
-                        textAttr(a.getString(
+                        textAttr(caseAttr.getString(
                                 R.styleable.Keyboard_Case_keyboardLayoutSetElement),
                                 "keyboardLayoutSetElement"),
-                        textAttr(a.getString(R.styleable.Keyboard_Case_mode), "mode"),
-                        textAttr(a.getString(R.styleable.Keyboard_Case_imeAction),
+                        textAttr(caseAttr.getString(R.styleable.Keyboard_Case_mode), "mode"),
+                        textAttr(caseAttr.getString(R.styleable.Keyboard_Case_imeAction),
                                 "imeAction"),
-                        booleanAttr(a, R.styleable.Keyboard_Case_navigateNext,
+                        booleanAttr(caseAttr, R.styleable.Keyboard_Case_navigateNext,
                                 "navigateNext"),
-                        booleanAttr(a, R.styleable.Keyboard_Case_navigatePrevious,
+                        booleanAttr(caseAttr, R.styleable.Keyboard_Case_navigatePrevious,
                                 "navigatePrevious"),
-                        booleanAttr(a, R.styleable.Keyboard_Case_clobberSettingsKey,
+                        booleanAttr(caseAttr, R.styleable.Keyboard_Case_clobberSettingsKey,
                                 "clobberSettingsKey"),
-                        booleanAttr(a, R.styleable.Keyboard_Case_passwordInput,
+                        booleanAttr(caseAttr, R.styleable.Keyboard_Case_passwordInput,
                                 "passwordInput"),
-                        booleanAttr(a, R.styleable.Keyboard_Case_shortcutKeyEnabled,
+                        booleanAttr(caseAttr, R.styleable.Keyboard_Case_shortcutKeyEnabled,
                                 "shortcutKeyEnabled"),
-                        booleanAttr(a, R.styleable.Keyboard_Case_shortcutKeyOnSymbols,
+                        booleanAttr(caseAttr, R.styleable.Keyboard_Case_shortcutKeyOnSymbols,
                                 "shortcutKeyOnSymbols"),
-                        booleanAttr(a, R.styleable.Keyboard_Case_hasShortcutKey,
+                        booleanAttr(caseAttr, R.styleable.Keyboard_Case_hasShortcutKey,
                                 "hasShortcutKey"),
-                        booleanAttr(a, R.styleable.Keyboard_Case_languageSwitchKeyEnabled,
+                        booleanAttr(caseAttr, R.styleable.Keyboard_Case_languageSwitchKeyEnabled,
                                 "languageSwitchKeyEnabled"),
-                        booleanAttr(a, R.styleable.Keyboard_Case_isMultiLine,
+                        booleanAttr(caseAttr, R.styleable.Keyboard_Case_isMultiLine,
                                 "isMultiLine"),
-                        textAttr(a.getString(R.styleable.Keyboard_Case_localeCode),
+                        textAttr(caseAttr.getString(R.styleable.Keyboard_Case_localeCode),
                                 "localeCode"),
-                        textAttr(a.getString(R.styleable.Keyboard_Case_languageCode),
+                        textAttr(caseAttr.getString(R.styleable.Keyboard_Case_languageCode),
                                 "languageCode"),
-                        textAttr(a.getString(R.styleable.Keyboard_Case_countryCode),
+                        textAttr(caseAttr.getString(R.styleable.Keyboard_Case_countryCode),
                                 "countryCode"),
                         selected ? "" : " skipped");
             }
 
             return selected;
         } finally {
-            a.recycle();
+            caseAttr.recycle();
         }
     }
 
@@ -692,7 +680,8 @@
         }
         if (ResourceUtils.isIntegerValue(v)) {
             return intValue == a.getInt(index, 0);
-        } else if (ResourceUtils.isStringValue(v)) {
+        }
+        if (ResourceUtils.isStringValue(v)) {
             return StringUtils.containsInArray(strValue, a.getString(index).split("\\|"));
         }
         return false;
@@ -711,10 +700,10 @@
 
     private void parseKeyStyle(final XmlPullParser parser, final boolean skip)
             throws XmlPullParserException, IOException {
-        TypedArray keyStyleAttr = mResources.obtainAttributes(Xml.asAttributeSet(parser),
-                R.styleable.Keyboard_KeyStyle);
-        TypedArray keyAttrs = mResources.obtainAttributes(Xml.asAttributeSet(parser),
-                R.styleable.Keyboard_Key);
+        final AttributeSet attr = Xml.asAttributeSet(parser);
+        final TypedArray keyStyleAttr = mResources.obtainAttributes(
+                attr, R.styleable.Keyboard_KeyStyle);
+        final TypedArray keyAttrs = mResources.obtainAttributes(attr, R.styleable.Keyboard_Key);
         try {
             if (!keyStyleAttr.hasValue(R.styleable.Keyboard_KeyStyle_styleName)) {
                 throw new XmlParseUtils.ParseException("<" + TAG_KEY_STYLE
@@ -756,7 +745,7 @@
             mRightEdgeKey = null;
         }
         addEdgeSpace(mParams.mRightPadding, row);
-        mCurrentY += row.mRowHeight;
+        mCurrentY += row.getRowHeight();
         mCurrentRow = null;
         mTopEdge = false;
     }
diff --git a/java/src/com/android/inputmethod/keyboard/internal/KeyboardParams.java b/java/src/com/android/inputmethod/keyboard/internal/KeyboardParams.java
index a57b83a..d32bb75 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/KeyboardParams.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/KeyboardParams.java
@@ -85,7 +85,7 @@
     public void onAddKey(final Key newKey) {
         final Key key = (mKeysCache != null) ? mKeysCache.get(newKey) : newKey;
         final boolean isSpacer = key.isSpacer();
-        if (isSpacer && key.mWidth == 0) {
+        if (isSpacer && key.getWidth() == 0) {
             // Ignore zero width {@link Spacer}.
             return;
         }
@@ -94,7 +94,7 @@
             return;
         }
         updateHistogram(key);
-        if (key.mCode == Constants.CODE_SHIFT) {
+        if (key.getCode() == Constants.CODE_SHIFT) {
             mShiftKeys.add(key);
         }
         if (key.altCodeWhileTyping()) {
@@ -125,14 +125,14 @@
     }
 
     private void updateHistogram(final Key key) {
-        final int height = key.mHeight + mVerticalGap;
+        final int height = key.getHeight() + mVerticalGap;
         final int heightCount = updateHistogramCounter(mHeightHistogram, height);
         if (heightCount > mMaxHeightCount) {
             mMaxHeightCount = heightCount;
             mMostCommonKeyHeight = height;
         }
 
-        final int width = key.mWidth + mHorizontalGap;
+        final int width = key.getWidth() + mHorizontalGap;
         final int widthCount = updateHistogramCounter(mWidthHistogram, width);
         if (widthCount > mMaxWidthCount) {
             mMaxWidthCount = widthCount;
diff --git a/java/src/com/android/inputmethod/keyboard/internal/KeyboardRow.java b/java/src/com/android/inputmethod/keyboard/internal/KeyboardRow.java
index 5fe84a7..23c0b91 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/KeyboardRow.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/KeyboardRow.java
@@ -38,10 +38,10 @@
     private static final int KEYWIDTH_FILL_RIGHT = -1;
 
     private final KeyboardParams mParams;
+    /** The height of this row. */
+    private final int mRowHeight;
     /** Default width of a key in this row. */
     private float mDefaultKeyWidth;
-    /** Default height of a key in this row. */
-    public final int mRowHeight;
     /** Default keyLabelFlags in this row. */
     private int mDefaultKeyLabelFlags;
     /** Default backgroundType for this row */
@@ -64,16 +64,19 @@
                 R.styleable.Keyboard_Key);
         mDefaultKeyWidth = keyAttr.getFraction(R.styleable.Keyboard_Key_keyWidth,
                 params.mBaseWidth, params.mBaseWidth, params.mDefaultKeyWidth);
+        mDefaultKeyLabelFlags = keyAttr.getInt(R.styleable.Keyboard_Key_keyLabelFlags, 0);
         mDefaultBackgroundType = keyAttr.getInt(R.styleable.Keyboard_Key_backgroundType,
                 Key.BACKGROUND_TYPE_NORMAL);
         keyAttr.recycle();
 
-        // TODO: Initialize this with <Row> attribute as backgroundType is done.
-        mDefaultKeyLabelFlags = 0;
         mCurrentY = y;
         mCurrentX = 0.0f;
     }
 
+    public int getRowHeight() {
+        return mRowHeight;
+    }
+
     public float getDefaultKeyWidth() {
         return mDefaultKeyWidth;
     }
@@ -111,22 +114,21 @@
     }
 
     public float getKeyX(final TypedArray keyAttr) {
-        if (keyAttr.hasValue(R.styleable.Keyboard_Key_keyXPos)) {
-            final float keyXPos = keyAttr.getFraction(R.styleable.Keyboard_Key_keyXPos,
-                    mParams.mBaseWidth, mParams.mBaseWidth, 0);
-            if (keyXPos < 0) {
-                // If keyXPos is negative, the actual x-coordinate will be
-                // keyboardWidth + keyXPos.
-                // keyXPos shouldn't be less than mCurrentX because drawable area for this
-                // key starts at mCurrentX. Or, this key will overlaps the adjacent key on
-                // its left hand side.
-                final int keyboardRightEdge = mParams.mOccupiedWidth - mParams.mRightPadding;
-                return Math.max(keyXPos + keyboardRightEdge, mCurrentX);
-            } else {
-                return keyXPos + mParams.mLeftPadding;
-            }
+        if (keyAttr == null || !keyAttr.hasValue(R.styleable.Keyboard_Key_keyXPos)) {
+            return mCurrentX;
         }
-        return mCurrentX;
+        final float keyXPos = keyAttr.getFraction(R.styleable.Keyboard_Key_keyXPos,
+                mParams.mBaseWidth, mParams.mBaseWidth, 0);
+        if (keyXPos >= 0) {
+            return keyXPos + mParams.mLeftPadding;
+        }
+        // If keyXPos is negative, the actual x-coordinate will be
+        // keyboardWidth + keyXPos.
+        // keyXPos shouldn't be less than mCurrentX because drawable area for this
+        // key starts at mCurrentX. Or, this key will overlaps the adjacent key on
+        // its left hand side.
+        final int keyboardRightEdge = mParams.mOccupiedWidth - mParams.mRightPadding;
+        return Math.max(keyXPos + keyboardRightEdge, mCurrentX);
     }
 
     public float getKeyWidth(final TypedArray keyAttr) {
@@ -134,6 +136,9 @@
     }
 
     public float getKeyWidth(final TypedArray keyAttr, final float keyXPos) {
+        if (keyAttr == null) {
+            return mDefaultKeyWidth;
+        }
         final int widthType = ResourceUtils.getEnumValue(keyAttr,
                 R.styleable.Keyboard_Key_keyWidth, KEYWIDTH_NOT_ENUM);
         switch (widthType) {
diff --git a/java/src/com/android/inputmethod/latin/BinaryDictionaryGetter.java b/java/src/com/android/inputmethod/latin/BinaryDictionaryGetter.java
index d0a4afd..7e497e9 100644
--- a/java/src/com/android/inputmethod/latin/BinaryDictionaryGetter.java
+++ b/java/src/com/android/inputmethod/latin/BinaryDictionaryGetter.java
@@ -21,7 +21,7 @@
 import android.content.res.AssetFileDescriptor;
 import android.util.Log;
 
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder;
 import com.android.inputmethod.latin.makedict.FormatSpec;
 import com.android.inputmethod.latin.utils.CollectionUtils;
 import com.android.inputmethod.latin.utils.DictionaryInfoUtils;
@@ -231,8 +231,8 @@
         try {
             // Read the version of the file
             inStream = new FileInputStream(f);
-            final BinaryDictInputOutput.ByteBufferWrapper buffer =
-                    new BinaryDictInputOutput.ByteBufferWrapper(inStream.getChannel().map(
+            final BinaryDictDecoder.ByteBufferWrapper buffer =
+                    new BinaryDictDecoder.ByteBufferWrapper(inStream.getChannel().map(
                             FileChannel.MapMode.READ_ONLY, 0, f.length()));
             final int magic = buffer.readInt();
             if (magic != FormatSpec.MAGIC_NUMBER) {
@@ -241,7 +241,7 @@
             final int formatVersion = buffer.readInt();
             final int headerSize = buffer.readInt();
             final HashMap<String, String> options = CollectionUtils.newHashMap();
-            BinaryDictInputOutput.populateOptions(buffer, headerSize, options);
+            BinaryDictDecoder.populateOptions(buffer, headerSize, options);
 
             final String version = options.get(VERSION_KEY);
             if (null == version) {
diff --git a/java/src/com/android/inputmethod/latin/DictionaryWriter.java b/java/src/com/android/inputmethod/latin/DictionaryWriter.java
index a3c6071..1ececd5 100644
--- a/java/src/com/android/inputmethod/latin/DictionaryWriter.java
+++ b/java/src/com/android/inputmethod/latin/DictionaryWriter.java
@@ -20,10 +20,10 @@
 
 import com.android.inputmethod.keyboard.ProximityInfo;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput;
+import com.android.inputmethod.latin.makedict.BinaryDictEncoder;
 import com.android.inputmethod.latin.makedict.FormatSpec;
 import com.android.inputmethod.latin.makedict.FusionDictionary;
-import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
 import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
 import com.android.inputmethod.latin.makedict.UnsupportedFormatException;
 import com.android.inputmethod.latin.utils.CollectionUtils;
@@ -51,7 +51,7 @@
     @Override
     public void clear() {
         final HashMap<String, String> attributes = CollectionUtils.newHashMap();
-        mFusionDictionary = new FusionDictionary(new Node(),
+        mFusionDictionary = new FusionDictionary(new PtNodeArray(),
                 new FusionDictionary.DictionaryOptions(attributes, false, false));
     }
 
@@ -87,7 +87,7 @@
     @Override
     protected void writeBinaryDictionary(final FileOutputStream out)
             throws IOException, UnsupportedFormatException {
-        BinaryDictInputOutput.writeDictionaryBinary(out, mFusionDictionary, FORMAT_OPTIONS);
+        BinaryDictEncoder.writeDictionaryBinary(out, mFusionDictionary, FORMAT_OPTIONS);
     }
 
     @Override
diff --git a/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java b/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
index b3e9301..3725677 100644
--- a/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
@@ -88,6 +88,9 @@
     /** Controls access to the local binary dictionary for this instance. */
     private final DictionaryController mLocalDictionaryController = new DictionaryController();
 
+    /* A extension for a binary dictionary file. */
+    public static final String DICT_FILE_EXTENSION = ".dict";
+
     /**
      * Abstract method for loading the unigrams and bigrams of a given dictionary in a background
      * thread.
@@ -146,7 +149,7 @@
     }
 
     protected static String getFilenameWithLocale(final String name, final String localeStr) {
-        return name + "." + localeStr + ".dict";
+        return name + "." + localeStr + DICT_FILE_EXTENSION;
     }
 
     /**
diff --git a/java/src/com/android/inputmethod/latin/LatinIME.java b/java/src/com/android/inputmethod/latin/LatinIME.java
index ffe3171..ee7478c 100644
--- a/java/src/com/android/inputmethod/latin/LatinIME.java
+++ b/java/src/com/android/inputmethod/latin/LatinIME.java
@@ -1948,7 +1948,8 @@
                     }
                 }
             }
-            if (currentSettings.isSuggestionsRequested(mDisplayOrientation)) {
+            if (currentSettings.isSuggestionsRequested(mDisplayOrientation)
+                    && currentSettings.mCurrentLanguageHasSpaces) {
                 restartSuggestionsOnWordBeforeCursorIfAtEndOfWord();
             }
             // We just removed a character. We need to update the auto-caps state.
@@ -1977,6 +1978,9 @@
 
     private void handleCharacter(final int primaryCode, final int x,
             final int y, final int spaceState) {
+        // TODO: refactor this method to stop flipping isComposingWord around all the time, and
+        // make it shorter (possibly cut into several pieces). Also factor handleNonSpecialCharacter
+        // which has the same name as other handle* methods but is not the same.
         boolean isComposingWord = mWordComposer.isComposingWord();
 
         // TODO: remove isWordConnector() and use isUsuallyFollowedBySpace() instead.
@@ -1996,12 +2000,20 @@
             resetEntireInputState(mLastSelectionStart);
             isComposingWord = false;
         }
-        // NOTE: isCursorTouchingWord() is a blocking IPC call, so it often takes several
-        // dozen milliseconds. Avoid calling it as much as possible, since we are on the UI
-        // thread here.
-        if (!isComposingWord && currentSettings.isWordCodePoint(primaryCode)
+        // We want to find out whether to start composing a new word with this character. If so,
+        // we need to reset the composing state and switch isComposingWord. The order of the
+        // tests is important for good performance.
+        // We only start composing if we're not already composing.
+        if (!isComposingWord
+        // We only start composing if this is a word code point. Essentially that means it's a
+        // a letter or a word connector.
+                && currentSettings.isWordCodePoint(primaryCode)
+        // We never go into composing state if suggestions are not requested.
                 && currentSettings.isSuggestionsRequested(mDisplayOrientation) &&
-                !mConnection.isCursorTouchingWord(currentSettings)) {
+        // In languages with spaces, we only start composing a word when we are not already
+        // touching a word. In languages without spaces, the above conditions are sufficient.
+                (!mConnection.isCursorTouchingWord(currentSettings)
+                        || !currentSettings.mCurrentLanguageHasSpaces)) {
             // Reset entirely the composing state anyway, then start composing a new word unless
             // the character is a single quote. The idea here is, single quote is not a
             // separator and it should be treated as a normal character, except in the first
@@ -2089,16 +2101,20 @@
     private boolean handleSeparator(final int primaryCode, final int x, final int y,
             final int spaceState) {
         boolean didAutoCorrect = false;
+        final SettingsValues currentSettings = mSettings.getCurrent();
+        // We avoid sending spaces in languages without spaces if we were composing.
+        final boolean shouldAvoidSendingCode = Constants.CODE_SPACE == primaryCode
+                && !currentSettings.mCurrentLanguageHasSpaces && mWordComposer.isComposingWord();
         if (mWordComposer.isCursorFrontOrMiddleOfComposingWord()) {
             // If we are in the middle of a recorrection, we need to commit the recorrection
             // first so that we can insert the separator at the current cursor position.
             resetEntireInputState(mLastSelectionStart);
         }
-        final SettingsValues currentSettings = mSettings.getCurrent();
-        if (mWordComposer.isComposingWord()) {
+        if (mWordComposer.isComposingWord()) { // May have changed since we stored wasComposing
             if (currentSettings.mCorrectionEnabled) {
-                // TODO: maybe cache Strings in an <String> sparse array or something
-                commitCurrentAutoCorrection(new String(new int[]{primaryCode}, 0, 1));
+                final String separator = shouldAvoidSendingCode ? LastComposedWord.NOT_A_SEPARATOR
+                        : new String(new int[] { primaryCode }, 0, 1);
+                commitCurrentAutoCorrection(separator);
                 didAutoCorrect = true;
             } else {
                 commitTyped(new String(new int[]{primaryCode}, 0, 1));
@@ -2115,7 +2131,10 @@
         if (ProductionFlag.USES_DEVELOPMENT_ONLY_DIAGNOSTICS) {
             ResearchLogger.latinIME_handleSeparator(primaryCode, mWordComposer.isComposingWord());
         }
-        sendKeyCodePoint(primaryCode);
+
+        if (!shouldAvoidSendingCode) {
+            sendKeyCodePoint(primaryCode);
+        }
 
         if (Constants.CODE_SPACE == primaryCode) {
             if (currentSettings.isSuggestionsRequested(mDisplayOrientation)) {
@@ -2260,11 +2279,17 @@
         // Get the word on which we should search the bigrams. If we are composing a word, it's
         // whatever is *before* the half-committed word in the buffer, hence 2; if we aren't, we
         // should just skip whitespace if any, so 1.
-        // TODO: this is slow (2-way IPC) - we should probably cache this instead.
         final SettingsValues currentSettings = mSettings.getCurrent();
-        final String prevWord =
-                mConnection.getNthPreviousWord(currentSettings.mWordSeparators,
-                mWordComposer.isComposingWord() ? 2 : 1);
+        final String prevWord;
+        if (currentSettings.mCurrentLanguageHasSpaces) {
+            // If we are typing in a language with spaces we can just look up the previous
+            // word from textview.
+            prevWord = mConnection.getNthPreviousWord(currentSettings.mWordSeparators,
+                    mWordComposer.isComposingWord() ? 2 : 1);
+        } else {
+            prevWord = LastComposedWord.NOT_A_COMPOSED_WORD == mLastComposedWord ? null
+                    : mLastComposedWord.mCommittedWord;
+        }
         return suggest.getSuggestedWords(mWordComposer, prevWord, keyboard.getProximityInfo(),
                 currentSettings.mBlockPotentiallyOffensive,
                 currentSettings.mCorrectionEnabled, sessionId);
@@ -2534,6 +2559,9 @@
         // recorrection. This is a temporary, stopgap measure that will be removed later.
         // TODO: remove this.
         if (mAppWorkAroundsUtils.isBrokenByRecorrection()) return;
+        // Recorrection is not supported in languages without spaces because we don't know
+        // how to segment them yet.
+        if (!mSettings.getCurrent().mCurrentLanguageHasSpaces) return;
         // If the cursor is not touching a word, or if there is a selection, return right away.
         if (mLastSelectionStart != mLastSelectionEnd) return;
         // If we don't know the cursor location, return.
@@ -2656,7 +2684,18 @@
         if (!TextUtils.isEmpty(previousWord) && !TextUtils.isEmpty(committedWord)) {
             mUserHistoryPredictionDictionary.cancelAddingUserHistory(previousWord, committedWord);
         }
-        mConnection.commitText(originallyTypedWord + mLastComposedWord.mSeparatorString, 1);
+        final String stringToCommit = originallyTypedWord + mLastComposedWord.mSeparatorString;
+        if (mSettings.getCurrent().mCurrentLanguageHasSpaces) {
+            // For languages with spaces, we revert to the typed string, but the cursor is still
+            // after the separator so we don't resume suggestions. If the user wants to correct
+            // the word, they have to press backspace again.
+            mConnection.commitText(stringToCommit, 1);
+        } else {
+            // For languages without spaces, we revert the typed string but the cursor is flush
+            // with the typed word, so we need to resume suggestions right away.
+            mWordComposer.setComposingWord(stringToCommit, mKeyboardSwitcher.getKeyboard());
+            mConnection.setComposingText(stringToCommit, 1);
+        }
         if (mSettings.isInternal()) {
             LatinImeLoggerUtils.onSeparator(mLastComposedWord.mSeparatorString,
                     Constants.NOT_A_COORDINATE, Constants.NOT_A_COORDINATE);
@@ -2674,7 +2713,9 @@
 
     // This essentially inserts a space, and that's it.
     public void promotePhantomSpace() {
-        if (mSettings.getCurrent().shouldInsertSpacesAutomatically()
+        final SettingsValues currentSettings = mSettings.getCurrent();
+        if (currentSettings.shouldInsertSpacesAutomatically()
+                && currentSettings.mCurrentLanguageHasSpaces
                 && !mConnection.textBeforeCursorLooksLikeURL()) {
             if (ProductionFlag.USES_DEVELOPMENT_ONLY_DIAGNOSTICS) {
                 ResearchLogger.latinIME_promotePhantomSpace();
@@ -2887,6 +2928,12 @@
         return mSuggest.hasMainDictionary();
     }
 
+    // DO NOT USE THIS for any other purpose than testing. This can break the keyboard badly.
+    @UsedForTesting
+    /* package for test */ void replaceMainDictionaryForTest(final Locale locale) {
+        mSuggest.resetMainDict(this, locale, null);
+    }
+
     public void debugDumpStateAndCrashWithException(final String context) {
         final StringBuilder s = new StringBuilder(mAppWorkAroundsUtils.toString());
         s.append("\nAttributes : ").append(mSettings.getCurrent().mInputAttributes)
diff --git a/java/src/com/android/inputmethod/latin/WordComposer.java b/java/src/com/android/inputmethod/latin/WordComposer.java
index a09ca60..039dadc 100644
--- a/java/src/com/android/inputmethod/latin/WordComposer.java
+++ b/java/src/com/android/inputmethod/latin/WordComposer.java
@@ -272,8 +272,8 @@
         final int x, y;
         final Key key;
         if (keyboard != null && (key = keyboard.getKey(codePoint)) != null) {
-            x = key.mX + key.mWidth / 2;
-            y = key.mY + key.mHeight / 2;
+            x = key.getX() + key.getWidth() / 2;
+            y = key.getY() + key.getHeight() / 2;
         } else {
             x = Constants.NOT_A_COORDINATE;
             y = Constants.NOT_A_COORDINATE;
diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictDecoder.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictDecoder.java
new file mode 100644
index 0000000..5e3d6d2
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictDecoder.java
@@ -0,0 +1,795 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.inputmethod.latin.makedict;
+
+import com.android.inputmethod.annotations.UsedForTesting;
+import com.android.inputmethod.latin.makedict.FormatSpec.FileHeader;
+import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
+import com.android.inputmethod.latin.makedict.FusionDictionary.CharGroup;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
+import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
+import com.android.inputmethod.latin.makedict.decoder.HeaderReaderInterface;
+import com.android.inputmethod.latin.utils.JniUtils;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.TreeMap;
+
+/**
+ * Decodes binary files for a FusionDictionary.
+ *
+ * All the methods in this class are static.
+ */
+public final class BinaryDictDecoder {
+
+    private static final boolean DBG = MakedictLog.DBG;
+
+    static {
+        JniUtils.loadNativeLibrary();
+    }
+
+    // TODO: implement something sensical instead of just a phony method
+    private static native int doNothing();
+
+    private BinaryDictDecoder() {
+        // This utility class is not publicly instantiable.
+    }
+
+    private static final int MAX_JUMPS = 12;
+
+    @UsedForTesting
+    public interface FusionDictionaryBufferInterface {
+        public int readUnsignedByte();
+        public int readUnsignedShort();
+        public int readUnsignedInt24();
+        public int readInt();
+        public int position();
+        public void position(int newPosition);
+        public void put(final byte b);
+        public int limit();
+        @UsedForTesting
+        public int capacity();
+    }
+
+    public static final class ByteBufferWrapper implements FusionDictionaryBufferInterface {
+        private ByteBuffer mBuffer;
+
+        public ByteBufferWrapper(final ByteBuffer buffer) {
+            mBuffer = buffer;
+        }
+
+        @Override
+        public int readUnsignedByte() {
+            return mBuffer.get() & 0xFF;
+        }
+
+        @Override
+        public int readUnsignedShort() {
+            return mBuffer.getShort() & 0xFFFF;
+        }
+
+        @Override
+        public int readUnsignedInt24() {
+            final int retval = readUnsignedByte();
+            return (retval << 16) + readUnsignedShort();
+        }
+
+        @Override
+        public int readInt() {
+            return mBuffer.getInt();
+        }
+
+        @Override
+        public int position() {
+            return mBuffer.position();
+        }
+
+        @Override
+        public void position(int newPos) {
+            mBuffer.position(newPos);
+        }
+
+        @Override
+        public void put(final byte b) {
+            mBuffer.put(b);
+        }
+
+        @Override
+        public int limit() {
+            return mBuffer.limit();
+        }
+
+        @Override
+        public int capacity() {
+            return mBuffer.capacity();
+        }
+    }
+
+    /**
+     * A class grouping utility function for our specific character encoding.
+     */
+    static final class CharEncoding {
+        private static final int MINIMAL_ONE_BYTE_CHARACTER_VALUE = 0x20;
+        private static final int MAXIMAL_ONE_BYTE_CHARACTER_VALUE = 0xFF;
+
+        /**
+         * Helper method to find out whether this code fits on one byte
+         */
+        private static boolean fitsOnOneByte(final int character) {
+            return character >= MINIMAL_ONE_BYTE_CHARACTER_VALUE
+                    && character <= MAXIMAL_ONE_BYTE_CHARACTER_VALUE;
+        }
+
+        /**
+         * Compute the size of a character given its character code.
+         *
+         * Char format is:
+         * 1 byte = bbbbbbbb match
+         * case 000xxxxx: xxxxx << 16 + next byte << 8 + next byte
+         * else: if 00011111 (= 0x1F) : this is the terminator. This is a relevant choice because
+         *       unicode code points range from 0 to 0x10FFFF, so any 3-byte value starting with
+         *       00011111 would be outside unicode.
+         * else: iso-latin-1 code
+         * This allows for the whole unicode range to be encoded, including chars outside of
+         * the BMP. Also everything in the iso-latin-1 charset is only 1 byte, except control
+         * characters which should never happen anyway (and still work, but take 3 bytes).
+         *
+         * @param character the character code.
+         * @return the size in binary encoded-form, either 1 or 3 bytes.
+         */
+        static int getCharSize(final int character) {
+            // See char encoding in FusionDictionary.java
+            if (fitsOnOneByte(character)) return 1;
+            if (FormatSpec.INVALID_CHARACTER == character) return 1;
+            return 3;
+        }
+
+        /**
+         * Compute the byte size of a character array.
+         */
+        static int getCharArraySize(final int[] chars) {
+            int size = 0;
+            for (int character : chars) size += getCharSize(character);
+            return size;
+        }
+
+        /**
+         * Writes a char array to a byte buffer.
+         *
+         * @param codePoints the code point array to write.
+         * @param buffer the byte buffer to write to.
+         * @param index the index in buffer to write the character array to.
+         * @return the index after the last character.
+         */
+        static int writeCharArray(final int[] codePoints, final byte[] buffer, int index) {
+            for (int codePoint : codePoints) {
+                if (1 == getCharSize(codePoint)) {
+                    buffer[index++] = (byte)codePoint;
+                } else {
+                    buffer[index++] = (byte)(0xFF & (codePoint >> 16));
+                    buffer[index++] = (byte)(0xFF & (codePoint >> 8));
+                    buffer[index++] = (byte)(0xFF & codePoint);
+                }
+            }
+            return index;
+        }
+
+        /**
+         * Writes a string with our character format to a byte buffer.
+         *
+         * This will also write the terminator byte.
+         *
+         * @param buffer the byte buffer to write to.
+         * @param origin the offset to write from.
+         * @param word the string to write.
+         * @return the size written, in bytes.
+         */
+        static int writeString(final byte[] buffer, final int origin,
+                final String word) {
+            final int length = word.length();
+            int index = origin;
+            for (int i = 0; i < length; i = word.offsetByCodePoints(i, 1)) {
+                final int codePoint = word.codePointAt(i);
+                if (1 == getCharSize(codePoint)) {
+                    buffer[index++] = (byte)codePoint;
+                } else {
+                    buffer[index++] = (byte)(0xFF & (codePoint >> 16));
+                    buffer[index++] = (byte)(0xFF & (codePoint >> 8));
+                    buffer[index++] = (byte)(0xFF & codePoint);
+                }
+            }
+            buffer[index++] = FormatSpec.GROUP_CHARACTERS_TERMINATOR;
+            return index - origin;
+        }
+
+        /**
+         * Writes a string with our character format to a ByteArrayOutputStream.
+         *
+         * This will also write the terminator byte.
+         *
+         * @param buffer the ByteArrayOutputStream to write to.
+         * @param word the string to write.
+         */
+        static void writeString(final ByteArrayOutputStream buffer, final String word) {
+            final int length = word.length();
+            for (int i = 0; i < length; i = word.offsetByCodePoints(i, 1)) {
+                final int codePoint = word.codePointAt(i);
+                if (1 == getCharSize(codePoint)) {
+                    buffer.write((byte) codePoint);
+                } else {
+                    buffer.write((byte) (0xFF & (codePoint >> 16)));
+                    buffer.write((byte) (0xFF & (codePoint >> 8)));
+                    buffer.write((byte) (0xFF & codePoint));
+                }
+            }
+            buffer.write(FormatSpec.GROUP_CHARACTERS_TERMINATOR);
+        }
+
+        /**
+         * Reads a string from a buffer. This is the converse of the above method.
+         */
+        static String readString(final FusionDictionaryBufferInterface buffer) {
+            final StringBuilder s = new StringBuilder();
+            int character = readChar(buffer);
+            while (character != FormatSpec.INVALID_CHARACTER) {
+                s.appendCodePoint(character);
+                character = readChar(buffer);
+            }
+            return s.toString();
+        }
+
+        /**
+         * Reads a character from the buffer.
+         *
+         * This follows the character format documented earlier in this source file.
+         *
+         * @param buffer the buffer, positioned over an encoded character.
+         * @return the character code.
+         */
+        static int readChar(final FusionDictionaryBufferInterface buffer) {
+            int character = buffer.readUnsignedByte();
+            if (!fitsOnOneByte(character)) {
+                if (FormatSpec.GROUP_CHARACTERS_TERMINATOR == character) {
+                    return FormatSpec.INVALID_CHARACTER;
+                }
+                character <<= 16;
+                character += buffer.readUnsignedShort();
+            }
+            return character;
+        }
+    }
+
+    // Input methods: Read a binary dictionary to memory.
+    // readDictionaryBinary is the public entry point for them.
+
+    static int readChildrenAddress(final FusionDictionaryBufferInterface buffer,
+            final int optionFlags, final FormatOptions options) {
+        if (options.mSupportsDynamicUpdate) {
+            final int address = buffer.readUnsignedInt24();
+            if (address == 0) return FormatSpec.NO_CHILDREN_ADDRESS;
+            if ((address & FormatSpec.MSB24) != 0) {
+                return -(address & FormatSpec.SINT24_MAX);
+            } else {
+                return address;
+            }
+        }
+        int address;
+        switch (optionFlags & FormatSpec.MASK_GROUP_ADDRESS_TYPE) {
+            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_ONEBYTE:
+                return buffer.readUnsignedByte();
+            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_TWOBYTES:
+                return buffer.readUnsignedShort();
+            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_THREEBYTES:
+                return buffer.readUnsignedInt24();
+            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_NOADDRESS:
+            default:
+                return FormatSpec.NO_CHILDREN_ADDRESS;
+        }
+    }
+
+    static int readParentAddress(final FusionDictionaryBufferInterface buffer,
+            final FormatOptions formatOptions) {
+        if (BinaryDictIOUtils.supportsDynamicUpdate(formatOptions)) {
+            final int parentAddress = buffer.readUnsignedInt24();
+            final int sign = ((parentAddress & FormatSpec.MSB24) != 0) ? -1 : 1;
+            return sign * (parentAddress & FormatSpec.SINT24_MAX);
+        } else {
+            return FormatSpec.NO_PARENT_ADDRESS;
+        }
+    }
+
+    private static final int[] CHARACTER_BUFFER = new int[FormatSpec.MAX_WORD_LENGTH];
+    public static CharGroupInfo readCharGroup(final FusionDictionaryBufferInterface buffer,
+            final int originalGroupAddress, final FormatOptions options) {
+        int addressPointer = originalGroupAddress;
+        final int flags = buffer.readUnsignedByte();
+        ++addressPointer;
+
+        final int parentAddress = readParentAddress(buffer, options);
+        if (BinaryDictIOUtils.supportsDynamicUpdate(options)) {
+            addressPointer += 3;
+        }
+
+        final int characters[];
+        if (0 != (flags & FormatSpec.FLAG_HAS_MULTIPLE_CHARS)) {
+            int index = 0;
+            int character = CharEncoding.readChar(buffer);
+            addressPointer += CharEncoding.getCharSize(character);
+            while (-1 != character) {
+                // FusionDictionary is making sure that the length of the word is smaller than
+                // MAX_WORD_LENGTH.
+                // So we'll never write past the end of CHARACTER_BUFFER.
+                CHARACTER_BUFFER[index++] = character;
+                character = CharEncoding.readChar(buffer);
+                addressPointer += CharEncoding.getCharSize(character);
+            }
+            characters = Arrays.copyOfRange(CHARACTER_BUFFER, 0, index);
+        } else {
+            final int character = CharEncoding.readChar(buffer);
+            addressPointer += CharEncoding.getCharSize(character);
+            characters = new int[] { character };
+        }
+        final int frequency;
+        if (0 != (FormatSpec.FLAG_IS_TERMINAL & flags)) {
+            ++addressPointer;
+            frequency = buffer.readUnsignedByte();
+        } else {
+            frequency = CharGroup.NOT_A_TERMINAL;
+        }
+        int childrenAddress = readChildrenAddress(buffer, flags, options);
+        if (childrenAddress != FormatSpec.NO_CHILDREN_ADDRESS) {
+            childrenAddress += addressPointer;
+        }
+        addressPointer += BinaryDictIOUtils.getChildrenAddressSize(flags, options);
+        ArrayList<WeightedString> shortcutTargets = null;
+        if (0 != (flags & FormatSpec.FLAG_HAS_SHORTCUT_TARGETS)) {
+            final int pointerBefore = buffer.position();
+            shortcutTargets = new ArrayList<WeightedString>();
+            buffer.readUnsignedShort(); // Skip the size
+            while (true) {
+                final int targetFlags = buffer.readUnsignedByte();
+                final String word = CharEncoding.readString(buffer);
+                shortcutTargets.add(new WeightedString(word,
+                        targetFlags & FormatSpec.FLAG_ATTRIBUTE_FREQUENCY));
+                if (0 == (targetFlags & FormatSpec.FLAG_ATTRIBUTE_HAS_NEXT)) break;
+            }
+            addressPointer += buffer.position() - pointerBefore;
+        }
+        ArrayList<PendingAttribute> bigrams = null;
+        if (0 != (flags & FormatSpec.FLAG_HAS_BIGRAMS)) {
+            bigrams = new ArrayList<PendingAttribute>();
+            int bigramCount = 0;
+            while (bigramCount++ < FormatSpec.MAX_BIGRAMS_IN_A_GROUP) {
+                final int bigramFlags = buffer.readUnsignedByte();
+                ++addressPointer;
+                final int sign = 0 == (bigramFlags & FormatSpec.FLAG_ATTRIBUTE_OFFSET_NEGATIVE)
+                        ? 1 : -1;
+                int bigramAddress = addressPointer;
+                switch (bigramFlags & FormatSpec.MASK_ATTRIBUTE_ADDRESS_TYPE) {
+                case FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE:
+                    bigramAddress += sign * buffer.readUnsignedByte();
+                    addressPointer += 1;
+                    break;
+                case FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES:
+                    bigramAddress += sign * buffer.readUnsignedShort();
+                    addressPointer += 2;
+                    break;
+                case FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES:
+                    final int offset = (buffer.readUnsignedByte() << 16)
+                            + buffer.readUnsignedShort();
+                    bigramAddress += sign * offset;
+                    addressPointer += 3;
+                    break;
+                default:
+                    throw new RuntimeException("Has bigrams with no address");
+                }
+                bigrams.add(new PendingAttribute(bigramFlags & FormatSpec.FLAG_ATTRIBUTE_FREQUENCY,
+                        bigramAddress));
+                if (0 == (bigramFlags & FormatSpec.FLAG_ATTRIBUTE_HAS_NEXT)) break;
+            }
+            if (bigramCount >= FormatSpec.MAX_BIGRAMS_IN_A_GROUP) {
+                MakedictLog.d("too many bigrams in a group.");
+            }
+        }
+        return new CharGroupInfo(originalGroupAddress, addressPointer, flags, characters, frequency,
+                parentAddress, childrenAddress, shortcutTargets, bigrams);
+    }
+
+    /**
+     * Reads and returns the char group count out of a buffer and forwards the pointer.
+     */
+    public static int readCharGroupCount(final FusionDictionaryBufferInterface buffer) {
+        final int msb = buffer.readUnsignedByte();
+        if (FormatSpec.MAX_CHARGROUPS_FOR_ONE_BYTE_CHARGROUP_COUNT >= msb) {
+            return msb;
+        } else {
+            return ((FormatSpec.MAX_CHARGROUPS_FOR_ONE_BYTE_CHARGROUP_COUNT & msb) << 8)
+                    + buffer.readUnsignedByte();
+        }
+    }
+
+    /**
+     * Finds, as a string, the word at the address passed as an argument.
+     *
+     * @param buffer the buffer to read from.
+     * @param headerSize the size of the header.
+     * @param address the address to seek.
+     * @param formatOptions file format options.
+     * @return the word with its frequency, as a weighted string.
+     */
+    /* package for tests */ static WeightedString getWordAtAddress(
+            final FusionDictionaryBufferInterface buffer, final int headerSize, final int address,
+            final FormatOptions formatOptions) {
+        final WeightedString result;
+        final int originalPointer = buffer.position();
+        buffer.position(address);
+
+        if (BinaryDictIOUtils.supportsDynamicUpdate(formatOptions)) {
+            result = getWordAtAddressWithParentAddress(buffer, headerSize, address, formatOptions);
+        } else {
+            result = getWordAtAddressWithoutParentAddress(buffer, headerSize, address,
+                    formatOptions);
+        }
+
+        buffer.position(originalPointer);
+        return result;
+    }
+
+    @SuppressWarnings("unused")
+    private static WeightedString getWordAtAddressWithParentAddress(
+            final FusionDictionaryBufferInterface buffer, final int headerSize, final int address,
+            final FormatOptions options) {
+        int currentAddress = address;
+        int frequency = Integer.MIN_VALUE;
+        final StringBuilder builder = new StringBuilder();
+        // the length of the path from the root to the leaf is limited by MAX_WORD_LENGTH
+        for (int count = 0; count < FormatSpec.MAX_WORD_LENGTH; ++count) {
+            CharGroupInfo currentInfo;
+            int loopCounter = 0;
+            do {
+                buffer.position(currentAddress + headerSize);
+                currentInfo = readCharGroup(buffer, currentAddress, options);
+                if (BinaryDictIOUtils.isMovedGroup(currentInfo.mFlags, options)) {
+                    currentAddress = currentInfo.mParentAddress + currentInfo.mOriginalAddress;
+                }
+                if (DBG && loopCounter++ > MAX_JUMPS) {
+                    MakedictLog.d("Too many jumps - probably a bug");
+                }
+            } while (BinaryDictIOUtils.isMovedGroup(currentInfo.mFlags, options));
+            if (Integer.MIN_VALUE == frequency) frequency = currentInfo.mFrequency;
+            builder.insert(0,
+                    new String(currentInfo.mCharacters, 0, currentInfo.mCharacters.length));
+            if (currentInfo.mParentAddress == FormatSpec.NO_PARENT_ADDRESS) break;
+            currentAddress = currentInfo.mParentAddress + currentInfo.mOriginalAddress;
+        }
+        return new WeightedString(builder.toString(), frequency);
+    }
+
+    private static WeightedString getWordAtAddressWithoutParentAddress(
+            final FusionDictionaryBufferInterface buffer, final int headerSize, final int address,
+            final FormatOptions options) {
+        buffer.position(headerSize);
+        final int count = readCharGroupCount(buffer);
+        int groupOffset = BinaryDictIOUtils.getGroupCountSize(count);
+        final StringBuilder builder = new StringBuilder();
+        WeightedString result = null;
+
+        CharGroupInfo last = null;
+        for (int i = count - 1; i >= 0; --i) {
+            CharGroupInfo info = readCharGroup(buffer, groupOffset, options);
+            groupOffset = info.mEndAddress;
+            if (info.mOriginalAddress == address) {
+                builder.append(new String(info.mCharacters, 0, info.mCharacters.length));
+                result = new WeightedString(builder.toString(), info.mFrequency);
+                break; // and return
+            }
+            if (BinaryDictIOUtils.hasChildrenAddress(info.mChildrenAddress)) {
+                if (info.mChildrenAddress > address) {
+                    if (null == last) continue;
+                    builder.append(new String(last.mCharacters, 0, last.mCharacters.length));
+                    buffer.position(last.mChildrenAddress + headerSize);
+                    i = readCharGroupCount(buffer);
+                    groupOffset = last.mChildrenAddress + BinaryDictIOUtils.getGroupCountSize(i);
+                    last = null;
+                    continue;
+                }
+                last = info;
+            }
+            if (0 == i && BinaryDictIOUtils.hasChildrenAddress(last.mChildrenAddress)) {
+                builder.append(new String(last.mCharacters, 0, last.mCharacters.length));
+                buffer.position(last.mChildrenAddress + headerSize);
+                i = readCharGroupCount(buffer);
+                groupOffset = last.mChildrenAddress + BinaryDictIOUtils.getGroupCountSize(i);
+                last = null;
+                continue;
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Reads a single node array from a buffer.
+     *
+     * This methods reads the file at the current position. A node array is fully expected to start
+     * at the current position.
+     * This will recursively read other node arrays into the structure, populating the reverse
+     * maps on the fly and using them to keep track of already read nodes.
+     *
+     * @param buffer the buffer, correctly positioned at the start of a node array.
+     * @param headerSize the size, in bytes, of the file header.
+     * @param reverseNodeArrayMap a mapping from addresses to already read node arrays.
+     * @param reverseGroupMap a mapping from addresses to already read character groups.
+     * @param options file format options.
+     * @return the read node array with all his children already read.
+     */
+    private static PtNodeArray readNodeArray(final FusionDictionaryBufferInterface buffer,
+            final int headerSize, final Map<Integer, PtNodeArray> reverseNodeArrayMap,
+            final Map<Integer, CharGroup> reverseGroupMap, final FormatOptions options)
+            throws IOException {
+        final ArrayList<CharGroup> nodeArrayContents = new ArrayList<CharGroup>();
+        final int nodeArrayOrigin = buffer.position() - headerSize;
+
+        do { // Scan the linked-list node.
+            final int nodeArrayHeadPosition = buffer.position() - headerSize;
+            final int count = readCharGroupCount(buffer);
+            int groupOffset = nodeArrayHeadPosition + BinaryDictIOUtils.getGroupCountSize(count);
+            for (int i = count; i > 0; --i) { // Scan the array of CharGroup.
+                CharGroupInfo info = readCharGroup(buffer, groupOffset, options);
+                if (BinaryDictIOUtils.isMovedGroup(info.mFlags, options)) continue;
+                ArrayList<WeightedString> shortcutTargets = info.mShortcutTargets;
+                ArrayList<WeightedString> bigrams = null;
+                if (null != info.mBigrams) {
+                    bigrams = new ArrayList<WeightedString>();
+                    for (PendingAttribute bigram : info.mBigrams) {
+                        final WeightedString word = getWordAtAddress(
+                                buffer, headerSize, bigram.mAddress, options);
+                        final int reconstructedFrequency =
+                                reconstructBigramFrequency(word.mFrequency, bigram.mFrequency);
+                        bigrams.add(new WeightedString(word.mWord, reconstructedFrequency));
+                    }
+                }
+                if (BinaryDictIOUtils.hasChildrenAddress(info.mChildrenAddress)) {
+                    PtNodeArray children = reverseNodeArrayMap.get(info.mChildrenAddress);
+                    if (null == children) {
+                        final int currentPosition = buffer.position();
+                        buffer.position(info.mChildrenAddress + headerSize);
+                        children = readNodeArray(
+                                buffer, headerSize, reverseNodeArrayMap, reverseGroupMap, options);
+                        buffer.position(currentPosition);
+                    }
+                    nodeArrayContents.add(
+                            new CharGroup(info.mCharacters, shortcutTargets, bigrams,
+                                    info.mFrequency,
+                                    0 != (info.mFlags & FormatSpec.FLAG_IS_NOT_A_WORD),
+                                    0 != (info.mFlags & FormatSpec.FLAG_IS_BLACKLISTED), children));
+                } else {
+                    nodeArrayContents.add(
+                            new CharGroup(info.mCharacters, shortcutTargets, bigrams,
+                                    info.mFrequency,
+                                    0 != (info.mFlags & FormatSpec.FLAG_IS_NOT_A_WORD),
+                                    0 != (info.mFlags & FormatSpec.FLAG_IS_BLACKLISTED)));
+                }
+                groupOffset = info.mEndAddress;
+            }
+
+            // reach the end of the array.
+            if (options.mSupportsDynamicUpdate) {
+                final int nextAddress = buffer.readUnsignedInt24();
+                if (nextAddress >= 0 && nextAddress < buffer.limit()) {
+                    buffer.position(nextAddress);
+                } else {
+                    break;
+                }
+            }
+        } while (options.mSupportsDynamicUpdate &&
+                buffer.position() != FormatSpec.NO_FORWARD_LINK_ADDRESS);
+
+        final PtNodeArray nodeArray = new PtNodeArray(nodeArrayContents);
+        nodeArray.mCachedAddressBeforeUpdate = nodeArrayOrigin;
+        nodeArray.mCachedAddressAfterUpdate = nodeArrayOrigin;
+        reverseNodeArrayMap.put(nodeArray.mCachedAddressAfterUpdate, nodeArray);
+        return nodeArray;
+    }
+
+    /**
+     * Helper function to get the binary format version from the header.
+     * @throws IOException
+     */
+    private static int getFormatVersion(final FusionDictionaryBufferInterface buffer)
+            throws IOException {
+        final int magic = buffer.readInt();
+        if (FormatSpec.MAGIC_NUMBER == magic) return buffer.readUnsignedShort();
+        return FormatSpec.NOT_A_VERSION_NUMBER;
+    }
+
+    /**
+     * Helper function to get and validate the binary format version.
+     * @throws UnsupportedFormatException
+     * @throws IOException
+     */
+    static int checkFormatVersion(final FusionDictionaryBufferInterface buffer)
+            throws IOException, UnsupportedFormatException {
+        final int version = getFormatVersion(buffer);
+        if (version < FormatSpec.MINIMUM_SUPPORTED_VERSION
+                || version > FormatSpec.MAXIMUM_SUPPORTED_VERSION) {
+            throw new UnsupportedFormatException("This file has version " + version
+                    + ", but this implementation does not support versions above "
+                    + FormatSpec.MAXIMUM_SUPPORTED_VERSION);
+        }
+        return version;
+    }
+
+    /**
+     * Reads a header from a buffer.
+     * @param headerReader the header reader
+     * @throws IOException
+     * @throws UnsupportedFormatException
+     */
+    public static FileHeader readHeader(final HeaderReaderInterface headerReader)
+            throws IOException, UnsupportedFormatException {
+        final int version = headerReader.readVersion();
+        final int optionsFlags = headerReader.readOptionFlags();
+
+        final int headerSize = headerReader.readHeaderSize();
+
+        if (headerSize < 0) {
+            throw new UnsupportedFormatException("header size can't be negative.");
+        }
+
+        final HashMap<String, String> attributes = headerReader.readAttributes(headerSize);
+
+        final FileHeader header = new FileHeader(headerSize,
+                new FusionDictionary.DictionaryOptions(attributes,
+                        0 != (optionsFlags & FormatSpec.GERMAN_UMLAUT_PROCESSING_FLAG),
+                        0 != (optionsFlags & FormatSpec.FRENCH_LIGATURE_PROCESSING_FLAG)),
+                new FormatOptions(version,
+                        0 != (optionsFlags & FormatSpec.SUPPORTS_DYNAMIC_UPDATE)));
+        return header;
+    }
+
+    /**
+     * Reads options from a buffer and populate a map with their contents.
+     *
+     * The buffer is read at the current position, so the caller must take care the pointer
+     * is in the right place before calling this.
+     */
+    public static void populateOptions(final FusionDictionaryBufferInterface buffer,
+            final int headerSize, final HashMap<String, String> options) {
+        while (buffer.position() < headerSize) {
+            final String key = CharEncoding.readString(buffer);
+            final String value = CharEncoding.readString(buffer);
+            options.put(key, value);
+        }
+    }
+
+    /**
+     * Reads a buffer and returns the memory representation of the dictionary.
+     *
+     * This high-level method takes a buffer and reads its contents, populating a
+     * FusionDictionary structure. The optional dict argument is an existing dictionary to
+     * which words from the buffer should be added. If it is null, a new dictionary is created.
+     *
+     * @param reader the reader.
+     * @param dict an optional dictionary to add words to, or null.
+     * @return the created (or merged) dictionary.
+     */
+    @UsedForTesting
+    public static FusionDictionary readDictionaryBinary(final BinaryDictReader reader,
+            final FusionDictionary dict) throws FileNotFoundException, IOException,
+            UnsupportedFormatException {
+
+        // if the buffer has not been opened, open the buffer with bytebuffer.
+        if (reader.getBuffer() == null) reader.openBuffer(
+                new BinaryDictReader.FusionDictionaryBufferFromByteBufferFactory());
+        if (reader.getBuffer() == null) {
+            MakedictLog.e("Cannot open the buffer");
+        }
+
+        // Read header
+        final FileHeader fileHeader = readHeader(reader);
+
+        Map<Integer, PtNodeArray> reverseNodeArrayMapping = new TreeMap<Integer, PtNodeArray>();
+        Map<Integer, CharGroup> reverseGroupMapping = new TreeMap<Integer, CharGroup>();
+        final PtNodeArray root = readNodeArray(reader.getBuffer(), fileHeader.mHeaderSize,
+                reverseNodeArrayMapping, reverseGroupMapping, fileHeader.mFormatOptions);
+
+        FusionDictionary newDict = new FusionDictionary(root, fileHeader.mDictionaryOptions);
+        if (null != dict) {
+            for (final Word w : dict) {
+                if (w.mIsBlacklistEntry) {
+                    newDict.addBlacklistEntry(w.mWord, w.mShortcutTargets, w.mIsNotAWord);
+                } else {
+                    newDict.add(w.mWord, w.mFrequency, w.mShortcutTargets, w.mIsNotAWord);
+                }
+            }
+            for (final Word w : dict) {
+                // By construction a binary dictionary may not have bigrams pointing to
+                // words that are not also registered as unigrams so we don't have to avoid
+                // them explicitly here.
+                for (final WeightedString bigram : w.mBigrams) {
+                    newDict.setBigram(w.mWord, bigram.mWord, bigram.mFrequency);
+                }
+            }
+        }
+
+        return newDict;
+    }
+
+    /**
+     * Helper method to pass a file name instead of a File object to isBinaryDictionary.
+     */
+    public static boolean isBinaryDictionary(final String filename) {
+        final File file = new File(filename);
+        return isBinaryDictionary(file);
+    }
+
+    /**
+     * Basic test to find out whether the file is a binary dictionary or not.
+     *
+     * Concretely this only tests the magic number.
+     *
+     * @param file The file to test.
+     * @return true if it's a binary dictionary, false otherwise
+     */
+    public static boolean isBinaryDictionary(final File file) {
+        FileInputStream inStream = null;
+        try {
+            inStream = new FileInputStream(file);
+            final ByteBuffer buffer = inStream.getChannel().map(
+                    FileChannel.MapMode.READ_ONLY, 0, file.length());
+            final int version = getFormatVersion(new ByteBufferWrapper(buffer));
+            return (version >= FormatSpec.MINIMUM_SUPPORTED_VERSION
+                    && version <= FormatSpec.MAXIMUM_SUPPORTED_VERSION);
+        } catch (FileNotFoundException e) {
+            return false;
+        } catch (IOException e) {
+            return false;
+        } finally {
+            if (inStream != null) {
+                try {
+                    inStream.close();
+                } catch (IOException e) {
+                    // do nothing
+                }
+            }
+        }
+    }
+
+    /**
+     * Calculate bigram frequency from compressed value
+     *
+     * @param unigramFrequency
+     * @param bigramFrequency compressed frequency
+     * @return approximate bigram frequency
+     */
+    public static int reconstructBigramFrequency(final int unigramFrequency,
+            final int bigramFrequency) {
+        final float stepSize = (FormatSpec.MAX_TERMINAL_FREQUENCY - unigramFrequency)
+                / (1.5f + FormatSpec.MAX_BIGRAM_FREQUENCY);
+        final float resultFreqFloat = unigramFrequency + stepSize * (bigramFrequency + 1.0f);
+        return (int)resultFreqFloat;
+    }
+}
diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoder.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoder.java
new file mode 100644
index 0000000..d9005b9
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoder.java
@@ -0,0 +1,1006 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.inputmethod.latin.makedict;
+
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder.CharEncoding;
+import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
+import com.android.inputmethod.latin.makedict.FusionDictionary.CharGroup;
+import com.android.inputmethod.latin.makedict.FusionDictionary.DictionaryOptions;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
+import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.ArrayList;
+import java.util.Iterator;
+
+/**
+ * Encodes binary files for a FusionDictionary.
+ *
+ * All the methods in this class are static.
+ */
+public class BinaryDictEncoder {
+
+    private static final boolean DBG = MakedictLog.DBG;
+
+    private BinaryDictEncoder() {
+        // This utility class is not publicly instantiable.
+    }
+
+    // Arbitrary limit to how much passes we consider address size compression should
+    // terminate in. At the time of this writing, our largest dictionary completes
+    // compression in five passes.
+    // If the number of passes exceeds this number, makedict bails with an exception on
+    // suspicion that a bug might be causing an infinite loop.
+    private static final int MAX_PASSES = 24;
+
+    /**
+     * Compute the binary size of the character array.
+     *
+     * If only one character, this is the size of this character. If many, it's the sum of their
+     * sizes + 1 byte for the terminator.
+     *
+     * @param characters the character array
+     * @return the size of the char array, including the terminator if any
+     */
+    static int getGroupCharactersSize(final int[] characters) {
+        int size = CharEncoding.getCharArraySize(characters);
+        if (characters.length > 1) size += FormatSpec.GROUP_TERMINATOR_SIZE;
+        return size;
+    }
+
+    /**
+     * Compute the binary size of the character array in a group
+     *
+     * If only one character, this is the size of this character. If many, it's the sum of their
+     * sizes + 1 byte for the terminator.
+     *
+     * @param group the group
+     * @return the size of the char array, including the terminator if any
+     */
+    private static int getGroupCharactersSize(final CharGroup group) {
+        return getGroupCharactersSize(group.mChars);
+    }
+
+    /**
+     * Compute the binary size of the group count for a node array.
+     * @param nodeArray the nodeArray
+     * @return the size of the group count, either 1 or 2 bytes.
+     */
+    private static int getGroupCountSize(final PtNodeArray nodeArray) {
+        return BinaryDictIOUtils.getGroupCountSize(nodeArray.mData.size());
+    }
+
+    /**
+     * Compute the size of a shortcut in bytes.
+     */
+    private static int getShortcutSize(final WeightedString shortcut) {
+        int size = FormatSpec.GROUP_ATTRIBUTE_FLAGS_SIZE;
+        final String word = shortcut.mWord;
+        final int length = word.length();
+        for (int i = 0; i < length; i = word.offsetByCodePoints(i, 1)) {
+            final int codePoint = word.codePointAt(i);
+            size += CharEncoding.getCharSize(codePoint);
+        }
+        size += FormatSpec.GROUP_TERMINATOR_SIZE;
+        return size;
+    }
+
+    /**
+     * Compute the size of a shortcut list in bytes.
+     *
+     * This is known in advance and does not change according to position in the file
+     * like address lists do.
+     */
+    static int getShortcutListSize(final ArrayList<WeightedString> shortcutList) {
+        if (null == shortcutList) return 0;
+        int size = FormatSpec.GROUP_SHORTCUT_LIST_SIZE_SIZE;
+        for (final WeightedString shortcut : shortcutList) {
+            size += getShortcutSize(shortcut);
+        }
+        return size;
+    }
+
+    /**
+     * Compute the maximum size of a CharGroup, assuming 3-byte addresses for everything.
+     *
+     * @param group the CharGroup to compute the size of.
+     * @param options file format options.
+     * @return the maximum size of the group.
+     */
+    private static int getCharGroupMaximumSize(final CharGroup group, final FormatOptions options) {
+        int size = getGroupHeaderSize(group, options);
+        // If terminal, one byte for the frequency
+        if (group.isTerminal()) size += FormatSpec.GROUP_FREQUENCY_SIZE;
+        size += FormatSpec.GROUP_MAX_ADDRESS_SIZE; // For children address
+        size += getShortcutListSize(group.mShortcutTargets);
+        if (null != group.mBigrams) {
+            size += (FormatSpec.GROUP_ATTRIBUTE_FLAGS_SIZE
+                    + FormatSpec.GROUP_ATTRIBUTE_MAX_ADDRESS_SIZE)
+                    * group.mBigrams.size();
+        }
+        return size;
+    }
+
+    /**
+     * Compute the maximum size of each node of a node array, assuming 3-byte addresses for
+     * everything, and caches it in the `mCachedSize' member of the nodes; deduce the size of
+     * the containing node array, and cache it it its 'mCachedSize' member.
+     *
+     * @param nodeArray the node array to compute the maximum size of.
+     * @param options file format options.
+     */
+    private static void calculateNodeArrayMaximumSize(final PtNodeArray nodeArray,
+            final FormatOptions options) {
+        int size = getGroupCountSize(nodeArray);
+        for (CharGroup g : nodeArray.mData) {
+            final int groupSize = getCharGroupMaximumSize(g, options);
+            g.mCachedSize = groupSize;
+            size += groupSize;
+        }
+        if (options.mSupportsDynamicUpdate) {
+            size += FormatSpec.FORWARD_LINK_ADDRESS_SIZE;
+        }
+        nodeArray.mCachedSize = size;
+    }
+
+    /**
+     * Compute the size of the header (flag + [parent address] + characters size) of a CharGroup.
+     *
+     * @param group the group of which to compute the size of the header
+     * @param options file format options.
+     */
+    private static int getGroupHeaderSize(final CharGroup group, final FormatOptions options) {
+        if (BinaryDictIOUtils.supportsDynamicUpdate(options)) {
+            return FormatSpec.GROUP_FLAGS_SIZE + FormatSpec.PARENT_ADDRESS_SIZE
+                    + getGroupCharactersSize(group);
+        } else {
+            return FormatSpec.GROUP_FLAGS_SIZE + getGroupCharactersSize(group);
+        }
+    }
+
+    /**
+     * Compute the size, in bytes, that an address will occupy.
+     *
+     * This can be used either for children addresses (which are always positive) or for
+     * attribute, which may be positive or negative but
+     * store their sign bit separately.
+     *
+     * @param address the address
+     * @return the byte size.
+     */
+    static int getByteSize(final int address) {
+        assert(address <= FormatSpec.UINT24_MAX);
+        if (!BinaryDictIOUtils.hasChildrenAddress(address)) {
+            return 0;
+        } else if (Math.abs(address) <= FormatSpec.UINT8_MAX) {
+            return 1;
+        } else if (Math.abs(address) <= FormatSpec.UINT16_MAX) {
+            return 2;
+        } else {
+            return 3;
+        }
+    }
+
+    // End utility methods
+
+    // This method is responsible for finding a nice ordering of the nodes that favors run-time
+    // cache performance and dictionary size.
+    /* package for tests */ static ArrayList<PtNodeArray> flattenTree(
+            final PtNodeArray rootNodeArray) {
+        final int treeSize = FusionDictionary.countCharGroups(rootNodeArray);
+        MakedictLog.i("Counted nodes : " + treeSize);
+        final ArrayList<PtNodeArray> flatTree = new ArrayList<PtNodeArray>(treeSize);
+        return flattenTreeInner(flatTree, rootNodeArray);
+    }
+
+    private static ArrayList<PtNodeArray> flattenTreeInner(final ArrayList<PtNodeArray> list,
+            final PtNodeArray nodeArray) {
+        // Removing the node is necessary if the tails are merged, because we would then
+        // add the same node several times when we only want it once. A number of places in
+        // the code also depends on any node being only once in the list.
+        // Merging tails can only be done if there are no attributes. Searching for attributes
+        // in LatinIME code depends on a total breadth-first ordering, which merging tails
+        // breaks. If there are no attributes, it should be fine (and reduce the file size)
+        // to merge tails, and removing the node from the list would be necessary. However,
+        // we don't merge tails because breaking the breadth-first ordering would result in
+        // extreme overhead at bigram lookup time (it would make the search function O(n) instead
+        // of the current O(log(n)), where n=number of nodes in the dictionary which is pretty
+        // high).
+        // If no nodes are ever merged, we can't have the same node twice in the list, hence
+        // searching for duplicates in unnecessary. It is also very performance consuming,
+        // since `list' is an ArrayList so it's an O(n) operation that runs on all nodes, making
+        // this simple list.remove operation O(n*n) overall. On Android this overhead is very
+        // high.
+        // For future reference, the code to remove duplicate is a simple : list.remove(node);
+        list.add(nodeArray);
+        final ArrayList<CharGroup> branches = nodeArray.mData;
+        final int nodeSize = branches.size();
+        for (CharGroup group : branches) {
+            if (null != group.mChildren) flattenTreeInner(list, group.mChildren);
+        }
+        return list;
+    }
+
+    /**
+     * Get the offset from a position inside a current node array to a target node array, during
+     * update.
+     *
+     * If the current node array is before the target node array, the target node array has not
+     * been updated yet, so we should return the offset from the old position of the current node
+     * array to the old position of the target node array. If on the other hand the target is
+     * before the current node array, it already has been updated, so we should return the offset
+     * from the new position in the current node array to the new position in the target node
+     * array.
+     *
+     * @param currentNodeArray node array containing the CharGroup where the offset will be written
+     * @param offsetFromStartOfCurrentNodeArray offset, in bytes, from the start of currentNodeArray
+     * @param targetNodeArray the target node array to get the offset to
+     * @return the offset to the target node array
+     */
+    private static int getOffsetToTargetNodeArrayDuringUpdate(final PtNodeArray currentNodeArray,
+            final int offsetFromStartOfCurrentNodeArray, final PtNodeArray targetNodeArray) {
+        final boolean isTargetBeforeCurrent = (targetNodeArray.mCachedAddressBeforeUpdate
+                < currentNodeArray.mCachedAddressBeforeUpdate);
+        if (isTargetBeforeCurrent) {
+            return targetNodeArray.mCachedAddressAfterUpdate
+                    - (currentNodeArray.mCachedAddressAfterUpdate
+                            + offsetFromStartOfCurrentNodeArray);
+        } else {
+            return targetNodeArray.mCachedAddressBeforeUpdate
+                    - (currentNodeArray.mCachedAddressBeforeUpdate
+                            + offsetFromStartOfCurrentNodeArray);
+        }
+    }
+
+    /**
+     * Get the offset from a position inside a current node array to a target CharGroup, during
+     * update.
+     *
+     * @param currentNodeArray node array containing the CharGroup where the offset will be written
+     * @param offsetFromStartOfCurrentNodeArray offset, in bytes, from the start of currentNodeArray
+     * @param targetCharGroup the target CharGroup to get the offset to
+     * @return the offset to the target CharGroup
+     */
+    // TODO: is there any way to factorize this method with the one above?
+    private static int getOffsetToTargetCharGroupDuringUpdate(final PtNodeArray currentNodeArray,
+            final int offsetFromStartOfCurrentNodeArray, final CharGroup targetCharGroup) {
+        final int oldOffsetBasePoint = currentNodeArray.mCachedAddressBeforeUpdate
+                + offsetFromStartOfCurrentNodeArray;
+        final boolean isTargetBeforeCurrent = (targetCharGroup.mCachedAddressBeforeUpdate
+                < oldOffsetBasePoint);
+        // If the target is before the current node array, then its address has already been
+        // updated. We can use the AfterUpdate member, and compare it to our own member after
+        // update. Otherwise, the AfterUpdate member is not updated yet, so we need to use the
+        // BeforeUpdate member, and of course we have to compare this to our own address before
+        // update.
+        if (isTargetBeforeCurrent) {
+            final int newOffsetBasePoint = currentNodeArray.mCachedAddressAfterUpdate
+                    + offsetFromStartOfCurrentNodeArray;
+            return targetCharGroup.mCachedAddressAfterUpdate - newOffsetBasePoint;
+        } else {
+            return targetCharGroup.mCachedAddressBeforeUpdate - oldOffsetBasePoint;
+        }
+    }
+
+    /**
+     * Computes the actual node array size, based on the cached addresses of the children nodes.
+     *
+     * Each node array stores its tentative address. During dictionary address computing, these
+     * are not final, but they can be used to compute the node array size (the node array size
+     * depends on the address of the children because the number of bytes necessary to store an
+     * address depends on its numeric value. The return value indicates whether the node array
+     * contents (as in, any of the addresses stored in the cache fields) have changed with
+     * respect to their previous value.
+     *
+     * @param nodeArray the node array to compute the size of.
+     * @param dict the dictionary in which the word/attributes are to be found.
+     * @param formatOptions file format options.
+     * @return false if none of the cached addresses inside the node array changed, true otherwise.
+     */
+    private static boolean computeActualNodeArraySize(final PtNodeArray nodeArray,
+            final FusionDictionary dict, final FormatOptions formatOptions) {
+        boolean changed = false;
+        int size = getGroupCountSize(nodeArray);
+        for (CharGroup group : nodeArray.mData) {
+            group.mCachedAddressAfterUpdate = nodeArray.mCachedAddressAfterUpdate + size;
+            if (group.mCachedAddressAfterUpdate != group.mCachedAddressBeforeUpdate) {
+                changed = true;
+            }
+            int groupSize = getGroupHeaderSize(group, formatOptions);
+            if (group.isTerminal()) groupSize += FormatSpec.GROUP_FREQUENCY_SIZE;
+            if (null == group.mChildren && formatOptions.mSupportsDynamicUpdate) {
+                groupSize += FormatSpec.SIGNED_CHILDREN_ADDRESS_SIZE;
+            } else if (null != group.mChildren) {
+                if (formatOptions.mSupportsDynamicUpdate) {
+                    groupSize += FormatSpec.SIGNED_CHILDREN_ADDRESS_SIZE;
+                } else {
+                    groupSize += getByteSize(getOffsetToTargetNodeArrayDuringUpdate(nodeArray,
+                            groupSize + size, group.mChildren));
+                }
+            }
+            groupSize += getShortcutListSize(group.mShortcutTargets);
+            if (null != group.mBigrams) {
+                for (WeightedString bigram : group.mBigrams) {
+                    final int offset = getOffsetToTargetCharGroupDuringUpdate(nodeArray,
+                            groupSize + size + FormatSpec.GROUP_FLAGS_SIZE,
+                            FusionDictionary.findWordInTree(dict.mRootNodeArray, bigram.mWord));
+                    groupSize += getByteSize(offset) + FormatSpec.GROUP_FLAGS_SIZE;
+                }
+            }
+            group.mCachedSize = groupSize;
+            size += groupSize;
+        }
+        if (formatOptions.mSupportsDynamicUpdate) {
+            size += FormatSpec.FORWARD_LINK_ADDRESS_SIZE;
+        }
+        if (nodeArray.mCachedSize != size) {
+            nodeArray.mCachedSize = size;
+            changed = true;
+        }
+        return changed;
+    }
+
+    /**
+     * Initializes the cached addresses of node arrays and their containing nodes from their size.
+     *
+     * @param flatNodes the list of node arrays.
+     * @param formatOptions file format options.
+     * @return the byte size of the entire stack.
+     */
+    private static int initializeNodeArraysCachedAddresses(final ArrayList<PtNodeArray> flatNodes,
+            final FormatOptions formatOptions) {
+        int nodeArrayOffset = 0;
+        for (final PtNodeArray nodeArray : flatNodes) {
+            nodeArray.mCachedAddressBeforeUpdate = nodeArrayOffset;
+            int groupCountSize = getGroupCountSize(nodeArray);
+            int groupOffset = 0;
+            for (final CharGroup g : nodeArray.mData) {
+                g.mCachedAddressBeforeUpdate = g.mCachedAddressAfterUpdate =
+                        groupCountSize + nodeArrayOffset + groupOffset;
+                groupOffset += g.mCachedSize;
+            }
+            final int nodeSize = groupCountSize + groupOffset
+                    + (formatOptions.mSupportsDynamicUpdate
+                            ? FormatSpec.FORWARD_LINK_ADDRESS_SIZE : 0);
+            nodeArrayOffset += nodeArray.mCachedSize;
+        }
+        return nodeArrayOffset;
+    }
+
+    /**
+     * Updates the cached addresses of node arrays after recomputing their new positions.
+     *
+     * @param flatNodes the list of node arrays.
+     */
+    private static void updateNodeArraysCachedAddresses(final ArrayList<PtNodeArray> flatNodes) {
+        for (final PtNodeArray nodeArray : flatNodes) {
+            nodeArray.mCachedAddressBeforeUpdate = nodeArray.mCachedAddressAfterUpdate;
+            for (final CharGroup g : nodeArray.mData) {
+                g.mCachedAddressBeforeUpdate = g.mCachedAddressAfterUpdate;
+            }
+        }
+    }
+
+    /**
+     * Compute the cached parent addresses after all has been updated.
+     *
+     * The parent addresses are used by some binary formats at write-to-disk time. Not all formats
+     * need them. In particular, version 2 does not need them, and version 3 does.
+     *
+     * @param flatNodes the flat array of node arrays to fill in
+     */
+    private static void computeParentAddresses(final ArrayList<PtNodeArray> flatNodes) {
+        for (final PtNodeArray nodeArray : flatNodes) {
+            for (final CharGroup group : nodeArray.mData) {
+                if (null != group.mChildren) {
+                    // Assign my address to children's parent address
+                    // Here BeforeUpdate and AfterUpdate addresses have the same value, so it
+                    // does not matter which we use.
+                    group.mChildren.mCachedParentAddress = group.mCachedAddressAfterUpdate
+                            - group.mChildren.mCachedAddressAfterUpdate;
+                }
+            }
+        }
+    }
+
+    /**
+     * Compute the addresses and sizes of an ordered list of node arrays.
+     *
+     * This method takes a list of node arrays and will update their cached address and size
+     * values so that they can be written into a file. It determines the smallest size each of the
+     * nodes arrays can be given the addresses of its children and attributes, and store that into
+     * each node.
+     * The order of the node is given by the order of the array. This method makes no effort
+     * to find a good order; it only mechanically computes the size this order results in.
+     *
+     * @param dict the dictionary
+     * @param flatNodes the ordered list of nodes arrays
+     * @param formatOptions file format options.
+     * @return the same array it was passed. The nodes have been updated for address and size.
+     */
+    private static ArrayList<PtNodeArray> computeAddresses(final FusionDictionary dict,
+            final ArrayList<PtNodeArray> flatNodes, final FormatOptions formatOptions) {
+        // First get the worst possible sizes and offsets
+        for (final PtNodeArray n : flatNodes) calculateNodeArrayMaximumSize(n, formatOptions);
+        final int offset = initializeNodeArraysCachedAddresses(flatNodes, formatOptions);
+
+        MakedictLog.i("Compressing the array addresses. Original size : " + offset);
+        MakedictLog.i("(Recursively seen size : " + offset + ")");
+
+        int passes = 0;
+        boolean changesDone = false;
+        do {
+            changesDone = false;
+            int nodeArrayStartOffset = 0;
+            for (final PtNodeArray nodeArray : flatNodes) {
+                nodeArray.mCachedAddressAfterUpdate = nodeArrayStartOffset;
+                final int oldNodeArraySize = nodeArray.mCachedSize;
+                final boolean changed = computeActualNodeArraySize(nodeArray, dict, formatOptions);
+                final int newNodeArraySize = nodeArray.mCachedSize;
+                if (oldNodeArraySize < newNodeArraySize) {
+                    throw new RuntimeException("Increased size ?!");
+                }
+                nodeArrayStartOffset += newNodeArraySize;
+                changesDone |= changed;
+            }
+            updateNodeArraysCachedAddresses(flatNodes);
+            ++passes;
+            if (passes > MAX_PASSES) throw new RuntimeException("Too many passes - probably a bug");
+        } while (changesDone);
+
+        if (formatOptions.mSupportsDynamicUpdate) {
+            computeParentAddresses(flatNodes);
+        }
+        final PtNodeArray lastNodeArray = flatNodes.get(flatNodes.size() - 1);
+        MakedictLog.i("Compression complete in " + passes + " passes.");
+        MakedictLog.i("After address compression : "
+                + (lastNodeArray.mCachedAddressAfterUpdate + lastNodeArray.mCachedSize));
+
+        return flatNodes;
+    }
+
+    /**
+     * Sanity-checking method.
+     *
+     * This method checks a list of node arrays for juxtaposition, that is, it will do
+     * nothing if each node array's cached address is actually the previous node array's address
+     * plus the previous node's size.
+     * If this is not the case, it will throw an exception.
+     *
+     * @param arrays the list of node arrays to check
+     */
+    private static void checkFlatNodeArrayList(final ArrayList<PtNodeArray> arrays) {
+        int offset = 0;
+        int index = 0;
+        for (final PtNodeArray nodeArray : arrays) {
+            // BeforeUpdate and AfterUpdate addresses are the same here, so it does not matter
+            // which we use.
+            if (nodeArray.mCachedAddressAfterUpdate != offset) {
+                throw new RuntimeException("Wrong address for node " + index
+                        + " : expected " + offset + ", got " + nodeArray.mCachedAddressAfterUpdate);
+            }
+            ++index;
+            offset += nodeArray.mCachedSize;
+        }
+    }
+
+    /**
+     * Helper method to write a variable-size address to a file.
+     *
+     * @param buffer the buffer to write to.
+     * @param index the index in the buffer to write the address to.
+     * @param address the address to write.
+     * @return the size in bytes the address actually took.
+     */
+    private static int writeVariableAddress(final byte[] buffer, int index, final int address) {
+        switch (getByteSize(address)) {
+        case 1:
+            buffer[index++] = (byte)address;
+            return 1;
+        case 2:
+            buffer[index++] = (byte)(0xFF & (address >> 8));
+            buffer[index++] = (byte)(0xFF & address);
+            return 2;
+        case 3:
+            buffer[index++] = (byte)(0xFF & (address >> 16));
+            buffer[index++] = (byte)(0xFF & (address >> 8));
+            buffer[index++] = (byte)(0xFF & address);
+            return 3;
+        case 0:
+            return 0;
+        default:
+            throw new RuntimeException("Address " + address + " has a strange size");
+        }
+    }
+
+    /**
+     * Helper method to write a variable-size signed address to a file.
+     *
+     * @param buffer the buffer to write to.
+     * @param index the index in the buffer to write the address to.
+     * @param address the address to write.
+     * @return the size in bytes the address actually took.
+     */
+    private static int writeVariableSignedAddress(final byte[] buffer, int index,
+            final int address) {
+        if (!BinaryDictIOUtils.hasChildrenAddress(address)) {
+            buffer[index] = buffer[index + 1] = buffer[index + 2] = 0;
+        } else {
+            final int absAddress = Math.abs(address);
+            buffer[index++] =
+                    (byte)((address < 0 ? FormatSpec.MSB8 : 0) | (0xFF & (absAddress >> 16)));
+            buffer[index++] = (byte)(0xFF & (absAddress >> 8));
+            buffer[index++] = (byte)(0xFF & absAddress);
+        }
+        return 3;
+    }
+
+    /**
+     * Makes the flag value for a char group.
+     *
+     * @param hasMultipleChars whether the group has multiple chars.
+     * @param isTerminal whether the group is terminal.
+     * @param childrenAddressSize the size of a children address.
+     * @param hasShortcuts whether the group has shortcuts.
+     * @param hasBigrams whether the group has bigrams.
+     * @param isNotAWord whether the group is not a word.
+     * @param isBlackListEntry whether the group is a blacklist entry.
+     * @param formatOptions file format options.
+     * @return the flags
+     */
+    static int makeCharGroupFlags(final boolean hasMultipleChars, final boolean isTerminal,
+            final int childrenAddressSize, final boolean hasShortcuts, final boolean hasBigrams,
+            final boolean isNotAWord, final boolean isBlackListEntry,
+            final FormatOptions formatOptions) {
+        byte flags = 0;
+        if (hasMultipleChars) flags |= FormatSpec.FLAG_HAS_MULTIPLE_CHARS;
+        if (isTerminal) flags |= FormatSpec.FLAG_IS_TERMINAL;
+        if (formatOptions.mSupportsDynamicUpdate) {
+            flags |= FormatSpec.FLAG_IS_NOT_MOVED;
+        } else if (true) {
+            switch (childrenAddressSize) {
+                case 1:
+                    flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_ONEBYTE;
+                    break;
+                case 2:
+                    flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_TWOBYTES;
+                    break;
+                case 3:
+                    flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_THREEBYTES;
+                    break;
+                case 0:
+                    flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_NOADDRESS;
+                    break;
+                default:
+                    throw new RuntimeException("Node with a strange address");
+            }
+        }
+        if (hasShortcuts) flags |= FormatSpec.FLAG_HAS_SHORTCUT_TARGETS;
+        if (hasBigrams) flags |= FormatSpec.FLAG_HAS_BIGRAMS;
+        if (isNotAWord) flags |= FormatSpec.FLAG_IS_NOT_A_WORD;
+        if (isBlackListEntry) flags |= FormatSpec.FLAG_IS_BLACKLISTED;
+        return flags;
+    }
+
+    private static byte makeCharGroupFlags(final CharGroup group, final int groupAddress,
+            final int childrenOffset, final FormatOptions formatOptions) {
+        return (byte) makeCharGroupFlags(group.mChars.length > 1, group.mFrequency >= 0,
+                getByteSize(childrenOffset), group.mShortcutTargets != null, group.mBigrams != null,
+                group.mIsNotAWord, group.mIsBlacklistEntry, formatOptions);
+    }
+
+    /**
+     * Makes the flag value for a bigram.
+     *
+     * @param more whether there are more bigrams after this one.
+     * @param offset the offset of the bigram.
+     * @param bigramFrequency the frequency of the bigram, 0..255.
+     * @param unigramFrequency the unigram frequency of the same word, 0..255.
+     * @param word the second bigram, for debugging purposes
+     * @return the flags
+     */
+    private static final int makeBigramFlags(final boolean more, final int offset,
+            int bigramFrequency, final int unigramFrequency, final String word) {
+        int bigramFlags = (more ? FormatSpec.FLAG_ATTRIBUTE_HAS_NEXT : 0)
+                + (offset < 0 ? FormatSpec.FLAG_ATTRIBUTE_OFFSET_NEGATIVE : 0);
+        switch (getByteSize(offset)) {
+        case 1:
+            bigramFlags |= FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE;
+            break;
+        case 2:
+            bigramFlags |= FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES;
+            break;
+        case 3:
+            bigramFlags |= FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES;
+            break;
+        default:
+            throw new RuntimeException("Strange offset size");
+        }
+        if (unigramFrequency > bigramFrequency) {
+            MakedictLog.e("Unigram freq is superior to bigram freq for \"" + word
+                    + "\". Bigram freq is " + bigramFrequency + ", unigram freq for "
+                    + word + " is " + unigramFrequency);
+            bigramFrequency = unigramFrequency;
+        }
+        // We compute the difference between 255 (which means probability = 1) and the
+        // unigram score. We split this into a number of discrete steps.
+        // Now, the steps are numbered 0~15; 0 represents an increase of 1 step while 15
+        // represents an increase of 16 steps: a value of 15 will be interpreted as the median
+        // value of the 16th step. In all justice, if the bigram frequency is low enough to be
+        // rounded below the first step (which means it is less than half a step higher than the
+        // unigram frequency) then the unigram frequency itself is the best approximation of the
+        // bigram freq that we could possibly supply, hence we should *not* include this bigram
+        // in the file at all.
+        // until this is done, we'll write 0 and slightly overestimate this case.
+        // In other words, 0 means "between 0.5 step and 1.5 step", 1 means "between 1.5 step
+        // and 2.5 steps", and 15 means "between 15.5 steps and 16.5 steps". So we want to
+        // divide our range [unigramFreq..MAX_TERMINAL_FREQUENCY] in 16.5 steps to get the
+        // step size. Then we compute the start of the first step (the one where value 0 starts)
+        // by adding half-a-step to the unigramFrequency. From there, we compute the integer
+        // number of steps to the bigramFrequency. One last thing: we want our steps to include
+        // their lower bound and exclude their higher bound so we need to have the first step
+        // start at exactly 1 unit higher than floor(unigramFreq + half a step).
+        // Note : to reconstruct the score, the dictionary reader will need to divide
+        // MAX_TERMINAL_FREQUENCY - unigramFreq by 16.5 likewise to get the value of the step,
+        // and add (discretizedFrequency + 0.5 + 0.5) times this value to get the best
+        // approximation. (0.5 to get the first step start, and 0.5 to get the middle of the
+        // step pointed by the discretized frequency.
+        final float stepSize =
+                (FormatSpec.MAX_TERMINAL_FREQUENCY - unigramFrequency)
+                / (1.5f + FormatSpec.MAX_BIGRAM_FREQUENCY);
+        final float firstStepStart = 1 + unigramFrequency + (stepSize / 2.0f);
+        final int discretizedFrequency = (int)((bigramFrequency - firstStepStart) / stepSize);
+        // If the bigram freq is less than half-a-step higher than the unigram freq, we get -1
+        // here. The best approximation would be the unigram freq itself, so we should not
+        // include this bigram in the dictionary. For now, register as 0, and live with the
+        // small over-estimation that we get in this case. TODO: actually remove this bigram
+        // if discretizedFrequency < 0.
+        final int finalBigramFrequency = discretizedFrequency > 0 ? discretizedFrequency : 0;
+        bigramFlags += finalBigramFrequency & FormatSpec.FLAG_ATTRIBUTE_FREQUENCY;
+        return bigramFlags;
+    }
+
+    /**
+     * Makes the 2-byte value for options flags.
+     */
+    private static final int makeOptionsValue(final FusionDictionary dictionary,
+            final FormatOptions formatOptions) {
+        final DictionaryOptions options = dictionary.mOptions;
+        final boolean hasBigrams = dictionary.hasBigrams();
+        return (options.mFrenchLigatureProcessing ? FormatSpec.FRENCH_LIGATURE_PROCESSING_FLAG : 0)
+                + (options.mGermanUmlautProcessing ? FormatSpec.GERMAN_UMLAUT_PROCESSING_FLAG : 0)
+                + (hasBigrams ? FormatSpec.CONTAINS_BIGRAMS_FLAG : 0)
+                + (formatOptions.mSupportsDynamicUpdate ? FormatSpec.SUPPORTS_DYNAMIC_UPDATE : 0);
+    }
+
+    /**
+     * Makes the flag value for a shortcut.
+     *
+     * @param more whether there are more attributes after this one.
+     * @param frequency the frequency of the attribute, 0..15
+     * @return the flags
+     */
+    static final int makeShortcutFlags(final boolean more, final int frequency) {
+        return (more ? FormatSpec.FLAG_ATTRIBUTE_HAS_NEXT : 0)
+                + (frequency & FormatSpec.FLAG_ATTRIBUTE_FREQUENCY);
+    }
+
+    private static final int writeParentAddress(final byte[] buffer, final int index,
+            final int address, final FormatOptions formatOptions) {
+        if (BinaryDictIOUtils.supportsDynamicUpdate(formatOptions)) {
+            if (address == FormatSpec.NO_PARENT_ADDRESS) {
+                buffer[index] = buffer[index + 1] = buffer[index + 2] = 0;
+            } else {
+                final int absAddress = Math.abs(address);
+                assert(absAddress <= FormatSpec.SINT24_MAX);
+                buffer[index] = (byte)((address < 0 ? FormatSpec.MSB8 : 0)
+                        | ((absAddress >> 16) & 0xFF));
+                buffer[index + 1] = (byte)((absAddress >> 8) & 0xFF);
+                buffer[index + 2] = (byte)(absAddress & 0xFF);
+            }
+            return index + 3;
+        } else {
+            return index;
+        }
+    }
+
+    /**
+     * Write a node array to memory. The node array is expected to have its final position cached.
+     *
+     * @param dict the dictionary the node array is a part of (for relative offsets).
+     * @param buffer the memory buffer to write to.
+     * @param nodeArray the node array to write.
+     * @param formatOptions file format options.
+     * @return the address of the END of the node.
+     */
+    @SuppressWarnings("unused")
+    private static int writePlacedNode(final FusionDictionary dict, byte[] buffer,
+            final PtNodeArray nodeArray, final FormatOptions formatOptions) {
+        // TODO: Make the code in common with BinaryDictIOUtils#writeCharGroup
+        int index = nodeArray.mCachedAddressAfterUpdate;
+
+        final int groupCount = nodeArray.mData.size();
+        final int countSize = getGroupCountSize(nodeArray);
+        final int parentAddress = nodeArray.mCachedParentAddress;
+        if (1 == countSize) {
+            buffer[index++] = (byte)groupCount;
+        } else if (2 == countSize) {
+            // We need to signal 2-byte size by setting the top bit of the MSB to 1, so
+            // we | 0x80 to do this.
+            buffer[index++] = (byte)((groupCount >> 8) | 0x80);
+            buffer[index++] = (byte)(groupCount & 0xFF);
+        } else {
+            throw new RuntimeException("Strange size from getGroupCountSize : " + countSize);
+        }
+        int groupAddress = index;
+        for (int i = 0; i < groupCount; ++i) {
+            final CharGroup group = nodeArray.mData.get(i);
+            if (index != group.mCachedAddressAfterUpdate) {
+                throw new RuntimeException("Bug: write index is not the same as the cached address "
+                        + "of the group : " + index + " <> " + group.mCachedAddressAfterUpdate);
+            }
+            groupAddress += getGroupHeaderSize(group, formatOptions);
+            // Sanity checks.
+            if (DBG && group.mFrequency > FormatSpec.MAX_TERMINAL_FREQUENCY) {
+                throw new RuntimeException("A node has a frequency > "
+                        + FormatSpec.MAX_TERMINAL_FREQUENCY
+                        + " : " + group.mFrequency);
+            }
+            if (group.mFrequency >= 0) groupAddress += FormatSpec.GROUP_FREQUENCY_SIZE;
+            final int childrenOffset = null == group.mChildren
+                    ? FormatSpec.NO_CHILDREN_ADDRESS
+                            : group.mChildren.mCachedAddressAfterUpdate - groupAddress;
+            buffer[index++] =
+                    makeCharGroupFlags(group, groupAddress, childrenOffset, formatOptions);
+
+            if (parentAddress == FormatSpec.NO_PARENT_ADDRESS) {
+                index = writeParentAddress(buffer, index, parentAddress, formatOptions);
+            } else {
+                index = writeParentAddress(buffer, index, parentAddress
+                        + (nodeArray.mCachedAddressAfterUpdate - group.mCachedAddressAfterUpdate),
+                        formatOptions);
+            }
+
+            index = CharEncoding.writeCharArray(group.mChars, buffer, index);
+            if (group.hasSeveralChars()) {
+                buffer[index++] = FormatSpec.GROUP_CHARACTERS_TERMINATOR;
+            }
+            if (group.mFrequency >= 0) {
+                buffer[index++] = (byte) group.mFrequency;
+            }
+
+            final int shift;
+            if (formatOptions.mSupportsDynamicUpdate) {
+                shift = writeVariableSignedAddress(buffer, index, childrenOffset);
+            } else {
+                shift = writeVariableAddress(buffer, index, childrenOffset);
+            }
+            index += shift;
+            groupAddress += shift;
+
+            // Write shortcuts
+            if (null != group.mShortcutTargets) {
+                final int indexOfShortcutByteSize = index;
+                index += FormatSpec.GROUP_SHORTCUT_LIST_SIZE_SIZE;
+                groupAddress += FormatSpec.GROUP_SHORTCUT_LIST_SIZE_SIZE;
+                final Iterator<WeightedString> shortcutIterator = group.mShortcutTargets.iterator();
+                while (shortcutIterator.hasNext()) {
+                    final WeightedString target = shortcutIterator.next();
+                    ++groupAddress;
+                    int shortcutFlags = makeShortcutFlags(shortcutIterator.hasNext(),
+                            target.mFrequency);
+                    buffer[index++] = (byte)shortcutFlags;
+                    final int shortcutShift = CharEncoding.writeString(buffer, index, target.mWord);
+                    index += shortcutShift;
+                    groupAddress += shortcutShift;
+                }
+                final int shortcutByteSize = index - indexOfShortcutByteSize;
+                if (shortcutByteSize > 0xFFFF) {
+                    throw new RuntimeException("Shortcut list too large");
+                }
+                buffer[indexOfShortcutByteSize] = (byte)(shortcutByteSize >> 8);
+                buffer[indexOfShortcutByteSize + 1] = (byte)(shortcutByteSize & 0xFF);
+            }
+            // Write bigrams
+            if (null != group.mBigrams) {
+                final Iterator<WeightedString> bigramIterator = group.mBigrams.iterator();
+                while (bigramIterator.hasNext()) {
+                    final WeightedString bigram = bigramIterator.next();
+                    final CharGroup target =
+                            FusionDictionary.findWordInTree(dict.mRootNodeArray, bigram.mWord);
+                    final int addressOfBigram = target.mCachedAddressAfterUpdate;
+                    final int unigramFrequencyForThisWord = target.mFrequency;
+                    ++groupAddress;
+                    final int offset = addressOfBigram - groupAddress;
+                    int bigramFlags = makeBigramFlags(bigramIterator.hasNext(), offset,
+                            bigram.mFrequency, unigramFrequencyForThisWord, bigram.mWord);
+                    buffer[index++] = (byte)bigramFlags;
+                    final int bigramShift = writeVariableAddress(buffer, index, Math.abs(offset));
+                    index += bigramShift;
+                    groupAddress += bigramShift;
+                }
+            }
+
+        }
+        if (formatOptions.mSupportsDynamicUpdate) {
+            buffer[index] = buffer[index + 1] = buffer[index + 2]
+                    = FormatSpec.NO_FORWARD_LINK_ADDRESS;
+            index += FormatSpec.FORWARD_LINK_ADDRESS_SIZE;
+        }
+        if (index != nodeArray.mCachedAddressAfterUpdate + nodeArray.mCachedSize) {
+            throw new RuntimeException(
+                    "Not the same size : written " + (index - nodeArray.mCachedAddressAfterUpdate)
+                     + " bytes from a node that should have " + nodeArray.mCachedSize + " bytes");
+        }
+        return index;
+    }
+
+    /**
+     * Dumps a collection of useful statistics about a list of node arrays.
+     *
+     * This prints purely informative stuff, like the total estimated file size, the
+     * number of node arrays, of character groups, the repartition of each address size, etc
+     *
+     * @param nodeArrays the list of node arrays.
+     */
+    private static void showStatistics(ArrayList<PtNodeArray> nodeArrays) {
+        int firstTerminalAddress = Integer.MAX_VALUE;
+        int lastTerminalAddress = Integer.MIN_VALUE;
+        int size = 0;
+        int charGroups = 0;
+        int maxGroups = 0;
+        int maxRuns = 0;
+        for (final PtNodeArray nodeArray : nodeArrays) {
+            if (maxGroups < nodeArray.mData.size()) maxGroups = nodeArray.mData.size();
+            for (final CharGroup cg : nodeArray.mData) {
+                ++charGroups;
+                if (cg.mChars.length > maxRuns) maxRuns = cg.mChars.length;
+                if (cg.mFrequency >= 0) {
+                    if (nodeArray.mCachedAddressAfterUpdate < firstTerminalAddress)
+                        firstTerminalAddress = nodeArray.mCachedAddressAfterUpdate;
+                    if (nodeArray.mCachedAddressAfterUpdate > lastTerminalAddress)
+                        lastTerminalAddress = nodeArray.mCachedAddressAfterUpdate;
+                }
+            }
+            if (nodeArray.mCachedAddressAfterUpdate + nodeArray.mCachedSize > size) {
+                size = nodeArray.mCachedAddressAfterUpdate + nodeArray.mCachedSize;
+            }
+        }
+        final int[] groupCounts = new int[maxGroups + 1];
+        final int[] runCounts = new int[maxRuns + 1];
+        for (final PtNodeArray nodeArray : nodeArrays) {
+            ++groupCounts[nodeArray.mData.size()];
+            for (final CharGroup cg : nodeArray.mData) {
+                ++runCounts[cg.mChars.length];
+            }
+        }
+
+        MakedictLog.i("Statistics:\n"
+                + "  total file size " + size + "\n"
+                + "  " + nodeArrays.size() + " node arrays\n"
+                + "  " + charGroups + " groups (" + ((float)charGroups / nodeArrays.size())
+                        + " groups per node)\n"
+                + "  first terminal at " + firstTerminalAddress + "\n"
+                + "  last terminal at " + lastTerminalAddress + "\n"
+                + "  Group stats : max = " + maxGroups);
+        for (int i = 0; i < groupCounts.length; ++i) {
+            MakedictLog.i("    " + i + " : " + groupCounts[i]);
+        }
+        MakedictLog.i("  Character run stats : max = " + maxRuns);
+        for (int i = 0; i < runCounts.length; ++i) {
+            MakedictLog.i("    " + i + " : " + runCounts[i]);
+        }
+    }
+
+    /**
+     * Dumps a FusionDictionary to a file.
+     *
+     * This is the public entry point to write a dictionary to a file.
+     *
+     * @param destination the stream to write the binary data to.
+     * @param dict the dictionary to write.
+     * @param formatOptions file format options.
+     */
+    public static void writeDictionaryBinary(final OutputStream destination,
+            final FusionDictionary dict, final FormatOptions formatOptions)
+            throws IOException, UnsupportedFormatException {
+
+        // Addresses are limited to 3 bytes, but since addresses can be relative to each node
+        // array, the structure itself is not limited to 16MB. However, if it is over 16MB deciding
+        // the order of the node arrays becomes a quite complicated problem, because though the
+        // dictionary itself does not have a size limit, each node array must still be within 16MB
+        // of all its children and parents. As long as this is ensured, the dictionary file may
+        // grow to any size.
+
+        final int version = formatOptions.mVersion;
+        if (version < FormatSpec.MINIMUM_SUPPORTED_VERSION
+                || version > FormatSpec.MAXIMUM_SUPPORTED_VERSION) {
+            throw new UnsupportedFormatException("Requested file format version " + version
+                    + ", but this implementation only supports versions "
+                    + FormatSpec.MINIMUM_SUPPORTED_VERSION + " through "
+                    + FormatSpec.MAXIMUM_SUPPORTED_VERSION);
+        }
+
+        ByteArrayOutputStream headerBuffer = new ByteArrayOutputStream(256);
+
+        // The magic number in big-endian order.
+        // Magic number for all versions.
+        headerBuffer.write((byte) (0xFF & (FormatSpec.MAGIC_NUMBER >> 24)));
+        headerBuffer.write((byte) (0xFF & (FormatSpec.MAGIC_NUMBER >> 16)));
+        headerBuffer.write((byte) (0xFF & (FormatSpec.MAGIC_NUMBER >> 8)));
+        headerBuffer.write((byte) (0xFF & FormatSpec.MAGIC_NUMBER));
+        // Dictionary version.
+        headerBuffer.write((byte) (0xFF & (version >> 8)));
+        headerBuffer.write((byte) (0xFF & version));
+
+        // Options flags
+        final int options = makeOptionsValue(dict, formatOptions);
+        headerBuffer.write((byte) (0xFF & (options >> 8)));
+        headerBuffer.write((byte) (0xFF & options));
+        final int headerSizeOffset = headerBuffer.size();
+        // Placeholder to be written later with header size.
+        for (int i = 0; i < 4; ++i) {
+            headerBuffer.write(0);
+        }
+        // Write out the options.
+        for (final String key : dict.mOptions.mAttributes.keySet()) {
+            final String value = dict.mOptions.mAttributes.get(key);
+            CharEncoding.writeString(headerBuffer, key);
+            CharEncoding.writeString(headerBuffer, value);
+        }
+        final int size = headerBuffer.size();
+        final byte[] bytes = headerBuffer.toByteArray();
+        // Write out the header size.
+        bytes[headerSizeOffset] = (byte) (0xFF & (size >> 24));
+        bytes[headerSizeOffset + 1] = (byte) (0xFF & (size >> 16));
+        bytes[headerSizeOffset + 2] = (byte) (0xFF & (size >> 8));
+        bytes[headerSizeOffset + 3] = (byte) (0xFF & (size >> 0));
+        destination.write(bytes);
+
+        headerBuffer.close();
+
+        // Leave the choice of the optimal node order to the flattenTree function.
+        MakedictLog.i("Flattening the tree...");
+        ArrayList<PtNodeArray> flatNodes = flattenTree(dict.mRootNodeArray);
+
+        MakedictLog.i("Computing addresses...");
+        computeAddresses(dict, flatNodes, formatOptions);
+        MakedictLog.i("Checking array...");
+        if (DBG) checkFlatNodeArrayList(flatNodes);
+
+        // Create a buffer that matches the final dictionary size.
+        final PtNodeArray lastNodeArray = flatNodes.get(flatNodes.size() - 1);
+        final int bufferSize = lastNodeArray.mCachedAddressAfterUpdate + lastNodeArray.mCachedSize;
+        final byte[] buffer = new byte[bufferSize];
+        int index = 0;
+
+        MakedictLog.i("Writing file...");
+        int dataEndOffset = 0;
+        for (PtNodeArray nodeArray : flatNodes) {
+            dataEndOffset = writePlacedNode(dict, buffer, nodeArray, formatOptions);
+        }
+
+        if (DBG) showStatistics(flatNodes);
+
+        destination.write(buffer, 0, dataEndOffset);
+
+        destination.close();
+        MakedictLog.i("Done");
+    }
+}
diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
index 2e6c4b2..e5735aa 100644
--- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
+++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
@@ -18,19 +18,19 @@
 
 import com.android.inputmethod.annotations.UsedForTesting;
 import com.android.inputmethod.latin.Constants;
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput.CharEncoding;
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput.FusionDictionaryBufferInterface;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder.CharEncoding;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder.FusionDictionaryBufferInterface;
 import com.android.inputmethod.latin.makedict.FormatSpec.FileHeader;
 import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
 import com.android.inputmethod.latin.makedict.FusionDictionary.CharGroup;
 import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
+import com.android.inputmethod.latin.utils.ByteArrayWrapper;
 
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.OutputStream;
-import java.nio.channels.FileChannel;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.Map;
@@ -59,7 +59,7 @@
     }
 
     /**
-     * Tours all node without recursive call.
+     * Retrieves all node arrays without recursive call.
      */
     private static void readUnigramsAndBigramsBinaryInner(
             final FusionDictionaryBufferInterface buffer, final int headerSize,
@@ -86,7 +86,7 @@
             if (index != p.mLength) index = p.mLength;
 
             if (p.mNumOfCharGroup == Position.NOT_READ_GROUPCOUNT) {
-                p.mNumOfCharGroup = BinaryDictInputOutput.readCharGroupCount(buffer);
+                p.mNumOfCharGroup = BinaryDictDecoder.readCharGroupCount(buffer);
                 p.mAddress += getGroupCountSize(p.mNumOfCharGroup);
                 p.mPosition = 0;
             }
@@ -94,7 +94,7 @@
                 stack.pop();
                 continue;
             }
-            CharGroupInfo info = BinaryDictInputOutput.readCharGroup(buffer,
+            CharGroupInfo info = BinaryDictDecoder.readCharGroup(buffer,
                     p.mAddress - headerSize, formatOptions);
             for (int i = 0; i < info.mCharacters.length; ++i) {
                 pushedChars[index++] = info.mCharacters[i];
@@ -116,7 +116,7 @@
                 if (formatOptions.mSupportsDynamicUpdate) {
                     final int forwardLinkAddress = buffer.readUnsignedInt24();
                     if (forwardLinkAddress != FormatSpec.NO_FORWARD_LINK_ADDRESS) {
-                        // the node has a forward link.
+                        // The node array has a forward link.
                         p.mNumOfCharGroup = Position.NOT_READ_GROUPCOUNT;
                         p.mAddress = forwardLinkAddress;
                     } else {
@@ -126,7 +126,7 @@
                     stack.pop();
                 }
             } else {
-                // the node has more groups.
+                // The node array has more groups.
                 p.mAddress = buffer.position();
             }
 
@@ -139,22 +139,22 @@
 
     /**
      * Reads unigrams and bigrams from the binary file.
-     * Doesn't make the memory representation of the dictionary.
+     * Doesn't store a full memory representation of the dictionary.
      *
-     * @param reader the reader.
+     * @param dictReader the dict reader.
      * @param words the map to store the address as a key and the word as a value.
      * @param frequencies the map to store the address as a key and the frequency as a value.
      * @param bigrams the map to store the address as a key and the list of address as a value.
-     * @throws IOException
-     * @throws UnsupportedFormatException
+     * @throws IOException if the file can't be read.
+     * @throws UnsupportedFormatException if the format of the file is not recognized.
      */
-    public static void readUnigramsAndBigramsBinary(final BinaryDictReader reader,
+    public static void readUnigramsAndBigramsBinary(final BinaryDictReader dictReader,
             final Map<Integer, String> words, final Map<Integer, Integer> frequencies,
             final Map<Integer, ArrayList<PendingAttribute>> bigrams) throws IOException,
             UnsupportedFormatException {
         // Read header
-        final FileHeader header = BinaryDictInputOutput.readHeader(reader.getBuffer());
-        readUnigramsAndBigramsBinaryInner(reader.getBuffer(), header.mHeaderSize, words,
+        final FileHeader header = BinaryDictDecoder.readHeader(dictReader);
+        readUnigramsAndBigramsBinaryInner(dictReader.getBuffer(), header.mHeaderSize, words,
                 frequencies, bigrams, header.mFormatOptions);
     }
 
@@ -162,30 +162,31 @@
      * Gets the address of the last CharGroup of the exact matching word in the dictionary.
      * If no match is found, returns NOT_VALID_WORD.
      *
-     * @param buffer the buffer to read.
+     * @param dictReader the dict reader.
      * @param word the word we search for.
      * @return the address of the terminal node.
-     * @throws IOException
-     * @throws UnsupportedFormatException
+     * @throws IOException if the file can't be read.
+     * @throws UnsupportedFormatException if the format of the file is not recognized.
      */
     @UsedForTesting
-    public static int getTerminalPosition(final FusionDictionaryBufferInterface buffer,
+    public static int getTerminalPosition(final BinaryDictReader dictReader,
             final String word) throws IOException, UnsupportedFormatException {
+        final FusionDictionaryBufferInterface buffer = dictReader.getBuffer();
         if (word == null) return FormatSpec.NOT_VALID_WORD;
         if (buffer.position() != 0) buffer.position(0);
 
-        final FileHeader header = BinaryDictInputOutput.readHeader(buffer);
+        final FileHeader header = BinaryDictDecoder.readHeader(dictReader);
         int wordPos = 0;
         final int wordLen = word.codePointCount(0, word.length());
         for (int depth = 0; depth < Constants.DICTIONARY_MAX_WORD_LENGTH; ++depth) {
             if (wordPos >= wordLen) return FormatSpec.NOT_VALID_WORD;
 
             do {
-                final int charGroupCount = BinaryDictInputOutput.readCharGroupCount(buffer);
+                final int charGroupCount = BinaryDictDecoder.readCharGroupCount(buffer);
                 boolean foundNextCharGroup = false;
                 for (int i = 0; i < charGroupCount; ++i) {
                     final int charGroupPos = buffer.position();
-                    final CharGroupInfo currentInfo = BinaryDictInputOutput.readCharGroup(buffer,
+                    final CharGroupInfo currentInfo = BinaryDictDecoder.readCharGroup(buffer,
                             buffer.position(), header.mFormatOptions);
                     final boolean isMovedGroup = isMovedGroup(currentInfo.mFlags,
                             header.mFormatOptions);
@@ -224,9 +225,9 @@
                 }
 
                 // If we found the next char group, it is under the file pointer.
-                // But if not, we are at the end of this node so we expect to have
+                // But if not, we are at the end of this node array so we expect to have
                 // a forward link address that we need to consult and possibly resume
-                // search on the next node in the linked list.
+                // search on the next node array in the linked list.
                 if (foundNextCharGroup) break;
                 if (!header.mFormatOptions.mSupportsDynamicUpdate) {
                     return FormatSpec.NOT_VALID_WORD;
@@ -271,7 +272,7 @@
      */
     private static int writeVariableAddress(final OutputStream destination, final int value)
             throws IOException {
-        switch (BinaryDictInputOutput.getByteSize(value)) {
+        switch (BinaryDictEncoder.getByteSize(value)) {
         case 1:
             destination.write((byte)value);
             break;
@@ -285,15 +286,15 @@
             destination.write((byte)(0xFF & value));
             break;
         }
-        return BinaryDictInputOutput.getByteSize(value);
+        return BinaryDictEncoder.getByteSize(value);
     }
 
     static void skipCharGroup(final FusionDictionaryBufferInterface buffer,
             final FormatOptions formatOptions) {
         final int flags = buffer.readUnsignedByte();
-        BinaryDictInputOutput.readParentAddress(buffer, formatOptions);
+        BinaryDictDecoder.readParentAddress(buffer, formatOptions);
         skipString(buffer, (flags & FormatSpec.FLAG_HAS_MULTIPLE_CHARS) != 0);
-        BinaryDictInputOutput.readChildrenAddress(buffer, flags, formatOptions);
+        BinaryDictDecoder.readChildrenAddress(buffer, flags, formatOptions);
         if ((flags & FormatSpec.FLAG_IS_TERMINAL) != 0) buffer.readUnsignedByte();
         if ((flags & FormatSpec.FLAG_HAS_SHORTCUT_TARGETS) != 0) {
             final int shortcutsSize = buffer.readUnsignedShort();
@@ -365,9 +366,10 @@
     }
 
     /**
-     * Write a char group to an output stream.
-     * A char group is an in-memory representation of a node in trie.
-     * A char group info is an on-disk representation of a node.
+     * Write a char group to an output stream from a CharGroupInfo.
+     * A char group is an in-memory representation of a node in the patricia trie.
+     * A char group info is a container for low-level information about how the
+     * char group is stored in the binary format.
      *
      * @param destination the stream to write.
      * @param info the char group info to be written.
@@ -411,14 +413,14 @@
 
         if (info.mShortcutTargets != null && info.mShortcutTargets.size() > 0) {
             final int shortcutListSize =
-                    BinaryDictInputOutput.getShortcutListSize(info.mShortcutTargets);
+                    BinaryDictEncoder.getShortcutListSize(info.mShortcutTargets);
             destination.write((byte)(shortcutListSize >> 8));
             destination.write((byte)(shortcutListSize & 0xFF));
             size += 2;
             final Iterator<WeightedString> shortcutIterator = info.mShortcutTargets.iterator();
             while (shortcutIterator.hasNext()) {
                 final WeightedString target = shortcutIterator.next();
-                destination.write((byte)BinaryDictInputOutput.makeShortcutFlags(
+                destination.write((byte)BinaryDictEncoder.makeShortcutFlags(
                         shortcutIterator.hasNext(), target.mFrequency));
                 size++;
                 size += writeString(destination, target.mWord);
@@ -427,7 +429,7 @@
 
         if (info.mBigrams != null) {
             // TODO: Consolidate this code with the code that computes the size of the bigram list
-            //        in BinaryDictionaryInputOutput#computeActualNodeSize
+            //        in BinaryDictEncoder#computeActualNodeArraySize
             for (int i = 0; i < info.mBigrams.size(); ++i) {
 
                 final int bigramFrequency = info.mBigrams.get(i).mFrequency;
@@ -437,7 +439,7 @@
                 final int bigramOffset = info.mBigrams.get(i).mAddress - (info.mOriginalAddress
                         + size);
                 bigramFlags |= (bigramOffset < 0) ? FormatSpec.FLAG_ATTRIBUTE_OFFSET_NEGATIVE : 0;
-                switch (BinaryDictInputOutput.getByteSize(bigramOffset)) {
+                switch (BinaryDictEncoder.getByteSize(bigramOffset)) {
                 case 1:
                     bigramFlags |= FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE;
                     break;
@@ -461,32 +463,32 @@
      */
     static int computeGroupSize(final CharGroupInfo info, final FormatOptions formatOptions) {
         int size = FormatSpec.GROUP_FLAGS_SIZE + FormatSpec.PARENT_ADDRESS_SIZE
-                + BinaryDictInputOutput.getGroupCharactersSize(info.mCharacters)
-                + BinaryDictInputOutput.getChildrenAddressSize(info.mFlags, formatOptions);
+                + BinaryDictEncoder.getGroupCharactersSize(info.mCharacters)
+                + getChildrenAddressSize(info.mFlags, formatOptions);
         if ((info.mFlags & FormatSpec.FLAG_IS_TERMINAL) != 0) {
             size += FormatSpec.GROUP_FREQUENCY_SIZE;
         }
         if (info.mShortcutTargets != null && !info.mShortcutTargets.isEmpty()) {
-            size += BinaryDictInputOutput.getShortcutListSize(info.mShortcutTargets);
+            size += BinaryDictEncoder.getShortcutListSize(info.mShortcutTargets);
         }
         if (info.mBigrams != null) {
             for (final PendingAttribute attr : info.mBigrams) {
                 size += FormatSpec.GROUP_FLAGS_SIZE;
-                size += BinaryDictInputOutput.getByteSize(attr.mAddress);
+                size += BinaryDictEncoder.getByteSize(attr.mAddress);
             }
         }
         return size;
     }
 
     /**
-     * Write a node to the stream.
+     * Write a node array to the stream.
      *
      * @param destination the stream to write.
-     * @param infos groups to be written.
+     * @param infos an array of CharGroupInfo to be written.
      * @return the size written, in bytes.
      * @throws IOException
      */
-    static int writeNode(final OutputStream destination, final CharGroupInfo[] infos)
+    static int writeNodes(final OutputStream destination, final CharGroupInfo[] infos)
             throws IOException {
         int size = getGroupCountSize(infos.length);
         switch (getGroupCountSize(infos.length)) {
@@ -506,23 +508,24 @@
     }
 
     /**
-     * Find a word from the buffer.
+     * Find a word using the BinaryDictReader.
      *
-     * @param buffer the buffer representing the body of the dictionary file.
+     * @param dictReader the dict reader
      * @param word the word searched
      * @return the found group
      * @throws IOException
      * @throws UnsupportedFormatException
      */
     @UsedForTesting
-    public static CharGroupInfo findWordFromBuffer(final FusionDictionaryBufferInterface buffer,
+    public static CharGroupInfo findWordByBinaryDictReader(final BinaryDictReader dictReader,
             final String word) throws IOException, UnsupportedFormatException {
-        int position = getTerminalPosition(buffer, word);
+        int position = getTerminalPosition(dictReader, word);
+        final FusionDictionaryBufferInterface buffer = dictReader.getBuffer();
         if (position != FormatSpec.NOT_VALID_WORD) {
             buffer.position(0);
-            final FileHeader header = BinaryDictInputOutput.readHeader(buffer);
+            final FileHeader header = BinaryDictDecoder.readHeader(dictReader);
             buffer.position(position);
-            return BinaryDictInputOutput.readCharGroup(buffer, position, header.mFormatOptions);
+            return BinaryDictDecoder.readCharGroup(buffer, position, header.mFormatOptions);
         }
         return null;
     }
@@ -541,16 +544,21 @@
             final File file, final long offset, final long length)
             throws FileNotFoundException, IOException, UnsupportedFormatException {
         final byte[] buffer = new byte[HEADER_READING_BUFFER_SIZE];
-        final FileInputStream inStream = new FileInputStream(file);
-        try {
-            inStream.read(buffer);
-            final BinaryDictInputOutput.ByteBufferWrapper wrapper =
-                    new BinaryDictInputOutput.ByteBufferWrapper(inStream.getChannel().map(
-                            FileChannel.MapMode.READ_ONLY, offset, length));
-            return BinaryDictInputOutput.readHeader(wrapper);
-        } finally {
-            inStream.close();
-        }
+        final BinaryDictReader dictReader = new BinaryDictReader(file);
+        dictReader.openBuffer(new BinaryDictReader.FusionDictionaryBufferFactory() {
+            @Override
+            public FusionDictionaryBufferInterface getFusionDictionaryBuffer(File file)
+                    throws FileNotFoundException, IOException {
+                final FileInputStream inStream = new FileInputStream(file);
+                try {
+                    inStream.read(buffer);
+                    return new ByteArrayWrapper(buffer);
+                } finally {
+                    inStream.close();
+                }
+            }
+        });
+        return BinaryDictDecoder.readHeader(dictReader);
     }
 
     public static FileHeader getDictionaryFileHeaderOrNull(final File file, final long offset,
@@ -604,12 +612,28 @@
     public static int getGroupCountSize(final int count) {
         if (FormatSpec.MAX_CHARGROUPS_FOR_ONE_BYTE_CHARGROUP_COUNT >= count) {
             return 1;
-        } else if (FormatSpec.MAX_CHARGROUPS_IN_A_NODE >= count) {
+        } else if (FormatSpec.MAX_CHARGROUPS_IN_A_PT_NODE_ARRAY >= count) {
             return 2;
         } else {
             throw new RuntimeException("Can't have more than "
-                    + FormatSpec.MAX_CHARGROUPS_IN_A_NODE + " groups in a node (found " + count
-                    + ")");
+                    + FormatSpec.MAX_CHARGROUPS_IN_A_PT_NODE_ARRAY + " groups in a node (found "
+                    + count + ")");
+        }
+    }
+
+    static int getChildrenAddressSize(final int optionFlags,
+            final FormatOptions formatOptions) {
+        if (formatOptions.mSupportsDynamicUpdate) return FormatSpec.SIGNED_CHILDREN_ADDRESS_SIZE;
+        switch (optionFlags & FormatSpec.MASK_GROUP_ADDRESS_TYPE) {
+            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_ONEBYTE:
+                return 1;
+            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_TWOBYTES:
+                return 2;
+            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_THREEBYTES:
+                return 3;
+            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_NOADDRESS:
+            default:
+                return 0;
         }
     }
 }
diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java
deleted file mode 100644
index a33cddb..0000000
--- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java
+++ /dev/null
@@ -1,1783 +0,0 @@
-/*
- * Copyright (C) 2011 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.android.inputmethod.latin.makedict;
-
-import com.android.inputmethod.annotations.UsedForTesting;
-import com.android.inputmethod.latin.makedict.FormatSpec.FileHeader;
-import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
-import com.android.inputmethod.latin.makedict.FusionDictionary.CharGroup;
-import com.android.inputmethod.latin.makedict.FusionDictionary.DictionaryOptions;
-import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
-import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
-import com.android.inputmethod.latin.utils.JniUtils;
-
-import java.io.ByteArrayOutputStream;
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileNotFoundException;
-import java.io.IOException;
-import java.io.OutputStream;
-import java.nio.ByteBuffer;
-import java.nio.channels.FileChannel;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.HashMap;
-import java.util.Iterator;
-import java.util.Map;
-import java.util.TreeMap;
-
-/**
- * Reads and writes XML files for a FusionDictionary.
- *
- * All the methods in this class are static.
- */
-public final class BinaryDictInputOutput {
-
-    private static final boolean DBG = MakedictLog.DBG;
-
-    static {
-        JniUtils.loadNativeLibrary();
-    }
-
-    // TODO: implement something sensical instead of just a phony method
-    private static native int doNothing();
-
-    // Arbitrary limit to how much passes we consider address size compression should
-    // terminate in. At the time of this writing, our largest dictionary completes
-    // compression in five passes.
-    // If the number of passes exceeds this number, makedict bails with an exception on
-    // suspicion that a bug might be causing an infinite loop.
-    private static final int MAX_PASSES = 24;
-    private static final int MAX_JUMPS = 12;
-
-    @UsedForTesting
-    public interface FusionDictionaryBufferInterface {
-        public int readUnsignedByte();
-        public int readUnsignedShort();
-        public int readUnsignedInt24();
-        public int readInt();
-        public int position();
-        public void position(int newPosition);
-        public void put(final byte b);
-        public int limit();
-        @UsedForTesting
-        public int capacity();
-    }
-
-    public static final class ByteBufferWrapper implements FusionDictionaryBufferInterface {
-        private ByteBuffer mBuffer;
-
-        public ByteBufferWrapper(final ByteBuffer buffer) {
-            mBuffer = buffer;
-        }
-
-        @Override
-        public int readUnsignedByte() {
-            return mBuffer.get() & 0xFF;
-        }
-
-        @Override
-        public int readUnsignedShort() {
-            return mBuffer.getShort() & 0xFFFF;
-        }
-
-        @Override
-        public int readUnsignedInt24() {
-            final int retval = readUnsignedByte();
-            return (retval << 16) + readUnsignedShort();
-        }
-
-        @Override
-        public int readInt() {
-            return mBuffer.getInt();
-        }
-
-        @Override
-        public int position() {
-            return mBuffer.position();
-        }
-
-        @Override
-        public void position(int newPos) {
-            mBuffer.position(newPos);
-        }
-
-        @Override
-        public void put(final byte b) {
-            mBuffer.put(b);
-        }
-
-        @Override
-        public int limit() {
-            return mBuffer.limit();
-        }
-
-        @Override
-        public int capacity() {
-            return mBuffer.capacity();
-        }
-    }
-
-    /**
-     * A class grouping utility function for our specific character encoding.
-     */
-    static final class CharEncoding {
-        private static final int MINIMAL_ONE_BYTE_CHARACTER_VALUE = 0x20;
-        private static final int MAXIMAL_ONE_BYTE_CHARACTER_VALUE = 0xFF;
-
-        /**
-         * Helper method to find out whether this code fits on one byte
-         */
-        private static boolean fitsOnOneByte(final int character) {
-            return character >= MINIMAL_ONE_BYTE_CHARACTER_VALUE
-                    && character <= MAXIMAL_ONE_BYTE_CHARACTER_VALUE;
-        }
-
-        /**
-         * Compute the size of a character given its character code.
-         *
-         * Char format is:
-         * 1 byte = bbbbbbbb match
-         * case 000xxxxx: xxxxx << 16 + next byte << 8 + next byte
-         * else: if 00011111 (= 0x1F) : this is the terminator. This is a relevant choice because
-         *       unicode code points range from 0 to 0x10FFFF, so any 3-byte value starting with
-         *       00011111 would be outside unicode.
-         * else: iso-latin-1 code
-         * This allows for the whole unicode range to be encoded, including chars outside of
-         * the BMP. Also everything in the iso-latin-1 charset is only 1 byte, except control
-         * characters which should never happen anyway (and still work, but take 3 bytes).
-         *
-         * @param character the character code.
-         * @return the size in binary encoded-form, either 1 or 3 bytes.
-         */
-        static int getCharSize(final int character) {
-            // See char encoding in FusionDictionary.java
-            if (fitsOnOneByte(character)) return 1;
-            if (FormatSpec.INVALID_CHARACTER == character) return 1;
-            return 3;
-        }
-
-        /**
-         * Compute the byte size of a character array.
-         */
-        private static int getCharArraySize(final int[] chars) {
-            int size = 0;
-            for (int character : chars) size += getCharSize(character);
-            return size;
-        }
-
-        /**
-         * Writes a char array to a byte buffer.
-         *
-         * @param codePoints the code point array to write.
-         * @param buffer the byte buffer to write to.
-         * @param index the index in buffer to write the character array to.
-         * @return the index after the last character.
-         */
-        private static int writeCharArray(final int[] codePoints, final byte[] buffer, int index) {
-            for (int codePoint : codePoints) {
-                if (1 == getCharSize(codePoint)) {
-                    buffer[index++] = (byte)codePoint;
-                } else {
-                    buffer[index++] = (byte)(0xFF & (codePoint >> 16));
-                    buffer[index++] = (byte)(0xFF & (codePoint >> 8));
-                    buffer[index++] = (byte)(0xFF & codePoint);
-                }
-            }
-            return index;
-        }
-
-        /**
-         * Writes a string with our character format to a byte buffer.
-         *
-         * This will also write the terminator byte.
-         *
-         * @param buffer the byte buffer to write to.
-         * @param origin the offset to write from.
-         * @param word the string to write.
-         * @return the size written, in bytes.
-         */
-        private static int writeString(final byte[] buffer, final int origin,
-                final String word) {
-            final int length = word.length();
-            int index = origin;
-            for (int i = 0; i < length; i = word.offsetByCodePoints(i, 1)) {
-                final int codePoint = word.codePointAt(i);
-                if (1 == getCharSize(codePoint)) {
-                    buffer[index++] = (byte)codePoint;
-                } else {
-                    buffer[index++] = (byte)(0xFF & (codePoint >> 16));
-                    buffer[index++] = (byte)(0xFF & (codePoint >> 8));
-                    buffer[index++] = (byte)(0xFF & codePoint);
-                }
-            }
-            buffer[index++] = FormatSpec.GROUP_CHARACTERS_TERMINATOR;
-            return index - origin;
-        }
-
-        /**
-         * Writes a string with our character format to a ByteArrayOutputStream.
-         *
-         * This will also write the terminator byte.
-         *
-         * @param buffer the ByteArrayOutputStream to write to.
-         * @param word the string to write.
-         */
-        private static void writeString(final ByteArrayOutputStream buffer, final String word) {
-            final int length = word.length();
-            for (int i = 0; i < length; i = word.offsetByCodePoints(i, 1)) {
-                final int codePoint = word.codePointAt(i);
-                if (1 == getCharSize(codePoint)) {
-                    buffer.write((byte) codePoint);
-                } else {
-                    buffer.write((byte) (0xFF & (codePoint >> 16)));
-                    buffer.write((byte) (0xFF & (codePoint >> 8)));
-                    buffer.write((byte) (0xFF & codePoint));
-                }
-            }
-            buffer.write(FormatSpec.GROUP_CHARACTERS_TERMINATOR);
-        }
-
-        /**
-         * Reads a string from a buffer. This is the converse of the above method.
-         */
-        private static String readString(final FusionDictionaryBufferInterface buffer) {
-            final StringBuilder s = new StringBuilder();
-            int character = readChar(buffer);
-            while (character != FormatSpec.INVALID_CHARACTER) {
-                s.appendCodePoint(character);
-                character = readChar(buffer);
-            }
-            return s.toString();
-        }
-
-        /**
-         * Reads a character from the buffer.
-         *
-         * This follows the character format documented earlier in this source file.
-         *
-         * @param buffer the buffer, positioned over an encoded character.
-         * @return the character code.
-         */
-        static int readChar(final FusionDictionaryBufferInterface buffer) {
-            int character = buffer.readUnsignedByte();
-            if (!fitsOnOneByte(character)) {
-                if (FormatSpec.GROUP_CHARACTERS_TERMINATOR == character) {
-                    return FormatSpec.INVALID_CHARACTER;
-                }
-                character <<= 16;
-                character += buffer.readUnsignedShort();
-            }
-            return character;
-        }
-    }
-
-    /**
-     * Compute the binary size of the character array.
-     *
-     * If only one character, this is the size of this character. If many, it's the sum of their
-     * sizes + 1 byte for the terminator.
-     *
-     * @param characters the character array
-     * @return the size of the char array, including the terminator if any
-     */
-    static int getGroupCharactersSize(final int[] characters) {
-        int size = CharEncoding.getCharArraySize(characters);
-        if (characters.length > 1) size += FormatSpec.GROUP_TERMINATOR_SIZE;
-        return size;
-    }
-
-    /**
-     * Compute the binary size of the character array in a group
-     *
-     * If only one character, this is the size of this character. If many, it's the sum of their
-     * sizes + 1 byte for the terminator.
-     *
-     * @param group the group
-     * @return the size of the char array, including the terminator if any
-     */
-    private static int getGroupCharactersSize(final CharGroup group) {
-        return getGroupCharactersSize(group.mChars);
-    }
-
-    /**
-     * Compute the binary size of the group count for a node
-     * @param node the node
-     * @return the size of the group count, either 1 or 2 bytes.
-     */
-    private static int getGroupCountSize(final Node node) {
-        return BinaryDictIOUtils.getGroupCountSize(node.mData.size());
-    }
-
-    /**
-     * Compute the size of a shortcut in bytes.
-     */
-    private static int getShortcutSize(final WeightedString shortcut) {
-        int size = FormatSpec.GROUP_ATTRIBUTE_FLAGS_SIZE;
-        final String word = shortcut.mWord;
-        final int length = word.length();
-        for (int i = 0; i < length; i = word.offsetByCodePoints(i, 1)) {
-            final int codePoint = word.codePointAt(i);
-            size += CharEncoding.getCharSize(codePoint);
-        }
-        size += FormatSpec.GROUP_TERMINATOR_SIZE;
-        return size;
-    }
-
-    /**
-     * Compute the size of a shortcut list in bytes.
-     *
-     * This is known in advance and does not change according to position in the file
-     * like address lists do.
-     */
-    static int getShortcutListSize(final ArrayList<WeightedString> shortcutList) {
-        if (null == shortcutList) return 0;
-        int size = FormatSpec.GROUP_SHORTCUT_LIST_SIZE_SIZE;
-        for (final WeightedString shortcut : shortcutList) {
-            size += getShortcutSize(shortcut);
-        }
-        return size;
-    }
-
-    /**
-     * Compute the maximum size of a CharGroup, assuming 3-byte addresses for everything.
-     *
-     * @param group the CharGroup to compute the size of.
-     * @param options file format options.
-     * @return the maximum size of the group.
-     */
-    private static int getCharGroupMaximumSize(final CharGroup group, final FormatOptions options) {
-        int size = getGroupHeaderSize(group, options);
-        // If terminal, one byte for the frequency
-        if (group.isTerminal()) size += FormatSpec.GROUP_FREQUENCY_SIZE;
-        size += FormatSpec.GROUP_MAX_ADDRESS_SIZE; // For children address
-        size += getShortcutListSize(group.mShortcutTargets);
-        if (null != group.mBigrams) {
-            size += (FormatSpec.GROUP_ATTRIBUTE_FLAGS_SIZE
-                    + FormatSpec.GROUP_ATTRIBUTE_MAX_ADDRESS_SIZE)
-                    * group.mBigrams.size();
-        }
-        return size;
-    }
-
-    /**
-     * Compute the maximum size of a node, assuming 3-byte addresses for everything, and caches
-     * it in the 'actualSize' member of the node.
-     *
-     * @param node the node to compute the maximum size of.
-     * @param options file format options.
-     */
-    private static void calculateNodeMaximumSize(final Node node, final FormatOptions options) {
-        int size = getGroupCountSize(node);
-        for (CharGroup g : node.mData) {
-            final int groupSize = getCharGroupMaximumSize(g, options);
-            g.mCachedSize = groupSize;
-            size += groupSize;
-        }
-        if (options.mSupportsDynamicUpdate) {
-            size += FormatSpec.FORWARD_LINK_ADDRESS_SIZE;
-        }
-        node.mCachedSize = size;
-    }
-
-    /**
-     * Compute the size of the header (flag + [parent address] + characters size) of a CharGroup.
-     *
-     * @param group the group of which to compute the size of the header
-     * @param options file format options.
-     */
-    private static int getGroupHeaderSize(final CharGroup group, final FormatOptions options) {
-        if (BinaryDictIOUtils.supportsDynamicUpdate(options)) {
-            return FormatSpec.GROUP_FLAGS_SIZE + FormatSpec.PARENT_ADDRESS_SIZE
-                    + getGroupCharactersSize(group);
-        } else {
-            return FormatSpec.GROUP_FLAGS_SIZE + getGroupCharactersSize(group);
-        }
-    }
-
-    /**
-     * Compute the size, in bytes, that an address will occupy.
-     *
-     * This can be used either for children addresses (which are always positive) or for
-     * attribute, which may be positive or negative but
-     * store their sign bit separately.
-     *
-     * @param address the address
-     * @return the byte size.
-     */
-    static int getByteSize(final int address) {
-        assert(address <= FormatSpec.UINT24_MAX);
-        if (!BinaryDictIOUtils.hasChildrenAddress(address)) {
-            return 0;
-        } else if (Math.abs(address) <= FormatSpec.UINT8_MAX) {
-            return 1;
-        } else if (Math.abs(address) <= FormatSpec.UINT16_MAX) {
-            return 2;
-        } else {
-            return 3;
-        }
-    }
-
-    // End utility methods.
-
-    // This method is responsible for finding a nice ordering of the nodes that favors run-time
-    // cache performance and dictionary size.
-    /* package for tests */ static ArrayList<Node> flattenTree(final Node root) {
-        final int treeSize = FusionDictionary.countCharGroups(root);
-        MakedictLog.i("Counted nodes : " + treeSize);
-        final ArrayList<Node> flatTree = new ArrayList<Node>(treeSize);
-        return flattenTreeInner(flatTree, root);
-    }
-
-    private static ArrayList<Node> flattenTreeInner(final ArrayList<Node> list, final Node node) {
-        // Removing the node is necessary if the tails are merged, because we would then
-        // add the same node several times when we only want it once. A number of places in
-        // the code also depends on any node being only once in the list.
-        // Merging tails can only be done if there are no attributes. Searching for attributes
-        // in LatinIME code depends on a total breadth-first ordering, which merging tails
-        // breaks. If there are no attributes, it should be fine (and reduce the file size)
-        // to merge tails, and removing the node from the list would be necessary. However,
-        // we don't merge tails because breaking the breadth-first ordering would result in
-        // extreme overhead at bigram lookup time (it would make the search function O(n) instead
-        // of the current O(log(n)), where n=number of nodes in the dictionary which is pretty
-        // high).
-        // If no nodes are ever merged, we can't have the same node twice in the list, hence
-        // searching for duplicates in unnecessary. It is also very performance consuming,
-        // since `list' is an ArrayList so it's an O(n) operation that runs on all nodes, making
-        // this simple list.remove operation O(n*n) overall. On Android this overhead is very
-        // high.
-        // For future reference, the code to remove duplicate is a simple : list.remove(node);
-        list.add(node);
-        final ArrayList<CharGroup> branches = node.mData;
-        final int nodeSize = branches.size();
-        for (CharGroup group : branches) {
-            if (null != group.mChildren) flattenTreeInner(list, group.mChildren);
-        }
-        return list;
-    }
-
-    /**
-     * Get the offset from a position inside a current node to a target node, during update.
-     *
-     * If the current node is before the target node, the target node has not been updated yet,
-     * so we should return the offset from the old position of the current node to the old position
-     * of the target node. If on the other hand the target is before the current node, it already
-     * has been updated, so we should return the offset from the new position in the current node
-     * to the new position in the target node.
-     * @param currentNode the node containing the CharGroup where the offset will be written
-     * @param offsetFromStartOfCurrentNode the offset, in bytes, from the start of currentNode
-     * @param targetNode the target node to get the offset to
-     * @return the offset to the target node
-     */
-    private static int getOffsetToTargetNodeDuringUpdate(final Node currentNode,
-            final int offsetFromStartOfCurrentNode, final Node targetNode) {
-        final boolean isTargetBeforeCurrent = (targetNode.mCachedAddressBeforeUpdate
-                < currentNode.mCachedAddressBeforeUpdate);
-        if (isTargetBeforeCurrent) {
-            return targetNode.mCachedAddressAfterUpdate
-                    - (currentNode.mCachedAddressAfterUpdate + offsetFromStartOfCurrentNode);
-        } else {
-            return targetNode.mCachedAddressBeforeUpdate
-                    - (currentNode.mCachedAddressBeforeUpdate + offsetFromStartOfCurrentNode);
-        }
-    }
-
-    /**
-     * Get the offset from a position inside a current node to a target CharGroup, during update.
-     * @param currentNode the node containing the CharGroup where the offset will be written
-     * @param offsetFromStartOfCurrentNode the offset, in bytes, from the start of currentNode
-     * @param targetCharGroup the target CharGroup to get the offset to
-     * @return the offset to the target CharGroup
-     */
-    // TODO: is there any way to factorize this method with the one above?
-    private static int getOffsetToTargetCharGroupDuringUpdate(final Node currentNode,
-            final int offsetFromStartOfCurrentNode, final CharGroup targetCharGroup) {
-        final int oldOffsetBasePoint = currentNode.mCachedAddressBeforeUpdate
-                + offsetFromStartOfCurrentNode;
-        final boolean isTargetBeforeCurrent = (targetCharGroup.mCachedAddressBeforeUpdate
-                < oldOffsetBasePoint);
-        // If the target is before the current node, then its address has already been updated.
-        // We can use the AfterUpdate member, and compare it to our own member after update.
-        // Otherwise, the AfterUpdate member is not updated yet, so we need to use the BeforeUpdate
-        // member, and of course we have to compare this to our own address before update.
-        if (isTargetBeforeCurrent) {
-            final int newOffsetBasePoint = currentNode.mCachedAddressAfterUpdate
-                    + offsetFromStartOfCurrentNode;
-            return targetCharGroup.mCachedAddressAfterUpdate - newOffsetBasePoint;
-        } else {
-            return targetCharGroup.mCachedAddressBeforeUpdate - oldOffsetBasePoint;
-        }
-    }
-
-    /**
-     * Computes the actual node size, based on the cached addresses of the children nodes.
-     *
-     * Each node stores its tentative address. During dictionary address computing, these
-     * are not final, but they can be used to compute the node size (the node size depends
-     * on the address of the children because the number of bytes necessary to store an
-     * address depends on its numeric value. The return value indicates whether the node
-     * contents (as in, any of the addresses stored in the cache fields) have changed with
-     * respect to their previous value.
-     *
-     * @param node the node to compute the size of.
-     * @param dict the dictionary in which the word/attributes are to be found.
-     * @param formatOptions file format options.
-     * @return false if none of the cached addresses inside the node changed, true otherwise.
-     */
-    private static boolean computeActualNodeSize(final Node node, final FusionDictionary dict,
-            final FormatOptions formatOptions) {
-        boolean changed = false;
-        int size = getGroupCountSize(node);
-        for (CharGroup group : node.mData) {
-            group.mCachedAddressAfterUpdate = node.mCachedAddressAfterUpdate + size;
-            if (group.mCachedAddressAfterUpdate != group.mCachedAddressBeforeUpdate) {
-                changed = true;
-            }
-            int groupSize = getGroupHeaderSize(group, formatOptions);
-            if (group.isTerminal()) groupSize += FormatSpec.GROUP_FREQUENCY_SIZE;
-            if (null == group.mChildren && formatOptions.mSupportsDynamicUpdate) {
-                groupSize += FormatSpec.SIGNED_CHILDREN_ADDRESS_SIZE;
-            } else if (null != group.mChildren) {
-                if (formatOptions.mSupportsDynamicUpdate) {
-                    groupSize += FormatSpec.SIGNED_CHILDREN_ADDRESS_SIZE;
-                } else {
-                    groupSize += getByteSize(getOffsetToTargetNodeDuringUpdate(node,
-                            groupSize + size, group.mChildren));
-                }
-            }
-            groupSize += getShortcutListSize(group.mShortcutTargets);
-            if (null != group.mBigrams) {
-                for (WeightedString bigram : group.mBigrams) {
-                    final int offset = getOffsetToTargetCharGroupDuringUpdate(node,
-                            groupSize + size + FormatSpec.GROUP_FLAGS_SIZE,
-                            FusionDictionary.findWordInTree(dict.mRoot, bigram.mWord));
-                    groupSize += getByteSize(offset) + FormatSpec.GROUP_FLAGS_SIZE;
-                }
-            }
-            group.mCachedSize = groupSize;
-            size += groupSize;
-        }
-        if (formatOptions.mSupportsDynamicUpdate) {
-            size += FormatSpec.FORWARD_LINK_ADDRESS_SIZE;
-        }
-        if (node.mCachedSize != size) {
-            node.mCachedSize = size;
-            changed = true;
-        }
-        return changed;
-    }
-
-    /**
-     * Initializes the cached addresses of nodes from their size.
-     *
-     * @param flatNodes the array of nodes.
-     * @param formatOptions file format options.
-     * @return the byte size of the entire stack.
-     */
-    private static int initializeNodesCachedAddresses(final ArrayList<Node> flatNodes,
-            final FormatOptions formatOptions) {
-        int nodeOffset = 0;
-        for (final Node n : flatNodes) {
-            n.mCachedAddressBeforeUpdate = nodeOffset;
-            int groupCountSize = getGroupCountSize(n);
-            int groupOffset = 0;
-            for (final CharGroup g : n.mData) {
-                g.mCachedAddressBeforeUpdate = g.mCachedAddressAfterUpdate =
-                        groupCountSize + nodeOffset + groupOffset;
-                groupOffset += g.mCachedSize;
-            }
-            final int nodeSize = groupCountSize + groupOffset
-                    + (formatOptions.mSupportsDynamicUpdate
-                            ? FormatSpec.FORWARD_LINK_ADDRESS_SIZE : 0);
-            nodeOffset += n.mCachedSize;
-        }
-        return nodeOffset;
-    }
-
-    /**
-     * Updates the cached addresses of nodes after recomputing their new positions.
-     *
-     * @param flatNodes the array of nodes.
-     */
-    private static void updateNodeCachedAddresses(final ArrayList<Node> flatNodes) {
-        for (final Node n : flatNodes) {
-            n.mCachedAddressBeforeUpdate = n.mCachedAddressAfterUpdate;
-            for (final CharGroup g : n.mData) {
-                g.mCachedAddressBeforeUpdate = g.mCachedAddressAfterUpdate;
-            }
-        }
-    }
-
-    /**
-     * Compute the cached parent addresses after all has been updated.
-     *
-     * The parent addresses are used by some binary formats at write-to-disk time. Not all formats
-     * need them. In particular, version 2 does not need them, and version 3 does.
-     *
-     * @param flatNodes the flat array of nodes to fill in
-     */
-    private static void computeParentAddresses(final ArrayList<Node> flatNodes) {
-        for (final Node node : flatNodes) {
-            for (final CharGroup group : node.mData) {
-                if (null != group.mChildren) {
-                    // Assign my address to children's parent address
-                    // Here BeforeUpdate and AfterUpdate addresses have the same value, so it
-                    // does not matter which we use.
-                    group.mChildren.mCachedParentAddress = group.mCachedAddressAfterUpdate
-                            - group.mChildren.mCachedAddressAfterUpdate;
-                }
-            }
-        }
-    }
-
-    /**
-     * Compute the addresses and sizes of an ordered node array.
-     *
-     * This method takes a node array and will update its cached address and size values
-     * so that they can be written into a file. It determines the smallest size each of the
-     * nodes can be given the addresses of its children and attributes, and store that into
-     * each node.
-     * The order of the node is given by the order of the array. This method makes no effort
-     * to find a good order; it only mechanically computes the size this order results in.
-     *
-     * @param dict the dictionary
-     * @param flatNodes the ordered array of nodes
-     * @param formatOptions file format options.
-     * @return the same array it was passed. The nodes have been updated for address and size.
-     */
-    private static ArrayList<Node> computeAddresses(final FusionDictionary dict,
-            final ArrayList<Node> flatNodes, final FormatOptions formatOptions) {
-        // First get the worst possible sizes and offsets
-        for (final Node n : flatNodes) calculateNodeMaximumSize(n, formatOptions);
-        final int offset = initializeNodesCachedAddresses(flatNodes, formatOptions);
-
-        MakedictLog.i("Compressing the array addresses. Original size : " + offset);
-        MakedictLog.i("(Recursively seen size : " + offset + ")");
-
-        int passes = 0;
-        boolean changesDone = false;
-        do {
-            changesDone = false;
-            int nodeStartOffset = 0;
-            for (final Node n : flatNodes) {
-                n.mCachedAddressAfterUpdate = nodeStartOffset;
-                final int oldNodeSize = n.mCachedSize;
-                final boolean changed = computeActualNodeSize(n, dict, formatOptions);
-                final int newNodeSize = n.mCachedSize;
-                if (oldNodeSize < newNodeSize) throw new RuntimeException("Increased size ?!");
-                nodeStartOffset += newNodeSize;
-                changesDone |= changed;
-            }
-            updateNodeCachedAddresses(flatNodes);
-            ++passes;
-            if (passes > MAX_PASSES) throw new RuntimeException("Too many passes - probably a bug");
-        } while (changesDone);
-
-        if (formatOptions.mSupportsDynamicUpdate) {
-            computeParentAddresses(flatNodes);
-        }
-        final Node lastNode = flatNodes.get(flatNodes.size() - 1);
-        MakedictLog.i("Compression complete in " + passes + " passes.");
-        MakedictLog.i("After address compression : "
-                + (lastNode.mCachedAddressAfterUpdate + lastNode.mCachedSize));
-
-        return flatNodes;
-    }
-
-    /**
-     * Sanity-checking method.
-     *
-     * This method checks an array of node for juxtaposition, that is, it will do
-     * nothing if each node's cached address is actually the previous node's address
-     * plus the previous node's size.
-     * If this is not the case, it will throw an exception.
-     *
-     * @param array the array node to check
-     */
-    private static void checkFlatNodeArray(final ArrayList<Node> array) {
-        int offset = 0;
-        int index = 0;
-        for (final Node n : array) {
-            // BeforeUpdate and AfterUpdate addresses are the same here, so it does not matter
-            // which we use.
-            if (n.mCachedAddressAfterUpdate != offset) {
-                throw new RuntimeException("Wrong address for node " + index
-                        + " : expected " + offset + ", got " + n.mCachedAddressAfterUpdate);
-            }
-            ++index;
-            offset += n.mCachedSize;
-        }
-    }
-
-    /**
-     * Helper method to write a variable-size address to a file.
-     *
-     * @param buffer the buffer to write to.
-     * @param index the index in the buffer to write the address to.
-     * @param address the address to write.
-     * @return the size in bytes the address actually took.
-     */
-    private static int writeVariableAddress(final byte[] buffer, int index, final int address) {
-        switch (getByteSize(address)) {
-        case 1:
-            buffer[index++] = (byte)address;
-            return 1;
-        case 2:
-            buffer[index++] = (byte)(0xFF & (address >> 8));
-            buffer[index++] = (byte)(0xFF & address);
-            return 2;
-        case 3:
-            buffer[index++] = (byte)(0xFF & (address >> 16));
-            buffer[index++] = (byte)(0xFF & (address >> 8));
-            buffer[index++] = (byte)(0xFF & address);
-            return 3;
-        case 0:
-            return 0;
-        default:
-            throw new RuntimeException("Address " + address + " has a strange size");
-        }
-    }
-
-    /**
-     * Helper method to write a variable-size signed address to a file.
-     *
-     * @param buffer the buffer to write to.
-     * @param index the index in the buffer to write the address to.
-     * @param address the address to write.
-     * @return the size in bytes the address actually took.
-     */
-    private static int writeVariableSignedAddress(final byte[] buffer, int index,
-            final int address) {
-        if (!BinaryDictIOUtils.hasChildrenAddress(address)) {
-            buffer[index] = buffer[index + 1] = buffer[index + 2] = 0;
-        } else {
-            final int absAddress = Math.abs(address);
-            buffer[index++] =
-                    (byte)((address < 0 ? FormatSpec.MSB8 : 0) | (0xFF & (absAddress >> 16)));
-            buffer[index++] = (byte)(0xFF & (absAddress >> 8));
-            buffer[index++] = (byte)(0xFF & absAddress);
-        }
-        return 3;
-    }
-
-    /**
-     * Makes the flag value for a char group.
-     *
-     * @param hasMultipleChars whether the group has multiple chars.
-     * @param isTerminal whether the group is terminal.
-     * @param childrenAddressSize the size of a children address.
-     * @param hasShortcuts whether the group has shortcuts.
-     * @param hasBigrams whether the group has bigrams.
-     * @param isNotAWord whether the group is not a word.
-     * @param isBlackListEntry whether the group is a blacklist entry.
-     * @param formatOptions file format options.
-     * @return the flags
-     */
-    static int makeCharGroupFlags(final boolean hasMultipleChars, final boolean isTerminal,
-            final int childrenAddressSize, final boolean hasShortcuts, final boolean hasBigrams,
-            final boolean isNotAWord, final boolean isBlackListEntry,
-            final FormatOptions formatOptions) {
-        byte flags = 0;
-        if (hasMultipleChars) flags |= FormatSpec.FLAG_HAS_MULTIPLE_CHARS;
-        if (isTerminal) flags |= FormatSpec.FLAG_IS_TERMINAL;
-        if (formatOptions.mSupportsDynamicUpdate) {
-            flags |= FormatSpec.FLAG_IS_NOT_MOVED;
-        } else if (true) {
-            switch (childrenAddressSize) {
-                case 1:
-                    flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_ONEBYTE;
-                    break;
-                case 2:
-                    flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_TWOBYTES;
-                    break;
-                case 3:
-                    flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_THREEBYTES;
-                    break;
-                case 0:
-                    flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_NOADDRESS;
-                    break;
-                default:
-                    throw new RuntimeException("Node with a strange address");
-            }
-        }
-        if (hasShortcuts) flags |= FormatSpec.FLAG_HAS_SHORTCUT_TARGETS;
-        if (hasBigrams) flags |= FormatSpec.FLAG_HAS_BIGRAMS;
-        if (isNotAWord) flags |= FormatSpec.FLAG_IS_NOT_A_WORD;
-        if (isBlackListEntry) flags |= FormatSpec.FLAG_IS_BLACKLISTED;
-        return flags;
-    }
-
-    private static byte makeCharGroupFlags(final CharGroup group, final int groupAddress,
-            final int childrenOffset, final FormatOptions formatOptions) {
-        return (byte) makeCharGroupFlags(group.mChars.length > 1, group.mFrequency >= 0,
-                getByteSize(childrenOffset), group.mShortcutTargets != null, group.mBigrams != null,
-                group.mIsNotAWord, group.mIsBlacklistEntry, formatOptions);
-    }
-
-    /**
-     * Makes the flag value for a bigram.
-     *
-     * @param more whether there are more bigrams after this one.
-     * @param offset the offset of the bigram.
-     * @param bigramFrequency the frequency of the bigram, 0..255.
-     * @param unigramFrequency the unigram frequency of the same word, 0..255.
-     * @param word the second bigram, for debugging purposes
-     * @return the flags
-     */
-    private static final int makeBigramFlags(final boolean more, final int offset,
-            int bigramFrequency, final int unigramFrequency, final String word) {
-        int bigramFlags = (more ? FormatSpec.FLAG_ATTRIBUTE_HAS_NEXT : 0)
-                + (offset < 0 ? FormatSpec.FLAG_ATTRIBUTE_OFFSET_NEGATIVE : 0);
-        switch (getByteSize(offset)) {
-        case 1:
-            bigramFlags |= FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE;
-            break;
-        case 2:
-            bigramFlags |= FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES;
-            break;
-        case 3:
-            bigramFlags |= FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES;
-            break;
-        default:
-            throw new RuntimeException("Strange offset size");
-        }
-        if (unigramFrequency > bigramFrequency) {
-            MakedictLog.e("Unigram freq is superior to bigram freq for \"" + word
-                    + "\". Bigram freq is " + bigramFrequency + ", unigram freq for "
-                    + word + " is " + unigramFrequency);
-            bigramFrequency = unigramFrequency;
-        }
-        // We compute the difference between 255 (which means probability = 1) and the
-        // unigram score. We split this into a number of discrete steps.
-        // Now, the steps are numbered 0~15; 0 represents an increase of 1 step while 15
-        // represents an increase of 16 steps: a value of 15 will be interpreted as the median
-        // value of the 16th step. In all justice, if the bigram frequency is low enough to be
-        // rounded below the first step (which means it is less than half a step higher than the
-        // unigram frequency) then the unigram frequency itself is the best approximation of the
-        // bigram freq that we could possibly supply, hence we should *not* include this bigram
-        // in the file at all.
-        // until this is done, we'll write 0 and slightly overestimate this case.
-        // In other words, 0 means "between 0.5 step and 1.5 step", 1 means "between 1.5 step
-        // and 2.5 steps", and 15 means "between 15.5 steps and 16.5 steps". So we want to
-        // divide our range [unigramFreq..MAX_TERMINAL_FREQUENCY] in 16.5 steps to get the
-        // step size. Then we compute the start of the first step (the one where value 0 starts)
-        // by adding half-a-step to the unigramFrequency. From there, we compute the integer
-        // number of steps to the bigramFrequency. One last thing: we want our steps to include
-        // their lower bound and exclude their higher bound so we need to have the first step
-        // start at exactly 1 unit higher than floor(unigramFreq + half a step).
-        // Note : to reconstruct the score, the dictionary reader will need to divide
-        // MAX_TERMINAL_FREQUENCY - unigramFreq by 16.5 likewise to get the value of the step,
-        // and add (discretizedFrequency + 0.5 + 0.5) times this value to get the best
-        // approximation. (0.5 to get the first step start, and 0.5 to get the middle of the
-        // step pointed by the discretized frequency.
-        final float stepSize =
-                (FormatSpec.MAX_TERMINAL_FREQUENCY - unigramFrequency)
-                / (1.5f + FormatSpec.MAX_BIGRAM_FREQUENCY);
-        final float firstStepStart = 1 + unigramFrequency + (stepSize / 2.0f);
-        final int discretizedFrequency = (int)((bigramFrequency - firstStepStart) / stepSize);
-        // If the bigram freq is less than half-a-step higher than the unigram freq, we get -1
-        // here. The best approximation would be the unigram freq itself, so we should not
-        // include this bigram in the dictionary. For now, register as 0, and live with the
-        // small over-estimation that we get in this case. TODO: actually remove this bigram
-        // if discretizedFrequency < 0.
-        final int finalBigramFrequency = discretizedFrequency > 0 ? discretizedFrequency : 0;
-        bigramFlags += finalBigramFrequency & FormatSpec.FLAG_ATTRIBUTE_FREQUENCY;
-        return bigramFlags;
-    }
-
-    /**
-     * Makes the 2-byte value for options flags.
-     */
-    private static final int makeOptionsValue(final FusionDictionary dictionary,
-            final FormatOptions formatOptions) {
-        final DictionaryOptions options = dictionary.mOptions;
-        final boolean hasBigrams = dictionary.hasBigrams();
-        return (options.mFrenchLigatureProcessing ? FormatSpec.FRENCH_LIGATURE_PROCESSING_FLAG : 0)
-                + (options.mGermanUmlautProcessing ? FormatSpec.GERMAN_UMLAUT_PROCESSING_FLAG : 0)
-                + (hasBigrams ? FormatSpec.CONTAINS_BIGRAMS_FLAG : 0)
-                + (formatOptions.mSupportsDynamicUpdate ? FormatSpec.SUPPORTS_DYNAMIC_UPDATE : 0);
-    }
-
-    /**
-     * Makes the flag value for a shortcut.
-     *
-     * @param more whether there are more attributes after this one.
-     * @param frequency the frequency of the attribute, 0..15
-     * @return the flags
-     */
-    static final int makeShortcutFlags(final boolean more, final int frequency) {
-        return (more ? FormatSpec.FLAG_ATTRIBUTE_HAS_NEXT : 0)
-                + (frequency & FormatSpec.FLAG_ATTRIBUTE_FREQUENCY);
-    }
-
-    private static final int writeParentAddress(final byte[] buffer, final int index,
-            final int address, final FormatOptions formatOptions) {
-        if (BinaryDictIOUtils.supportsDynamicUpdate(formatOptions)) {
-            if (address == FormatSpec.NO_PARENT_ADDRESS) {
-                buffer[index] = buffer[index + 1] = buffer[index + 2] = 0;
-            } else {
-                final int absAddress = Math.abs(address);
-                assert(absAddress <= FormatSpec.SINT24_MAX);
-                buffer[index] = (byte)((address < 0 ? FormatSpec.MSB8 : 0)
-                        | ((absAddress >> 16) & 0xFF));
-                buffer[index + 1] = (byte)((absAddress >> 8) & 0xFF);
-                buffer[index + 2] = (byte)(absAddress & 0xFF);
-            }
-            return index + 3;
-        } else {
-            return index;
-        }
-    }
-
-    /**
-     * Write a node to memory. The node is expected to have its final position cached.
-     *
-     * This can be an empty map, but the more is inside the faster the lookups will be. It can
-     * be carried on as long as nodes do not move.
-     *
-     * @param dict the dictionary the node is a part of (for relative offsets).
-     * @param buffer the memory buffer to write to.
-     * @param node the node to write.
-     * @param formatOptions file format options.
-     * @return the address of the END of the node.
-     */
-    @SuppressWarnings("unused")
-    private static int writePlacedNode(final FusionDictionary dict, byte[] buffer,
-            final Node node, final FormatOptions formatOptions) {
-        // TODO: Make the code in common with BinaryDictIOUtils#writeCharGroup
-        int index = node.mCachedAddressAfterUpdate;
-
-        final int groupCount = node.mData.size();
-        final int countSize = getGroupCountSize(node);
-        final int parentAddress = node.mCachedParentAddress;
-        if (1 == countSize) {
-            buffer[index++] = (byte)groupCount;
-        } else if (2 == countSize) {
-            // We need to signal 2-byte size by setting the top bit of the MSB to 1, so
-            // we | 0x80 to do this.
-            buffer[index++] = (byte)((groupCount >> 8) | 0x80);
-            buffer[index++] = (byte)(groupCount & 0xFF);
-        } else {
-            throw new RuntimeException("Strange size from getGroupCountSize : " + countSize);
-        }
-        int groupAddress = index;
-        for (int i = 0; i < groupCount; ++i) {
-            final CharGroup group = node.mData.get(i);
-            if (index != group.mCachedAddressAfterUpdate) {
-                throw new RuntimeException("Bug: write index is not the same as the cached address "
-                        + "of the group : " + index + " <> " + group.mCachedAddressAfterUpdate);
-            }
-            groupAddress += getGroupHeaderSize(group, formatOptions);
-            // Sanity checks.
-            if (DBG && group.mFrequency > FormatSpec.MAX_TERMINAL_FREQUENCY) {
-                throw new RuntimeException("A node has a frequency > "
-                        + FormatSpec.MAX_TERMINAL_FREQUENCY
-                        + " : " + group.mFrequency);
-            }
-            if (group.mFrequency >= 0) groupAddress += FormatSpec.GROUP_FREQUENCY_SIZE;
-            final int childrenOffset = null == group.mChildren
-                    ? FormatSpec.NO_CHILDREN_ADDRESS
-                            : group.mChildren.mCachedAddressAfterUpdate - groupAddress;
-            buffer[index++] =
-                    makeCharGroupFlags(group, groupAddress, childrenOffset, formatOptions);
-
-            if (parentAddress == FormatSpec.NO_PARENT_ADDRESS) {
-                index = writeParentAddress(buffer, index, parentAddress, formatOptions);
-            } else {
-                index = writeParentAddress(buffer, index, parentAddress
-                        + (node.mCachedAddressAfterUpdate - group.mCachedAddressAfterUpdate),
-                        formatOptions);
-            }
-
-            index = CharEncoding.writeCharArray(group.mChars, buffer, index);
-            if (group.hasSeveralChars()) {
-                buffer[index++] = FormatSpec.GROUP_CHARACTERS_TERMINATOR;
-            }
-            if (group.mFrequency >= 0) {
-                buffer[index++] = (byte) group.mFrequency;
-            }
-
-            final int shift;
-            if (formatOptions.mSupportsDynamicUpdate) {
-                shift = writeVariableSignedAddress(buffer, index, childrenOffset);
-            } else {
-                shift = writeVariableAddress(buffer, index, childrenOffset);
-            }
-            index += shift;
-            groupAddress += shift;
-
-            // Write shortcuts
-            if (null != group.mShortcutTargets) {
-                final int indexOfShortcutByteSize = index;
-                index += FormatSpec.GROUP_SHORTCUT_LIST_SIZE_SIZE;
-                groupAddress += FormatSpec.GROUP_SHORTCUT_LIST_SIZE_SIZE;
-                final Iterator<WeightedString> shortcutIterator = group.mShortcutTargets.iterator();
-                while (shortcutIterator.hasNext()) {
-                    final WeightedString target = shortcutIterator.next();
-                    ++groupAddress;
-                    int shortcutFlags = makeShortcutFlags(shortcutIterator.hasNext(),
-                            target.mFrequency);
-                    buffer[index++] = (byte)shortcutFlags;
-                    final int shortcutShift = CharEncoding.writeString(buffer, index, target.mWord);
-                    index += shortcutShift;
-                    groupAddress += shortcutShift;
-                }
-                final int shortcutByteSize = index - indexOfShortcutByteSize;
-                if (shortcutByteSize > 0xFFFF) {
-                    throw new RuntimeException("Shortcut list too large");
-                }
-                buffer[indexOfShortcutByteSize] = (byte)(shortcutByteSize >> 8);
-                buffer[indexOfShortcutByteSize + 1] = (byte)(shortcutByteSize & 0xFF);
-            }
-            // Write bigrams
-            if (null != group.mBigrams) {
-                final Iterator<WeightedString> bigramIterator = group.mBigrams.iterator();
-                while (bigramIterator.hasNext()) {
-                    final WeightedString bigram = bigramIterator.next();
-                    final CharGroup target =
-                            FusionDictionary.findWordInTree(dict.mRoot, bigram.mWord);
-                    final int addressOfBigram = target.mCachedAddressAfterUpdate;
-                    final int unigramFrequencyForThisWord = target.mFrequency;
-                    ++groupAddress;
-                    final int offset = addressOfBigram - groupAddress;
-                    int bigramFlags = makeBigramFlags(bigramIterator.hasNext(), offset,
-                            bigram.mFrequency, unigramFrequencyForThisWord, bigram.mWord);
-                    buffer[index++] = (byte)bigramFlags;
-                    final int bigramShift = writeVariableAddress(buffer, index, Math.abs(offset));
-                    index += bigramShift;
-                    groupAddress += bigramShift;
-                }
-            }
-
-        }
-        if (formatOptions.mSupportsDynamicUpdate) {
-            buffer[index] = buffer[index + 1] = buffer[index + 2]
-                    = FormatSpec.NO_FORWARD_LINK_ADDRESS;
-            index += FormatSpec.FORWARD_LINK_ADDRESS_SIZE;
-        }
-        if (index != node.mCachedAddressAfterUpdate + node.mCachedSize) throw new RuntimeException(
-                "Not the same size : written "
-                + (index - node.mCachedAddressAfterUpdate) + " bytes from a node that should have "
-                + node.mCachedSize + " bytes");
-        return index;
-    }
-
-    /**
-     * Dumps a collection of useful statistics about a node array.
-     *
-     * This prints purely informative stuff, like the total estimated file size, the
-     * number of nodes, of character groups, the repartition of each address size, etc
-     *
-     * @param nodes the node array.
-     */
-    private static void showStatistics(ArrayList<Node> nodes) {
-        int firstTerminalAddress = Integer.MAX_VALUE;
-        int lastTerminalAddress = Integer.MIN_VALUE;
-        int size = 0;
-        int charGroups = 0;
-        int maxGroups = 0;
-        int maxRuns = 0;
-        for (final Node n : nodes) {
-            if (maxGroups < n.mData.size()) maxGroups = n.mData.size();
-            for (final CharGroup cg : n.mData) {
-                ++charGroups;
-                if (cg.mChars.length > maxRuns) maxRuns = cg.mChars.length;
-                if (cg.mFrequency >= 0) {
-                    if (n.mCachedAddressAfterUpdate < firstTerminalAddress)
-                        firstTerminalAddress = n.mCachedAddressAfterUpdate;
-                    if (n.mCachedAddressAfterUpdate > lastTerminalAddress)
-                        lastTerminalAddress = n.mCachedAddressAfterUpdate;
-                }
-            }
-            if (n.mCachedAddressAfterUpdate + n.mCachedSize > size) {
-                size = n.mCachedAddressAfterUpdate + n.mCachedSize;
-            }
-        }
-        final int[] groupCounts = new int[maxGroups + 1];
-        final int[] runCounts = new int[maxRuns + 1];
-        for (final Node n : nodes) {
-            ++groupCounts[n.mData.size()];
-            for (final CharGroup cg : n.mData) {
-                ++runCounts[cg.mChars.length];
-            }
-        }
-
-        MakedictLog.i("Statistics:\n"
-                + "  total file size " + size + "\n"
-                + "  " + nodes.size() + " nodes\n"
-                + "  " + charGroups + " groups (" + ((float)charGroups / nodes.size())
-                        + " groups per node)\n"
-                + "  first terminal at " + firstTerminalAddress + "\n"
-                + "  last terminal at " + lastTerminalAddress + "\n"
-                + "  Group stats : max = " + maxGroups);
-        for (int i = 0; i < groupCounts.length; ++i) {
-            MakedictLog.i("    " + i + " : " + groupCounts[i]);
-        }
-        MakedictLog.i("  Character run stats : max = " + maxRuns);
-        for (int i = 0; i < runCounts.length; ++i) {
-            MakedictLog.i("    " + i + " : " + runCounts[i]);
-        }
-    }
-
-    /**
-     * Dumps a FusionDictionary to a file.
-     *
-     * This is the public entry point to write a dictionary to a file.
-     *
-     * @param destination the stream to write the binary data to.
-     * @param dict the dictionary to write.
-     * @param formatOptions file format options.
-     */
-    public static void writeDictionaryBinary(final OutputStream destination,
-            final FusionDictionary dict, final FormatOptions formatOptions)
-            throws IOException, UnsupportedFormatException {
-
-        // Addresses are limited to 3 bytes, but since addresses can be relative to each node, the
-        // structure itself is not limited to 16MB. However, if it is over 16MB deciding the order
-        // of the nodes becomes a quite complicated problem, because though the dictionary itself
-        // does not have a size limit, each node must still be within 16MB of all its children and
-        // parents. As long as this is ensured, the dictionary file may grow to any size.
-
-        final int version = formatOptions.mVersion;
-        if (version < FormatSpec.MINIMUM_SUPPORTED_VERSION
-                || version > FormatSpec.MAXIMUM_SUPPORTED_VERSION) {
-            throw new UnsupportedFormatException("Requested file format version " + version
-                    + ", but this implementation only supports versions "
-                    + FormatSpec.MINIMUM_SUPPORTED_VERSION + " through "
-                    + FormatSpec.MAXIMUM_SUPPORTED_VERSION);
-        }
-
-        ByteArrayOutputStream headerBuffer = new ByteArrayOutputStream(256);
-
-        // The magic number in big-endian order.
-        // Magic number for all versions.
-        headerBuffer.write((byte) (0xFF & (FormatSpec.MAGIC_NUMBER >> 24)));
-        headerBuffer.write((byte) (0xFF & (FormatSpec.MAGIC_NUMBER >> 16)));
-        headerBuffer.write((byte) (0xFF & (FormatSpec.MAGIC_NUMBER >> 8)));
-        headerBuffer.write((byte) (0xFF & FormatSpec.MAGIC_NUMBER));
-        // Dictionary version.
-        headerBuffer.write((byte) (0xFF & (version >> 8)));
-        headerBuffer.write((byte) (0xFF & version));
-
-        // Options flags
-        final int options = makeOptionsValue(dict, formatOptions);
-        headerBuffer.write((byte) (0xFF & (options >> 8)));
-        headerBuffer.write((byte) (0xFF & options));
-        final int headerSizeOffset = headerBuffer.size();
-        // Placeholder to be written later with header size.
-        for (int i = 0; i < 4; ++i) {
-            headerBuffer.write(0);
-        }
-        // Write out the options.
-        for (final String key : dict.mOptions.mAttributes.keySet()) {
-            final String value = dict.mOptions.mAttributes.get(key);
-            CharEncoding.writeString(headerBuffer, key);
-            CharEncoding.writeString(headerBuffer, value);
-        }
-        final int size = headerBuffer.size();
-        final byte[] bytes = headerBuffer.toByteArray();
-        // Write out the header size.
-        bytes[headerSizeOffset] = (byte) (0xFF & (size >> 24));
-        bytes[headerSizeOffset + 1] = (byte) (0xFF & (size >> 16));
-        bytes[headerSizeOffset + 2] = (byte) (0xFF & (size >> 8));
-        bytes[headerSizeOffset + 3] = (byte) (0xFF & (size >> 0));
-        destination.write(bytes);
-
-        headerBuffer.close();
-
-        // Leave the choice of the optimal node order to the flattenTree function.
-        MakedictLog.i("Flattening the tree...");
-        ArrayList<Node> flatNodes = flattenTree(dict.mRoot);
-
-        MakedictLog.i("Computing addresses...");
-        computeAddresses(dict, flatNodes, formatOptions);
-        MakedictLog.i("Checking array...");
-        if (DBG) checkFlatNodeArray(flatNodes);
-
-        // Create a buffer that matches the final dictionary size.
-        final Node lastNode = flatNodes.get(flatNodes.size() - 1);
-        final int bufferSize = lastNode.mCachedAddressAfterUpdate + lastNode.mCachedSize;
-        final byte[] buffer = new byte[bufferSize];
-        int index = 0;
-
-        MakedictLog.i("Writing file...");
-        int dataEndOffset = 0;
-        for (Node n : flatNodes) {
-            dataEndOffset = writePlacedNode(dict, buffer, n, formatOptions);
-        }
-
-        if (DBG) showStatistics(flatNodes);
-
-        destination.write(buffer, 0, dataEndOffset);
-
-        destination.close();
-        MakedictLog.i("Done");
-    }
-
-
-    // Input methods: Read a binary dictionary to memory.
-    // readDictionaryBinary is the public entry point for them.
-
-    static int getChildrenAddressSize(final int optionFlags,
-            final FormatOptions formatOptions) {
-        if (formatOptions.mSupportsDynamicUpdate) return FormatSpec.SIGNED_CHILDREN_ADDRESS_SIZE;
-        switch (optionFlags & FormatSpec.MASK_GROUP_ADDRESS_TYPE) {
-            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_ONEBYTE:
-                return 1;
-            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_TWOBYTES:
-                return 2;
-            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_THREEBYTES:
-                return 3;
-            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_NOADDRESS:
-            default:
-                return 0;
-        }
-    }
-
-    static int readChildrenAddress(final FusionDictionaryBufferInterface buffer,
-            final int optionFlags, final FormatOptions options) {
-        if (options.mSupportsDynamicUpdate) {
-            final int address = buffer.readUnsignedInt24();
-            if (address == 0) return FormatSpec.NO_CHILDREN_ADDRESS;
-            if ((address & FormatSpec.MSB24) != 0) {
-                return -(address & FormatSpec.SINT24_MAX);
-            } else {
-                return address;
-            }
-        }
-        int address;
-        switch (optionFlags & FormatSpec.MASK_GROUP_ADDRESS_TYPE) {
-            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_ONEBYTE:
-                return buffer.readUnsignedByte();
-            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_TWOBYTES:
-                return buffer.readUnsignedShort();
-            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_THREEBYTES:
-                return buffer.readUnsignedInt24();
-            case FormatSpec.FLAG_GROUP_ADDRESS_TYPE_NOADDRESS:
-            default:
-                return FormatSpec.NO_CHILDREN_ADDRESS;
-        }
-    }
-
-    static int readParentAddress(final FusionDictionaryBufferInterface buffer,
-            final FormatOptions formatOptions) {
-        if (BinaryDictIOUtils.supportsDynamicUpdate(formatOptions)) {
-            final int parentAddress = buffer.readUnsignedInt24();
-            final int sign = ((parentAddress & FormatSpec.MSB24) != 0) ? -1 : 1;
-            return sign * (parentAddress & FormatSpec.SINT24_MAX);
-        } else {
-            return FormatSpec.NO_PARENT_ADDRESS;
-        }
-    }
-
-    private static final int[] CHARACTER_BUFFER = new int[FormatSpec.MAX_WORD_LENGTH];
-    public static CharGroupInfo readCharGroup(final FusionDictionaryBufferInterface buffer,
-            final int originalGroupAddress, final FormatOptions options) {
-        int addressPointer = originalGroupAddress;
-        final int flags = buffer.readUnsignedByte();
-        ++addressPointer;
-
-        final int parentAddress = readParentAddress(buffer, options);
-        if (BinaryDictIOUtils.supportsDynamicUpdate(options)) {
-            addressPointer += 3;
-        }
-
-        final int characters[];
-        if (0 != (flags & FormatSpec.FLAG_HAS_MULTIPLE_CHARS)) {
-            int index = 0;
-            int character = CharEncoding.readChar(buffer);
-            addressPointer += CharEncoding.getCharSize(character);
-            while (-1 != character) {
-                // FusionDictionary is making sure that the length of the word is smaller than
-                // MAX_WORD_LENGTH.
-                // So we'll never write past the end of CHARACTER_BUFFER.
-                CHARACTER_BUFFER[index++] = character;
-                character = CharEncoding.readChar(buffer);
-                addressPointer += CharEncoding.getCharSize(character);
-            }
-            characters = Arrays.copyOfRange(CHARACTER_BUFFER, 0, index);
-        } else {
-            final int character = CharEncoding.readChar(buffer);
-            addressPointer += CharEncoding.getCharSize(character);
-            characters = new int[] { character };
-        }
-        final int frequency;
-        if (0 != (FormatSpec.FLAG_IS_TERMINAL & flags)) {
-            ++addressPointer;
-            frequency = buffer.readUnsignedByte();
-        } else {
-            frequency = CharGroup.NOT_A_TERMINAL;
-        }
-        int childrenAddress = readChildrenAddress(buffer, flags, options);
-        if (childrenAddress != FormatSpec.NO_CHILDREN_ADDRESS) {
-            childrenAddress += addressPointer;
-        }
-        addressPointer += getChildrenAddressSize(flags, options);
-        ArrayList<WeightedString> shortcutTargets = null;
-        if (0 != (flags & FormatSpec.FLAG_HAS_SHORTCUT_TARGETS)) {
-            final int pointerBefore = buffer.position();
-            shortcutTargets = new ArrayList<WeightedString>();
-            buffer.readUnsignedShort(); // Skip the size
-            while (true) {
-                final int targetFlags = buffer.readUnsignedByte();
-                final String word = CharEncoding.readString(buffer);
-                shortcutTargets.add(new WeightedString(word,
-                        targetFlags & FormatSpec.FLAG_ATTRIBUTE_FREQUENCY));
-                if (0 == (targetFlags & FormatSpec.FLAG_ATTRIBUTE_HAS_NEXT)) break;
-            }
-            addressPointer += buffer.position() - pointerBefore;
-        }
-        ArrayList<PendingAttribute> bigrams = null;
-        if (0 != (flags & FormatSpec.FLAG_HAS_BIGRAMS)) {
-            bigrams = new ArrayList<PendingAttribute>();
-            int bigramCount = 0;
-            while (bigramCount++ < FormatSpec.MAX_BIGRAMS_IN_A_GROUP) {
-                final int bigramFlags = buffer.readUnsignedByte();
-                ++addressPointer;
-                final int sign = 0 == (bigramFlags & FormatSpec.FLAG_ATTRIBUTE_OFFSET_NEGATIVE)
-                        ? 1 : -1;
-                int bigramAddress = addressPointer;
-                switch (bigramFlags & FormatSpec.MASK_ATTRIBUTE_ADDRESS_TYPE) {
-                case FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE:
-                    bigramAddress += sign * buffer.readUnsignedByte();
-                    addressPointer += 1;
-                    break;
-                case FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES:
-                    bigramAddress += sign * buffer.readUnsignedShort();
-                    addressPointer += 2;
-                    break;
-                case FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES:
-                    final int offset = (buffer.readUnsignedByte() << 16)
-                            + buffer.readUnsignedShort();
-                    bigramAddress += sign * offset;
-                    addressPointer += 3;
-                    break;
-                default:
-                    throw new RuntimeException("Has bigrams with no address");
-                }
-                bigrams.add(new PendingAttribute(bigramFlags & FormatSpec.FLAG_ATTRIBUTE_FREQUENCY,
-                        bigramAddress));
-                if (0 == (bigramFlags & FormatSpec.FLAG_ATTRIBUTE_HAS_NEXT)) break;
-            }
-            if (bigramCount >= FormatSpec.MAX_BIGRAMS_IN_A_GROUP) {
-                MakedictLog.d("too many bigrams in a group.");
-            }
-        }
-        return new CharGroupInfo(originalGroupAddress, addressPointer, flags, characters, frequency,
-                parentAddress, childrenAddress, shortcutTargets, bigrams);
-    }
-
-    /**
-     * Reads and returns the char group count out of a buffer and forwards the pointer.
-     */
-    public static int readCharGroupCount(final FusionDictionaryBufferInterface buffer) {
-        final int msb = buffer.readUnsignedByte();
-        if (FormatSpec.MAX_CHARGROUPS_FOR_ONE_BYTE_CHARGROUP_COUNT >= msb) {
-            return msb;
-        } else {
-            return ((FormatSpec.MAX_CHARGROUPS_FOR_ONE_BYTE_CHARGROUP_COUNT & msb) << 8)
-                    + buffer.readUnsignedByte();
-        }
-    }
-
-    // The word cache here is a stopgap bandaid to help the catastrophic performance
-    // of this method. Since it performs direct, unbuffered random access to the file and
-    // may be called hundreds of thousands of times, the resulting performance is not
-    // reasonable without some kind of cache. Thus:
-    private static TreeMap<Integer, WeightedString> wordCache =
-            new TreeMap<Integer, WeightedString>();
-    /**
-     * Finds, as a string, the word at the address passed as an argument.
-     *
-     * @param buffer the buffer to read from.
-     * @param headerSize the size of the header.
-     * @param address the address to seek.
-     * @param formatOptions file format options.
-     * @return the word with its frequency, as a weighted string.
-     */
-    /* package for tests */ static WeightedString getWordAtAddress(
-            final FusionDictionaryBufferInterface buffer, final int headerSize, final int address,
-            final FormatOptions formatOptions) {
-        final WeightedString cachedString = wordCache.get(address);
-        if (null != cachedString) return cachedString;
-
-        final WeightedString result;
-        final int originalPointer = buffer.position();
-        buffer.position(address);
-
-        if (BinaryDictIOUtils.supportsDynamicUpdate(formatOptions)) {
-            result = getWordAtAddressWithParentAddress(buffer, headerSize, address, formatOptions);
-        } else {
-            result = getWordAtAddressWithoutParentAddress(buffer, headerSize, address,
-                    formatOptions);
-        }
-
-        wordCache.put(address, result);
-        buffer.position(originalPointer);
-        return result;
-    }
-
-    // TODO: static!? This will behave erratically when used in multi-threaded code.
-    // We need to fix this
-    private static int[] sGetWordBuffer = new int[FormatSpec.MAX_WORD_LENGTH];
-    @SuppressWarnings("unused")
-    private static WeightedString getWordAtAddressWithParentAddress(
-            final FusionDictionaryBufferInterface buffer, final int headerSize, final int address,
-            final FormatOptions options) {
-        int currentAddress = address;
-        int index = FormatSpec.MAX_WORD_LENGTH - 1;
-        int frequency = Integer.MIN_VALUE;
-        // the length of the path from the root to the leaf is limited by MAX_WORD_LENGTH
-        for (int count = 0; count < FormatSpec.MAX_WORD_LENGTH; ++count) {
-            CharGroupInfo currentInfo;
-            int loopCounter = 0;
-            do {
-                buffer.position(currentAddress + headerSize);
-                currentInfo = readCharGroup(buffer, currentAddress, options);
-                if (BinaryDictIOUtils.isMovedGroup(currentInfo.mFlags, options)) {
-                    currentAddress = currentInfo.mParentAddress + currentInfo.mOriginalAddress;
-                }
-                if (DBG && loopCounter++ > MAX_JUMPS) {
-                    MakedictLog.d("Too many jumps - probably a bug");
-                }
-            } while (BinaryDictIOUtils.isMovedGroup(currentInfo.mFlags, options));
-            if (Integer.MIN_VALUE == frequency) frequency = currentInfo.mFrequency;
-            for (int i = 0; i < currentInfo.mCharacters.length; ++i) {
-                sGetWordBuffer[index--] =
-                        currentInfo.mCharacters[currentInfo.mCharacters.length - i - 1];
-            }
-            if (currentInfo.mParentAddress == FormatSpec.NO_PARENT_ADDRESS) break;
-            currentAddress = currentInfo.mParentAddress + currentInfo.mOriginalAddress;
-        }
-
-        return new WeightedString(
-                new String(sGetWordBuffer, index + 1, FormatSpec.MAX_WORD_LENGTH - index - 1),
-                        frequency);
-    }
-
-    private static WeightedString getWordAtAddressWithoutParentAddress(
-            final FusionDictionaryBufferInterface buffer, final int headerSize, final int address,
-            final FormatOptions options) {
-        buffer.position(headerSize);
-        final int count = readCharGroupCount(buffer);
-        int groupOffset = BinaryDictIOUtils.getGroupCountSize(count);
-        final StringBuilder builder = new StringBuilder();
-        WeightedString result = null;
-
-        CharGroupInfo last = null;
-        for (int i = count - 1; i >= 0; --i) {
-            CharGroupInfo info = readCharGroup(buffer, groupOffset, options);
-            groupOffset = info.mEndAddress;
-            if (info.mOriginalAddress == address) {
-                builder.append(new String(info.mCharacters, 0, info.mCharacters.length));
-                result = new WeightedString(builder.toString(), info.mFrequency);
-                break; // and return
-            }
-            if (BinaryDictIOUtils.hasChildrenAddress(info.mChildrenAddress)) {
-                if (info.mChildrenAddress > address) {
-                    if (null == last) continue;
-                    builder.append(new String(last.mCharacters, 0, last.mCharacters.length));
-                    buffer.position(last.mChildrenAddress + headerSize);
-                    i = readCharGroupCount(buffer);
-                    groupOffset = last.mChildrenAddress + BinaryDictIOUtils.getGroupCountSize(i);
-                    last = null;
-                    continue;
-                }
-                last = info;
-            }
-            if (0 == i && BinaryDictIOUtils.hasChildrenAddress(last.mChildrenAddress)) {
-                builder.append(new String(last.mCharacters, 0, last.mCharacters.length));
-                buffer.position(last.mChildrenAddress + headerSize);
-                i = readCharGroupCount(buffer);
-                groupOffset = last.mChildrenAddress + BinaryDictIOUtils.getGroupCountSize(i);
-                last = null;
-                continue;
-            }
-        }
-        return result;
-    }
-
-    /**
-     * Reads a single node from a buffer.
-     *
-     * This methods reads the file at the current position. A node is fully expected to start at
-     * the current position.
-     * This will recursively read other nodes into the structure, populating the reverse
-     * maps on the fly and using them to keep track of already read nodes.
-     *
-     * @param buffer the buffer, correctly positioned at the start of a node.
-     * @param headerSize the size, in bytes, of the file header.
-     * @param reverseNodeMap a mapping from addresses to already read nodes.
-     * @param reverseGroupMap a mapping from addresses to already read character groups.
-     * @param options file format options.
-     * @return the read node with all his children already read.
-     */
-    private static Node readNode(final FusionDictionaryBufferInterface buffer, final int headerSize,
-            final Map<Integer, Node> reverseNodeMap, final Map<Integer, CharGroup> reverseGroupMap,
-            final FormatOptions options)
-            throws IOException {
-        final ArrayList<CharGroup> nodeContents = new ArrayList<CharGroup>();
-        final int nodeOrigin = buffer.position() - headerSize;
-
-        do { // Scan the linked-list node.
-            final int nodeHeadPosition = buffer.position() - headerSize;
-            final int count = readCharGroupCount(buffer);
-            int groupOffset = nodeHeadPosition + BinaryDictIOUtils.getGroupCountSize(count);
-            for (int i = count; i > 0; --i) { // Scan the array of CharGroup.
-                CharGroupInfo info = readCharGroup(buffer, groupOffset, options);
-                if (BinaryDictIOUtils.isMovedGroup(info.mFlags, options)) continue;
-                ArrayList<WeightedString> shortcutTargets = info.mShortcutTargets;
-                ArrayList<WeightedString> bigrams = null;
-                if (null != info.mBigrams) {
-                    bigrams = new ArrayList<WeightedString>();
-                    for (PendingAttribute bigram : info.mBigrams) {
-                        final WeightedString word = getWordAtAddress(
-                                buffer, headerSize, bigram.mAddress, options);
-                        final int reconstructedFrequency =
-                                reconstructBigramFrequency(word.mFrequency, bigram.mFrequency);
-                        bigrams.add(new WeightedString(word.mWord, reconstructedFrequency));
-                    }
-                }
-                if (BinaryDictIOUtils.hasChildrenAddress(info.mChildrenAddress)) {
-                    Node children = reverseNodeMap.get(info.mChildrenAddress);
-                    if (null == children) {
-                        final int currentPosition = buffer.position();
-                        buffer.position(info.mChildrenAddress + headerSize);
-                        children = readNode(
-                                buffer, headerSize, reverseNodeMap, reverseGroupMap, options);
-                        buffer.position(currentPosition);
-                    }
-                    nodeContents.add(
-                            new CharGroup(info.mCharacters, shortcutTargets, bigrams,
-                                    info.mFrequency,
-                                    0 != (info.mFlags & FormatSpec.FLAG_IS_NOT_A_WORD),
-                                    0 != (info.mFlags & FormatSpec.FLAG_IS_BLACKLISTED), children));
-                } else {
-                    nodeContents.add(
-                            new CharGroup(info.mCharacters, shortcutTargets, bigrams,
-                                    info.mFrequency,
-                                    0 != (info.mFlags & FormatSpec.FLAG_IS_NOT_A_WORD),
-                                    0 != (info.mFlags & FormatSpec.FLAG_IS_BLACKLISTED)));
-                }
-                groupOffset = info.mEndAddress;
-            }
-
-            // reach the end of the array.
-            if (options.mSupportsDynamicUpdate) {
-                final int nextAddress = buffer.readUnsignedInt24();
-                if (nextAddress >= 0 && nextAddress < buffer.limit()) {
-                    buffer.position(nextAddress);
-                } else {
-                    break;
-                }
-            }
-        } while (options.mSupportsDynamicUpdate &&
-                buffer.position() != FormatSpec.NO_FORWARD_LINK_ADDRESS);
-
-        final Node node = new Node(nodeContents);
-        node.mCachedAddressBeforeUpdate = nodeOrigin;
-        node.mCachedAddressAfterUpdate = nodeOrigin;
-        reverseNodeMap.put(node.mCachedAddressAfterUpdate, node);
-        return node;
-    }
-
-    /**
-     * Helper function to get the binary format version from the header.
-     * @throws IOException
-     */
-    private static int getFormatVersion(final FusionDictionaryBufferInterface buffer)
-            throws IOException {
-        final int magic = buffer.readInt();
-        if (FormatSpec.MAGIC_NUMBER == magic) return buffer.readUnsignedShort();
-        return FormatSpec.NOT_A_VERSION_NUMBER;
-    }
-
-    /**
-     * Helper function to get and validate the binary format version.
-     * @throws UnsupportedFormatException
-     * @throws IOException
-     */
-    private static int checkFormatVersion(final FusionDictionaryBufferInterface buffer)
-            throws IOException, UnsupportedFormatException {
-        final int version = getFormatVersion(buffer);
-        if (version < FormatSpec.MINIMUM_SUPPORTED_VERSION
-                || version > FormatSpec.MAXIMUM_SUPPORTED_VERSION) {
-            throw new UnsupportedFormatException("This file has version " + version
-                    + ", but this implementation does not support versions above "
-                    + FormatSpec.MAXIMUM_SUPPORTED_VERSION);
-        }
-        return version;
-    }
-
-    /**
-     * Reads a header from a buffer.
-     * @param buffer the buffer to read.
-     * @throws IOException
-     * @throws UnsupportedFormatException
-     */
-    public static FileHeader readHeader(final FusionDictionaryBufferInterface buffer)
-            throws IOException, UnsupportedFormatException {
-        final int version = checkFormatVersion(buffer);
-        final int optionsFlags = buffer.readUnsignedShort();
-
-        final HashMap<String, String> attributes = new HashMap<String, String>();
-        final int headerSize;
-        headerSize = buffer.readInt();
-
-        if (headerSize < 0) {
-            throw new UnsupportedFormatException("header size can't be negative.");
-        }
-
-        populateOptions(buffer, headerSize, attributes);
-        buffer.position(headerSize);
-
-        final FileHeader header = new FileHeader(headerSize,
-                new FusionDictionary.DictionaryOptions(attributes,
-                        0 != (optionsFlags & FormatSpec.GERMAN_UMLAUT_PROCESSING_FLAG),
-                        0 != (optionsFlags & FormatSpec.FRENCH_LIGATURE_PROCESSING_FLAG)),
-                new FormatOptions(version,
-                        0 != (optionsFlags & FormatSpec.SUPPORTS_DYNAMIC_UPDATE)));
-        return header;
-    }
-
-    /**
-     * Reads options from a buffer and populate a map with their contents.
-     *
-     * The buffer is read at the current position, so the caller must take care the pointer
-     * is in the right place before calling this.
-     */
-    public static void populateOptions(final FusionDictionaryBufferInterface buffer,
-            final int headerSize, final HashMap<String, String> options) {
-        while (buffer.position() < headerSize) {
-            final String key = CharEncoding.readString(buffer);
-            final String value = CharEncoding.readString(buffer);
-            options.put(key, value);
-        }
-    }
-
-    /**
-     * Reads a buffer and returns the memory representation of the dictionary.
-     *
-     * This high-level method takes a buffer and reads its contents, populating a
-     * FusionDictionary structure. The optional dict argument is an existing dictionary to
-     * which words from the buffer should be added. If it is null, a new dictionary is created.
-     *
-     * @param reader the reader.
-     * @param dict an optional dictionary to add words to, or null.
-     * @return the created (or merged) dictionary.
-     */
-    @UsedForTesting
-    public static FusionDictionary readDictionaryBinary(final BinaryDictReader reader,
-            final FusionDictionary dict) throws FileNotFoundException, IOException,
-            UnsupportedFormatException {
-        // clear cache
-        wordCache.clear();
-
-        // if the buffer has not been opened, open the buffer with bytebuffer.
-        if (reader.getBuffer() == null) reader.openBuffer(
-                new BinaryDictReader.FusionDictionaryBufferFromByteBufferFactory());
-        if (reader.getBuffer() == null) {
-            MakedictLog.e("Cannot open the buffer");
-        }
-
-        // Read header
-        final FileHeader header = readHeader(reader.getBuffer());
-
-        Map<Integer, Node> reverseNodeMapping = new TreeMap<Integer, Node>();
-        Map<Integer, CharGroup> reverseGroupMapping = new TreeMap<Integer, CharGroup>();
-        final Node root = readNode(reader.getBuffer(), header.mHeaderSize, reverseNodeMapping,
-                reverseGroupMapping, header.mFormatOptions);
-
-        FusionDictionary newDict = new FusionDictionary(root, header.mDictionaryOptions);
-        if (null != dict) {
-            for (final Word w : dict) {
-                if (w.mIsBlacklistEntry) {
-                    newDict.addBlacklistEntry(w.mWord, w.mShortcutTargets, w.mIsNotAWord);
-                } else {
-                    newDict.add(w.mWord, w.mFrequency, w.mShortcutTargets, w.mIsNotAWord);
-                }
-            }
-            for (final Word w : dict) {
-                // By construction a binary dictionary may not have bigrams pointing to
-                // words that are not also registered as unigrams so we don't have to avoid
-                // them explicitly here.
-                for (final WeightedString bigram : w.mBigrams) {
-                    newDict.setBigram(w.mWord, bigram.mWord, bigram.mFrequency);
-                }
-            }
-        }
-
-        return newDict;
-    }
-
-    /**
-     * Helper method to pass a file name instead of a File object to isBinaryDictionary.
-     */
-    public static boolean isBinaryDictionary(final String filename) {
-        final File file = new File(filename);
-        return isBinaryDictionary(file);
-    }
-
-    /**
-     * Basic test to find out whether the file is a binary dictionary or not.
-     *
-     * Concretely this only tests the magic number.
-     *
-     * @param file The file to test.
-     * @return true if it's a binary dictionary, false otherwise
-     */
-    public static boolean isBinaryDictionary(final File file) {
-        FileInputStream inStream = null;
-        try {
-            inStream = new FileInputStream(file);
-            final ByteBuffer buffer = inStream.getChannel().map(
-                    FileChannel.MapMode.READ_ONLY, 0, file.length());
-            final int version = getFormatVersion(new ByteBufferWrapper(buffer));
-            return (version >= FormatSpec.MINIMUM_SUPPORTED_VERSION
-                    && version <= FormatSpec.MAXIMUM_SUPPORTED_VERSION);
-        } catch (FileNotFoundException e) {
-            return false;
-        } catch (IOException e) {
-            return false;
-        } finally {
-            if (inStream != null) {
-                try {
-                    inStream.close();
-                } catch (IOException e) {
-                    // do nothing
-                }
-            }
-        }
-    }
-
-    /**
-     * Calculate bigram frequency from compressed value
-     *
-     * @see #makeBigramFlags
-     *
-     * @param unigramFrequency
-     * @param bigramFrequency compressed frequency
-     * @return approximate bigram frequency
-     */
-    public static int reconstructBigramFrequency(final int unigramFrequency,
-            final int bigramFrequency) {
-        final float stepSize = (FormatSpec.MAX_TERMINAL_FREQUENCY - unigramFrequency)
-                / (1.5f + FormatSpec.MAX_BIGRAM_FREQUENCY);
-        final float resultFreqFloat = unigramFrequency + stepSize * (bigramFrequency + 1.0f);
-        return (int)resultFreqFloat;
-    }
-}
diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictReader.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictReader.java
index a4a7ce4..6d3b31a 100644
--- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictReader.java
+++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictReader.java
@@ -17,7 +17,9 @@
 package com.android.inputmethod.latin.makedict;
 
 import com.android.inputmethod.annotations.UsedForTesting;
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput.FusionDictionaryBufferInterface;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder.CharEncoding;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder.FusionDictionaryBufferInterface;
+import com.android.inputmethod.latin.makedict.decoder.HeaderReaderInterface;
 import com.android.inputmethod.latin.utils.ByteArrayWrapper;
 
 import java.io.File;
@@ -27,8 +29,9 @@
 import java.io.RandomAccessFile;
 import java.nio.ByteBuffer;
 import java.nio.channels.FileChannel;
+import java.util.HashMap;
 
-public class BinaryDictReader {
+public class BinaryDictReader implements HeaderReaderInterface {
 
     public interface FusionDictionaryBufferFactory {
         public FusionDictionaryBufferInterface getFusionDictionaryBuffer(final File file)
@@ -55,7 +58,7 @@
                 }
             }
             if (buffer != null) {
-                return new BinaryDictInputOutput.ByteBufferWrapper(buffer);
+                return new BinaryDictDecoder.ByteBufferWrapper(buffer);
             }
             return null;
         }
@@ -103,7 +106,7 @@
                 }
             }
             if (buffer != null) {
-                return new BinaryDictInputOutput.ByteBufferWrapper(buffer);
+                return new BinaryDictDecoder.ByteBufferWrapper(buffer);
             }
             return null;
         }
@@ -133,4 +136,34 @@
         openBuffer(factory);
         return getBuffer();
     }
+
+    // The implementation of HeaderReaderInterface
+    @Override
+    public int readVersion() throws IOException, UnsupportedFormatException {
+        return BinaryDictDecoder.checkFormatVersion(mFusionDictionaryBuffer);
+    }
+
+    @Override
+    public int readOptionFlags() {
+        return mFusionDictionaryBuffer.readUnsignedShort();
+    }
+
+    @Override
+    public int readHeaderSize() {
+        return mFusionDictionaryBuffer.readInt();
+    }
+
+    @Override
+    public HashMap<String, String> readAttributes(final int headerSize) {
+        final HashMap<String, String> attributes = new HashMap<String, String>();
+        while (mFusionDictionaryBuffer.position() < headerSize) {
+            // We can avoid infinite loop here since mFusionDictonary.position() is always increased
+            // by calling CharEncoding.readString.
+            final String key = CharEncoding.readString(mFusionDictionaryBuffer);
+            final String value = CharEncoding.readString(mFusionDictionaryBuffer);
+            attributes.put(key, value);
+        }
+        mFusionDictionaryBuffer.position(headerSize);
+        return attributes;
+    }
 }
diff --git a/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java b/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java
index 5b10912..584b793 100644
--- a/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java
+++ b/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java
@@ -18,7 +18,7 @@
 
 import com.android.inputmethod.annotations.UsedForTesting;
 import com.android.inputmethod.latin.Constants;
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput.FusionDictionaryBufferInterface;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder.FusionDictionaryBufferInterface;
 import com.android.inputmethod.latin.makedict.FormatSpec.FileHeader;
 import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
 import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
@@ -49,17 +49,18 @@
     /**
      * Delete the word from the binary file.
      *
-     * @param buffer the buffer to write.
+     * @param dictReader the dict reader.
      * @param word the word we delete
      * @throws IOException
      * @throws UnsupportedFormatException
      */
     @UsedForTesting
-    public static void deleteWord(final FusionDictionaryBufferInterface buffer,
-            final String word) throws IOException, UnsupportedFormatException {
+    public static void deleteWord(final BinaryDictReader dictReader, final String word)
+            throws IOException, UnsupportedFormatException {
+        final FusionDictionaryBufferInterface buffer = dictReader.getBuffer();
         buffer.position(0);
-        final FileHeader header = BinaryDictInputOutput.readHeader(buffer);
-        final int wordPosition = BinaryDictIOUtils.getTerminalPosition(buffer, word);
+        final FileHeader header = BinaryDictDecoder.readHeader(dictReader);
+        final int wordPosition = BinaryDictIOUtils.getTerminalPosition(dictReader, word);
         if (wordPosition == FormatSpec.NOT_VALID_WORD) return;
 
         buffer.position(wordPosition);
@@ -86,7 +87,7 @@
         }
         final int flags = buffer.readUnsignedByte();
         if (BinaryDictIOUtils.isMovedGroup(flags, formatOptions)) {
-            // if the group is moved, the parent address is stored in the destination group.
+            // If the group is moved, the parent address is stored in the destination group.
             // We are guaranteed to process the destination group later, so there is no need to
             // update anything here.
             buffer.position(originalPosition);
@@ -101,10 +102,10 @@
     }
 
     /**
-     * Update parent addresses in a Node that is referred to by nodeOriginAddress.
+     * Update parent addresses in a node array stored at nodeOriginAddress.
      *
      * @param buffer the buffer to be modified.
-     * @param nodeOriginAddress the address of a modified Node.
+     * @param nodeOriginAddress the address of the node array to update.
      * @param newParentAddress the address to be written.
      * @param formatOptions file format options.
      */
@@ -114,7 +115,7 @@
         final int originalPosition = buffer.position();
         buffer.position(nodeOriginAddress);
         do {
-            final int count = BinaryDictInputOutput.readCharGroupCount(buffer);
+            final int count = BinaryDictDecoder.readCharGroupCount(buffer);
             for (int i = 0; i < count; ++i) {
                 updateParentAddress(buffer, buffer.position(), newParentAddress, formatOptions);
                 BinaryDictIOUtils.skipCharGroup(buffer, formatOptions);
@@ -140,7 +141,7 @@
         final int originalPosition = buffer.position();
         buffer.position(groupOriginAddress);
         final int flags = buffer.readUnsignedByte();
-        final int parentAddress = BinaryDictInputOutput.readParentAddress(buffer, formatOptions);
+        final int parentAddress = BinaryDictDecoder.readParentAddress(buffer, formatOptions);
         BinaryDictIOUtils.skipString(buffer, (flags & FormatSpec.FLAG_HAS_MULTIPLE_CHARS) != 0);
         if ((flags & FormatSpec.FLAG_IS_TERMINAL) != 0) buffer.readUnsignedByte();
         final int childrenOffset = newChildrenAddress == FormatSpec.NO_CHILDREN_ADDRESS
@@ -154,7 +155,7 @@
      */
     private static int moveCharGroup(final OutputStream destination,
             final FusionDictionaryBufferInterface buffer, final CharGroupInfo info,
-            final int nodeOriginAddress, final int oldGroupAddress,
+            final int nodeArrayOriginAddress, final int oldGroupAddress,
             final FormatOptions formatOptions) throws IOException {
         updateParentAddress(buffer, oldGroupAddress, buffer.limit() + 1, formatOptions);
         buffer.position(oldGroupAddress);
@@ -163,23 +164,24 @@
         buffer.put((byte)(FormatSpec.FLAG_IS_MOVED | (currentFlags
                 & (~FormatSpec.MASK_MOVE_AND_DELETE_FLAG))));
         int size = FormatSpec.GROUP_FLAGS_SIZE;
-        updateForwardLink(buffer, nodeOriginAddress, buffer.limit(), formatOptions);
-        size += BinaryDictIOUtils.writeNode(destination, new CharGroupInfo[] { info });
+        updateForwardLink(buffer, nodeArrayOriginAddress, buffer.limit(), formatOptions);
+        size += BinaryDictIOUtils.writeNodes(destination, new CharGroupInfo[] { info });
         return size;
     }
+
     @SuppressWarnings("unused")
     private static void updateForwardLink(final FusionDictionaryBufferInterface buffer,
-            final int nodeOriginAddress, final int newNodeAddress,
+            final int nodeArrayOriginAddress, final int newNodeArrayAddress,
             final FormatOptions formatOptions) {
-        buffer.position(nodeOriginAddress);
+        buffer.position(nodeArrayOriginAddress);
         int jumpCount = 0;
         while (jumpCount++ < MAX_JUMPS) {
-            final int count = BinaryDictInputOutput.readCharGroupCount(buffer);
+            final int count = BinaryDictDecoder.readCharGroupCount(buffer);
             for (int i = 0; i < count; ++i) BinaryDictIOUtils.skipCharGroup(buffer, formatOptions);
             final int forwardLinkAddress = buffer.readUnsignedInt24();
             if (forwardLinkAddress == FormatSpec.NO_FORWARD_LINK_ADDRESS) {
                 buffer.position(buffer.position() - FormatSpec.FORWARD_LINK_ADDRESS_SIZE);
-                BinaryDictIOUtils.writeSInt24ToBuffer(buffer, newNodeAddress);
+                BinaryDictIOUtils.writeSInt24ToBuffer(buffer, newNodeArrayAddress);
                 return;
             }
             buffer.position(forwardLinkAddress);
@@ -190,71 +192,73 @@
     }
 
     /**
-     * Move a group that is referred to by oldGroupOrigin to the tail of the file.
-     * And set the children address to the byte after the group.
+     * Move a group that is referred to by oldGroupOrigin to the tail of the file, and set the
+     * children address to the byte after the group
      *
-     * @param nodeOrigin the address of the tail of the file.
-     * @param characters
-     * @param length
-     * @param flags
-     * @param frequency
-     * @param parentAddress
-     * @param shortcutTargets
-     * @param bigrams
+     * @param fileEndAddress the address of the tail of the file.
+     * @param codePoints the characters to put inside the group.
+     * @param length how many code points to read from codePoints.
+     * @param flags the flags for this group.
+     * @param frequency the frequency of this terminal.
+     * @param parentAddress the address of the parent group of this group.
+     * @param shortcutTargets the shortcut targets for this group.
+     * @param bigrams the bigrams for this group.
      * @param destination the stream representing the tail of the file.
      * @param buffer the buffer representing the (constant-size) body of the file.
-     * @param oldNodeOrigin
-     * @param oldGroupOrigin
-     * @param formatOptions
+     * @param oldNodeArrayOrigin the origin of the old node array this group was a part of.
+     * @param oldGroupOrigin the old origin where this group used to be stored.
+     * @param formatOptions format options for this dictionary.
      * @return the size written, in bytes.
-     * @throws IOException
+     * @throws IOException if the file can't be accessed
      */
-    private static int moveGroup(final int nodeOrigin, final int[] characters, final int length,
-            final int flags, final int frequency, final int parentAddress,
+    private static int moveGroup(final int fileEndAddress, final int[] codePoints,
+            final int length, final int flags, final int frequency, final int parentAddress,
             final ArrayList<WeightedString> shortcutTargets,
             final ArrayList<PendingAttribute> bigrams, final OutputStream destination,
-            final FusionDictionaryBufferInterface buffer, final int oldNodeOrigin,
+            final FusionDictionaryBufferInterface buffer, final int oldNodeArrayOrigin,
             final int oldGroupOrigin, final FormatOptions formatOptions) throws IOException {
         int size = 0;
-        final int newGroupOrigin = nodeOrigin + 1;
-        final int[] writtenCharacters = Arrays.copyOfRange(characters, 0, length);
+        final int newGroupOrigin = fileEndAddress + 1;
+        final int[] writtenCharacters = Arrays.copyOfRange(codePoints, 0, length);
         final CharGroupInfo tmpInfo = new CharGroupInfo(newGroupOrigin, -1 /* endAddress */,
                 flags, writtenCharacters, frequency, parentAddress, FormatSpec.NO_CHILDREN_ADDRESS,
                 shortcutTargets, bigrams);
         size = BinaryDictIOUtils.computeGroupSize(tmpInfo, formatOptions);
         final CharGroupInfo newInfo = new CharGroupInfo(newGroupOrigin, newGroupOrigin + size,
                 flags, writtenCharacters, frequency, parentAddress,
-                nodeOrigin + 1 + size + FormatSpec.FORWARD_LINK_ADDRESS_SIZE, shortcutTargets,
+                fileEndAddress + 1 + size + FormatSpec.FORWARD_LINK_ADDRESS_SIZE, shortcutTargets,
                 bigrams);
-        moveCharGroup(destination, buffer, newInfo, oldNodeOrigin, oldGroupOrigin, formatOptions);
+        moveCharGroup(destination, buffer, newInfo, oldNodeArrayOrigin, oldGroupOrigin,
+                formatOptions);
         return 1 + size + FormatSpec.FORWARD_LINK_ADDRESS_SIZE;
     }
 
     /**
      * Insert a word into a binary dictionary.
      *
-     * @param buffer
-     * @param destination
-     * @param word
-     * @param frequency
-     * @param bigramStrings
-     * @param shortcuts
-     * @throws IOException
-     * @throws UnsupportedFormatException
+     * @param dictReader the dict reader.
+     * @param destination a stream to the underlying file, with the pointer at the end of the file.
+     * @param word the word to insert.
+     * @param frequency the frequency of the new word.
+     * @param bigramStrings bigram list, or null if none.
+     * @param shortcuts shortcut list, or null if none.
+     * @param isBlackListEntry whether this should be a blacklist entry.
+     * @throws IOException if the file can't be accessed.
+     * @throws UnsupportedFormatException if the existing dictionary is in an unexpected format.
      */
     // TODO: Support batch insertion.
     // TODO: Remove @UsedForTesting once UserHistoryDictionary is implemented by BinaryDictionary.
     @UsedForTesting
-    public static void insertWord(final FusionDictionaryBufferInterface buffer,
-            final OutputStream destination, final String word, final int frequency,
-            final ArrayList<WeightedString> bigramStrings,
+    public static void insertWord(final BinaryDictReader dictReader, final OutputStream destination,
+            final String word, final int frequency, final ArrayList<WeightedString> bigramStrings,
             final ArrayList<WeightedString> shortcuts, final boolean isNotAWord,
             final boolean isBlackListEntry)
                     throws IOException, UnsupportedFormatException {
         final ArrayList<PendingAttribute> bigrams = new ArrayList<PendingAttribute>();
+        final FusionDictionaryBufferInterface buffer = dictReader.getBuffer();
         if (bigramStrings != null) {
             for (final WeightedString bigram : bigramStrings) {
-                int position = BinaryDictIOUtils.getTerminalPosition(buffer, bigram.mWord);
+                int position = BinaryDictIOUtils.getTerminalPosition(dictReader, bigram.mWord);
                 if (position == FormatSpec.NOT_VALID_WORD) {
                     // TODO: figure out what is the correct thing to do here.
                 } else {
@@ -269,7 +273,7 @@
 
         // find the insert position of the word.
         if (buffer.position() != 0) buffer.position(0);
-        final FileHeader header = BinaryDictInputOutput.readHeader(buffer);
+        final FileHeader fileHeader = BinaryDictDecoder.readHeader(dictReader);
 
         int wordPos = 0, address = buffer.position(), nodeOriginAddress = buffer.position();
         final int[] codePoints = FusionDictionary.getCodePoints(word);
@@ -279,15 +283,15 @@
             if (wordPos >= wordLen) break;
             nodeOriginAddress = buffer.position();
             int nodeParentAddress = -1;
-            final int charGroupCount = BinaryDictInputOutput.readCharGroupCount(buffer);
+            final int charGroupCount = BinaryDictDecoder.readCharGroupCount(buffer);
             boolean foundNextGroup = false;
 
             for (int i = 0; i < charGroupCount; ++i) {
                 address = buffer.position();
-                final CharGroupInfo currentInfo = BinaryDictInputOutput.readCharGroup(buffer,
-                        buffer.position(), header.mFormatOptions);
+                final CharGroupInfo currentInfo = BinaryDictDecoder.readCharGroup(buffer,
+                        buffer.position(), fileHeader.mFormatOptions);
                 final boolean isMovedGroup = BinaryDictIOUtils.isMovedGroup(currentInfo.mFlags,
-                        header.mFormatOptions);
+                        fileHeader.mFormatOptions);
                 if (isMovedGroup) continue;
                 nodeParentAddress = (currentInfo.mParentAddress == FormatSpec.NO_PARENT_ADDRESS)
                         ? FormatSpec.NO_PARENT_ADDRESS : currentInfo.mParentAddress + address;
@@ -305,25 +309,25 @@
                          *  abc - d - ef
                          */
                         final int newNodeAddress = buffer.limit();
-                        final int flags = BinaryDictInputOutput.makeCharGroupFlags(p > 1,
+                        final int flags = BinaryDictEncoder.makeCharGroupFlags(p > 1,
                                 isTerminal, 0, hasShortcuts, hasBigrams, false /* isNotAWord */,
-                                false /* isBlackListEntry */, header.mFormatOptions);
+                                false /* isBlackListEntry */, fileHeader.mFormatOptions);
                         int written = moveGroup(newNodeAddress, currentInfo.mCharacters, p, flags,
                                 frequency, nodeParentAddress, shortcuts, bigrams, destination,
-                                buffer, nodeOriginAddress, address, header.mFormatOptions);
+                                buffer, nodeOriginAddress, address, fileHeader.mFormatOptions);
 
                         final int[] characters2 = Arrays.copyOfRange(currentInfo.mCharacters, p,
                                 currentInfo.mCharacters.length);
                         if (currentInfo.mChildrenAddress != FormatSpec.NO_CHILDREN_ADDRESS) {
                             updateParentAddresses(buffer, currentInfo.mChildrenAddress,
-                                    newNodeAddress + written + 1, header.mFormatOptions);
+                                    newNodeAddress + written + 1, fileHeader.mFormatOptions);
                         }
                         final CharGroupInfo newInfo2 = new CharGroupInfo(
                                 newNodeAddress + written + 1, -1 /* endAddress */,
                                 currentInfo.mFlags, characters2, currentInfo.mFrequency,
                                 newNodeAddress + 1, currentInfo.mChildrenAddress,
                                 currentInfo.mShortcutTargets, currentInfo.mBigrams);
-                        BinaryDictIOUtils.writeNode(destination, new CharGroupInfo[] { newInfo2 });
+                        BinaryDictIOUtils.writeNodes(destination, new CharGroupInfo[] { newInfo2 });
                         return;
                     } else if (codePoints[wordPos + p] != currentInfo.mCharacters[p]) {
                         if (p > 0) {
@@ -344,49 +348,49 @@
                             final int childrenAddress = currentInfo.mChildrenAddress;
 
                             // move prefix
-                            final int prefixFlags = BinaryDictInputOutput.makeCharGroupFlags(p > 1,
+                            final int prefixFlags = BinaryDictEncoder.makeCharGroupFlags(p > 1,
                                     false /* isTerminal */, 0 /* childrenAddressSize*/,
                                     false /* hasShortcut */, false /* hasBigrams */,
                                     false /* isNotAWord */, false /* isBlackListEntry */,
-                                    header.mFormatOptions);
+                                    fileHeader.mFormatOptions);
                             int written = moveGroup(newNodeAddress, currentInfo.mCharacters, p,
                                     prefixFlags, -1 /* frequency */, nodeParentAddress, null, null,
                                     destination, buffer, nodeOriginAddress, address,
-                                    header.mFormatOptions);
+                                    fileHeader.mFormatOptions);
 
                             final int[] suffixCharacters = Arrays.copyOfRange(
                                     currentInfo.mCharacters, p, currentInfo.mCharacters.length);
                             if (currentInfo.mChildrenAddress != FormatSpec.NO_CHILDREN_ADDRESS) {
                                 updateParentAddresses(buffer, currentInfo.mChildrenAddress,
-                                        newNodeAddress + written + 1, header.mFormatOptions);
+                                        newNodeAddress + written + 1, fileHeader.mFormatOptions);
                             }
-                            final int suffixFlags = BinaryDictInputOutput.makeCharGroupFlags(
+                            final int suffixFlags = BinaryDictEncoder.makeCharGroupFlags(
                                     suffixCharacters.length > 1,
                                     (currentInfo.mFlags & FormatSpec.FLAG_IS_TERMINAL) != 0,
                                     0 /* childrenAddressSize */,
                                     (currentInfo.mFlags & FormatSpec.FLAG_HAS_SHORTCUT_TARGETS)
                                             != 0,
                                     (currentInfo.mFlags & FormatSpec.FLAG_HAS_BIGRAMS) != 0,
-                                    isNotAWord, isBlackListEntry, header.mFormatOptions);
+                                    isNotAWord, isBlackListEntry, fileHeader.mFormatOptions);
                             final CharGroupInfo suffixInfo = new CharGroupInfo(
                                     newNodeAddress + written + 1, -1 /* endAddress */, suffixFlags,
                                     suffixCharacters, currentInfo.mFrequency, newNodeAddress + 1,
                                     currentInfo.mChildrenAddress, currentInfo.mShortcutTargets,
                                     currentInfo.mBigrams);
                             written += BinaryDictIOUtils.computeGroupSize(suffixInfo,
-                                    header.mFormatOptions) + 1;
+                                    fileHeader.mFormatOptions) + 1;
 
                             final int[] newCharacters = Arrays.copyOfRange(codePoints, wordPos + p,
                                     codePoints.length);
-                            final int flags = BinaryDictInputOutput.makeCharGroupFlags(
+                            final int flags = BinaryDictEncoder.makeCharGroupFlags(
                                     newCharacters.length > 1, isTerminal,
                                     0 /* childrenAddressSize */, hasShortcuts, hasBigrams,
-                                    isNotAWord, isBlackListEntry, header.mFormatOptions);
+                                    isNotAWord, isBlackListEntry, fileHeader.mFormatOptions);
                             final CharGroupInfo newInfo = new CharGroupInfo(
                                     newNodeAddress + written, -1 /* endAddress */, flags,
                                     newCharacters, frequency, newNodeAddress + 1,
                                     FormatSpec.NO_CHILDREN_ADDRESS, shortcuts, bigrams);
-                            BinaryDictIOUtils.writeNode(destination,
+                            BinaryDictIOUtils.writeNodes(destination,
                                     new CharGroupInfo[] { suffixInfo, newInfo });
                             return;
                         }
@@ -401,15 +405,15 @@
                         // only update group.
                         final int newNodeAddress = buffer.limit();
                         final boolean hasMultipleChars = currentInfo.mCharacters.length > 1;
-                        final int flags = BinaryDictInputOutput.makeCharGroupFlags(hasMultipleChars,
+                        final int flags = BinaryDictEncoder.makeCharGroupFlags(hasMultipleChars,
                                 isTerminal, 0 /* childrenAddressSize */, hasShortcuts, hasBigrams,
-                                isNotAWord, isBlackListEntry, header.mFormatOptions);
+                                isNotAWord, isBlackListEntry, fileHeader.mFormatOptions);
                         final CharGroupInfo newInfo = new CharGroupInfo(newNodeAddress + 1,
                                 -1 /* endAddress */, flags, currentInfo.mCharacters, frequency,
                                 nodeParentAddress, currentInfo.mChildrenAddress, shortcuts,
                                 bigrams);
                         moveCharGroup(destination, buffer, newInfo, nodeOriginAddress, address,
-                                header.mFormatOptions);
+                                fileHeader.mFormatOptions);
                         return;
                     }
                     wordPos += currentInfo.mCharacters.length;
@@ -428,17 +432,17 @@
                          */
                         final int newNodeAddress = buffer.limit();
                         updateChildrenAddress(buffer, address, newNodeAddress,
-                                header.mFormatOptions);
+                                fileHeader.mFormatOptions);
                         final int newGroupAddress = newNodeAddress + 1;
                         final boolean hasMultipleChars = (wordLen - wordPos) > 1;
-                        final int flags = BinaryDictInputOutput.makeCharGroupFlags(hasMultipleChars,
+                        final int flags = BinaryDictEncoder.makeCharGroupFlags(hasMultipleChars,
                                 isTerminal, 0 /* childrenAddressSize */, hasShortcuts, hasBigrams,
-                                isNotAWord, isBlackListEntry, header.mFormatOptions);
+                                isNotAWord, isBlackListEntry, fileHeader.mFormatOptions);
                         final int[] characters = Arrays.copyOfRange(codePoints, wordPos, wordLen);
                         final CharGroupInfo newInfo = new CharGroupInfo(newGroupAddress, -1, flags,
                                 characters, frequency, address, FormatSpec.NO_CHILDREN_ADDRESS,
                                 shortcuts, bigrams);
-                        BinaryDictIOUtils.writeNode(destination, new CharGroupInfo[] { newInfo });
+                        BinaryDictIOUtils.writeNodes(destination, new CharGroupInfo[] { newInfo });
                         return;
                     }
                     buffer.position(currentInfo.mChildrenAddress);
@@ -476,13 +480,13 @@
                 BinaryDictIOUtils.writeSInt24ToBuffer(buffer, newNodeAddress);
 
                 final int[] characters = Arrays.copyOfRange(codePoints, wordPos, wordLen);
-                final int flags = BinaryDictInputOutput.makeCharGroupFlags(characters.length > 1,
+                final int flags = BinaryDictEncoder.makeCharGroupFlags(characters.length > 1,
                         isTerminal, 0 /* childrenAddressSize */, hasShortcuts, hasBigrams,
-                        isNotAWord, isBlackListEntry, header.mFormatOptions);
+                        isNotAWord, isBlackListEntry, fileHeader.mFormatOptions);
                 final CharGroupInfo newInfo = new CharGroupInfo(newNodeAddress + 1,
                         -1 /* endAddress */, flags, characters, frequency, nodeParentAddress,
                         FormatSpec.NO_CHILDREN_ADDRESS, shortcuts, bigrams);
-                BinaryDictIOUtils.writeNode(destination, new CharGroupInfo[]{ newInfo });
+                BinaryDictIOUtils.writeNodes(destination, new CharGroupInfo[]{ newInfo });
                 return;
             } else {
                 depth--;
diff --git a/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java b/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
index 9af66ed..5e33121 100644
--- a/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
+++ b/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
@@ -60,7 +60,7 @@
      */
 
     /*
-     * Array of Node(FusionDictionary.Node) layout is as follows:
+     * Node array (FusionDictionary.PtNodeArray) layout is as follows:
      *
      * g |
      * r | the number of groups, 1 or 2 bytes.
@@ -86,7 +86,7 @@
      * linkaddress
      */
 
-    /* Node(CharGroup) layout is as follows:
+    /* Node (FusionDictionary.CharGroup) layout is as follows:
      *   | IF !SUPPORTS_DYNAMIC_UPDATE
      *   |   addressType                         xx     : mask with MASK_GROUP_ADDRESS_TYPE
      *   |                           2 bits, 00 = no children : FLAG_GROUP_ADDRESS_TYPE_NOADDRESS
@@ -251,7 +251,7 @@
     static final int INVALID_CHARACTER = -1;
 
     static final int MAX_CHARGROUPS_FOR_ONE_BYTE_CHARGROUP_COUNT = 0x7F; // 127
-    static final int MAX_CHARGROUPS_IN_A_NODE = 0x7FFF; // 32767
+    static final int MAX_CHARGROUPS_IN_A_PT_NODE_ARRAY = 0x7FFF; // 32767
     static final int MAX_BIGRAMS_IN_A_GROUP = 10000;
 
     static final int MAX_TERMINAL_FREQUENCY = 255;
diff --git a/java/src/com/android/inputmethod/latin/makedict/FusionDictionary.java b/java/src/com/android/inputmethod/latin/makedict/FusionDictionary.java
index 118dc22..fce1c5c 100644
--- a/java/src/com/android/inputmethod/latin/makedict/FusionDictionary.java
+++ b/java/src/com/android/inputmethod/latin/makedict/FusionDictionary.java
@@ -37,14 +37,14 @@
     private static int CHARACTER_NOT_FOUND_INDEX = -1;
 
     /**
-     * A node of the dictionary, containing several CharGroups.
+     * A node array of the dictionary, containing several CharGroups.
      *
-     * A node is but an ordered array of CharGroups, which essentially contain all the
+     * A PtNodeArray is but an ordered array of CharGroups, which essentially contain all the
      * real information.
      * This class also contains fields to cache size and address, to help with binary
      * generation.
      */
-    public static final class Node {
+    public static final class PtNodeArray {
         ArrayList<CharGroup> mData;
         // To help with binary generation
         int mCachedSize = Integer.MIN_VALUE;
@@ -57,10 +57,10 @@
         int mCachedAddressAfterUpdate = Integer.MIN_VALUE;
         int mCachedParentAddress = 0;
 
-        public Node() {
+        public PtNodeArray() {
             mData = new ArrayList<CharGroup>();
         }
-        public Node(ArrayList<CharGroup> data) {
+        public PtNodeArray(ArrayList<CharGroup> data) {
             mData = data;
         }
     }
@@ -98,7 +98,7 @@
      * This is the central class of the in-memory representation. A CharGroup is what can
      * be seen as a traditional "trie node", except it can hold several characters at the
      * same time. A CharGroup essentially represents one or several characters in the middle
-     * of the trie trie; as such, it can be a terminal, and it can have children.
+     * of the trie tree; as such, it can be a terminal, and it can have children.
      * In this in-memory representation, whether the CharGroup is a terminal or not is represented
      * in the frequency, where NOT_A_TERMINAL (= -1) means this is not a terminal and any other
      * value is the frequency of this terminal. A terminal may have non-null shortcuts and/or
@@ -110,7 +110,7 @@
         ArrayList<WeightedString> mShortcutTargets;
         ArrayList<WeightedString> mBigrams;
         int mFrequency; // NOT_A_TERMINAL == mFrequency indicates this is not a terminal.
-        Node mChildren;
+        PtNodeArray mChildren;
         boolean mIsNotAWord; // Only a shortcut
         boolean mIsBlacklistEntry;
         // mCachedSize and mCachedAddressBefore/AfterUpdate are helpers for binary dictionary
@@ -137,7 +137,8 @@
 
         public CharGroup(final int[] chars, final ArrayList<WeightedString> shortcutTargets,
                 final ArrayList<WeightedString> bigrams, final int frequency,
-                final boolean isNotAWord, final boolean isBlacklistEntry, final Node children) {
+                final boolean isNotAWord, final boolean isBlacklistEntry,
+                final PtNodeArray children) {
             mChars = chars;
             mFrequency = frequency;
             mShortcutTargets = shortcutTargets;
@@ -149,7 +150,7 @@
 
         public void addChild(CharGroup n) {
             if (null == mChildren) {
-                mChildren = new Node();
+                mChildren = new PtNodeArray();
             }
             mChildren.mData.add(n);
         }
@@ -344,10 +345,10 @@
     }
 
     public final DictionaryOptions mOptions;
-    public final Node mRoot;
+    public final PtNodeArray mRootNodeArray;
 
-    public FusionDictionary(final Node root, final DictionaryOptions options) {
-        mRoot = root;
+    public FusionDictionary(final PtNodeArray rootNodeArray, final DictionaryOptions options) {
+        mRootNodeArray = rootNodeArray;
         mOptions = options;
     }
 
@@ -406,13 +407,13 @@
     }
 
     /**
-     * Sanity check for a node.
+     * Sanity check for a node array.
      *
-     * This method checks that all CharGroups in a node are ordered as expected.
+     * This method checks that all CharGroups in a node array are ordered as expected.
      * If they are, nothing happens. If they aren't, an exception is thrown.
      */
-    private void checkStack(Node node) {
-        ArrayList<CharGroup> stack = node.mData;
+    private void checkStack(PtNodeArray nodeArray) {
+        ArrayList<CharGroup> stack = nodeArray.mData;
         int lastValue = -1;
         for (int i = 0; i < stack.size(); ++i) {
             int currentValue = stack.get(i).mChars[0];
@@ -431,16 +432,16 @@
      * @param frequency the bigram frequency
      */
     public void setBigram(final String word1, final String word2, final int frequency) {
-        CharGroup charGroup = findWordInTree(mRoot, word1);
+        CharGroup charGroup = findWordInTree(mRootNodeArray, word1);
         if (charGroup != null) {
-            final CharGroup charGroup2 = findWordInTree(mRoot, word2);
+            final CharGroup charGroup2 = findWordInTree(mRootNodeArray, word2);
             if (charGroup2 == null) {
                 add(getCodePoints(word2), 0, null, false /* isNotAWord */,
                         false /* isBlacklistEntry */);
                 // The chargroup for the first word may have moved by the above insertion,
                 // if word1 and word2 share a common stem that happens not to have been
                 // a cutting point until now. In this case, we need to refresh charGroup.
-                charGroup = findWordInTree(mRoot, word1);
+                charGroup = findWordInTree(mRootNodeArray, word1);
             }
             charGroup.addBigram(word2, frequency);
         } else {
@@ -469,38 +470,38 @@
             return;
         }
 
-        Node currentNode = mRoot;
+        PtNodeArray currentNodeArray = mRootNodeArray;
         int charIndex = 0;
 
         CharGroup currentGroup = null;
         int differentCharIndex = 0; // Set by the loop to the index of the char that differs
-        int nodeIndex = findIndexOfChar(mRoot, word[charIndex]);
+        int nodeIndex = findIndexOfChar(mRootNodeArray, word[charIndex]);
         while (CHARACTER_NOT_FOUND_INDEX != nodeIndex) {
-            currentGroup = currentNode.mData.get(nodeIndex);
-            differentCharIndex = compareArrays(currentGroup.mChars, word, charIndex);
+            currentGroup = currentNodeArray.mData.get(nodeIndex);
+            differentCharIndex = compareCharArrays(currentGroup.mChars, word, charIndex);
             if (ARRAYS_ARE_EQUAL != differentCharIndex
                     && differentCharIndex < currentGroup.mChars.length) break;
             if (null == currentGroup.mChildren) break;
             charIndex += currentGroup.mChars.length;
             if (charIndex >= word.length) break;
-            currentNode = currentGroup.mChildren;
-            nodeIndex = findIndexOfChar(currentNode, word[charIndex]);
+            currentNodeArray = currentGroup.mChildren;
+            nodeIndex = findIndexOfChar(currentNodeArray, word[charIndex]);
         }
 
         if (CHARACTER_NOT_FOUND_INDEX == nodeIndex) {
             // No node at this point to accept the word. Create one.
-            final int insertionIndex = findInsertionIndex(currentNode, word[charIndex]);
+            final int insertionIndex = findInsertionIndex(currentNodeArray, word[charIndex]);
             final CharGroup newGroup = new CharGroup(
                     Arrays.copyOfRange(word, charIndex, word.length),
                     shortcutTargets, null /* bigrams */, frequency, isNotAWord, isBlacklistEntry);
-            currentNode.mData.add(insertionIndex, newGroup);
-            if (DBG) checkStack(currentNode);
+            currentNodeArray.mData.add(insertionIndex, newGroup);
+            if (DBG) checkStack(currentNodeArray);
         } else {
             // There is a word with a common prefix.
             if (differentCharIndex == currentGroup.mChars.length) {
                 if (charIndex + differentCharIndex >= word.length) {
                     // The new word is a prefix of an existing word, but the node on which it
-                    // should end already exists as is. Since the old CharNode was not a terminal,
+                    // should end already exists as is. Since the old CharGroup was not a terminal,
                     // make it one by filling in its frequency and other attributes
                     currentGroup.update(frequency, shortcutTargets, null, isNotAWord,
                             isBlacklistEntry);
@@ -511,7 +512,7 @@
                             Arrays.copyOfRange(word, charIndex + differentCharIndex, word.length),
                                     shortcutTargets, null /* bigrams */, frequency, isNotAWord,
                                     isBlacklistEntry);
-                    currentGroup.mChildren = new Node();
+                    currentGroup.mChildren = new PtNodeArray();
                     currentGroup.mChildren.mData.add(newNode);
                 }
             } else {
@@ -524,7 +525,7 @@
                 } else {
                     // Partial prefix match only. We have to replace the current node with a node
                     // containing the current prefix and create two new ones for the tails.
-                    Node newChildren = new Node();
+                    PtNodeArray newChildren = new PtNodeArray();
                     final CharGroup newOldWord = new CharGroup(
                             Arrays.copyOfRange(currentGroup.mChars, differentCharIndex,
                                     currentGroup.mChars.length), currentGroup.mShortcutTargets,
@@ -552,9 +553,9 @@
                                 > currentGroup.mChars[differentCharIndex] ? 1 : 0;
                         newChildren.mData.add(addIndex, newWord);
                     }
-                    currentNode.mData.set(nodeIndex, newParent);
+                    currentNodeArray.mData.set(nodeIndex, newParent);
                 }
-                if (DBG) checkStack(currentNode);
+                if (DBG) checkStack(currentNodeArray);
             }
         }
     }
@@ -576,7 +577,7 @@
      * @param dstOffset the offset in the right-hand side string.
      * @return the index at which the strings differ, or ARRAYS_ARE_EQUAL = 0 if they don't.
      */
-    private static int compareArrays(final int[] src, final int[] dst, int dstOffset) {
+    private static int compareCharArrays(final int[] src, final int[] dst, int dstOffset) {
         // We do NOT test the first char, because we come from a method that already
         // tested it.
         for (int i = 1; i < src.length; ++i) {
@@ -603,10 +604,10 @@
     final static private CharGroupComparator CHARGROUP_COMPARATOR = new CharGroupComparator();
 
     /**
-     * Finds the insertion index of a character within a node.
+     * Finds the insertion index of a character within a node array.
      */
-    private static int findInsertionIndex(final Node node, int character) {
-        final ArrayList<CharGroup> data = node.mData;
+    private static int findInsertionIndex(final PtNodeArray nodeArray, int character) {
+        final ArrayList<CharGroup> data = nodeArray.mData;
         final CharGroup reference = new CharGroup(new int[] { character },
                 null /* shortcutTargets */, null /* bigrams */, 0, false /* isNotAWord */,
                 false /* isBlacklistEntry */);
@@ -615,16 +616,16 @@
     }
 
     /**
-     * Find the index of a char in a node, if it exists.
+     * Find the index of a char in a node array, if it exists.
      *
-     * @param node the node to search in.
+     * @param nodeArray the node array to search in.
      * @param character the character to search for.
      * @return the position of the character if it's there, or CHARACTER_NOT_FOUND_INDEX = -1 else.
      */
-    private static int findIndexOfChar(final Node node, int character) {
-        final int insertionIndex = findInsertionIndex(node, character);
-        if (node.mData.size() <= insertionIndex) return CHARACTER_NOT_FOUND_INDEX;
-        return character == node.mData.get(insertionIndex).mChars[0] ? insertionIndex
+    private static int findIndexOfChar(final PtNodeArray nodeArray, int character) {
+        final int insertionIndex = findInsertionIndex(nodeArray, character);
+        if (nodeArray.mData.size() <= insertionIndex) return CHARACTER_NOT_FOUND_INDEX;
+        return character == nodeArray.mData.get(insertionIndex).mChars[0] ? insertionIndex
                 : CHARACTER_NOT_FOUND_INDEX;
     }
 
@@ -632,16 +633,16 @@
      * Helper method to find a word in a given branch.
      */
     @SuppressWarnings("unused")
-    public static CharGroup findWordInTree(Node node, final String string) {
+    public static CharGroup findWordInTree(PtNodeArray nodeArray, final String string) {
         int index = 0;
         final StringBuilder checker = DBG ? new StringBuilder() : null;
         final int[] codePoints = getCodePoints(string);
 
         CharGroup currentGroup;
         do {
-            int indexOfGroup = findIndexOfChar(node, codePoints[index]);
+            int indexOfGroup = findIndexOfChar(nodeArray, codePoints[index]);
             if (CHARACTER_NOT_FOUND_INDEX == indexOfGroup) return null;
-            currentGroup = node.mData.get(indexOfGroup);
+            currentGroup = nodeArray.mData.get(indexOfGroup);
 
             if (codePoints.length - index < currentGroup.mChars.length) return null;
             int newIndex = index;
@@ -653,9 +654,9 @@
 
             if (DBG) checker.append(new String(currentGroup.mChars, 0, currentGroup.mChars.length));
             if (index < codePoints.length) {
-                node = currentGroup.mChildren;
+                nodeArray = currentGroup.mChildren;
             }
-        } while (null != node && index < codePoints.length);
+        } while (null != nodeArray && index < codePoints.length);
 
         if (index < codePoints.length) return null;
         if (!currentGroup.isTerminal()) return null;
@@ -670,20 +671,20 @@
         if (null == s || "".equals(s)) {
             throw new RuntimeException("Can't search for a null or empty string");
         }
-        return null != findWordInTree(mRoot, s);
+        return null != findWordInTree(mRootNodeArray, s);
     }
 
     /**
      * Recursively count the number of character groups in a given branch of the trie.
      *
-     * @param node the parent node.
+     * @param nodeArray the parent node.
      * @return the number of char groups in all the branch under this node.
      */
-    public static int countCharGroups(final Node node) {
-        final int nodeSize = node.mData.size();
+    public static int countCharGroups(final PtNodeArray nodeArray) {
+        final int nodeSize = nodeArray.mData.size();
         int size = nodeSize;
         for (int i = nodeSize - 1; i >= 0; --i) {
-            CharGroup group = node.mData.get(i);
+            CharGroup group = nodeArray.mData.get(i);
             if (null != group.mChildren)
                 size += countCharGroups(group.mChildren);
         }
@@ -693,15 +694,15 @@
     /**
      * Recursively count the number of nodes in a given branch of the trie.
      *
-     * @param node the node to count.
+     * @param nodeArray the node array to count.
      * @return the number of nodes in this branch.
      */
-    public static int countNodes(final Node node) {
+    public static int countNodeArrays(final PtNodeArray nodeArray) {
         int size = 1;
-        for (int i = node.mData.size() - 1; i >= 0; --i) {
-            CharGroup group = node.mData.get(i);
+        for (int i = nodeArray.mData.size() - 1; i >= 0; --i) {
+            CharGroup group = nodeArray.mData.get(i);
             if (null != group.mChildren)
-                size += countNodes(group.mChildren);
+                size += countNodeArrays(group.mChildren);
         }
         return size;
     }
@@ -709,10 +710,10 @@
     // Recursively find out whether there are any bigrams.
     // This can be pretty expensive especially if there aren't any (we return as soon
     // as we find one, so it's much cheaper if there are bigrams)
-    private static boolean hasBigramsInternal(final Node node) {
-        if (null == node) return false;
-        for (int i = node.mData.size() - 1; i >= 0; --i) {
-            CharGroup group = node.mData.get(i);
+    private static boolean hasBigramsInternal(final PtNodeArray nodeArray) {
+        if (null == nodeArray) return false;
+        for (int i = nodeArray.mData.size() - 1; i >= 0; --i) {
+            CharGroup group = nodeArray.mData.get(i);
             if (null != group.mBigrams) return true;
             if (hasBigramsInternal(group.mChildren)) return true;
         }
@@ -729,7 +730,7 @@
     // find a more efficient way of doing this, without compromising too much on memory
     // and ease of use.
     public boolean hasBigrams() {
-        return hasBigramsInternal(mRoot);
+        return hasBigramsInternal(mRootNodeArray);
     }
 
     // Historically, the tails of the words were going to be merged to save space.
@@ -750,13 +751,13 @@
 //        MakedictLog.i("Merging nodes. Number of nodes : " + countNodes(root));
 //        MakedictLog.i("Number of groups : " + countCharGroups(root));
 //
-//        final HashMap<String, ArrayList<Node>> repository =
-//                  new HashMap<String, ArrayList<Node>>();
+//        final HashMap<String, ArrayList<PtNodeArray>> repository =
+//                  new HashMap<String, ArrayList<PtNodeArray>>();
 //        mergeTailsInner(repository, root);
 //
 //        MakedictLog.i("Number of different pseudohashes : " + repository.size());
 //        int size = 0;
-//        for (ArrayList<Node> a : repository.values()) {
+//        for (ArrayList<PtNodeArray> a : repository.values()) {
 //            size += a.size();
 //        }
 //        MakedictLog.i("Number of nodes after merge : " + (1 + size));
@@ -764,7 +765,7 @@
     }
 
     // The following methods are used by the deactivated mergeTails()
-//   private static boolean isEqual(Node a, Node b) {
+//   private static boolean isEqual(PtNodeArray a, PtNodeArray b) {
 //       if (null == a && null == b) return true;
 //       if (null == a || null == b) return false;
 //       if (a.data.size() != b.data.size()) return false;
@@ -781,21 +782,21 @@
 //       return true;
 //   }
 
-//   static private HashMap<String, ArrayList<Node>> mergeTailsInner(
-//           final HashMap<String, ArrayList<Node>> map, final Node node) {
-//       final ArrayList<CharGroup> branches = node.data;
+//   static private HashMap<String, ArrayList<PtNodeArray>> mergeTailsInner(
+//           final HashMap<String, ArrayList<PtNodeArray>> map, final PtNodeArray nodeArray) {
+//       final ArrayList<CharGroup> branches = nodeArray.data;
 //       final int nodeSize = branches.size();
 //       for (int i = 0; i < nodeSize; ++i) {
 //           CharGroup group = branches.get(i);
 //           if (null != group.children) {
 //               String pseudoHash = getPseudoHash(group.children);
-//               ArrayList<Node> similarList = map.get(pseudoHash);
+//               ArrayList<PtNodeArray> similarList = map.get(pseudoHash);
 //               if (null == similarList) {
-//                   similarList = new ArrayList<Node>();
+//                   similarList = new ArrayList<PtNodeArray>();
 //                   map.put(pseudoHash, similarList);
 //               }
 //               boolean merged = false;
-//               for (Node similar : similarList) {
+//               for (PtNodeArray similar : similarList) {
 //                   if (isEqual(group.children, similar)) {
 //                       group.children = similar;
 //                       merged = true;
@@ -811,9 +812,9 @@
 //       return map;
 //   }
 
-//  private static String getPseudoHash(final Node node) {
+//  private static String getPseudoHash(final PtNodeArray nodeArray) {
 //      StringBuilder s = new StringBuilder();
-//      for (CharGroup g : node.data) {
+//      for (CharGroup g : nodeArray.data) {
 //          s.append(g.frequency);
 //          for (int ch : g.chars) {
 //              s.append(Character.toChars(ch));
@@ -901,6 +902,6 @@
      */
     @Override
     public Iterator<Word> iterator() {
-        return new DictionaryIterator(mRoot.mData);
+        return new DictionaryIterator(mRootNodeArray.mData);
     }
 }
diff --git a/java/src/com/android/inputmethod/latin/makedict/decoder/HeaderReaderInterface.java b/java/src/com/android/inputmethod/latin/makedict/decoder/HeaderReaderInterface.java
new file mode 100644
index 0000000..7cddef2
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/makedict/decoder/HeaderReaderInterface.java
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.inputmethod.latin.makedict.decoder;
+
+import com.android.inputmethod.latin.makedict.UnsupportedFormatException;
+
+import java.io.IOException;
+import java.util.HashMap;
+
+/**
+ * An interface to read a binary dictionary file header.
+ */
+public interface HeaderReaderInterface {
+    public int readVersion() throws IOException, UnsupportedFormatException;
+    public int readOptionFlags();
+    public int readHeaderSize();
+    public HashMap<String, String> readAttributes(final int headerSize);
+}
diff --git a/java/src/com/android/inputmethod/latin/personalization/DynamicPredictionDictionaryBase.java b/java/src/com/android/inputmethod/latin/personalization/DynamicPredictionDictionaryBase.java
index 065e00e..525d3cd 100644
--- a/java/src/com/android/inputmethod/latin/personalization/DynamicPredictionDictionaryBase.java
+++ b/java/src/com/android/inputmethod/latin/personalization/DynamicPredictionDictionaryBase.java
@@ -43,6 +43,7 @@
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.concurrent.locks.ReentrantLock;
 
 /**
@@ -75,6 +76,8 @@
     private final ArrayList<PersonalizationDictionaryUpdateSession> mSessions =
             CollectionUtils.newArrayList();
 
+    private final AtomicReference<AsyncTask<Void, Void, Void>> mWaitingTask;
+
     // Should always be false except when we use this class for test
     @UsedForTesting boolean mIsTest = false;
 
@@ -83,6 +86,7 @@
         super(context, dictionaryType);
         mLocale = locale;
         mPrefs = sp;
+        mWaitingTask = new AtomicReference<AsyncTask<Void, Void, Void>>();
         if (mLocale != null && mLocale.length() > 1) {
             loadDictionary();
         }
@@ -174,7 +178,11 @@
      */
     private void flushPendingWrites() {
         // Create a background thread to write the pending entries
-        new UpdateBinaryTask(mBigramList, mLocale, this, mPrefs, getContext()).execute();
+        final AsyncTask<Void, Void, Void> old = mWaitingTask.getAndSet(new UpdateBinaryTask(
+                mBigramList, mLocale, this, mPrefs, getContext()).execute());
+        if (old != null) {
+            old.cancel(false);
+        }
     }
 
     @Override
@@ -287,6 +295,7 @@
 
         @Override
         protected Void doInBackground(final Void... v) {
+            if (isCancelled()) return null;
             if (mDynamicPredictionDictionary.mIsTest) {
                 // If mIsTest == true, wait until the lock is released.
                 mDynamicPredictionDictionary.mBigramListLock.lock();
@@ -306,6 +315,9 @@
         }
 
         private void doWriteTaskLocked() {
+            if (isCancelled()) return;
+            mDynamicPredictionDictionary.mWaitingTask.compareAndSet(this, null);
+
             if (DBG_STRESS_TEST) {
                 try {
                     Log.w(TAG, "Start stress in closing: " + mLocale);
diff --git a/java/src/com/android/inputmethod/latin/personalization/PersonalizationDictionaryUpdateSession.java b/java/src/com/android/inputmethod/latin/personalization/PersonalizationDictionaryUpdateSession.java
index a755f90..858aa32 100644
--- a/java/src/com/android/inputmethod/latin/personalization/PersonalizationDictionaryUpdateSession.java
+++ b/java/src/com/android/inputmethod/latin/personalization/PersonalizationDictionaryUpdateSession.java
@@ -48,6 +48,8 @@
 
     public abstract void onDictionaryReady();
 
+    public abstract void onDictionaryClosed();
+
     public void setPredictionDictionary(String locale, DynamicPredictionDictionaryBase dictionary) {
         mPredictionDictionary = new WeakReference<DynamicPredictionDictionaryBase>(dictionary);
         mLocale = locale;
@@ -68,6 +70,7 @@
 
     public void closeSession() {
         unsetPredictionDictionary();
+        onDictionaryClosed();
     }
 
     public void addBigramToPersonalizationDictionary(String word0, String word1, boolean isValid,
diff --git a/java/src/com/android/inputmethod/latin/personalization/PersonalizationPredictionDictionary.java b/java/src/com/android/inputmethod/latin/personalization/PersonalizationPredictionDictionary.java
index 955bd27..a038d0a 100644
--- a/java/src/com/android/inputmethod/latin/personalization/PersonalizationPredictionDictionary.java
+++ b/java/src/com/android/inputmethod/latin/personalization/PersonalizationPredictionDictionary.java
@@ -17,6 +17,7 @@
 package com.android.inputmethod.latin.personalization;
 
 import com.android.inputmethod.latin.Dictionary;
+import com.android.inputmethod.latin.ExpandableBinaryDictionary;
 
 import android.content.Context;
 import android.content.SharedPreferences;
@@ -31,6 +32,6 @@
 
     @Override
     protected String getDictionaryFileName() {
-        return NAME + "." + getLocale() + ".dict";
+        return NAME + "." + getLocale() + ExpandableBinaryDictionary.DICT_FILE_EXTENSION;
     }
 }
diff --git a/java/src/com/android/inputmethod/latin/personalization/UserHistoryPredictionDictionary.java b/java/src/com/android/inputmethod/latin/personalization/UserHistoryPredictionDictionary.java
index d117844..76e48c7 100644
--- a/java/src/com/android/inputmethod/latin/personalization/UserHistoryPredictionDictionary.java
+++ b/java/src/com/android/inputmethod/latin/personalization/UserHistoryPredictionDictionary.java
@@ -17,6 +17,7 @@
 package com.android.inputmethod.latin.personalization;
 
 import com.android.inputmethod.latin.Dictionary;
+import com.android.inputmethod.latin.ExpandableBinaryDictionary;
 
 import android.content.Context;
 import android.content.SharedPreferences;
@@ -26,7 +27,8 @@
  * cancellation or manual picks. This allows the keyboard to adapt to the typist over time.
  */
 public class UserHistoryPredictionDictionary extends DynamicPredictionDictionaryBase {
-    private static final String NAME = UserHistoryPredictionDictionary.class.getSimpleName();
+    /* package for tests */ static final String NAME =
+            UserHistoryPredictionDictionary.class.getSimpleName();
     /* package */ UserHistoryPredictionDictionary(final Context context, final String locale,
             final SharedPreferences sp) {
         super(context, locale, sp, Dictionary.TYPE_USER_HISTORY);
@@ -34,6 +36,6 @@
 
     @Override
     protected String getDictionaryFileName() {
-        return NAME + "." + getLocale() + ".dict";
+        return NAME + "." + getLocale() + ExpandableBinaryDictionary.DICT_FILE_EXTENSION;
     }
 }
diff --git a/java/src/com/android/inputmethod/latin/settings/Settings.java b/java/src/com/android/inputmethod/latin/settings/Settings.java
index d432087..20b6752 100644
--- a/java/src/com/android/inputmethod/latin/settings/Settings.java
+++ b/java/src/com/android/inputmethod/latin/settings/Settings.java
@@ -27,10 +27,10 @@
 import com.android.inputmethod.latin.InputAttributes;
 import com.android.inputmethod.latin.R;
 import com.android.inputmethod.latin.utils.AdditionalSubtypeUtils;
-import com.android.inputmethod.latin.utils.DebugLogUtils;
 import com.android.inputmethod.latin.utils.LocaleUtils;
 import com.android.inputmethod.latin.utils.ResourceUtils;
 import com.android.inputmethod.latin.utils.RunInLocale;
+import com.android.inputmethod.latin.utils.StringUtils;
 
 import java.util.HashMap;
 import java.util.Locale;
@@ -90,6 +90,8 @@
     private static final String PREF_SUPPRESS_LANGUAGE_SWITCH_KEY =
             "pref_suppress_language_switch_key";
 
+    private static final String PREF_LAST_USED_PERSONALIZATION_TOKEN =
+            "pref_last_used_personalization_token";
     public static final String PREF_SEND_FEEDBACK = "send_feedback";
     public static final String PREF_ABOUT_KEYBOARD = "about_keyboard";
 
@@ -343,4 +345,14 @@
         return prefs.getBoolean(
                 DebugSettings.PREF_USE_ONLY_PERSONALIZATION_DICTIONARY_FOR_DEBUG, false);
     }
+
+    public void writeLastUsedPersonalizationToken(byte[] token) {
+        final String tokenStr = StringUtils.byteArrayToHexString(token);
+        mPrefs.edit().putString(PREF_LAST_USED_PERSONALIZATION_TOKEN, tokenStr).apply();
+    }
+
+    public byte[] readLastUsedPersonalizationToken() {
+        final String tokenStr = mPrefs.getString(PREF_LAST_USED_PERSONALIZATION_TOKEN, null);
+        return StringUtils.hexStringToByteArray(tokenStr);
+    }
 }
diff --git a/java/src/com/android/inputmethod/latin/settings/SettingsValues.java b/java/src/com/android/inputmethod/latin/settings/SettingsValues.java
index 195f9f8..a0b744d 100644
--- a/java/src/com/android/inputmethod/latin/settings/SettingsValues.java
+++ b/java/src/com/android/inputmethod/latin/settings/SettingsValues.java
@@ -57,6 +57,7 @@
     public final SuggestedWords mSuggestPuncList;
     public final String mWordSeparators;
     public final CharSequence mHintToSaveText;
+    public final boolean mCurrentLanguageHasSpaces;
 
     // From preferences, in the same order as xml/prefs.xml:
     public final boolean mAutoCap;
@@ -118,6 +119,7 @@
         mSuggestPuncList = createSuggestPuncList(suggestPuncsSpec);
         mWordSeparators = res.getString(R.string.symbols_word_separators);
         mHintToSaveText = res.getText(R.string.hint_add_to_dictionary);
+        mCurrentLanguageHasSpaces = res.getBoolean(R.bool.current_language_has_spaces);
 
         // Store the input attributes
         if (null == inputAttributes) {
@@ -186,6 +188,7 @@
         mSuggestPuncList = createSuggestPuncList(suggestPuncsSpec);
         mWordSeparators = "&\t \n()[]{}*&<>+=|.,;:!?/_\"";
         mHintToSaveText = "Touch again to save";
+        mCurrentLanguageHasSpaces = true;
         mInputAttributes = new InputAttributes(null, false /* isFullscreenMode */);
         mAutoCap = true;
         mVibrateOn = true;
diff --git a/java/src/com/android/inputmethod/latin/utils/ByteArrayWrapper.java b/java/src/com/android/inputmethod/latin/utils/ByteArrayWrapper.java
index 1bb27aa..d93b614 100644
--- a/java/src/com/android/inputmethod/latin/utils/ByteArrayWrapper.java
+++ b/java/src/com/android/inputmethod/latin/utils/ByteArrayWrapper.java
@@ -16,7 +16,7 @@
 
 package com.android.inputmethod.latin.utils;
 
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput.FusionDictionaryBufferInterface;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder.FusionDictionaryBufferInterface;
 
 /**
  * This class provides an implementation for the FusionDictionary buffer interface that is backed
diff --git a/java/src/com/android/inputmethod/latin/utils/StringUtils.java b/java/src/com/android/inputmethod/latin/utils/StringUtils.java
index 0b4838c..be41840 100644
--- a/java/src/com/android/inputmethod/latin/utils/StringUtils.java
+++ b/java/src/com/android/inputmethod/latin/utils/StringUtils.java
@@ -357,4 +357,37 @@
         }
         return true;
     }
+
+    @UsedForTesting
+    public static String byteArrayToHexString(byte[] bytes) {
+        if (bytes == null || bytes.length == 0) {
+            return "";
+        }
+        final StringBuilder sb = new StringBuilder();
+        for (byte b : bytes) {
+            sb.append(String.format("%02x", b & 0xff));
+        }
+        return sb.toString();
+    }
+
+    /**
+     * Convert hex string to byte array. The string length must be an even number.
+     */
+    @UsedForTesting
+    public static byte[] hexStringToByteArray(String hexString) {
+        if (TextUtils.isEmpty(hexString)) {
+            return null;
+        }
+        final int N = hexString.length();
+        if (N % 2 != 0) {
+            throw new NumberFormatException("Input hex string length must be an even number."
+                    + " Length = " + N);
+        }
+        final byte[] bytes = new byte[N / 2];
+        for (int i = 0; i < N; i += 2) {
+            bytes[i / 2] = (byte) ((Character.digit(hexString.charAt(i), 16) << 4)
+                    + Character.digit(hexString.charAt(i + 1), 16));
+        }
+        return bytes;
+    }
 }
diff --git a/java/src/com/android/inputmethod/latin/utils/UserHistoryDictIOUtils.java b/java/src/com/android/inputmethod/latin/utils/UserHistoryDictIOUtils.java
index a0ad27c..cd03b38 100644
--- a/java/src/com/android/inputmethod/latin/utils/UserHistoryDictIOUtils.java
+++ b/java/src/com/android/inputmethod/latin/utils/UserHistoryDictIOUtils.java
@@ -19,12 +19,13 @@
 import android.util.Log;
 
 import com.android.inputmethod.annotations.UsedForTesting;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder;
+import com.android.inputmethod.latin.makedict.BinaryDictEncoder;
 import com.android.inputmethod.latin.makedict.BinaryDictIOUtils;
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput;
 import com.android.inputmethod.latin.makedict.BinaryDictReader;
 import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
 import com.android.inputmethod.latin.makedict.FusionDictionary;
-import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
 import com.android.inputmethod.latin.makedict.PendingAttribute;
 import com.android.inputmethod.latin.makedict.UnsupportedFormatException;
 import com.android.inputmethod.latin.personalization.UserHistoryDictionaryBigramList;
@@ -62,7 +63,7 @@
             final FormatOptions formatOptions) {
         final FusionDictionary fusionDict = constructFusionDictionary(dict, bigrams);
         try {
-            BinaryDictInputOutput.writeDictionaryBinary(destination, fusionDict, formatOptions);
+            BinaryDictEncoder.writeDictionaryBinary(destination, fusionDict, formatOptions);
             Log.d(TAG, "end writing");
         } catch (IOException e) {
             Log.e(TAG, "IO exception while writing file", e);
@@ -77,7 +78,7 @@
     @UsedForTesting
     static FusionDictionary constructFusionDictionary(
             final BigramDictionaryInterface dict, final UserHistoryDictionaryBigramList bigrams) {
-        final FusionDictionary fusionDict = new FusionDictionary(new Node(),
+        final FusionDictionary fusionDict = new FusionDictionary(new PtNodeArray(),
                 new FusionDictionary.DictionaryOptions(new HashMap<String, String>(), false,
                         false));
         int profTotal = 0;
@@ -101,7 +102,7 @@
                 if (word1 == null) { // unigram
                     fusionDict.add(word2, freq, null, false /* isNotAWord */);
                 } else { // bigram
-                    if (FusionDictionary.findWordInTree(fusionDict.mRoot, word1) == null) {
+                    if (FusionDictionary.findWordInTree(fusionDict.mRootNodeArray, word1) == null) {
                         fusionDict.add(word1, 2, null, false /* isNotAWord */);
                     }
                     fusionDict.setBigram(word1, word2, freq);
@@ -156,7 +157,7 @@
                         continue;
                     }
                     to.setBigram(word1, word2,
-                            BinaryDictInputOutput.reconstructBigramFrequency(unigramFrequency,
+                            BinaryDictDecoder.reconstructBigramFrequency(unigramFrequency,
                                     attr.mFrequency));
                 }
             }
diff --git a/java/src/com/android/inputmethod/research/JsonUtils.java b/java/src/com/android/inputmethod/research/JsonUtils.java
index 63d524d..977f843 100644
--- a/java/src/com/android/inputmethod/research/JsonUtils.java
+++ b/java/src/com/android/inputmethod/research/JsonUtils.java
@@ -75,12 +75,12 @@
 
     private static void writeJson(final Key key, final JsonWriter jsonWriter) throws IOException {
         jsonWriter.beginObject();
-        jsonWriter.name("code").value(key.mCode);
+        jsonWriter.name("code").value(key.getCode());
         jsonWriter.name("altCode").value(key.getAltCode());
-        jsonWriter.name("x").value(key.mX);
-        jsonWriter.name("y").value(key.mY);
-        jsonWriter.name("w").value(key.mWidth);
-        jsonWriter.name("h").value(key.mHeight);
+        jsonWriter.name("x").value(key.getX());
+        jsonWriter.name("y").value(key.getY());
+        jsonWriter.name("w").value(key.getWidth());
+        jsonWriter.name("h").value(key.getHeight());
         jsonWriter.endObject();
     }
 
diff --git a/native/jni/Android.mk b/native/jni/Android.mk
index 8d51a2f..9e7407a 100644
--- a/native/jni/Android.mk
+++ b/native/jni/Android.mk
@@ -43,7 +43,7 @@
     com_android_inputmethod_keyboard_ProximityInfo.cpp \
     com_android_inputmethod_latin_BinaryDictionary.cpp \
     com_android_inputmethod_latin_DicTraverseSession.cpp \
-    com_android_inputmethod_latin_makedict_BinaryDictInputOutput.cpp \
+    com_android_inputmethod_latin_makedict_BinaryDictDecoder.cpp \
     jni_common.cpp
 
 LATIN_IME_CORE_SRC_FILES := \
diff --git a/native/jni/com_android_inputmethod_latin_makedict_BinaryDictInputOutput.cpp b/native/jni/com_android_inputmethod_latin_makedict_BinaryDictDecoder.cpp
similarity index 75%
rename from native/jni/com_android_inputmethod_latin_makedict_BinaryDictInputOutput.cpp
rename to native/jni/com_android_inputmethod_latin_makedict_BinaryDictDecoder.cpp
index f78883c..457b226 100644
--- a/native/jni/com_android_inputmethod_latin_makedict_BinaryDictInputOutput.cpp
+++ b/native/jni/com_android_inputmethod_latin_makedict_BinaryDictDecoder.cpp
@@ -14,16 +14,16 @@
  * limitations under the License.
  */
 
-#define LOG_TAG "LatinIME: jni: BinaryDictInputOutput"
+#define LOG_TAG "LatinIME: jni: BinaryDictDecoder"
 
-#include "com_android_inputmethod_latin_makedict_BinaryDictInputOutput.h"
+#include "com_android_inputmethod_latin_makedict_BinaryDictDecoder.h"
 
 #include "defines.h"
 #include "jni.h"
 #include "jni_common.h"
 
 namespace latinime {
-static int latinime_BinaryDictInputOutput_doNothing(JNIEnv *env, jclass clazz) {
+static int latinime_BinaryDictDecoder_doNothing(JNIEnv *env, jclass clazz) {
     // This is a phony method for test - it does nothing. It just returns some value
     // unlikely to be in memory by chance for testing purposes.
     // TODO: remove this method.
@@ -35,13 +35,13 @@
         // TODO: remove this entry when we have one useful method in here
         const_cast<char *>("doNothing"),
         const_cast<char *>("()I"),
-        reinterpret_cast<void *>(latinime_BinaryDictInputOutput_doNothing)
+        reinterpret_cast<void *>(latinime_BinaryDictDecoder_doNothing)
     },
 };
 
-int register_BinaryDictInputOutput(JNIEnv *env) {
+int register_BinaryDictDecoder(JNIEnv *env) {
     const char *const kClassPathName =
-            "com/android/inputmethod/latin/makedict/BinaryDictInputOutput";
+            "com/android/inputmethod/latin/makedict/BinaryDictDecoder";
     return registerNativeMethods(env, kClassPathName, sMethods, NELEMS(sMethods));
 }
 } // namespace latinime
diff --git a/native/jni/com_android_inputmethod_latin_makedict_BinaryDictInputOutput.h b/native/jni/com_android_inputmethod_latin_makedict_BinaryDictDecoder.h
similarity index 71%
rename from native/jni/com_android_inputmethod_latin_makedict_BinaryDictInputOutput.h
rename to native/jni/com_android_inputmethod_latin_makedict_BinaryDictDecoder.h
index e622ed4..7f3cb67 100644
--- a/native/jni/com_android_inputmethod_latin_makedict_BinaryDictInputOutput.h
+++ b/native/jni/com_android_inputmethod_latin_makedict_BinaryDictDecoder.h
@@ -14,12 +14,12 @@
  * limitations under the License.
  */
 
-#ifndef _COM_ANDROID_INPUTMETHOD_LATIN_MAKEDICT_BINARYDICTINPUTOUTPUT_H
-#define _COM_ANDROID_INPUTMETHOD_LATIN_MAKEDICT_BINARYDICTINPUTOUTPUT_H
+#ifndef _COM_ANDROID_INPUTMETHOD_LATIN_MAKEDICT_BINARYDICTDECODER_H
+#define _COM_ANDROID_INPUTMETHOD_LATIN_MAKEDICT_BINARYDICTDECODER_H
 
 #include "jni.h"
 
 namespace latinime {
-int register_BinaryDictInputOutput(JNIEnv *env);
+int register_BinaryDictDecoder(JNIEnv *env);
 } // namespace latinime
-#endif // _COM_ANDROID_INPUTMETHOD_LATIN_MAKEDICT_BINARYDICTINPUTOUTPUT_H
+#endif // _COM_ANDROID_INPUTMETHOD_LATIN_MAKEDICT_BINARYDICTDECODER_H
diff --git a/native/jni/jni_common.cpp b/native/jni/jni_common.cpp
index 733e15f..d44be67 100644
--- a/native/jni/jni_common.cpp
+++ b/native/jni/jni_common.cpp
@@ -23,7 +23,7 @@
 #include "com_android_inputmethod_latin_BinaryDictionary.h"
 #include "com_android_inputmethod_latin_DicTraverseSession.h"
 #endif
-#include "com_android_inputmethod_latin_makedict_BinaryDictInputOutput.h"
+#include "com_android_inputmethod_latin_makedict_BinaryDictDecoder.h"
 #include "defines.h"
 
 /*
@@ -55,8 +55,8 @@
         return -1;
     }
 #endif
-    if (!latinime::register_BinaryDictInputOutput(env)) {
-        AKLOGE("ERROR: BinaryDictInputOutput native registration failed");
+    if (!latinime::register_BinaryDictDecoder(env)) {
+        AKLOGE("ERROR: BinaryDictDecoder native registration failed");
         return -1;
     }
     /* success -- return valid version number */
diff --git a/native/jni/src/suggest/core/dictionary/probability_utils.h b/native/jni/src/suggest/core/dictionary/probability_utils.h
index f450087..2192135 100644
--- a/native/jni/src/suggest/core/dictionary/probability_utils.h
+++ b/native/jni/src/suggest/core/dictionary/probability_utils.h
@@ -41,7 +41,7 @@
         // the unigram probability to be the median value of the 17th step from the top. A value of
         // 0 for the bigram probability represents the middle of the 16th step from the top,
         // while a value of 15 represents the middle of the top step.
-        // See makedict.BinaryDictInputOutput for details.
+        // See makedict.BinaryDictDecoder for details.
         const float stepSize = static_cast<float>(MAX_PROBABILITY - unigramProbability)
                 / (1.5f + MAX_BIGRAM_ENCODED_PROBABILITY);
         return unigramProbability
diff --git a/native/jni/src/suggest/policyimpl/dictionary/binary_format.h b/native/jni/src/suggest/policyimpl/dictionary/binary_format.h
deleted file mode 100644
index 23f4c7f..0000000
--- a/native/jni/src/suggest/policyimpl/dictionary/binary_format.h
+++ /dev/null
@@ -1,470 +0,0 @@
-/*
- * Copyright (C) 2011 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef LATINIME_BINARY_FORMAT_H
-#define LATINIME_BINARY_FORMAT_H
-
-#include <stdint.h>
-
-#include "suggest/core/dictionary/probability_utils.h"
-#include "utils/char_utils.h"
-
-namespace latinime {
-
-class BinaryFormat {
- public:
-    // Mask and flags for children address type selection.
-    static const int MASK_GROUP_ADDRESS_TYPE = 0xC0;
-
-    // Flag for single/multiple char group
-    static const int FLAG_HAS_MULTIPLE_CHARS = 0x20;
-
-    // Flag for terminal groups
-    static const int FLAG_IS_TERMINAL = 0x10;
-
-    // Flag for shortcut targets presence
-    static const int FLAG_HAS_SHORTCUT_TARGETS = 0x08;
-    // Flag for bigram presence
-    static const int FLAG_HAS_BIGRAMS = 0x04;
-    // Flag for non-words (typically, shortcut only entries)
-    static const int FLAG_IS_NOT_A_WORD = 0x02;
-    // Flag for blacklist
-    static const int FLAG_IS_BLACKLISTED = 0x01;
-
-    // Attribute (bigram/shortcut) related flags:
-    // Flag for presence of more attributes
-    static const int FLAG_ATTRIBUTE_HAS_NEXT = 0x80;
-    // Flag for sign of offset. If this flag is set, the offset value must be negated.
-    static const int FLAG_ATTRIBUTE_OFFSET_NEGATIVE = 0x40;
-
-    // Mask for attribute probability, stored on 4 bits inside the flags byte.
-    static const int MASK_ATTRIBUTE_PROBABILITY = 0x0F;
-
-    // Mask and flags for attribute address type selection.
-    static const int MASK_ATTRIBUTE_ADDRESS_TYPE = 0x30;
-
-    static int getGroupCountAndForwardPointer(const uint8_t *const dict, int *pos);
-    static uint8_t getFlagsAndForwardPointer(const uint8_t *const dict, int *pos);
-    static int getCodePointAndForwardPointer(const uint8_t *const dict, int *pos);
-    static int readProbabilityWithoutMovingPointer(const uint8_t *const dict, const int pos);
-    static int skipOtherCharacters(const uint8_t *const dict, const int pos);
-    static int skipChildrenPosition(const uint8_t flags, const int pos);
-    static int skipProbability(const uint8_t flags, const int pos);
-    static int skipShortcuts(const uint8_t *const dict, const uint8_t flags, const int pos);
-    static int skipChildrenPosAndAttributes(const uint8_t *const dict, const uint8_t flags,
-            const int pos);
-    static int readChildrenPosition(const uint8_t *const dict, const uint8_t flags, const int pos);
-    static bool hasChildrenInFlags(const uint8_t flags);
-    static int getTerminalPosition(const uint8_t *const root, const int *const inWord,
-            const int length, const bool forceLowerCaseSearch);
-    static int getCodePointsAndProbabilityAndReturnCodePointCount(
-            const uint8_t *const root, const int nodePos, const int maxCodePointCount,
-            int *const outCodePoints, int *const outUnigramProbability);
-
- private:
-    DISALLOW_IMPLICIT_CONSTRUCTORS(BinaryFormat);
-
-    static const int FLAG_GROUP_ADDRESS_TYPE_NOADDRESS = 0x00;
-    static const int FLAG_GROUP_ADDRESS_TYPE_ONEBYTE = 0x40;
-    static const int FLAG_GROUP_ADDRESS_TYPE_TWOBYTES = 0x80;
-    static const int FLAG_GROUP_ADDRESS_TYPE_THREEBYTES = 0xC0;
-    static const int FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE = 0x10;
-    static const int FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES = 0x20;
-    static const int FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES = 0x30;
-
-    static const int CHARACTER_ARRAY_TERMINATOR_SIZE = 1;
-    static const int MINIMAL_ONE_BYTE_CHARACTER_VALUE = 0x20;
-    static const int CHARACTER_ARRAY_TERMINATOR = 0x1F;
-    static const int MULTIPLE_BYTE_CHARACTER_ADDITIONAL_SIZE = 2;
-    static const int NO_FLAGS = 0;
-    static int skipAllAttributes(const uint8_t *const dict, const uint8_t flags, const int pos);
-    static int skipBigrams(const uint8_t *const dict, const uint8_t flags, const int pos);
-};
-
-AK_FORCE_INLINE int BinaryFormat::getGroupCountAndForwardPointer(const uint8_t *const dict,
-        int *pos) {
-    const int msb = dict[(*pos)++];
-    if (msb < 0x80) return msb;
-    return ((msb & 0x7F) << 8) | dict[(*pos)++];
-}
-
-inline uint8_t BinaryFormat::getFlagsAndForwardPointer(const uint8_t *const dict, int *pos) {
-    return dict[(*pos)++];
-}
-
-AK_FORCE_INLINE int BinaryFormat::getCodePointAndForwardPointer(const uint8_t *const dict,
-        int *pos) {
-    const int origin = *pos;
-    const int codePoint = dict[origin];
-    if (codePoint < MINIMAL_ONE_BYTE_CHARACTER_VALUE) {
-        if (codePoint == CHARACTER_ARRAY_TERMINATOR) {
-            *pos = origin + 1;
-            return NOT_A_CODE_POINT;
-        } else {
-            *pos = origin + 3;
-            const int char_1 = codePoint << 16;
-            const int char_2 = char_1 + (dict[origin + 1] << 8);
-            return char_2 + dict[origin + 2];
-        }
-    } else {
-        *pos = origin + 1;
-        return codePoint;
-    }
-}
-
-inline int BinaryFormat::readProbabilityWithoutMovingPointer(const uint8_t *const dict,
-        const int pos) {
-    return dict[pos];
-}
-
-AK_FORCE_INLINE int BinaryFormat::skipOtherCharacters(const uint8_t *const dict, const int pos) {
-    int currentPos = pos;
-    int character = dict[currentPos++];
-    while (CHARACTER_ARRAY_TERMINATOR != character) {
-        if (character < MINIMAL_ONE_BYTE_CHARACTER_VALUE) {
-            currentPos += MULTIPLE_BYTE_CHARACTER_ADDITIONAL_SIZE;
-        }
-        character = dict[currentPos++];
-    }
-    return currentPos;
-}
-
-static inline int attributeAddressSize(const uint8_t flags) {
-    static const int ATTRIBUTE_ADDRESS_SHIFT = 4;
-    return (flags & BinaryFormat::MASK_ATTRIBUTE_ADDRESS_TYPE) >> ATTRIBUTE_ADDRESS_SHIFT;
-    /* Note: this is a value-dependant optimization of what may probably be
-       more readably written this way:
-       switch (flags * BinaryFormat::MASK_ATTRIBUTE_ADDRESS_TYPE) {
-       case FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE: return 1;
-       case FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES: return 2;
-       case FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTE: return 3;
-       default: return 0;
-       }
-    */
-}
-
-static AK_FORCE_INLINE int skipExistingBigrams(const uint8_t *const dict, const int pos) {
-    int currentPos = pos;
-    uint8_t flags = BinaryFormat::getFlagsAndForwardPointer(dict, &currentPos);
-    while (flags & BinaryFormat::FLAG_ATTRIBUTE_HAS_NEXT) {
-        currentPos += attributeAddressSize(flags);
-        flags = BinaryFormat::getFlagsAndForwardPointer(dict, &currentPos);
-    }
-    currentPos += attributeAddressSize(flags);
-    return currentPos;
-}
-
-static inline int childrenAddressSize(const uint8_t flags) {
-    static const int CHILDREN_ADDRESS_SHIFT = 6;
-    return (BinaryFormat::MASK_GROUP_ADDRESS_TYPE & flags) >> CHILDREN_ADDRESS_SHIFT;
-    /* See the note in attributeAddressSize. The same applies here */
-}
-
-static AK_FORCE_INLINE int shortcutByteSize(const uint8_t *const dict, const int pos) {
-    return (static_cast<int>(dict[pos] << 8)) + (dict[pos + 1]);
-}
-
-inline int BinaryFormat::skipChildrenPosition(const uint8_t flags, const int pos) {
-    return pos + childrenAddressSize(flags);
-}
-
-inline int BinaryFormat::skipProbability(const uint8_t flags, const int pos) {
-    return FLAG_IS_TERMINAL & flags ? pos + 1 : pos;
-}
-
-AK_FORCE_INLINE int BinaryFormat::skipShortcuts(const uint8_t *const dict, const uint8_t flags,
-        const int pos) {
-    if (FLAG_HAS_SHORTCUT_TARGETS & flags) {
-        return pos + shortcutByteSize(dict, pos);
-    } else {
-        return pos;
-    }
-}
-
-AK_FORCE_INLINE int BinaryFormat::skipBigrams(const uint8_t *const dict, const uint8_t flags,
-        const int pos) {
-    if (FLAG_HAS_BIGRAMS & flags) {
-        return skipExistingBigrams(dict, pos);
-    } else {
-        return pos;
-    }
-}
-
-AK_FORCE_INLINE int BinaryFormat::skipAllAttributes(const uint8_t *const dict, const uint8_t flags,
-        const int pos) {
-    // This function skips all attributes: shortcuts and bigrams.
-    int newPos = pos;
-    newPos = skipShortcuts(dict, flags, newPos);
-    newPos = skipBigrams(dict, flags, newPos);
-    return newPos;
-}
-
-AK_FORCE_INLINE int BinaryFormat::skipChildrenPosAndAttributes(const uint8_t *const dict,
-        const uint8_t flags, const int pos) {
-    int currentPos = pos;
-    currentPos = skipChildrenPosition(flags, currentPos);
-    currentPos = skipAllAttributes(dict, flags, currentPos);
-    return currentPos;
-}
-
-AK_FORCE_INLINE int BinaryFormat::readChildrenPosition(const uint8_t *const dict,
-        const uint8_t flags, const int pos) {
-    int offset = 0;
-    switch (MASK_GROUP_ADDRESS_TYPE & flags) {
-        case FLAG_GROUP_ADDRESS_TYPE_ONEBYTE:
-            offset = dict[pos];
-            break;
-        case FLAG_GROUP_ADDRESS_TYPE_TWOBYTES:
-            offset = dict[pos] << 8;
-            offset += dict[pos + 1];
-            break;
-        case FLAG_GROUP_ADDRESS_TYPE_THREEBYTES:
-            offset = dict[pos] << 16;
-            offset += dict[pos + 1] << 8;
-            offset += dict[pos + 2];
-            break;
-        default:
-            // If we come here, it means we asked for the children of a word with
-            // no children.
-            return -1;
-    }
-    return pos + offset;
-}
-
-inline bool BinaryFormat::hasChildrenInFlags(const uint8_t flags) {
-    return (FLAG_GROUP_ADDRESS_TYPE_NOADDRESS != (MASK_GROUP_ADDRESS_TYPE & flags));
-}
-
-// This function gets the byte position of the last chargroup of the exact matching word in the
-// dictionary. If no match is found, it returns NOT_A_VALID_WORD_POS.
-AK_FORCE_INLINE int BinaryFormat::getTerminalPosition(const uint8_t *const root,
-        const int *const inWord, const int length, const bool forceLowerCaseSearch) {
-    int pos = 0;
-    int wordPos = 0;
-
-    while (true) {
-        // If we already traversed the tree further than the word is long, there means
-        // there was no match (or we would have found it).
-        if (wordPos >= length) return NOT_A_VALID_WORD_POS;
-        int charGroupCount = BinaryFormat::getGroupCountAndForwardPointer(root, &pos);
-        const int wChar = forceLowerCaseSearch
-                ? CharUtils::toLowerCase(inWord[wordPos]) : inWord[wordPos];
-        while (true) {
-            // If there are no more character groups in this node, it means we could not
-            // find a matching character for this depth, therefore there is no match.
-            if (0 >= charGroupCount) return NOT_A_VALID_WORD_POS;
-            const int charGroupPos = pos;
-            const uint8_t flags = BinaryFormat::getFlagsAndForwardPointer(root, &pos);
-            int character = BinaryFormat::getCodePointAndForwardPointer(root, &pos);
-            if (character == wChar) {
-                // This is the correct node. Only one character group may start with the same
-                // char within a node, so either we found our match in this node, or there is
-                // no match and we can return NOT_A_VALID_WORD_POS. So we will check all the
-                // characters in this character group indeed does match.
-                if (FLAG_HAS_MULTIPLE_CHARS & flags) {
-                    character = BinaryFormat::getCodePointAndForwardPointer(root, &pos);
-                    while (NOT_A_CODE_POINT != character) {
-                        ++wordPos;
-                        // If we shoot the length of the word we search for, or if we find a single
-                        // character that does not match, as explained above, it means the word is
-                        // not in the dictionary (by virtue of this chargroup being the only one to
-                        // match the word on the first character, but not matching the whole word).
-                        if (wordPos >= length) return NOT_A_VALID_WORD_POS;
-                        if (inWord[wordPos] != character) return NOT_A_VALID_WORD_POS;
-                        character = BinaryFormat::getCodePointAndForwardPointer(root, &pos);
-                    }
-                }
-                // If we come here we know that so far, we do match. Either we are on a terminal
-                // and we match the length, in which case we found it, or we traverse children.
-                // If we don't match the length AND don't have children, then a word in the
-                // dictionary fully matches a prefix of the searched word but not the full word.
-                ++wordPos;
-                if (FLAG_IS_TERMINAL & flags) {
-                    if (wordPos == length) {
-                        return charGroupPos;
-                    }
-                    pos = BinaryFormat::skipProbability(FLAG_IS_TERMINAL, pos);
-                }
-                if (FLAG_GROUP_ADDRESS_TYPE_NOADDRESS == (MASK_GROUP_ADDRESS_TYPE & flags)) {
-                    return NOT_A_VALID_WORD_POS;
-                }
-                // We have children and we are still shorter than the word we are searching for, so
-                // we need to traverse children. Put the pointer on the children position, and
-                // break
-                pos = BinaryFormat::readChildrenPosition(root, flags, pos);
-                break;
-            } else {
-                // This chargroup does not match, so skip the remaining part and go to the next.
-                if (FLAG_HAS_MULTIPLE_CHARS & flags) {
-                    pos = BinaryFormat::skipOtherCharacters(root, pos);
-                }
-                pos = BinaryFormat::skipProbability(flags, pos);
-                pos = BinaryFormat::skipChildrenPosAndAttributes(root, flags, pos);
-            }
-            --charGroupCount;
-        }
-    }
-}
-
-// This function searches for a terminal in the dictionary by its address.
-// Due to the fact that words are ordered in the dictionary in a strict breadth-first order,
-// it is possible to check for this with advantageous complexity. For each node, we search
-// for groups with children and compare the children address with the address we look for.
-// When we shoot the address we look for, it means the word we look for is in the children
-// of the previous group. The only tricky part is the fact that if we arrive at the end of a
-// node with the last group's children address still less than what we are searching for, we
-// must descend the last group's children (for example, if the word we are searching for starts
-// with a z, it's the last group of the root node, so all children addresses will be smaller
-// than the address we look for, and we have to descend the z node).
-/* Parameters :
- * root: the dictionary buffer
- * address: the byte position of the last chargroup of the word we are searching for (this is
- *   what is stored as the "bigram address" in each bigram)
- * outword: an array to write the found word, with MAX_WORD_LENGTH size.
- * outUnigramProbability: a pointer to an int to write the probability into.
- * Return value : the length of the word, of 0 if the word was not found.
- */
-AK_FORCE_INLINE int BinaryFormat::getCodePointsAndProbabilityAndReturnCodePointCount(
-        const uint8_t *const root, const int nodePos, const int maxCodePointCount,
-        int *const outCodePoints, int *const outUnigramProbability) {
-    int pos = 0;
-    int wordPos = 0;
-
-    // One iteration of the outer loop iterates through nodes. As stated above, we will only
-    // traverse nodes that are actually a part of the terminal we are searching, so each time
-    // we enter this loop we are one depth level further than last time.
-    // The only reason we count nodes is because we want to reduce the probability of infinite
-    // looping in case there is a bug. Since we know there is an upper bound to the depth we are
-    // supposed to traverse, it does not hurt to count iterations.
-    for (int loopCount = maxCodePointCount; loopCount > 0; --loopCount) {
-        int lastCandidateGroupPos = 0;
-        // Let's loop through char groups in this node searching for either the terminal
-        // or one of its ascendants.
-        for (int charGroupCount = getGroupCountAndForwardPointer(root, &pos); charGroupCount > 0;
-                 --charGroupCount) {
-            const int startPos = pos;
-            const uint8_t flags = getFlagsAndForwardPointer(root, &pos);
-            const int character = getCodePointAndForwardPointer(root, &pos);
-            if (nodePos == startPos) {
-                // We found the address. Copy the rest of the word in the buffer and return
-                // the length.
-                outCodePoints[wordPos] = character;
-                if (FLAG_HAS_MULTIPLE_CHARS & flags) {
-                    int nextChar = getCodePointAndForwardPointer(root, &pos);
-                    // We count chars in order to avoid infinite loops if the file is broken or
-                    // if there is some other bug
-                    int charCount = maxCodePointCount;
-                    while (NOT_A_CODE_POINT != nextChar && --charCount > 0) {
-                        outCodePoints[++wordPos] = nextChar;
-                        nextChar = getCodePointAndForwardPointer(root, &pos);
-                    }
-                }
-                *outUnigramProbability = readProbabilityWithoutMovingPointer(root, pos);
-                return ++wordPos;
-            }
-            // We need to skip past this char group, so skip any remaining chars after the
-            // first and possibly the probability.
-            if (FLAG_HAS_MULTIPLE_CHARS & flags) {
-                pos = skipOtherCharacters(root, pos);
-            }
-            pos = skipProbability(flags, pos);
-
-            // The fact that this group has children is very important. Since we already know
-            // that this group does not match, if it has no children we know it is irrelevant
-            // to what we are searching for.
-            const bool hasChildren = (FLAG_GROUP_ADDRESS_TYPE_NOADDRESS !=
-                    (MASK_GROUP_ADDRESS_TYPE & flags));
-            // We will write in `found' whether we have passed the children address we are
-            // searching for. For example if we search for "beer", the children of b are less
-            // than the address we are searching for and the children of c are greater. When we
-            // come here for c, we realize this is too big, and that we should descend b.
-            bool found;
-            if (hasChildren) {
-                // Here comes the tricky part. First, read the children position.
-                const int childrenPos = readChildrenPosition(root, flags, pos);
-                if (childrenPos > nodePos) {
-                    // If the children pos is greater than address, it means the previous chargroup,
-                    // which address is stored in lastCandidateGroupPos, was the right one.
-                    found = true;
-                } else if (1 >= charGroupCount) {
-                    // However if we are on the LAST group of this node, and we have NOT shot the
-                    // address we should descend THIS node. So we trick the lastCandidateGroupPos
-                    // so that we will descend this node, not the previous one.
-                    lastCandidateGroupPos = startPos;
-                    found = true;
-                } else {
-                    // Else, we should continue looking.
-                    found = false;
-                }
-            } else {
-                // Even if we don't have children here, we could still be on the last group of this
-                // node. If this is the case, we should descend the last group that had children,
-                // and their address is already in lastCandidateGroup.
-                found = (1 >= charGroupCount);
-            }
-
-            if (found) {
-                // Okay, we found the group we should descend. Its address is in
-                // the lastCandidateGroupPos variable, so we just re-read it.
-                if (0 != lastCandidateGroupPos) {
-                    const uint8_t lastFlags =
-                            getFlagsAndForwardPointer(root, &lastCandidateGroupPos);
-                    const int lastChar =
-                            getCodePointAndForwardPointer(root, &lastCandidateGroupPos);
-                    // We copy all the characters in this group to the buffer
-                    outCodePoints[wordPos] = lastChar;
-                    if (FLAG_HAS_MULTIPLE_CHARS & lastFlags) {
-                        int nextChar = getCodePointAndForwardPointer(root, &lastCandidateGroupPos);
-                        int charCount = maxCodePointCount;
-                        while (-1 != nextChar && --charCount > 0) {
-                            outCodePoints[++wordPos] = nextChar;
-                            nextChar = getCodePointAndForwardPointer(root, &lastCandidateGroupPos);
-                        }
-                    }
-                    ++wordPos;
-                    // Now we only need to branch to the children address. Skip the probability if
-                    // it's there, read pos, and break to resume the search at pos.
-                    lastCandidateGroupPos = skipProbability(lastFlags, lastCandidateGroupPos);
-                    pos = readChildrenPosition(root, lastFlags, lastCandidateGroupPos);
-                    break;
-                } else {
-                    // Here is a little tricky part: we come here if we found out that all children
-                    // addresses in this group are bigger than the address we are searching for.
-                    // Should we conclude the word is not in the dictionary? No! It could still be
-                    // one of the remaining chargroups in this node, so we have to keep looking in
-                    // this node until we find it (or we realize it's not there either, in which
-                    // case it's actually not in the dictionary). Pass the end of this group, ready
-                    // to start the next one.
-                    pos = skipChildrenPosAndAttributes(root, flags, pos);
-                }
-            } else {
-                // If we did not find it, we should record the last children address for the next
-                // iteration.
-                if (hasChildren) lastCandidateGroupPos = startPos;
-                // Now skip the end of this group (children pos and the attributes if any) so that
-                // our pos is after the end of this char group, at the start of the next one.
-                pos = skipChildrenPosAndAttributes(root, flags, pos);
-            }
-
-        }
-    }
-    // If we have looked through all the chargroups and found no match, the address is
-    // not the address of a terminal in this dictionary.
-    return 0;
-}
-
-} // namespace latinime
-#endif // LATINIME_BINARY_FORMAT_H
diff --git a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.cpp
index 3e664a2..15eb067 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.cpp
@@ -20,7 +20,6 @@
 #include "defines.h"
 #include "suggest/core/dicnode/dic_node.h"
 #include "suggest/core/dicnode/dic_node_vector.h"
-#include "suggest/policyimpl/dictionary/binary_format.h"
 #include "suggest/policyimpl/dictionary/patricia_trie_reading_utils.h"
 
 namespace latinime {
@@ -38,17 +37,273 @@
     }
 }
 
+// This retrieves code points and the probability of the word by its terminal position.
+// Due to the fact that words are ordered in the dictionary in a strict breadth-first order,
+// it is possible to check for this with advantageous complexity. For each node, we search
+// for groups with children and compare the children position with the position we look for.
+// When we shoot the position we look for, it means the word we look for is in the children
+// of the previous group. The only tricky part is the fact that if we arrive at the end of a
+// node with the last group's children position still less than what we are searching for, we
+// must descend the last group's children (for example, if the word we are searching for starts
+// with a z, it's the last group of the root node, so all children addresses will be smaller
+// than the position we look for, and we have to descend the z node).
+/* Parameters :
+ * nodePos: the byte position of the terminal chargroup of the word we are searching for (this is
+ *   what is stored as the "bigram position" in each bigram)
+ * outCodePoints: an array to write the found word, with MAX_WORD_LENGTH size.
+ * outUnigramProbability: a pointer to an int to write the probability into.
+ * Return value : the code point count, of 0 if the word was not found.
+ */
+// TODO: Split this function to be more readable
 int PatriciaTriePolicy::getCodePointsAndProbabilityAndReturnCodePointCount(
         const int nodePos, const int maxCodePointCount, int *const outCodePoints,
         int *const outUnigramProbability) const {
-    return BinaryFormat::getCodePointsAndProbabilityAndReturnCodePointCount(mDictRoot, nodePos,
-            maxCodePointCount, outCodePoints, outUnigramProbability);
+    int pos = getRootPosition();
+    int wordPos = 0;
+    // One iteration of the outer loop iterates through nodes. As stated above, we will only
+    // traverse nodes that are actually a part of the terminal we are searching, so each time
+    // we enter this loop we are one depth level further than last time.
+    // The only reason we count nodes is because we want to reduce the probability of infinite
+    // looping in case there is a bug. Since we know there is an upper bound to the depth we are
+    // supposed to traverse, it does not hurt to count iterations.
+    for (int loopCount = maxCodePointCount; loopCount > 0; --loopCount) {
+        int lastCandidateGroupPos = 0;
+        // Let's loop through char groups in this node searching for either the terminal
+        // or one of its ascendants.
+        for (int charGroupCount = PatriciaTrieReadingUtils::getGroupCountAndAdvancePosition(
+                mDictRoot, &pos); charGroupCount > 0; --charGroupCount) {
+            const int startPos = pos;
+            const PatriciaTrieReadingUtils::NodeFlags flags =
+                    PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(mDictRoot, &pos);
+            const int character = PatriciaTrieReadingUtils::getCodePointAndAdvancePosition(
+                    mDictRoot, &pos);
+            if (nodePos == startPos) {
+                // We found the position. Copy the rest of the code points in the buffer and return
+                // the length.
+                outCodePoints[wordPos] = character;
+                if (PatriciaTrieReadingUtils::hasMultipleChars(flags)) {
+                    int nextChar = PatriciaTrieReadingUtils::getCodePointAndAdvancePosition(
+                            mDictRoot, &pos);
+                    // We count code points in order to avoid infinite loops if the file is broken
+                    // or if there is some other bug
+                    int charCount = maxCodePointCount;
+                    while (NOT_A_CODE_POINT != nextChar && --charCount > 0) {
+                        outCodePoints[++wordPos] = nextChar;
+                        nextChar = PatriciaTrieReadingUtils::getCodePointAndAdvancePosition(
+                                mDictRoot, &pos);
+                    }
+                }
+                *outUnigramProbability =
+                        PatriciaTrieReadingUtils::readProbabilityAndAdvancePosition(mDictRoot,
+                                &pos);
+                return ++wordPos;
+            }
+            // We need to skip past this char group, so skip any remaining code points after the
+            // first and possibly the probability.
+            if (PatriciaTrieReadingUtils::hasMultipleChars(flags)) {
+                PatriciaTrieReadingUtils::skipCharacters(mDictRoot, flags, MAX_WORD_LENGTH, &pos);
+            }
+            if (PatriciaTrieReadingUtils::isTerminal(flags)) {
+                PatriciaTrieReadingUtils::readProbabilityAndAdvancePosition(mDictRoot, &pos);
+            }
+            // The fact that this group has children is very important. Since we already know
+            // that this group does not match, if it has no children we know it is irrelevant
+            // to what we are searching for.
+            const bool hasChildren = PatriciaTrieReadingUtils::hasChildrenInFlags(flags);
+            // We will write in `found' whether we have passed the children position we are
+            // searching for. For example if we search for "beer", the children of b are less
+            // than the address we are searching for and the children of c are greater. When we
+            // come here for c, we realize this is too big, and that we should descend b.
+            bool found;
+            if (hasChildren) {
+                int currentPos = pos;
+                // Here comes the tricky part. First, read the children position.
+                const int childrenPos = PatriciaTrieReadingUtils
+                        ::readChildrenPositionAndAdvancePosition(mDictRoot, flags, &currentPos);
+                if (childrenPos > nodePos) {
+                    // If the children pos is greater than the position, it means the previous
+                    // chargroup, which position is stored in lastCandidateGroupPos, was the right
+                    // one.
+                    found = true;
+                } else if (1 >= charGroupCount) {
+                    // However if we are on the LAST group of this node, and we have NOT shot the
+                    // position we should descend THIS node. So we trick the lastCandidateGroupPos
+                    // so that we will descend this node, not the previous one.
+                    lastCandidateGroupPos = startPos;
+                    found = true;
+                } else {
+                    // Else, we should continue looking.
+                    found = false;
+                }
+            } else {
+                // Even if we don't have children here, we could still be on the last group of this
+                // node. If this is the case, we should descend the last group that had children,
+                // and their position is already in lastCandidateGroup.
+                found = (1 >= charGroupCount);
+            }
+
+            if (found) {
+                // Okay, we found the group we should descend. Its position is in
+                // the lastCandidateGroupPos variable, so we just re-read it.
+                if (0 != lastCandidateGroupPos) {
+                    const PatriciaTrieReadingUtils::NodeFlags lastFlags =
+                            PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(
+                                    mDictRoot, &lastCandidateGroupPos);
+                    const int lastChar = PatriciaTrieReadingUtils::getCodePointAndAdvancePosition(
+                            mDictRoot, &lastCandidateGroupPos);
+                    // We copy all the characters in this group to the buffer
+                    outCodePoints[wordPos] = lastChar;
+                    if (PatriciaTrieReadingUtils::hasMultipleChars(lastFlags)) {
+                        int nextChar = PatriciaTrieReadingUtils::getCodePointAndAdvancePosition(
+                                mDictRoot, &lastCandidateGroupPos);
+                        int charCount = maxCodePointCount;
+                        while (-1 != nextChar && --charCount > 0) {
+                            outCodePoints[++wordPos] = nextChar;
+                            nextChar = PatriciaTrieReadingUtils::getCodePointAndAdvancePosition(
+                                    mDictRoot, &lastCandidateGroupPos);
+                        }
+                    }
+                    ++wordPos;
+                    // Now we only need to branch to the children address. Skip the probability if
+                    // it's there, read pos, and break to resume the search at pos.
+                    if (PatriciaTrieReadingUtils::isTerminal(lastFlags)) {
+                        PatriciaTrieReadingUtils::readProbabilityAndAdvancePosition(mDictRoot,
+                                &lastCandidateGroupPos);
+                    }
+                    pos = PatriciaTrieReadingUtils::readChildrenPositionAndAdvancePosition(
+                            mDictRoot, lastFlags, &lastCandidateGroupPos);
+                    break;
+                } else {
+                    // Here is a little tricky part: we come here if we found out that all children
+                    // addresses in this group are bigger than the address we are searching for.
+                    // Should we conclude the word is not in the dictionary? No! It could still be
+                    // one of the remaining chargroups in this node, so we have to keep looking in
+                    // this node until we find it (or we realize it's not there either, in which
+                    // case it's actually not in the dictionary). Pass the end of this group, ready
+                    // to start the next one.
+                    if (PatriciaTrieReadingUtils::hasChildrenInFlags(flags)) {
+                        PatriciaTrieReadingUtils::readChildrenPositionAndAdvancePosition(
+                                mDictRoot, flags, &pos);
+                    }
+                    if (PatriciaTrieReadingUtils::hasShortcutTargets(flags)) {
+                        mShortcutListPolicy.skipAllShortcuts(&pos);
+                    }
+                    if (PatriciaTrieReadingUtils::hasBigrams(flags)) {
+                        mBigramListPolicy.skipAllBigrams(&pos);
+                    }
+                }
+            } else {
+                // If we did not find it, we should record the last children address for the next
+                // iteration.
+                if (hasChildren) lastCandidateGroupPos = startPos;
+                // Now skip the end of this group (children pos and the attributes if any) so that
+                // our pos is after the end of this char group, at the start of the next one.
+                if (PatriciaTrieReadingUtils::hasChildrenInFlags(flags)) {
+                    PatriciaTrieReadingUtils::readChildrenPositionAndAdvancePosition(
+                            mDictRoot, flags, &pos);
+                }
+                if (PatriciaTrieReadingUtils::hasShortcutTargets(flags)) {
+                    mShortcutListPolicy.skipAllShortcuts(&pos);
+                }
+                if (PatriciaTrieReadingUtils::hasBigrams(flags)) {
+                    mBigramListPolicy.skipAllBigrams(&pos);
+                }
+            }
+
+        }
+    }
+    // If we have looked through all the chargroups and found no match, the nodePos is
+    // not the position of a terminal in this dictionary.
+    return 0;
 }
 
+// This function gets the position of the terminal node of the exact matching word in the
+// dictionary. If no match is found, it returns NOT_A_VALID_WORD_POS.
 int PatriciaTriePolicy::getTerminalNodePositionOfWord(const int *const inWord,
         const int length, const bool forceLowerCaseSearch) const {
-    return BinaryFormat::getTerminalPosition(mDictRoot, inWord,
-            length, forceLowerCaseSearch);
+    int pos = getRootPosition();
+    int wordPos = 0;
+
+    while (true) {
+        // If we already traversed the tree further than the word is long, there means
+        // there was no match (or we would have found it).
+        if (wordPos >= length) return NOT_A_VALID_WORD_POS;
+        int charGroupCount = PatriciaTrieReadingUtils::getGroupCountAndAdvancePosition(mDictRoot,
+                &pos);
+        const int wChar = forceLowerCaseSearch
+                ? CharUtils::toLowerCase(inWord[wordPos]) : inWord[wordPos];
+        while (true) {
+            // If there are no more character groups in this node, it means we could not
+            // find a matching character for this depth, therefore there is no match.
+            if (0 >= charGroupCount) return NOT_A_VALID_WORD_POS;
+            const int charGroupPos = pos;
+            const PatriciaTrieReadingUtils::NodeFlags flags =
+                    PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(mDictRoot, &pos);
+            int character = PatriciaTrieReadingUtils::getCodePointAndAdvancePosition(mDictRoot,
+                    &pos);
+            if (character == wChar) {
+                // This is the correct node. Only one character group may start with the same
+                // char within a node, so either we found our match in this node, or there is
+                // no match and we can return NOT_A_VALID_WORD_POS. So we will check all the
+                // characters in this character group indeed does match.
+                if (PatriciaTrieReadingUtils::hasMultipleChars(flags)) {
+                    character = PatriciaTrieReadingUtils::getCodePointAndAdvancePosition(mDictRoot,
+                            &pos);
+                    while (NOT_A_CODE_POINT != character) {
+                        ++wordPos;
+                        // If we shoot the length of the word we search for, or if we find a single
+                        // character that does not match, as explained above, it means the word is
+                        // not in the dictionary (by virtue of this chargroup being the only one to
+                        // match the word on the first character, but not matching the whole word).
+                        if (wordPos >= length) return NOT_A_VALID_WORD_POS;
+                        if (inWord[wordPos] != character) return NOT_A_VALID_WORD_POS;
+                        character = PatriciaTrieReadingUtils::getCodePointAndAdvancePosition(
+                                mDictRoot, &pos);
+                    }
+                }
+                // If we come here we know that so far, we do match. Either we are on a terminal
+                // and we match the length, in which case we found it, or we traverse children.
+                // If we don't match the length AND don't have children, then a word in the
+                // dictionary fully matches a prefix of the searched word but not the full word.
+                ++wordPos;
+                if (PatriciaTrieReadingUtils::isTerminal(flags)) {
+                    if (wordPos == length) {
+                        return charGroupPos;
+                    }
+                    PatriciaTrieReadingUtils::readProbabilityAndAdvancePosition(mDictRoot, &pos);
+                }
+                if (!PatriciaTrieReadingUtils::hasChildrenInFlags(flags)) {
+                    return NOT_A_VALID_WORD_POS;
+                }
+                // We have children and we are still shorter than the word we are searching for, so
+                // we need to traverse children. Put the pointer on the children position, and
+                // break
+                pos = PatriciaTrieReadingUtils::readChildrenPositionAndAdvancePosition(mDictRoot,
+                        flags, &pos);
+                break;
+            } else {
+                // This chargroup does not match, so skip the remaining part and go to the next.
+                if (PatriciaTrieReadingUtils::hasMultipleChars(flags)) {
+                    PatriciaTrieReadingUtils::skipCharacters(mDictRoot, flags, MAX_WORD_LENGTH,
+                            &pos);
+                }
+                if (PatriciaTrieReadingUtils::isTerminal(flags)) {
+                    PatriciaTrieReadingUtils::readProbabilityAndAdvancePosition(mDictRoot, &pos);
+                }
+                if (PatriciaTrieReadingUtils::hasChildrenInFlags(flags)) {
+                    PatriciaTrieReadingUtils::readChildrenPositionAndAdvancePosition(mDictRoot,
+                            flags, &pos);
+                }
+                if (PatriciaTrieReadingUtils::hasShortcutTargets(flags)) {
+                    mShortcutListPolicy.skipAllShortcuts(&pos);
+                }
+                if (PatriciaTrieReadingUtils::hasBigrams(flags)) {
+                    mBigramListPolicy.skipAllBigrams(&pos);
+                }
+            }
+            --charGroupCount;
+        }
+    }
 }
 
 int PatriciaTriePolicy::getUnigramProbability(const int nodePos) const {
diff --git a/native/jni/src/suggest/policyimpl/dictionary/utils/mmaped_buffer.h b/native/jni/src/suggest/policyimpl/dictionary/utils/mmaped_buffer.h
index e3aabb0..08add03 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/utils/mmaped_buffer.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/utils/mmaped_buffer.h
@@ -48,13 +48,13 @@
             close(fd);
             return 0;
         }
-        uint8_t *const buffer = static_cast<uint8_t *>(mmapedBuffer) + bufOffset;
+        uint8_t *const buffer = static_cast<uint8_t *>(mmapedBuffer) + offset;
         if (!buffer) {
             AKLOGE("DICT: buffer is null");
             close(fd);
             return 0;
         }
-        return new MmapedBuffer(buffer, adjSize, fd, adjOffset, isUpdatable);
+        return new MmapedBuffer(buffer, adjSize, fd, offset, isUpdatable);
     }
 
     ~MmapedBuffer() {
diff --git a/tests/src/com/android/inputmethod/latin/FusionDictionaryTests.java b/tests/src/com/android/inputmethod/latin/FusionDictionaryTests.java
index 65dfd2d..cadd0f8 100644
--- a/tests/src/com/android/inputmethod/latin/FusionDictionaryTests.java
+++ b/tests/src/com/android/inputmethod/latin/FusionDictionaryTests.java
@@ -20,7 +20,7 @@
 import android.test.suitebuilder.annotation.SmallTest;
 
 import com.android.inputmethod.latin.makedict.FusionDictionary;
-import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
 
 import java.util.HashMap;
 
@@ -30,21 +30,21 @@
 @SmallTest
 public class FusionDictionaryTests extends AndroidTestCase {
     public void testFindWordInTree() {
-        FusionDictionary dict = new FusionDictionary(new Node(),
+        FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
                 new FusionDictionary.DictionaryOptions(new HashMap<String,String>(), false, false));
 
         dict.add("abc", 10, null, false /* isNotAWord */);
-        assertNull(FusionDictionary.findWordInTree(dict.mRoot, "aaa"));
-        assertNotNull(FusionDictionary.findWordInTree(dict.mRoot, "abc"));
+        assertNull(FusionDictionary.findWordInTree(dict.mRootNodeArray, "aaa"));
+        assertNotNull(FusionDictionary.findWordInTree(dict.mRootNodeArray, "abc"));
 
         dict.add("aa", 10, null, false /* isNotAWord */);
-        assertNull(FusionDictionary.findWordInTree(dict.mRoot, "aaa"));
-        assertNotNull(FusionDictionary.findWordInTree(dict.mRoot, "aa"));
+        assertNull(FusionDictionary.findWordInTree(dict.mRootNodeArray, "aaa"));
+        assertNotNull(FusionDictionary.findWordInTree(dict.mRootNodeArray, "aa"));
 
         dict.add("babcd", 10, null, false /* isNotAWord */);
         dict.add("bacde", 10, null, false /* isNotAWord */);
-        assertNull(FusionDictionary.findWordInTree(dict.mRoot, "ba"));
-        assertNotNull(FusionDictionary.findWordInTree(dict.mRoot, "babcd"));
-        assertNotNull(FusionDictionary.findWordInTree(dict.mRoot, "bacde"));
+        assertNull(FusionDictionary.findWordInTree(dict.mRootNodeArray, "ba"));
+        assertNotNull(FusionDictionary.findWordInTree(dict.mRootNodeArray, "babcd"));
+        assertNotNull(FusionDictionary.findWordInTree(dict.mRootNodeArray, "bacde"));
     }
 }
diff --git a/tests/src/com/android/inputmethod/latin/InputLogicTests.java b/tests/src/com/android/inputmethod/latin/InputLogicTests.java
index d27a7a9..6cc4bef 100644
--- a/tests/src/com/android/inputmethod/latin/InputLogicTests.java
+++ b/tests/src/com/android/inputmethod/latin/InputLogicTests.java
@@ -17,6 +17,7 @@
 package com.android.inputmethod.latin;
 
 import android.test.suitebuilder.annotation.LargeTest;
+import android.view.inputmethod.BaseInputConnection;
 
 @LargeTest
 public class InputLogicTests extends InputTestsBase {
@@ -290,5 +291,19 @@
         }
         assertEquals("delete whole composing word", "", mEditText.getText().toString());
     }
+
+    public void testResumeSuggestionOnBackspace() {
+        final String WORD_TO_TYPE = "and this ";
+        type(WORD_TO_TYPE);
+        assertEquals("resume suggestion on backspace", -1,
+                BaseInputConnection.getComposingSpanStart(mEditText.getText()));
+        assertEquals("resume suggestion on backspace", -1,
+                BaseInputConnection.getComposingSpanEnd(mEditText.getText()));
+        type(Constants.CODE_DELETE);
+        assertEquals("resume suggestion on backspace", 4,
+                BaseInputConnection.getComposingSpanStart(mEditText.getText()));
+        assertEquals("resume suggestion on backspace", 8,
+                BaseInputConnection.getComposingSpanEnd(mEditText.getText()));
+    }
     // TODO: Add some tests for non-BMP characters
 }
diff --git a/tests/src/com/android/inputmethod/latin/InputLogicTestsLanguageWithoutSpaces.java b/tests/src/com/android/inputmethod/latin/InputLogicTestsLanguageWithoutSpaces.java
new file mode 100644
index 0000000..0f0ebaf
--- /dev/null
+++ b/tests/src/com/android/inputmethod/latin/InputLogicTestsLanguageWithoutSpaces.java
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.inputmethod.latin;
+
+import android.test.suitebuilder.annotation.LargeTest;
+import android.view.inputmethod.BaseInputConnection;
+
+import com.android.inputmethod.latin.suggestions.SuggestionStripView;
+
+@LargeTest
+public class InputLogicTestsLanguageWithoutSpaces extends InputTestsBase {
+    public void testAutoCorrectForLanguageWithoutSpaces() {
+        final String STRING_TO_TYPE = "tgis is";
+        final String EXPECTED_RESULT = "thisis";
+        changeKeyboardLocaleAndDictLocale("th", "en_US");
+        type(STRING_TO_TYPE);
+        assertEquals("simple auto-correct for language without spaces", EXPECTED_RESULT,
+                mEditText.getText().toString());
+    }
+
+    public void testRevertAutoCorrectForLanguageWithoutSpaces() {
+        final String STRING_TO_TYPE = "tgis ";
+        final String EXPECTED_INTERMEDIATE_RESULT = "this";
+        final String EXPECTED_FINAL_RESULT = "tgis";
+        changeKeyboardLocaleAndDictLocale("th", "en_US");
+        type(STRING_TO_TYPE);
+        assertEquals("simple auto-correct for language without spaces",
+                EXPECTED_INTERMEDIATE_RESULT, mEditText.getText().toString());
+        type(Constants.CODE_DELETE);
+        assertEquals("simple auto-correct for language without spaces",
+                EXPECTED_FINAL_RESULT, mEditText.getText().toString());
+        // Check we are back to composing the word
+        assertEquals("don't resume suggestion on backspace", 0,
+                BaseInputConnection.getComposingSpanStart(mEditText.getText()));
+        assertEquals("don't resume suggestion on backspace", 4,
+                BaseInputConnection.getComposingSpanEnd(mEditText.getText()));
+    }
+
+    public void testDontResumeSuggestionOnBackspace() {
+        final String WORD_TO_TYPE = "and this ";
+        changeKeyboardLocaleAndDictLocale("th", "en_US");
+        type(WORD_TO_TYPE);
+        assertEquals("don't resume suggestion on backspace", -1,
+                BaseInputConnection.getComposingSpanStart(mEditText.getText()));
+        assertEquals("don't resume suggestion on backspace", -1,
+                BaseInputConnection.getComposingSpanEnd(mEditText.getText()));
+        type(" ");
+        type(Constants.CODE_DELETE);
+        assertEquals("don't resume suggestion on backspace", -1,
+                BaseInputConnection.getComposingSpanStart(mEditText.getText()));
+        assertEquals("don't resume suggestion on backspace", -1,
+                BaseInputConnection.getComposingSpanEnd(mEditText.getText()));
+    }
+
+    public void testStartComposingInsideText() {
+        final String WORD_TO_TYPE = "abcdefgh ";
+        final int typedLength = WORD_TO_TYPE.length() - 1; // -1 because space gets eaten
+        final int CURSOR_POS = 4;
+        changeKeyboardLocaleAndDictLocale("th", "en_US");
+        type(WORD_TO_TYPE);
+        mLatinIME.onUpdateSelection(0, 0, typedLength, typedLength, -1, -1);
+        mInputConnection.setSelection(CURSOR_POS, CURSOR_POS);
+        mLatinIME.onUpdateSelection(typedLength, typedLength,
+                CURSOR_POS, CURSOR_POS, -1, -1);
+        sleep(DELAY_TO_WAIT_FOR_PREDICTIONS);
+        runMessages();
+        assertEquals("start composing inside text", -1,
+                BaseInputConnection.getComposingSpanStart(mEditText.getText()));
+        assertEquals("start composing inside text", -1,
+                BaseInputConnection.getComposingSpanEnd(mEditText.getText()));
+        type("xxxx");
+        assertEquals("start composing inside text", 4,
+                BaseInputConnection.getComposingSpanStart(mEditText.getText()));
+        assertEquals("start composing inside text", 8,
+                BaseInputConnection.getComposingSpanEnd(mEditText.getText()));
+    }
+
+    public void testPredictions() {
+        final String WORD_TO_TYPE = "Barack ";
+        changeKeyboardLocaleAndDictLocale("th", "en_US");
+        type(WORD_TO_TYPE);
+        sleep(DELAY_TO_WAIT_FOR_PREDICTIONS);
+        runMessages();
+        // Make sure there is no space
+        assertEquals("predictions in lang without spaces", "Barack",
+                mEditText.getText().toString());
+        // Test the first prediction is displayed
+        assertEquals("predictions in lang without spaces", "Obama",
+                mLatinIME.getFirstSuggestedWord());
+    }
+}
diff --git a/tests/src/com/android/inputmethod/latin/InputTestsBase.java b/tests/src/com/android/inputmethod/latin/InputTestsBase.java
index ead134b..480570e 100644
--- a/tests/src/com/android/inputmethod/latin/InputTestsBase.java
+++ b/tests/src/com/android/inputmethod/latin/InputTestsBase.java
@@ -46,6 +46,8 @@
 
     // The message that sets the underline is posted with a 100 ms delay
     protected static final int DELAY_TO_WAIT_FOR_UNDERLINE = 200;
+    // The message that sets predictions is posted with a 100 ms delay
+    protected static final int DELAY_TO_WAIT_FOR_PREDICTIONS = 200;
 
     protected LatinIME mLatinIME;
     protected Keyboard mKeyboard;
@@ -207,8 +209,8 @@
         //mLatinIME.onPressKey(codePoint, 0 /* repeatCount */, true /* isSinglePointer */);
         final Key key = mKeyboard.getKey(codePoint);
         if (key != null) {
-            final int x = key.mX + key.mWidth / 2;
-            final int y = key.mY + key.mHeight / 2;
+            final int x = key.getX() + key.getWidth() / 2;
+            final int y = key.getY() + key.getHeight() / 2;
             mLatinIME.onCodeInput(codePoint, x, y);
             return;
         }
@@ -233,9 +235,6 @@
                 --remainingAttempts;
             }
         }
-        if (!mLatinIME.hasMainDictionary()) {
-            throw new RuntimeException("Can't initialize the main dictionary");
-        }
     }
 
     protected void changeLanguage(final String locale) {
@@ -247,6 +246,16 @@
         waitForDictionaryToBeLoaded();
     }
 
+    protected void changeKeyboardLocaleAndDictLocale(final String keyboardLocale,
+            final String dictLocale) {
+        changeLanguage(keyboardLocale);
+        if (!keyboardLocale.equals(dictLocale)) {
+            mLatinIME.replaceMainDictionaryForTest(
+                    LocaleUtils.constructLocaleFromString(dictLocale));
+        }
+        waitForDictionaryToBeLoaded();
+    }
+
     protected void pickSuggestionManually(final int index, final String suggestion) {
         mLatinIME.pickSuggestionManually(index, new SuggestedWordInfo(suggestion, 1,
                 SuggestedWordInfo.KIND_CORRECTION, "main"));
diff --git a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOTests.java b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
similarity index 87%
rename from tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOTests.java
rename to tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
index 7bfd603..be468c1 100644
--- a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOTests.java
+++ b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
@@ -22,10 +22,10 @@
 import android.util.Log;
 import android.util.SparseArray;
 
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput.FusionDictionaryBufferInterface;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder.FusionDictionaryBufferInterface;
 import com.android.inputmethod.latin.makedict.FormatSpec.FileHeader;
 import com.android.inputmethod.latin.makedict.FusionDictionary.CharGroup;
-import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
 import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
 import com.android.inputmethod.latin.utils.CollectionUtils;
 
@@ -44,11 +44,11 @@
 import java.util.Set;
 
 /**
- * Unit tests for BinaryDictInputOutput
+ * Unit tests for BinaryDictDecoder and BinaryDictEncoder.
  */
 @LargeTest
-public class BinaryDictIOTests extends AndroidTestCase {
-    private static final String TAG = BinaryDictIOTests.class.getSimpleName();
+public class BinaryDictDecoderEncoderTests extends AndroidTestCase {
+    private static final String TAG = BinaryDictDecoderEncoderTests.class.getSimpleName();
     private static final int DEFAULT_MAX_UNIGRAMS = 100;
     private static final int DEFAULT_CODE_POINT_SET_SIZE = 50;
     private static final int UNIGRAM_FREQ = 10;
@@ -71,11 +71,13 @@
     private static final FormatSpec.FormatOptions VERSION3_WITH_DYNAMIC_UPDATE =
             new FormatSpec.FormatOptions(3, true /* supportsDynamicUpdate */);
 
-    public BinaryDictIOTests() {
+    private static final String TEST_DICT_FILE_EXTENSION = ".testDict";
+
+    public BinaryDictDecoderEncoderTests() {
         this(System.currentTimeMillis(), DEFAULT_MAX_UNIGRAMS);
     }
 
-    public BinaryDictIOTests(final long seed, final int maxUnigrams) {
+    public BinaryDictDecoderEncoderTests(final long seed, final int maxUnigrams) {
         super();
         Log.e(TAG, "Testing dictionary: seed is " + seed);
         final Random random = new Random(seed);
@@ -206,7 +208,7 @@
             // If you need to dump the dict to a textual file, uncomment the line below and the
             // function above
             // dumpToCombinedFileForDebug(file, "/tmp/foo");
-            BinaryDictInputOutput.writeDictionaryBinary(out, dict, formatOptions);
+            BinaryDictEncoder.writeDictionaryBinary(out, dict, formatOptions);
             diff = System.currentTimeMillis() - now;
 
             out.flush();
@@ -226,7 +228,7 @@
 
         // check unigram
         for (final String word : words) {
-            final CharGroup cg = FusionDictionary.findWordInTree(dict.mRoot, word);
+            final CharGroup cg = FusionDictionary.findWordInTree(dict.mRootNodeArray, word);
             assertNotNull(cg);
         }
 
@@ -234,7 +236,8 @@
         for (int i = 0; i < bigrams.size(); ++i) {
             final int w1 = bigrams.keyAt(i);
             for (final int w2 : bigrams.valueAt(i)) {
-                final CharGroup cg = FusionDictionary.findWordInTree(dict.mRoot, words.get(w1));
+                final CharGroup cg = FusionDictionary.findWordInTree(dict.mRootNodeArray,
+                        words.get(w1));
                 assertNotNull(words.get(w1) + "," + words.get(w2), cg.getBigram(words.get(w2)));
             }
         }
@@ -242,7 +245,8 @@
         // check shortcut
         if (shortcutMap != null) {
             for (final Map.Entry<String, List<String>> entry : shortcutMap.entrySet()) {
-                final CharGroup group = FusionDictionary.findWordInTree(dict.mRoot, entry.getKey());
+                final CharGroup group = FusionDictionary.findWordInTree(dict.mRootNodeArray,
+                        entry.getKey());
                 for (final String word : entry.getValue()) {
                     assertNotNull("shortcut not found: " + entry.getKey() + ", " + word,
                             group.getShortcut(word));
@@ -272,7 +276,7 @@
             getBuffer(reader, bufferType);
             assertNotNull(reader.getBuffer());
             now = System.currentTimeMillis();
-            dict = BinaryDictInputOutput.readDictionaryBinary(reader, null);
+            dict = BinaryDictDecoder.readDictionaryBinary(reader, null);
             diff  = System.currentTimeMillis() - now;
         } catch (IOException e) {
             Log.e(TAG, "IOException while reading dictionary", e);
@@ -291,13 +295,14 @@
             final String message) {
         File file = null;
         try {
-            file = File.createTempFile("runReadAndWrite", ".dict", getContext().getCacheDir());
+            file = File.createTempFile("runReadAndWrite", TEST_DICT_FILE_EXTENSION,
+                    getContext().getCacheDir());
         } catch (IOException e) {
             Log.e(TAG, "IOException", e);
         }
         assertNotNull(file);
 
-        final FusionDictionary dict = new FusionDictionary(new Node(),
+        final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
                 new FusionDictionary.DictionaryOptions(new HashMap<String,String>(), false, false));
         addUnigrams(words.size(), dict, words, shortcuts);
         addBigrams(dict, words, bigrams);
@@ -383,7 +388,7 @@
                 }
                 actBigrams.get(word1).add(word2);
 
-                final int bigramFreq = BinaryDictInputOutput.reconstructBigramFrequency(
+                final int bigramFreq = BinaryDictDecoder.reconstructBigramFrequency(
                         unigramFreq, attr.mFrequency);
                 assertTrue(Math.abs(bigramFreq - BIGRAM_FREQ) < TOLERANCE_OF_BIGRAM_FREQ);
             }
@@ -433,14 +438,15 @@
             final FormatSpec.FormatOptions formatOptions, final String message) {
         File file = null;
         try {
-            file = File.createTempFile("runReadUnigrams", ".dict", getContext().getCacheDir());
+            file = File.createTempFile("runReadUnigrams", TEST_DICT_FILE_EXTENSION,
+                    getContext().getCacheDir());
         } catch (IOException e) {
             Log.e(TAG, "IOException", e);
         }
         assertNotNull(file);
 
         // making the dictionary from lists of words.
-        final FusionDictionary dict = new FusionDictionary(new Node(),
+        final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
                 new FusionDictionary.DictionaryOptions(
                         new HashMap<String, String>(), false, false));
         addUnigrams(words.size(), dict, words, null /* shortcutMap */);
@@ -491,31 +497,31 @@
     }
 
     // Tests for getTerminalPosition
-    private String getWordFromBinary(final FusionDictionaryBufferInterface buffer,
-            final int address) {
+    private String getWordFromBinary(final BinaryDictReader dictReader, final int address) {
+        final FusionDictionaryBufferInterface buffer = dictReader.getBuffer();
         if (buffer.position() != 0) buffer.position(0);
 
-        FileHeader header = null;
+        FileHeader fileHeader = null;
         try {
-            header = BinaryDictInputOutput.readHeader(buffer);
+            fileHeader = BinaryDictDecoder.readHeader(dictReader);
         } catch (IOException e) {
             return null;
         } catch (UnsupportedFormatException e) {
             return null;
         }
-        if (header == null) return null;
-        return BinaryDictInputOutput.getWordAtAddress(buffer, header.mHeaderSize,
-                address - header.mHeaderSize, header.mFormatOptions).mWord;
+        if (fileHeader == null) return null;
+        return BinaryDictDecoder.getWordAtAddress(buffer, fileHeader.mHeaderSize,
+                address - fileHeader.mHeaderSize, fileHeader.mFormatOptions).mWord;
     }
 
-    private long runGetTerminalPosition(final FusionDictionaryBufferInterface buffer,
-            final String word, int index, boolean contained) {
+    private long runGetTerminalPosition(final BinaryDictReader reader, final String word, int index,
+            boolean contained) {
         final int expectedFrequency = (UNIGRAM_FREQ + index) % 255;
         long diff = -1;
         int position = -1;
         try {
             final long now = System.nanoTime();
-            position = BinaryDictIOUtils.getTerminalPosition(buffer, word);
+            position = BinaryDictIOUtils.getTerminalPosition(reader, word);
             diff = System.nanoTime() - now;
         } catch (IOException e) {
             Log.e(TAG, "IOException while getTerminalPosition", e);
@@ -524,50 +530,48 @@
         }
 
         assertEquals(FormatSpec.NOT_VALID_WORD != position, contained);
-        if (contained) assertEquals(getWordFromBinary(buffer, position), word);
+        if (contained) assertEquals(getWordFromBinary(reader, position), word);
         return diff;
     }
 
     public void testGetTerminalPosition() {
         File file = null;
         try {
-            file = File.createTempFile("testGetTerminalPosition", ".dict",
+            file = File.createTempFile("testGetTerminalPosition", TEST_DICT_FILE_EXTENSION,
                     getContext().getCacheDir());
         } catch (IOException e) {
             // do nothing
         }
         assertNotNull(file);
 
-        final FusionDictionary dict = new FusionDictionary(new Node(),
+        final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
                 new FusionDictionary.DictionaryOptions(
                         new HashMap<String, String>(), false, false));
         addUnigrams(sWords.size(), dict, sWords, null /* shortcutMap */);
         timeWritingDictToFile(file, dict, VERSION3_WITH_DYNAMIC_UPDATE);
 
         final BinaryDictReader reader = new BinaryDictReader(file);
-        FusionDictionaryBufferInterface buffer = null;
         try {
-            buffer = reader.openAndGetBuffer(
-                    new BinaryDictReader.FusionDictionaryBufferFromByteArrayFactory());
+            reader.openBuffer(new BinaryDictReader.FusionDictionaryBufferFromByteArrayFactory());
         } catch (IOException e) {
             // ignore
             Log.e(TAG, "IOException while opening the buffer", e);
         }
-        assertNotNull("Can't get the buffer", buffer);
+        assertNotNull("Can't get the buffer", reader.getBuffer());
 
         try {
             // too long word
             final String longWord = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";
             assertEquals(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, longWord));
+                    BinaryDictIOUtils.getTerminalPosition(reader, longWord));
 
             // null
             assertEquals(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, null));
+                    BinaryDictIOUtils.getTerminalPosition(reader, null));
 
             // empty string
             assertEquals(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, ""));
+                    BinaryDictIOUtils.getTerminalPosition(reader, ""));
         } catch (IOException e) {
         } catch (UnsupportedFormatException e) {
         }
@@ -575,7 +579,7 @@
         // Test a word that is contained within the dictionary.
         long sum = 0;
         for (int i = 0; i < sWords.size(); ++i) {
-            final long time = runGetTerminalPosition(buffer, sWords.get(i), i, true);
+            final long time = runGetTerminalPosition(reader, sWords.get(i), i, true);
             sum += time == -1 ? 0 : time;
         }
         Log.d(TAG, "per a search : " + (((double)sum) / sWords.size() / 1000000));
@@ -586,48 +590,48 @@
         for (int i = 0; i < 1000; ++i) {
             final String word = generateWord(random, codePointSet);
             if (sWords.indexOf(word) != -1) continue;
-            runGetTerminalPosition(buffer, word, i, false);
+            runGetTerminalPosition(reader, word, i, false);
         }
     }
 
     public void testDeleteWord() {
         File file = null;
         try {
-            file = File.createTempFile("testDeleteWord", ".dict", getContext().getCacheDir());
+            file = File.createTempFile("testDeleteWord", TEST_DICT_FILE_EXTENSION,
+                    getContext().getCacheDir());
         } catch (IOException e) {
             // do nothing
         }
         assertNotNull(file);
 
-        final FusionDictionary dict = new FusionDictionary(new Node(),
+        final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
                 new FusionDictionary.DictionaryOptions(
                         new HashMap<String, String>(), false, false));
         addUnigrams(sWords.size(), dict, sWords, null /* shortcutMap */);
         timeWritingDictToFile(file, dict, VERSION3_WITH_DYNAMIC_UPDATE);
 
         final BinaryDictReader reader = new BinaryDictReader(file);
-        FusionDictionaryBufferInterface buffer = null;
         try {
-            buffer = reader.openAndGetBuffer(
+            reader.openBuffer(
                     new BinaryDictReader.FusionDictionaryBufferFromByteArrayFactory());
         } catch (IOException e) {
             // ignore
             Log.e(TAG, "IOException while opening the buffer", e);
         }
-        assertNotNull("Can't get the buffer", buffer);
+        assertNotNull("Can't get the buffer", reader.getBuffer());
 
         try {
             MoreAsserts.assertNotEqual(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, sWords.get(0)));
-            DynamicBinaryDictIOUtils.deleteWord(buffer, sWords.get(0));
+                    BinaryDictIOUtils.getTerminalPosition(reader, sWords.get(0)));
+            DynamicBinaryDictIOUtils.deleteWord(reader, sWords.get(0));
             assertEquals(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, sWords.get(0)));
+                    BinaryDictIOUtils.getTerminalPosition(reader, sWords.get(0)));
 
             MoreAsserts.assertNotEqual(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, sWords.get(5)));
-            DynamicBinaryDictIOUtils.deleteWord(buffer, sWords.get(5));
+                    BinaryDictIOUtils.getTerminalPosition(reader, sWords.get(5)));
+            DynamicBinaryDictIOUtils.deleteWord(reader, sWords.get(5));
             assertEquals(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, sWords.get(5)));
+                    BinaryDictIOUtils.getTerminalPosition(reader, sWords.get(5)));
         } catch (IOException e) {
         } catch (UnsupportedFormatException e) {
         }
diff --git a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtilsTests.java b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtilsTests.java
index e759507..bcf2c31 100644
--- a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtilsTests.java
+++ b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtilsTests.java
@@ -21,10 +21,11 @@
 import android.test.suitebuilder.annotation.LargeTest;
 import android.util.Log;
 
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput.ByteBufferWrapper;
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput.FusionDictionaryBufferInterface;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder.FusionDictionaryBufferInterface;
+import com.android.inputmethod.latin.makedict.BinaryDictReader.
+        FusionDictionaryBufferFromWritableByteBufferFactory;
 import com.android.inputmethod.latin.makedict.FormatSpec.FileHeader;
-import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
 import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
 import com.android.inputmethod.latin.utils.CollectionUtils;
 
@@ -33,8 +34,6 @@
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
-import java.io.RandomAccessFile;
-import java.nio.channels.FileChannel;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Random;
@@ -49,6 +48,8 @@
     public static final int DEFAULT_MAX_UNIGRAMS = 1500;
     private final int mMaxUnigrams;
 
+    private static final String TEST_DICT_FILE_EXTENSION = ".testDict";
+
     private static final String[] CHARACTERS = {
         "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",
         "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z",
@@ -114,10 +115,10 @@
     private static void printNode(final FusionDictionaryBufferInterface buffer,
             final FormatSpec.FormatOptions formatOptions) {
         Log.d(TAG, "Node at " + buffer.position());
-        final int count = BinaryDictInputOutput.readCharGroupCount(buffer);
+        final int count = BinaryDictDecoder.readCharGroupCount(buffer);
         Log.d(TAG, "    charGroupCount = " + count);
         for (int i = 0; i < count; ++i) {
-            final CharGroupInfo currentInfo = BinaryDictInputOutput.readCharGroup(buffer,
+            final CharGroupInfo currentInfo = BinaryDictDecoder.readCharGroup(buffer,
                     buffer.position(), formatOptions);
             printCharGroup(currentInfo);
         }
@@ -127,22 +128,24 @@
         }
     }
 
-    private static void printBinaryFile(final FusionDictionaryBufferInterface buffer)
+    private static void printBinaryFile(final BinaryDictReader dictReader)
             throws IOException, UnsupportedFormatException {
-        FileHeader header = BinaryDictInputOutput.readHeader(buffer);
+        final FileHeader fileHeader = BinaryDictDecoder.readHeader(dictReader);
+        final FusionDictionaryBufferInterface buffer = dictReader.getBuffer();
         while (buffer.position() < buffer.limit()) {
-            printNode(buffer, header.mFormatOptions);
+            printNode(buffer, fileHeader.mFormatOptions);
         }
     }
 
     private int getWordPosition(final File file, final String word) {
         int position = FormatSpec.NOT_VALID_WORD;
+        final BinaryDictReader dictReader = new BinaryDictReader(file);
         FileInputStream inStream = null;
         try {
             inStream = new FileInputStream(file);
-            final FusionDictionaryBufferInterface buffer = new ByteBufferWrapper(
-                    inStream.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, file.length()));
-            position = BinaryDictIOUtils.getTerminalPosition(buffer, word);
+            dictReader.openBuffer(
+                    new BinaryDictReader.FusionDictionaryBufferFromByteBufferFactory());
+            position = BinaryDictIOUtils.getTerminalPosition(dictReader, word);
         } catch (IOException e) {
         } catch (UnsupportedFormatException e) {
         } finally {
@@ -158,23 +161,14 @@
     }
 
     private CharGroupInfo findWordFromFile(final File file, final String word) {
-        FileInputStream inStream = null;
+        final BinaryDictReader dictReader = new BinaryDictReader(file);
         CharGroupInfo info = null;
         try {
-            inStream = new FileInputStream(file);
-            final FusionDictionaryBufferInterface buffer = new ByteBufferWrapper(
-                    inStream.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, file.length()));
-            info = BinaryDictIOUtils.findWordFromBuffer(buffer, word);
+            dictReader.openBuffer(
+                    new BinaryDictReader.FusionDictionaryBufferFromByteBufferFactory());
+            info = BinaryDictIOUtils.findWordByBinaryDictReader(dictReader, word);
         } catch (IOException e) {
         } catch (UnsupportedFormatException e) {
-        } finally {
-            if (inStream != null) {
-                try {
-                    inStream.close();
-                } catch (IOException e) {
-                    // do nothing
-                }
-            }
         }
         return info;
     }
@@ -183,42 +177,33 @@
     private long insertAndCheckWord(final File file, final String word, final int frequency,
             final boolean exist, final ArrayList<WeightedString> bigrams,
             final ArrayList<WeightedString> shortcuts) {
-        RandomAccessFile raFile = null;
+        final BinaryDictReader dictReader = new BinaryDictReader(file);
         BufferedOutputStream outStream = null;
-        FusionDictionaryBufferInterface buffer = null;
         long amountOfTime = -1;
         try {
-            raFile = new RandomAccessFile(file, "rw");
-            buffer = new ByteBufferWrapper(raFile.getChannel().map(
-                    FileChannel.MapMode.READ_WRITE, 0, file.length()));
+            dictReader.openBuffer(new FusionDictionaryBufferFromWritableByteBufferFactory());
             outStream = new BufferedOutputStream(new FileOutputStream(file, true));
 
             if (!exist) {
                 assertEquals(FormatSpec.NOT_VALID_WORD, getWordPosition(file, word));
             }
             final long now = System.nanoTime();
-            DynamicBinaryDictIOUtils.insertWord(buffer, outStream, word, frequency, bigrams,
+            DynamicBinaryDictIOUtils.insertWord(dictReader, outStream, word, frequency, bigrams,
                     shortcuts, false, false);
             amountOfTime = System.nanoTime() - now;
             outStream.flush();
             MoreAsserts.assertNotEqual(FormatSpec.NOT_VALID_WORD, getWordPosition(file, word));
             outStream.close();
-            raFile.close();
         } catch (IOException e) {
+            Log.e(TAG, "Raised an IOException while inserting a word", e);
         } catch (UnsupportedFormatException e) {
+            Log.e(TAG, "Raised an UnsupportedFormatException error while inserting a word", e);
         } finally {
             if (outStream != null) {
                 try {
                     outStream.close();
                 } catch (IOException e) {
-                    // do nothing
-                }
-            }
-            if (raFile != null) {
-                try {
-                    raFile.close();
-                } catch (IOException e) {
-                    // do nothing
+                    Log.e(TAG, "Failed to close the output stream", e);
                 }
             }
         }
@@ -226,64 +211,49 @@
     }
 
     private void deleteWord(final File file, final String word) {
-        RandomAccessFile raFile = null;
-        FusionDictionaryBufferInterface buffer = null;
+        final BinaryDictReader dictReader = new BinaryDictReader(file);
         try {
-            raFile = new RandomAccessFile(file, "rw");
-            buffer = new ByteBufferWrapper(raFile.getChannel().map(
-                    FileChannel.MapMode.READ_WRITE, 0, file.length()));
-            DynamicBinaryDictIOUtils.deleteWord(buffer, word);
+            dictReader.openBuffer(new FusionDictionaryBufferFromWritableByteBufferFactory());
+            DynamicBinaryDictIOUtils.deleteWord(dictReader, word);
         } catch (IOException e) {
         } catch (UnsupportedFormatException e) {
-        } finally {
-            if (raFile != null) {
-                try {
-                    raFile.close();
-                } catch (IOException e) {
-                    // do nothing
-                }
-            }
         }
     }
 
     private void checkReverseLookup(final File file, final String word, final int position) {
-        FileInputStream inStream = null;
+        final BinaryDictReader dictReader = new BinaryDictReader(file);
         try {
-            inStream = new FileInputStream(file);
-            final FusionDictionaryBufferInterface buffer = new ByteBufferWrapper(
-                    inStream.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, file.length()));
-            final FileHeader header = BinaryDictInputOutput.readHeader(buffer);
-            assertEquals(word, BinaryDictInputOutput.getWordAtAddress(buffer, header.mHeaderSize,
-                    position - header.mHeaderSize, header.mFormatOptions).mWord);
+            final FusionDictionaryBufferInterface buffer = dictReader.openAndGetBuffer(
+                    new BinaryDictReader.FusionDictionaryBufferFromByteBufferFactory());
+            final FileHeader fileHeader = BinaryDictDecoder.readHeader(dictReader);
+            assertEquals(word,
+                    BinaryDictDecoder.getWordAtAddress(dictReader.getBuffer(),
+                            fileHeader.mHeaderSize, position - fileHeader.mHeaderSize,
+                            fileHeader.mFormatOptions).mWord);
         } catch (IOException e) {
+            Log.e(TAG, "Raised an IOException while looking up a word", e);
         } catch (UnsupportedFormatException e) {
-        } finally {
-            if (inStream != null) {
-                try {
-                    inStream.close();
-                } catch (IOException e) {
-                    // do nothing
-                }
-            }
+            Log.e(TAG, "Raised an UnsupportedFormatException error while looking up a word", e);
         }
     }
 
     public void testInsertWord() {
         File file = null;
         try {
-            file = File.createTempFile("testInsertWord", ".dict", getContext().getCacheDir());
+            file = File.createTempFile("testInsertWord", TEST_DICT_FILE_EXTENSION,
+                    getContext().getCacheDir());
         } catch (IOException e) {
             fail("IOException while creating temporary file: " + e);
         }
 
         // set an initial dictionary.
-        final FusionDictionary dict = new FusionDictionary(new Node(),
+        final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
                 new FusionDictionary.DictionaryOptions(new HashMap<String,String>(), false, false));
         dict.add("abcd", 10, null, false);
 
         try {
             final FileOutputStream out = new FileOutputStream(file);
-            BinaryDictInputOutput.writeDictionaryBinary(out, dict, FORMAT_OPTIONS);
+            BinaryDictEncoder.writeDictionaryBinary(out, dict, FORMAT_OPTIONS);
             out.close();
         } catch (IOException e) {
             fail("IOException while writing an initial dictionary : " + e);
@@ -321,21 +291,21 @@
     public void testInsertWordWithBigrams() {
         File file = null;
         try {
-            file = File.createTempFile("testInsertWordWithBigrams", ".dict",
+            file = File.createTempFile("testInsertWordWithBigrams", TEST_DICT_FILE_EXTENSION,
                     getContext().getCacheDir());
         } catch (IOException e) {
             fail("IOException while creating temporary file: " + e);
         }
 
         // set an initial dictionary.
-        final FusionDictionary dict = new FusionDictionary(new Node(),
+        final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
                 new FusionDictionary.DictionaryOptions(new HashMap<String,String>(), false, false));
         dict.add("abcd", 10, null, false);
         dict.add("efgh", 15, null, false);
 
         try {
             final FileOutputStream out = new FileOutputStream(file);
-            BinaryDictInputOutput.writeDictionaryBinary(out, dict, FORMAT_OPTIONS);
+            BinaryDictEncoder.writeDictionaryBinary(out, dict, FORMAT_OPTIONS);
             out.close();
         } catch (IOException e) {
             fail("IOException while writing an initial dictionary : " + e);
@@ -359,20 +329,21 @@
     public void testRandomWords() {
         File file = null;
         try {
-            file = File.createTempFile("testRandomWord", ".dict", getContext().getCacheDir());
+            file = File.createTempFile("testRandomWord", TEST_DICT_FILE_EXTENSION,
+                    getContext().getCacheDir());
         } catch (IOException e) {
         }
         assertNotNull(file);
 
         // set an initial dictionary.
-        final FusionDictionary dict = new FusionDictionary(new Node(),
+        final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
                 new FusionDictionary.DictionaryOptions(new HashMap<String, String>(), false,
                         false));
         dict.add("initial", 10, null, false);
 
         try {
             final FileOutputStream out = new FileOutputStream(file);
-            BinaryDictInputOutput.writeDictionaryBinary(out, dict, FORMAT_OPTIONS);
+            BinaryDictEncoder.writeDictionaryBinary(out, dict, FORMAT_OPTIONS);
             out.close();
         } catch (IOException e) {
             assertTrue(false);
diff --git a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictReaderTests.java b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictReaderTests.java
index a46e583..1c6de50 100644
--- a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictReaderTests.java
+++ b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictReaderTests.java
@@ -16,7 +16,7 @@
 
 package com.android.inputmethod.latin.makedict;
 
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput.FusionDictionaryBufferInterface;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder.FusionDictionaryBufferInterface;
 import com.android.inputmethod.latin.makedict.BinaryDictReader.FusionDictionaryBufferFactory;
 import com.android.inputmethod.latin.makedict.BinaryDictReader.
         FusionDictionaryBufferFromByteArrayFactory;
diff --git a/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java b/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
index b3e2ee0..304b792 100644
--- a/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
+++ b/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
@@ -22,6 +22,7 @@
 import android.test.suitebuilder.annotation.LargeTest;
 import android.util.Log;
 
+import com.android.inputmethod.latin.ExpandableBinaryDictionary;
 import com.android.inputmethod.latin.utils.CollectionUtils;
 
 import java.io.File;
@@ -29,6 +30,7 @@
 import java.util.List;
 import java.util.Random;
 import java.util.Set;
+import java.util.concurrent.TimeUnit;
 
 /**
  * Unit tests for UserHistoryDictionary
@@ -43,6 +45,8 @@
         "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"
     };
 
+    private static final int MIN_USER_HISTORY_DICTIONARY_FILE_SIZE = 1000;
+
     @Override
     public void setUp() {
         mPrefs = PreferenceManager.getDefaultSharedPreferences(getContext());
@@ -78,43 +82,43 @@
         }
     }
 
+    private void addAndWriteRandomWords(final String testFilenameSuffix, final int numberOfWords,
+            final Random random) {
+        final List<String> words = generateWords(numberOfWords, random);
+        final UserHistoryPredictionDictionary dict =
+                PersonalizationDictionaryHelper.getUserHistoryPredictionDictionary(getContext(),
+                        testFilenameSuffix /* locale */, mPrefs);
+        // Add random words to the user history dictionary.
+        addToDict(dict, words);
+        // write to file.
+        dict.close();
+    }
+
     public void testRandomWords() {
         File dictFile = null;
+        Log.d(TAG, "This test can be used for profiling.");
+        Log.d(TAG, "Usage: please set UserHistoryDictionary.PROFILE_SAVE_RESTORE to true.");
+        final String testFilenameSuffix = "testRandomWords" + System.currentTimeMillis();
+        final int numberOfWords = 1000;
+        final Random random = new Random(123456);
+
         try {
-            Log.d(TAG, "This test can be used for profiling.");
-            Log.d(TAG, "Usage: please set UserHistoryDictionary.PROFILE_SAVE_RESTORE to true.");
-            final int numberOfWords = 1000;
-            final Random random = new Random(123456);
-            List<String> words = generateWords(numberOfWords, random);
-
-            final String locale = "testRandomWords";
-            final String fileName = "UserHistoryDictionary." + locale + ".dict";
-            dictFile = new File(getContext().getFilesDir(), fileName);
-            final UserHistoryPredictionDictionary dict =
-                    PersonalizationDictionaryHelper.getUserHistoryPredictionDictionary(
-                            getContext(), locale, mPrefs);
-            dict.mIsTest = true;
-
-            addToDict(dict, words);
-
-            try {
-                Log.d(TAG, "waiting for adding the word ...");
-                Thread.sleep(2000);
-            } catch (InterruptedException e) {
-                Log.d(TAG, "InterruptedException: " + e);
-            }
-
-            // write to file
-            dict.close();
-
+            addAndWriteRandomWords(testFilenameSuffix, numberOfWords, random);
+        } finally {
             try {
                 Log.d(TAG, "waiting for writing ...");
-                Thread.sleep(5000);
+                Thread.sleep(TimeUnit.MILLISECONDS.convert(5L, TimeUnit.SECONDS));
             } catch (InterruptedException e) {
                 Log.d(TAG, "InterruptedException: " + e);
             }
-        } finally {
+
+            final String fileName = UserHistoryPredictionDictionary.NAME + "." + testFilenameSuffix
+                    + ExpandableBinaryDictionary.DICT_FILE_EXTENSION;
+            dictFile = new File(getContext().getFilesDir(), fileName);
+
             if (dictFile != null) {
+                assertTrue(dictFile.exists());
+                assertTrue(dictFile.length() >= MIN_USER_HISTORY_DICTIONARY_FILE_SIZE);
                 dictFile.delete();
             }
         }
@@ -122,49 +126,46 @@
 
     public void testStressTestForSwitchingLanguagesAndAddingWords() {
         final int numberOfLanguages = 2;
-        final int numberOfLanguageSwitching = 100;
-        final int numberOfWordsIntertedForEachLanguageSwitch = 100;
+        final int numberOfLanguageSwitching = 80;
+        final int numberOfWordsInsertedForEachLanguageSwitch = 100;
 
         final File dictFiles[] = new File[numberOfLanguages];
         try {
             final Random random = new Random(123456);
 
-            // Create locales for this test.
-            String locales[] = new String[numberOfLanguages];
+            // Create filename suffixes for this test.
+            String testFilenameSuffixes[] = new String[numberOfLanguages];
             for (int i = 0; i < numberOfLanguages; i++) {
-                locales[i] = "testSwitchingLanguages" + i;
-                final String fileName = "UserHistoryDictionary." + locales[i] + ".dict";
+                testFilenameSuffixes[i] = "testSwitchingLanguages" + i;
+                final String fileName = UserHistoryPredictionDictionary.NAME + "." +
+                        testFilenameSuffixes[i] + ExpandableBinaryDictionary.DICT_FILE_EXTENSION;
                 dictFiles[i] = new File(getContext().getFilesDir(), fileName);
             }
 
-            final long now = System.currentTimeMillis();
+            final long start = System.currentTimeMillis();
 
             for (int i = 0; i < numberOfLanguageSwitching; i++) {
                 final int index = i % numberOfLanguages;
-                // Switch languages to locales[index].
-                final UserHistoryPredictionDictionary dict =
-                        PersonalizationDictionaryHelper.getUserHistoryPredictionDictionary(
-                                getContext(), locales[index], mPrefs);
-                final List<String> words = generateWords(
-                        numberOfWordsIntertedForEachLanguageSwitch, random);
-                // Add random words to the user history dictionary.
-                addToDict(dict, words);
-                // write to file
-                dict.close();
+                // Switch languages to testFilenameSuffixes[index].
+                addAndWriteRandomWords(testFilenameSuffixes[index],
+                        numberOfWordsInsertedForEachLanguageSwitch, random);
             }
 
             final long end = System.currentTimeMillis();
             Log.d(TAG, "testStressTestForSwitchingLanguageAndAddingWords took "
-                    + (end - now) + " ms");
+                    + (end - start) + " ms");
+        } finally {
+            Log.d(TAG, "waiting for writing ...");
             try {
                 Log.d(TAG, "waiting for writing ...");
-                Thread.sleep(5000);
+                Thread.sleep(TimeUnit.MILLISECONDS.convert(5L, TimeUnit.SECONDS));
             } catch (InterruptedException e) {
                 Log.d(TAG, "InterruptedException: " + e);
             }
-        } finally {
             for (final File file : dictFiles) {
                 if (file != null) {
+                    assertTrue(file.exists());
+                    assertTrue(file.length() >= MIN_USER_HISTORY_DICTIONARY_FILE_SIZE);
                     file.delete();
                 }
             }
diff --git a/tests/src/com/android/inputmethod/latin/utils/StringUtilsTests.java b/tests/src/com/android/inputmethod/latin/utils/StringUtilsTests.java
index 175e511..c6fa943 100644
--- a/tests/src/com/android/inputmethod/latin/utils/StringUtilsTests.java
+++ b/tests/src/com/android/inputmethod/latin/utils/StringUtilsTests.java
@@ -256,4 +256,16 @@
         // code for now True is acceptable.
         assertTrue(StringUtils.lastPartLooksLikeURL(".abc/def"));
     }
+
+    public void testHexStringUtils() {
+        final byte[] bytes = new byte[] { (byte)0x01, (byte)0x11, (byte)0x22, (byte)0x33,
+                (byte)0x55, (byte)0x88, (byte)0xEE };
+        final String bytesStr = StringUtils.byteArrayToHexString(bytes);
+        final byte[] bytes2 = StringUtils.hexStringToByteArray(bytesStr);
+        for (int i = 0; i < bytes.length; ++i) {
+            assertTrue(bytes[i] == bytes2[i]);
+        }
+        final String bytesStr2 = StringUtils.byteArrayToHexString(bytes2);
+        assertTrue(bytesStr.equals(bytesStr2));
+    }
 }
diff --git a/tests/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtilsTests.java b/tests/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtilsTests.java
index baebda2..856b2db 100644
--- a/tests/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtilsTests.java
+++ b/tests/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtilsTests.java
@@ -214,7 +214,7 @@
                         SubtypeLocaleUtils.getSubtypeDisplayNameInSystemLocale(FR_CA));
                 assertEquals("de   ", "Allemand",
                         SubtypeLocaleUtils.getSubtypeDisplayNameInSystemLocale(DE));
-                assertEquals("zz   ", "Alphabet (QWERTY)",
+                assertEquals("zz   ", "Alphabet latin (QWERTY)",
                         SubtypeLocaleUtils.getSubtypeDisplayNameInSystemLocale(ZZ));
                 return null;
             }
@@ -236,7 +236,7 @@
                         SubtypeLocaleUtils.getSubtypeDisplayNameInSystemLocale(EN_UK_DVORAK));
                 assertEquals("es_US colemak","Espagnol (États-Unis) (Colemak)",
                         SubtypeLocaleUtils.getSubtypeDisplayNameInSystemLocale(ES_US_COLEMAK));
-                assertEquals("zz pc",    "Alphabet (PC)",
+                assertEquals("zz pc",    "Alphabet latin (PC)",
                         SubtypeLocaleUtils.getSubtypeDisplayNameInSystemLocale(ZZ_PC));
                 return null;
             }
diff --git a/tests/src/com/android/inputmethod/latin/utils/UserHistoryDictIOUtilsTests.java b/tests/src/com/android/inputmethod/latin/utils/UserHistoryDictIOUtilsTests.java
index ce62bf2..8f5bec8 100644
--- a/tests/src/com/android/inputmethod/latin/utils/UserHistoryDictIOUtilsTests.java
+++ b/tests/src/com/android/inputmethod/latin/utils/UserHistoryDictIOUtilsTests.java
@@ -49,6 +49,7 @@
     private static final int BIGRAM_FREQUENCY = 100;
     private static final ArrayList<String> NOT_HAVE_BIGRAM = new ArrayList<String>();
     private static final FormatSpec.FormatOptions FORMAT_OPTIONS = new FormatSpec.FormatOptions(2);
+    private static final String TEST_DICT_FILE_EXTENSION = ".testDict";
 
     /**
      * Return same frequency for all words and bigrams
@@ -86,7 +87,7 @@
 
     private void checkWordInFusionDict(final FusionDictionary dict, final String word,
             final ArrayList<String> expectedBigrams) {
-        final CharGroup group = FusionDictionary.findWordInTree(dict.mRoot, word);
+        final CharGroup group = FusionDictionary.findWordInTree(dict.mRootNodeArray, word);
         assertNotNull(group);
         assertTrue(group.isTerminal());
 
@@ -177,7 +178,8 @@
 
         File file = null;
         try {
-            file = File.createTempFile("testReadAndWrite", ".dict", getContext().getCacheDir());
+            file = File.createTempFile("testReadAndWrite", TEST_DICT_FILE_EXTENSION,
+                    getContext().getCacheDir());
         } catch (IOException e) {
             Log.d(TAG, "IOException while creating a temporary file", e);
         }
diff --git a/tools/dicttool/NativeLib.mk b/tools/dicttool/NativeLib.mk
index eeae003..84e54a9 100644
--- a/tools/dicttool/NativeLib.mk
+++ b/tools/dicttool/NativeLib.mk
@@ -34,7 +34,7 @@
 # Used in jni_common.cpp to avoid registering useless methods.
 
 LATIN_IME_JNI_SRC_FILES := \
-    com_android_inputmethod_latin_makedict_BinaryDictInputOutput.cpp \
+    com_android_inputmethod_latin_makedict_BinaryDictDecoder.cpp \
     jni_common.cpp
 
 LATIN_IME_CORE_SRC_FILES :=
diff --git a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/BinaryDictOffdeviceUtils.java b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/BinaryDictOffdeviceUtils.java
index d0b460a..4ddfb40 100644
--- a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/BinaryDictOffdeviceUtils.java
+++ b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/BinaryDictOffdeviceUtils.java
@@ -16,7 +16,7 @@
 
 package com.android.inputmethod.latin.dicttool;
 
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder;
 import com.android.inputmethod.latin.makedict.BinaryDictReader;
 import com.android.inputmethod.latin.makedict.FusionDictionary;
 import com.android.inputmethod.latin.makedict.UnsupportedFormatException;
@@ -31,8 +31,6 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.nio.ByteBuffer;
-import java.nio.channels.FileChannel;
 import java.util.ArrayList;
 
 import javax.xml.parsers.ParserConfigurationException;
@@ -99,7 +97,7 @@
         // over and over, ending in a stack overflow. Hence we limit the depth at which we try
         // decoding the file.
         if (depth > MAX_DECODE_DEPTH) return null;
-        if (BinaryDictInputOutput.isBinaryDictionary(src)) {
+        if (BinaryDictDecoder.isBinaryDictionary(src)) {
             spec.mFile = src;
             return spec;
         }
@@ -194,7 +192,7 @@
                         System.out.println("Packaging : " + decodedSpec.describeChain());
                         System.out.println("Uncompressed size : " + decodedSpec.mFile.length());
                     }
-                    return BinaryDictInputOutput.readDictionaryBinary(reader, null);
+                    return BinaryDictDecoder.readDictionaryBinary(reader, null);
                 }
             }
         } catch (IOException e) {
diff --git a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/CombinedInputOutput.java b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/CombinedInputOutput.java
index 092ee76..4b67169 100644
--- a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/CombinedInputOutput.java
+++ b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/CombinedInputOutput.java
@@ -19,7 +19,7 @@
 import com.android.inputmethod.latin.makedict.FormatSpec;
 import com.android.inputmethod.latin.makedict.FusionDictionary;
 import com.android.inputmethod.latin.makedict.FusionDictionary.DictionaryOptions;
-import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
 import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
 import com.android.inputmethod.latin.makedict.Word;
 
@@ -117,7 +117,7 @@
         final boolean processLigatures =
                 FRENCH_LIGATURE_PROCESSING_OPTION.equals(attributes.get(OPTIONS_TAG));
         attributes.remove(OPTIONS_TAG);
-        final FusionDictionary dict = new FusionDictionary(new Node(), new DictionaryOptions(
+        final FusionDictionary dict = new FusionDictionary(new PtNodeArray(), new DictionaryOptions(
                 attributes, processUmlauts, processLigatures));
 
         String line;
diff --git a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/DictionaryMaker.java b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/DictionaryMaker.java
index 9bce988..09052c9 100644
--- a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/DictionaryMaker.java
+++ b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/DictionaryMaker.java
@@ -16,7 +16,8 @@
 
 package com.android.inputmethod.latin.dicttool;
 
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder;
+import com.android.inputmethod.latin.makedict.BinaryDictEncoder;
 import com.android.inputmethod.latin.makedict.BinaryDictReader;
 import com.android.inputmethod.latin.makedict.FormatSpec;
 import com.android.inputmethod.latin.makedict.FusionDictionary;
@@ -30,8 +31,6 @@
 import java.io.FileOutputStream;
 import java.io.FileWriter;
 import java.io.IOException;
-import java.nio.ByteBuffer;
-import java.nio.channels.FileChannel;
 import java.util.Arrays;
 import java.util.LinkedList;
 
@@ -177,7 +176,7 @@
                                 inputUnigramXml = filename;
                             } else if (CombinedInputOutput.isCombinedDictionary(filename)) {
                                 inputCombined = filename;
-                            } else if (BinaryDictInputOutput.isBinaryDictionary(filename)) {
+                            } else if (BinaryDictDecoder.isBinaryDictionary(filename)) {
                                 inputBinary = filename;
                             } else {
                                 throw new IllegalArgumentException(
@@ -199,7 +198,7 @@
                     }
                 } else {
                     if (null == inputBinary && null == inputUnigramXml) {
-                        if (BinaryDictInputOutput.isBinaryDictionary(arg)) {
+                        if (BinaryDictDecoder.isBinaryDictionary(arg)) {
                             inputBinary = arg;
                         } else if (CombinedInputOutput.isCombinedDictionary(arg)) {
                             inputCombined = arg;
@@ -269,7 +268,7 @@
         final File file = new File(binaryFilename);
         final BinaryDictReader reader = new BinaryDictReader(file);
         reader.openBuffer(new BinaryDictReader.FusionDictionaryBufferFromByteBufferFactory());
-        return BinaryDictInputOutput.readDictionaryBinary(reader, null);
+        return BinaryDictDecoder.readDictionaryBinary(reader, null);
     }
 
     /**
@@ -358,7 +357,7 @@
             throws FileNotFoundException, IOException, UnsupportedFormatException {
         final File outputFile = new File(outputFilename);
         final FormatSpec.FormatOptions formatOptions = new FormatSpec.FormatOptions(version);
-        BinaryDictInputOutput.writeDictionaryBinary(new FileOutputStream(outputFilename), dict,
+        BinaryDictEncoder.writeDictionaryBinary(new FileOutputStream(outputFilename), dict,
                 formatOptions);
     }
 
diff --git a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Diff.java b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Diff.java
index 5c3e87e..d790d06 100644
--- a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Diff.java
+++ b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Diff.java
@@ -121,7 +121,8 @@
     private static void diffWords(final FusionDictionary dict0, final FusionDictionary dict1) {
         boolean hasDifferences = false;
         for (final Word word0 : dict0) {
-            final CharGroup word1 = FusionDictionary.findWordInTree(dict1.mRoot, word0.mWord);
+            final CharGroup word1 = FusionDictionary.findWordInTree(dict1.mRootNodeArray,
+                    word0.mWord);
             if (null == word1) {
                 // This word is not in dict1
                 System.out.println("Deleted: " + word0.mWord + " " + word0.mFrequency);
@@ -150,7 +151,8 @@
             }
         }
         for (final Word word1 : dict1) {
-            final CharGroup word0 = FusionDictionary.findWordInTree(dict0.mRoot, word1.mWord);
+            final CharGroup word0 = FusionDictionary.findWordInTree(dict0.mRootNodeArray,
+                    word1.mWord);
             if (null == word0) {
                 // This word is not in dict0
                 System.out.println("Added: " + word1.mWord + " " + word1.mFrequency);
diff --git a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Info.java b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Info.java
index f289454..fa8c5f7 100644
--- a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Info.java
+++ b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Info.java
@@ -65,7 +65,7 @@
 
     private static void showWordInfo(final FusionDictionary dict, final String word,
             final boolean plumbing) {
-        final CharGroup group = FusionDictionary.findWordInTree(dict.mRoot, word);
+        final CharGroup group = FusionDictionary.findWordInTree(dict.mRootNodeArray, word);
         if (null == group) {
             System.out.println(word + " is not in the dictionary");
             return;
diff --git a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Test.java b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Test.java
index 972b6e7..9174238 100644
--- a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Test.java
+++ b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Test.java
@@ -16,9 +16,9 @@
 
 package com.android.inputmethod.latin.dicttool;
 
-import com.android.inputmethod.latin.makedict.BinaryDictIOTests;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoderEncoderTests;
+import com.android.inputmethod.latin.makedict.BinaryDictEncoderFlattenTreeTests;
 import com.android.inputmethod.latin.makedict.BinaryDictIOUtilsTests;
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutputTest;
 import com.android.inputmethod.latin.makedict.FusionDictionaryTest;
 
 import java.lang.reflect.Constructor;
@@ -37,9 +37,9 @@
     private static final Class<?>[] sClassesToTest = {
         BinaryDictOffdeviceUtilsTests.class,
         FusionDictionaryTest.class,
-        BinaryDictInputOutputTest.class,
-        BinaryDictIOUtilsTests.class,
-        BinaryDictIOTests.class
+        BinaryDictDecoderEncoderTests.class,
+        BinaryDictEncoderFlattenTreeTests.class,
+        BinaryDictIOUtilsTests.class
     };
     private ArrayList<Method> mAllTestMethods = new ArrayList<Method>();
     private ArrayList<String> mUsedTestMethods = new ArrayList<String>();
diff --git a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/XmlDictInputOutput.java b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/XmlDictInputOutput.java
index 1fd2cba..4e99bf9 100644
--- a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/XmlDictInputOutput.java
+++ b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/XmlDictInputOutput.java
@@ -18,7 +18,7 @@
 
 import com.android.inputmethod.latin.makedict.FusionDictionary;
 import com.android.inputmethod.latin.makedict.FusionDictionary.DictionaryOptions;
-import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
 import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
 import com.android.inputmethod.latin.makedict.Word;
 
@@ -124,8 +124,8 @@
                         GERMAN_UMLAUT_PROCESSING_OPTION.equals(optionsString);
                 final boolean processLigatures =
                         FRENCH_LIGATURE_PROCESSING_OPTION.equals(optionsString);
-                mDictionary = new FusionDictionary(new Node(), new DictionaryOptions(attributes,
-                        processUmlauts, processLigatures));
+                mDictionary = new FusionDictionary(new PtNodeArray(),
+                        new DictionaryOptions(attributes, processUmlauts, processLigatures));
             } else {
                 mState = UNKNOWN;
             }
diff --git a/tools/dicttool/tests/com/android/inputmethod/latin/dicttool/BinaryDictOffdeviceUtilsTests.java b/tools/dicttool/tests/com/android/inputmethod/latin/dicttool/BinaryDictOffdeviceUtilsTests.java
index fb1cc84..3bda77f 100644
--- a/tools/dicttool/tests/com/android/inputmethod/latin/dicttool/BinaryDictOffdeviceUtilsTests.java
+++ b/tools/dicttool/tests/com/android/inputmethod/latin/dicttool/BinaryDictOffdeviceUtilsTests.java
@@ -16,36 +16,33 @@
 
 package com.android.inputmethod.latin.dicttool;
 
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput;
+import com.android.inputmethod.latin.makedict.BinaryDictDecoder;
+import com.android.inputmethod.latin.makedict.BinaryDictEncoder;
 import com.android.inputmethod.latin.makedict.BinaryDictReader;
 import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
 import com.android.inputmethod.latin.makedict.FusionDictionary;
 import com.android.inputmethod.latin.makedict.FusionDictionary.DictionaryOptions;
-import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
 import com.android.inputmethod.latin.makedict.UnsupportedFormatException;
 
 import junit.framework.TestCase;
 
 import java.io.File;
 import java.io.BufferedOutputStream;
-import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
-import java.nio.ByteBuffer;
-import java.nio.channels.FileChannel;
-import java.util.ArrayList;
 import java.util.HashMap;
 
 /**
- * Unit tests for BinaryDictOffdeviceUtilsTests
+ * Unit tests for BinaryDictOffdeviceUtils
  */
 public class BinaryDictOffdeviceUtilsTests extends TestCase {
     private static final int TEST_FREQ = 37; // Some arbitrary value unlikely to happen by chance
 
     public void testGetRawDictWorks() throws IOException, UnsupportedFormatException {
         // Create a thrice-compressed dictionary file.
-        final FusionDictionary dict = new FusionDictionary(new Node(),
+        final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
                 new DictionaryOptions(new HashMap<String, String>(),
                         false /* germanUmlautProcessing */, false /* frenchLigatureProcessing */));
         dict.add("foo", TEST_FREQ, null, false /* isNotAWord */);
@@ -61,7 +58,7 @@
                         Compress.getCompressedStream(
                                 new BufferedOutputStream(new FileOutputStream(dst)))));
 
-        BinaryDictInputOutput.writeDictionaryBinary(out, dict, new FormatOptions(2, false));
+        BinaryDictEncoder.writeDictionaryBinary(out, dict, new FormatOptions(2, false));
 
         // Test for an actually compressed dictionary and its contents
         final BinaryDictOffdeviceUtils.DecoderChainSpec decodeSpec =
@@ -72,10 +69,11 @@
         assertEquals("Wrong decode spec", 3, decodeSpec.mDecoderSpec.size());
         final BinaryDictReader reader = new BinaryDictReader(decodeSpec.mFile);
         reader.openBuffer(new BinaryDictReader.FusionDictionaryBufferFromByteBufferFactory());
-        final FusionDictionary resultDict = BinaryDictInputOutput.readDictionaryBinary(reader,
+        final FusionDictionary resultDict = BinaryDictDecoder.readDictionaryBinary(reader,
                 null /* dict : an optional dictionary to add words to, or null */);
         assertEquals("Dictionary can't be read back correctly",
-                resultDict.findWordInTree(resultDict.mRoot, "foo").getFrequency(), TEST_FREQ);
+                FusionDictionary.findWordInTree(resultDict.mRootNodeArray, "foo").getFrequency(),
+                TEST_FREQ);
     }
 
     public void testGetRawDictFails() throws IOException {
diff --git a/tools/dicttool/tests/com/android/inputmethod/latin/makedict/BinaryDictInputOutputTest.java b/tools/dicttool/tests/com/android/inputmethod/latin/makedict/BinaryDictEncoderFlattenTreeTests.java
similarity index 79%
rename from tools/dicttool/tests/com/android/inputmethod/latin/makedict/BinaryDictInputOutputTest.java
rename to tools/dicttool/tests/com/android/inputmethod/latin/makedict/BinaryDictEncoderFlattenTreeTests.java
index 0969028..fe67383 100644
--- a/tools/dicttool/tests/com/android/inputmethod/latin/makedict/BinaryDictInputOutputTest.java
+++ b/tools/dicttool/tests/com/android/inputmethod/latin/makedict/BinaryDictEncoderFlattenTreeTests.java
@@ -17,7 +17,7 @@
 package com.android.inputmethod.latin.makedict;
 
 import com.android.inputmethod.latin.makedict.FusionDictionary.DictionaryOptions;
-import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
 
 import junit.framework.TestCase;
 
@@ -25,13 +25,13 @@
 import java.util.HashMap;
 
 /**
- * Unit tests for BinaryDictInputOutput.
+ * Unit tests for BinaryDictEncoder.flattenTree().
  */
-public class BinaryDictInputOutputTest extends TestCase {
+public class BinaryDictEncoderFlattenTreeTests extends TestCase {
     // Test the flattened array contains the expected number of nodes, and
     // that it does not contain any duplicates.
     public void testFlattenNodes() {
-        final FusionDictionary dict = new FusionDictionary(new Node(),
+        final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
                 new DictionaryOptions(new HashMap<String, String>(),
                         false /* germanUmlautProcessing */, false /* frenchLigatureProcessing */));
         dict.add("foo", 1, null, false /* isNotAWord */);
@@ -39,10 +39,10 @@
         dict.add("ftb", 1, null, false /* isNotAWord */);
         dict.add("bar", 1, null, false /* isNotAWord */);
         dict.add("fool", 1, null, false /* isNotAWord */);
-        final ArrayList<Node> result = BinaryDictInputOutput.flattenTree(dict.mRoot);
+        final ArrayList<PtNodeArray> result = BinaryDictEncoder.flattenTree(dict.mRootNodeArray);
         assertEquals(4, result.size());
         while (!result.isEmpty()) {
-            final Node n = result.remove(0);
+            final PtNodeArray n = result.remove(0);
             assertFalse("Flattened array contained the same node twice", result.contains(n));
         }
     }
diff --git a/tools/dicttool/tests/com/android/inputmethod/latin/makedict/FusionDictionaryTest.java b/tools/dicttool/tests/com/android/inputmethod/latin/makedict/FusionDictionaryTest.java
index 7607113..22c0ceb 100644
--- a/tools/dicttool/tests/com/android/inputmethod/latin/makedict/FusionDictionaryTest.java
+++ b/tools/dicttool/tests/com/android/inputmethod/latin/makedict/FusionDictionaryTest.java
@@ -19,7 +19,7 @@
 import com.android.inputmethod.latin.makedict.FusionDictionary;
 import com.android.inputmethod.latin.makedict.FusionDictionary.CharGroup;
 import com.android.inputmethod.latin.makedict.FusionDictionary.DictionaryOptions;
-import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
 import com.android.inputmethod.latin.makedict.Word;
 
 import junit.framework.TestCase;
@@ -29,7 +29,7 @@
 import java.util.Random;
 
 /**
- * Unit tests for BinaryDictInputOutput.
+ * Unit tests for FusionDictionary.
  */
 public class FusionDictionaryTest extends TestCase {
     private static final ArrayList<String> sWords = new ArrayList<String>();
@@ -72,7 +72,7 @@
         assertNotNull(dict);
         for (final String word : words) {
             if (--limit < 0) return;
-            final CharGroup cg = FusionDictionary.findWordInTree(dict.mRoot, word);
+            final CharGroup cg = FusionDictionary.findWordInTree(dict.mRootNodeArray, word);
             assertNotNull(cg);
         }
     }
@@ -95,7 +95,7 @@
     // Test the flattened array contains the expected number of nodes, and
     // that it does not contain any duplicates.
     public void testFusion() {
-        final FusionDictionary dict = new FusionDictionary(new Node(),
+        final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
                 new DictionaryOptions(new HashMap<String, String>(),
                         false /* germanUmlautProcessing */, false /* frenchLigatureProcessing */));
         final long time = System.currentTimeMillis();
diff --git a/tools/dicttool/tests/etc/test-dicttool.sh b/tools/dicttool/tests/etc/test-dicttool.sh
index 0921207..5eb44fc 100755
--- a/tools/dicttool/tests/etc/test-dicttool.sh
+++ b/tools/dicttool/tests/etc/test-dicttool.sh
@@ -24,5 +24,5 @@
 find out -name "dicttool_aosp*" -exec rm -rf {} \; > /dev/null 2>&1
 mmm -j8 external/junit
 DICTTOOL_UNITTEST=true mmm -j8 packages/inputmethods/LatinIME/tools/dicttool
-java -classpath ${ANDROID_HOST_OUT}/framework/junit.jar:${ANDROID_HOST_OUT}/framework/dicttool_aosp.jar junit.textui.TestRunner com.android.inputmethod.latin.makedict.BinaryDictInputOutputTest
+java -classpath ${ANDROID_HOST_OUT}/framework/junit.jar:${ANDROID_HOST_OUT}/framework/dicttool_aosp.jar junit.textui.TestRunner com.android.inputmethod.latin.makedict.BinaryDictEncoderFlattenTreeTests
 java -classpath ${ANDROID_HOST_OUT}/framework/junit.jar:${ANDROID_HOST_OUT}/framework/dicttool_aosp.jar junit.textui.TestRunner com.android.inputmethod.latin.dicttool.BinaryDictOffdeviceUtilsTests