diff --git a/common/src/com/android/inputmethod/latin/common/LocaleUtils.java b/common/src/com/android/inputmethod/latin/common/LocaleUtils.java
index 14b3d22..7f2333b 100644
--- a/common/src/com/android/inputmethod/latin/common/LocaleUtils.java
+++ b/common/src/com/android/inputmethod/latin/common/LocaleUtils.java
@@ -17,8 +17,12 @@
 package com.android.inputmethod.latin.common;
 
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Locale;
 
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
 /**
  * A class to help with handling Locales in string form.
  *
@@ -160,26 +164,49 @@
 
     /**
      * Creates a locale from a string specification.
+     * @param localeString a string specification of a locale, in a format of "ll_cc_variant" where
+     * "ll" is a language code, "cc" is a country code.
      */
-    public static Locale constructLocaleFromString(final String localeStr) {
-        if (localeStr == null)
+    @Nullable
+    public static Locale constructLocaleFromString(@Nullable final String localeString) {
+        if (localeString == null) {
             return null;
-        synchronized (sLocaleCache) {
-            if (sLocaleCache.containsKey(localeStr))
-                return sLocaleCache.get(localeStr);
-            Locale retval = null;
-            String[] localeParams = localeStr.split("_", 3);
-            if (localeParams.length == 1) {
-                retval = new Locale(localeParams[0]);
-            } else if (localeParams.length == 2) {
-                retval = new Locale(localeParams[0], localeParams[1]);
-            } else if (localeParams.length == 3) {
-                retval = new Locale(localeParams[0], localeParams[1], localeParams[2]);
-            }
-            if (retval != null) {
-                sLocaleCache.put(localeStr, retval);
-            }
-            return retval;
         }
+        synchronized (sLocaleCache) {
+            if (sLocaleCache.containsKey(localeString)) {
+                return sLocaleCache.get(localeString);
+            }
+            final String[] elements = localeString.split("_", 3);
+            final Locale locale;
+            if (elements.length == 1) {
+                locale = new Locale(elements[0] /* language */);
+            } else if (elements.length == 2) {
+                locale = new Locale(elements[0] /* language */, elements[1] /* country */);
+            } else { // localeParams.length == 3
+                locale = new Locale(elements[0] /* language */, elements[1] /* country */,
+                        elements[2] /* variant */);
+            }
+            sLocaleCache.put(localeString, locale);
+            return locale;
+        }
+    }
+
+    // TODO: Get this information from the framework instead of maintaining here by ourselves.
+    private static final HashSet<String> sRtlLanguageCodes = new HashSet<>();
+    static {
+        // List of known Right-To-Left language codes.
+        sRtlLanguageCodes.add("ar"); // Arabic
+        sRtlLanguageCodes.add("fa"); // Persian
+        sRtlLanguageCodes.add("iw"); // Hebrew
+        sRtlLanguageCodes.add("ku"); // Kurdish
+        sRtlLanguageCodes.add("ps"); // Pashto
+        sRtlLanguageCodes.add("sd"); // Sindhi
+        sRtlLanguageCodes.add("ug"); // Uyghur
+        sRtlLanguageCodes.add("ur"); // Urdu
+        sRtlLanguageCodes.add("yi"); // Yiddish
+    }
+
+    public static boolean isRtlLanguage(@Nonnull final Locale locale) {
+        return sRtlLanguageCodes.contains(locale.getLanguage());
     }
 }
diff --git a/java-overridable/src/com/android/inputmethod/latin/define/ProductionFlags.java b/java-overridable/src/com/android/inputmethod/latin/define/ProductionFlags.java
index f806256..4367568 100644
--- a/java-overridable/src/com/android/inputmethod/latin/define/ProductionFlags.java
+++ b/java-overridable/src/com/android/inputmethod/latin/define/ProductionFlags.java
@@ -48,4 +48,10 @@
      * When {@code true}, personal dictionary sync feature is ready to be enabled.
      */
     public static final boolean ENABLE_PERSONAL_DICTIONARY_SYNC = ENABLE_ACCOUNT_SIGN_IN && false;
+
+    /**
+     * When {@code true}, the IME maintains per account {@link UserHistoryDictionary}.
+     */
+    public static final boolean ENABLE_PER_ACCOUNT_USER_HISTORY_DICTIONARY =
+            ENABLE_ACCOUNT_SIGN_IN && false;
 }
diff --git a/java/res/drawable/btn_keyboard_key_ics.xml b/java/res/drawable/btn_keyboard_key_ics.xml
index 0bb098d..bacd5d7 100644
--- a/java/res/drawable/btn_keyboard_key_ics.xml
+++ b/java/res/drawable/btn_keyboard_key_ics.xml
@@ -32,6 +32,8 @@
           android:drawable="@drawable/btn_keyboard_key_normal_off_holo_dark" />
 
     <!-- Empty background keys. -->
+    <item android:state_empty="true" android:state_pressed="true"
+          android:drawable="@drawable/btn_keyboard_key_pressed_ics_light" />
     <item android:state_empty="true"
           android:drawable="@android:color/transparent" />
 
diff --git a/java/res/drawable/btn_keyboard_key_klp.xml b/java/res/drawable/btn_keyboard_key_klp.xml
index 2a202a1..e2f2085 100644
--- a/java/res/drawable/btn_keyboard_key_klp.xml
+++ b/java/res/drawable/btn_keyboard_key_klp.xml
@@ -32,6 +32,8 @@
           android:drawable="@drawable/btn_keyboard_key_normal_off_holo_dark" />
 
     <!-- Empty background keys. -->
+    <item android:state_empty="true" android:state_pressed="true"
+          android:drawable="@drawable/btn_keyboard_key_pressed_klp_light" />
     <item android:state_empty="true"
           android:drawable="@android:color/transparent" />
 
diff --git a/java/res/drawable/btn_keyboard_key_lxx_dark.xml b/java/res/drawable/btn_keyboard_key_lxx_dark.xml
index bb1789a..161592d 100644
--- a/java/res/drawable/btn_keyboard_key_lxx_dark.xml
+++ b/java/res/drawable/btn_keyboard_key_lxx_dark.xml
@@ -32,8 +32,10 @@
           android:drawable="@drawable/btn_keyboard_key_normal_off_lxx_dark" />
 
     <!-- Empty background keys. -->
+    <item android:state_empty="true" android:state_pressed="true"
+          android:drawable="@color/key_background_pressed_lxx_dark" />
     <item android:state_empty="true"
-          android:drawable="@color/key_background_lxx_dark" />
+          android:drawable="@android:color/transparent" />
 
     <!-- Normal keys. -->
     <item android:state_pressed="true"
diff --git a/java/res/drawable/btn_keyboard_key_lxx_light.xml b/java/res/drawable/btn_keyboard_key_lxx_light.xml
index 60fe02d..0154d75 100644
--- a/java/res/drawable/btn_keyboard_key_lxx_light.xml
+++ b/java/res/drawable/btn_keyboard_key_lxx_light.xml
@@ -32,8 +32,10 @@
           android:drawable="@drawable/btn_keyboard_key_normal_off_lxx_light" />
 
     <!-- Empty background keys. -->
+    <item android:state_empty="true" android:state_pressed="true"
+          android:drawable="@color/key_background_pressed_lxx_light" />
     <item android:state_empty="true"
-          android:drawable="@color/key_background_lxx_light" />
+          android:drawable="@android:color/transparent" />
 
     <!-- Normal keys. -->
     <item android:state_pressed="true"
diff --git a/java/res/values-eu-rES/strings-emoji-descriptions.xml b/java/res/values-eu-rES/strings-emoji-descriptions.xml
index 2faec96..c774ae1 100644
--- a/java/res/values-eu-rES/strings-emoji-descriptions.xml
+++ b/java/res/values-eu-rES/strings-emoji-descriptions.xml
@@ -846,6 +846,6 @@
     <string name="spoken_emoji_1F6C1" msgid="2845056048320031158">"Bainuontzia"</string>
     <string name="spoken_emoji_1F6C2" msgid="8117262514698011877">"Pasaporte-kontrola"</string>
     <string name="spoken_emoji_1F6C3" msgid="1176342001834630675">"Aduana"</string>
-    <string name="spoken_emoji_1F6C4" msgid="1477622834179978886">"Maleta-erreklamazioa"</string>
+    <string name="spoken_emoji_1F6C4" msgid="1477622834179978886">"Ekipaje-erreklamazioa"</string>
     <string name="spoken_emoji_1F6C5" msgid="2495834050856617451">"Ahaztutako maletak"</string>
 </resources>
diff --git a/java/res/values-km-rKH/strings-emoji-descriptions.xml b/java/res/values-km-rKH/strings-emoji-descriptions.xml
index 757df50..e9b8780 100644
--- a/java/res/values-km-rKH/strings-emoji-descriptions.xml
+++ b/java/res/values-km-rKH/strings-emoji-descriptions.xml
@@ -267,7 +267,7 @@
     <string name="spoken_emoji_1F36A" msgid="2726271795913042295">"ខូគី"</string>
     <string name="spoken_emoji_1F36B" msgid="6342163604299875931">"​​សូកូឡា"</string>
     <string name="spoken_emoji_1F36C" msgid="2168934753998218790">"ស្ករគ្រាប់"</string>
-    <string name="spoken_emoji_1F36D" msgid="3671507903799975792">"ស្ករ​គ្រាប់​មាន​ដង​​កាន់"</string>
+    <string name="spoken_emoji_1F36D" msgid="3671507903799975792">"Lollipop"</string>
     <string name="spoken_emoji_1F36E" msgid="4630541402785165902">"សង់ខ្យា"</string>
     <string name="spoken_emoji_1F36F" msgid="5577915387425169439">"ថូ"</string>
     <string name="spoken_emoji_1F370" msgid="7243244547866114951">"នំ​ខេក"</string>
diff --git a/java/res/values-pt/strings.xml b/java/res/values-pt/strings.xml
index 2e0cd3b..2cc86e1 100644
--- a/java/res/values-pt/strings.xml
+++ b/java/res/values-pt/strings.xml
@@ -102,8 +102,7 @@
     <string name="subtype_with_layout_hi_ZZ" msgid="6827402953860547044">"Híndi-inglês (<xliff:g id="KEYBOARD_LAYOUT">%s</xliff:g>)"</string>
     <string name="subtype_with_layout_sr_ZZ" msgid="2859024772719772407">"Sérvio (<xliff:g id="KEYBOARD_LAYOUT">%s</xliff:g>)"</string>
     <string name="subtype_generic_traditional" msgid="8584594350973800586">"<xliff:g id="LANGUAGE_NAME">%s</xliff:g> (tradicional)"</string>
-    <!-- no translation found for subtype_generic_compact (3353673321203202922) -->
-    <skip />
+    <string name="subtype_generic_compact" msgid="3353673321203202922">"<xliff:g id="LANGUAGE_NAME">%s</xliff:g> (compacto)"</string>
     <string name="subtype_no_language" msgid="7137390094240139495">"Nenhum idioma (alfabeto)"</string>
     <string name="subtype_no_language_qwerty" msgid="244337630616742604">"Alfabeto (QWERTY)"</string>
     <string name="subtype_no_language_qwertz" msgid="443066912507547976">"Alfabeto (QWERTZ)"</string>
diff --git a/java/res/xml/kbd_emoji_category1.xml b/java/res/xml/kbd_emoji_category1.xml
index 2770cfb..5145ea9 100644
--- a/java/res/xml/kbd_emoji_category1.xml
+++ b/java/res/xml/kbd_emoji_category1.xml
@@ -27,5 +27,5 @@
     <GridRows
         latin:codesArray="@array/emoji_faces"
         latin:keyLabelFlags="fontNormal"
-        latin:backgroundType="normal" />
+        latin:backgroundType="empty" />
 </Keyboard>
diff --git a/java/res/xml/kbd_emoji_category2.xml b/java/res/xml/kbd_emoji_category2.xml
index d547056..ac8784f 100644
--- a/java/res/xml/kbd_emoji_category2.xml
+++ b/java/res/xml/kbd_emoji_category2.xml
@@ -27,5 +27,5 @@
     <GridRows
         latin:codesArray="@array/emoji_objects"
         latin:keyLabelFlags="fontNormal"
-        latin:backgroundType="normal" />
+        latin:backgroundType="empty" />
 </Keyboard>
diff --git a/java/res/xml/kbd_emoji_category3.xml b/java/res/xml/kbd_emoji_category3.xml
index 2172d98..88c4db9 100644
--- a/java/res/xml/kbd_emoji_category3.xml
+++ b/java/res/xml/kbd_emoji_category3.xml
@@ -27,5 +27,5 @@
     <GridRows
         latin:codesArray="@array/emoji_nature"
         latin:keyLabelFlags="fontNormal"
-        latin:backgroundType="normal" />
+        latin:backgroundType="empty" />
 </Keyboard>
diff --git a/java/res/xml/kbd_emoji_category4.xml b/java/res/xml/kbd_emoji_category4.xml
index 46b6d46..262384d 100644
--- a/java/res/xml/kbd_emoji_category4.xml
+++ b/java/res/xml/kbd_emoji_category4.xml
@@ -27,5 +27,5 @@
     <GridRows
         latin:codesArray="@array/emoji_places"
         latin:keyLabelFlags="fontNormal"
-        latin:backgroundType="normal" />
+        latin:backgroundType="empty" />
 </Keyboard>
diff --git a/java/res/xml/kbd_emoji_category5.xml b/java/res/xml/kbd_emoji_category5.xml
index 4304701..bf823f9 100644
--- a/java/res/xml/kbd_emoji_category5.xml
+++ b/java/res/xml/kbd_emoji_category5.xml
@@ -27,5 +27,5 @@
     <GridRows
         latin:codesArray="@array/emoji_symbols"
         latin:keyLabelFlags="fontNormal"
-        latin:backgroundType="normal" />
+        latin:backgroundType="empty" />
 </Keyboard>
diff --git a/java/res/xml/kbd_emoji_category6.xml b/java/res/xml/kbd_emoji_category6.xml
index 516ed7a..edb82fc 100644
--- a/java/res/xml/kbd_emoji_category6.xml
+++ b/java/res/xml/kbd_emoji_category6.xml
@@ -28,5 +28,5 @@
     <GridRows
         latin:textsArray="@array/emoji_emoticons"
         latin:keyLabelFlags="fontNormal"
-        latin:backgroundType="normal" />
+        latin:backgroundType="empty" />
 </Keyboard>
diff --git a/java/res/xml/kbd_emoji_recents.xml b/java/res/xml/kbd_emoji_recents.xml
index 4953c10..edf3872 100644
--- a/java/res/xml/kbd_emoji_recents.xml
+++ b/java/res/xml/kbd_emoji_recents.xml
@@ -28,5 +28,5 @@
     <GridRows
         latin:codesArray="@array/emoji_recents"
         latin:keyLabelFlags="fontNormal"
-        latin:backgroundType="normal" />
+        latin:backgroundType="empty" />
 </Keyboard>
diff --git a/java/src/com/android/inputmethod/dictionarypack/MetadataDbHelper.java b/java/src/com/android/inputmethod/dictionarypack/MetadataDbHelper.java
index db4315f..ce23eb7 100644
--- a/java/src/com/android/inputmethod/dictionarypack/MetadataDbHelper.java
+++ b/java/src/com/android/inputmethod/dictionarypack/MetadataDbHelper.java
@@ -47,7 +47,8 @@
     // used to identify the versions for upgrades. This should never change going forward.
     private static final int METADATA_DATABASE_VERSION_WITH_CLIENTID = 6;
     // The current database version.
-    private static final int CURRENT_METADATA_DATABASE_VERSION = 10;
+    // This MUST be increased every time the dictionary pack metadata URL changes.
+    private static final int CURRENT_METADATA_DATABASE_VERSION = 11;
 
     private final static long NOT_A_DOWNLOAD_ID = -1;
 
diff --git a/java/src/com/android/inputmethod/dictionarypack/UpdateHandler.java b/java/src/com/android/inputmethod/dictionarypack/UpdateHandler.java
index bd61521..aeb6667 100644
--- a/java/src/com/android/inputmethod/dictionarypack/UpdateHandler.java
+++ b/java/src/com/android/inputmethod/dictionarypack/UpdateHandler.java
@@ -40,6 +40,7 @@
 import com.android.inputmethod.compat.NotificationCompatUtils;
 import com.android.inputmethod.latin.R;
 import com.android.inputmethod.latin.common.LocaleUtils;
+import com.android.inputmethod.latin.makedict.FormatSpec;
 import com.android.inputmethod.latin.utils.ApplicationUtils;
 import com.android.inputmethod.latin.utils.DebugLogUtils;
 
@@ -79,7 +80,8 @@
     // DownloadManager uses as an ID numbers returned out of an AUTOINCREMENT column
     // in SQLite, so it should never return anything < 0.
     public static final int NOT_AN_ID = -1;
-    public static final int MAXIMUM_SUPPORTED_FORMAT_VERSION = 2;
+    public static final int MAXIMUM_SUPPORTED_FORMAT_VERSION =
+            FormatSpec.MAXIMUM_SUPPORTED_STATIC_VERSION;
 
     // Arbitrary. Probably good if it's a power of 2, and a couple thousand bytes long.
     private static final int FILE_COPY_BUFFER_SIZE = 8192;
diff --git a/java/src/com/android/inputmethod/keyboard/KeyboardLayoutSet.java b/java/src/com/android/inputmethod/keyboard/KeyboardLayoutSet.java
index 51f37fd..b105138 100644
--- a/java/src/com/android/inputmethod/keyboard/KeyboardLayoutSet.java
+++ b/java/src/com/android/inputmethod/keyboard/KeyboardLayoutSet.java
@@ -294,7 +294,7 @@
                     : subtype;
             mParams.mSubtype = keyboardSubtype;
             mParams.mKeyboardLayoutSetName = KEYBOARD_LAYOUT_SET_RESOURCE_PREFIX
-                    + SubtypeLocaleUtils.getKeyboardLayoutSetName(keyboardSubtype);
+                    + keyboardSubtype.getKeyboardLayoutSetName();
             return this;
         }
 
diff --git a/java/src/com/android/inputmethod/keyboard/KeyboardView.java b/java/src/com/android/inputmethod/keyboard/KeyboardView.java
index b07693c..01980ea 100644
--- a/java/src/com/android/inputmethod/keyboard/KeyboardView.java
+++ b/java/src/com/android/inputmethod/keyboard/KeyboardView.java
@@ -25,7 +25,6 @@
 import android.graphics.Paint.Align;
 import android.graphics.PorterDuff;
 import android.graphics.Rect;
-import android.graphics.Region;
 import android.graphics.Typeface;
 import android.graphics.drawable.Drawable;
 import android.graphics.drawable.NinePatchDrawable;
@@ -41,6 +40,7 @@
 
 import java.util.HashSet;
 
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
 /**
@@ -100,6 +100,8 @@
     private static final float MAX_LABEL_RATIO = 0.90f;
 
     // Main keyboard
+    // TODO: Consider having a dummy keyboard object to make this @Nonnull
+    @Nullable
     private Keyboard mKeyboard;
     protected final KeyDrawParams mKeyDrawParams = new KeyDrawParams();
 
@@ -108,14 +110,14 @@
     private boolean mInvalidateAllKeys;
     /** The keys that should be drawn */
     private final HashSet<Key> mInvalidatedKeys = new HashSet<>();
-    /** The working rectangle variable */
-    private final Rect mWorkingRect = new Rect();
+    /** The working rectangle for clipping */
+    private final Rect mClipRect = new Rect();
     /** The keyboard bitmap buffer for faster updates */
-    /** The clip region to draw keys */
-    private final Region mClipRegion = new Region();
     private Bitmap mOffscreenBuffer;
     /** The canvas for the above mutable keyboard bitmap */
+    @Nonnull
     private final Canvas mOffscreenCanvas = new Canvas();
+    @Nonnull
     private final Paint mPaint = new Paint();
     private final Paint.FontMetrics mFontMetrics = new Paint.FontMetrics();
     public KeyboardView(final Context context, final AttributeSet attrs) {
@@ -161,11 +163,12 @@
         mPaint.setAntiAlias(true);
     }
 
+    @Nullable
     public KeyVisualAttributes getKeyVisualAttribute() {
         return mKeyVisualAttributes;
     }
 
-    private static void blendAlpha(final Paint paint, final int alpha) {
+    private static void blendAlpha(@Nonnull final Paint paint, final int alpha) {
         final int color = paint.getColor();
         paint.setARGB((paint.getAlpha() * alpha) / Constants.Color.ALPHA_OPAQUE,
                 Color.red(color), Color.green(color), Color.blue(color));
@@ -184,7 +187,7 @@
      * @see #getKeyboard()
      * @param keyboard the keyboard to display in this view
      */
-    public void setKeyboard(final Keyboard keyboard) {
+    public void setKeyboard(@Nonnull final Keyboard keyboard) {
         mKeyboard = keyboard;
         final int keyHeight = keyboard.mMostCommonKeyHeight - keyboard.mVerticalGap;
         mKeyDrawParams.updateParams(keyHeight, mKeyVisualAttributes);
@@ -198,6 +201,7 @@
      * @return the currently attached keyboard
      * @see #setKeyboard(Keyboard)
      */
+    @Nullable
     public Keyboard getKeyboard() {
         return mKeyboard;
     }
@@ -212,13 +216,14 @@
 
     @Override
     protected void onMeasure(final int widthMeasureSpec, final int heightMeasureSpec) {
-        if (mKeyboard == null) {
+        final Keyboard keyboard = getKeyboard();
+        if (keyboard == null) {
             super.onMeasure(widthMeasureSpec, heightMeasureSpec);
             return;
         }
         // The main keyboard expands to the entire this {@link KeyboardView}.
-        final int width = mKeyboard.mOccupiedWidth + getPaddingLeft() + getPaddingRight();
-        final int height = mKeyboard.mOccupiedHeight + getPaddingTop() + getPaddingBottom();
+        final int width = keyboard.mOccupiedWidth + getPaddingLeft() + getPaddingRight();
+        final int height = keyboard.mOccupiedHeight + getPaddingTop() + getPaddingBottom();
         setMeasuredDimension(width, height);
     }
 
@@ -266,52 +271,45 @@
         }
     }
 
-    private void onDrawKeyboard(final Canvas canvas) {
-        if (mKeyboard == null) return;
+    private void onDrawKeyboard(@Nonnull final Canvas canvas) {
+        final Keyboard keyboard = getKeyboard();
+        if (keyboard == null) {
+            return;
+        }
 
-        final int width = getWidth();
-        final int height = getHeight();
         final Paint paint = mPaint;
-
+        final Drawable background = getBackground();
         // Calculate clip region and set.
         final boolean drawAllKeys = mInvalidateAllKeys || mInvalidatedKeys.isEmpty();
         final boolean isHardwareAccelerated = canvas.isHardwareAccelerated();
         // TODO: Confirm if it's really required to draw all keys when hardware acceleration is on.
         if (drawAllKeys || isHardwareAccelerated) {
-            mClipRegion.set(0, 0, width, height);
-        } else {
-            mClipRegion.setEmpty();
-            for (final Key key : mInvalidatedKeys) {
-                if (mKeyboard.hasKey(key)) {
-                    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);
-                }
-            }
-        }
-        if (!isHardwareAccelerated) {
-            canvas.clipRegion(mClipRegion, Region.Op.REPLACE);
-            // Draw keyboard background.
-            canvas.drawColor(Color.BLACK, PorterDuff.Mode.CLEAR);
-            final Drawable background = getBackground();
-            if (background != null) {
+            if (!isHardwareAccelerated && background != null) {
+                // Need to draw keyboard background on {@link #mOffscreenBuffer}.
+                canvas.drawColor(Color.BLACK, PorterDuff.Mode.CLEAR);
                 background.draw(canvas);
             }
-        }
-
-        // TODO: Confirm if it's really required to draw all keys when hardware acceleration is on.
-        if (drawAllKeys || isHardwareAccelerated) {
             // Draw all keys.
-            for (final Key key : mKeyboard.getSortedKeys()) {
+            for (final Key key : keyboard.getSortedKeys()) {
                 onDrawKey(key, canvas, paint);
             }
         } else {
-            // Draw invalidated keys.
             for (final Key key : mInvalidatedKeys) {
-                if (mKeyboard.hasKey(key)) {
-                    onDrawKey(key, canvas, paint);
+                if (!keyboard.hasKey(key)) {
+                    continue;
                 }
+                if (background != null) {
+                    // Need to redraw key's background on {@link #mOffscreenBuffer}.
+                    final int x = key.getX() + getPaddingLeft();
+                    final int y = key.getY() + getPaddingTop();
+                    mClipRect.set(x, y, x + key.getWidth(), y + key.getHeight());
+                    canvas.save();
+                    canvas.clipRect(mClipRect);
+                    canvas.drawColor(Color.BLACK, PorterDuff.Mode.CLEAR);
+                    background.draw(canvas);
+                    canvas.restore();
+                }
+                onDrawKey(key, canvas, paint);
             }
         }
 
@@ -319,20 +317,22 @@
         mInvalidateAllKeys = false;
     }
 
-    private void onDrawKey(final Key key, final Canvas canvas, final Paint paint) {
+    private void onDrawKey(@Nonnull final Key key, @Nonnull final Canvas canvas,
+            @Nonnull final Paint paint) {
         final int keyDrawX = key.getDrawX() + getPaddingLeft();
         final int keyDrawY = key.getY() + getPaddingTop();
         canvas.translate(keyDrawX, keyDrawY);
 
-        final int keyHeight = mKeyboard.mMostCommonKeyHeight - mKeyboard.mVerticalGap;
         final KeyVisualAttributes attr = key.getVisualAttributes();
-        final KeyDrawParams params = mKeyDrawParams.mayCloneAndUpdateParams(keyHeight, attr);
+        final KeyDrawParams params = mKeyDrawParams.mayCloneAndUpdateParams(key.getHeight(), attr);
         params.mAnimAlpha = Constants.Color.ALPHA_OPAQUE;
 
         if (!key.isSpacer()) {
             final Drawable background = key.selectBackgroundDrawable(
                     mKeyBackground, mFunctionalKeyBackground, mSpacebarBackground);
-            onDrawKeyBackground(key, canvas, background);
+            if (background != null) {
+                onDrawKeyBackground(key, canvas, background);
+            }
         }
         onDrawKeyTopVisuals(key, canvas, paint, params);
 
@@ -340,8 +340,8 @@
     }
 
     // Draw key background.
-    protected void onDrawKeyBackground(final Key key, final Canvas canvas,
-            final Drawable background) {
+    protected void onDrawKeyBackground(@Nonnull final Key key, @Nonnull final Canvas canvas,
+            @Nonnull final Drawable background) {
         final int keyWidth = key.getDrawWidth();
         final int keyHeight = key.getHeight();
         final int bgWidth, bgHeight, bgX, bgY;
@@ -373,15 +373,17 @@
     }
 
     // Draw key top visuals.
-    protected void onDrawKeyTopVisuals(final Key key, final Canvas canvas, final Paint paint,
-            final KeyDrawParams params) {
+    protected void onDrawKeyTopVisuals(@Nonnull final Key key, @Nonnull final Canvas canvas,
+            @Nonnull final Paint paint, @Nonnull final KeyDrawParams params) {
         final int keyWidth = key.getDrawWidth();
         final int keyHeight = key.getHeight();
         final float centerX = keyWidth * 0.5f;
         final float centerY = keyHeight * 0.5f;
 
         // Draw key label.
-        final Drawable icon = key.getIcon(mKeyboard.mIconsSet, params.mAnimAlpha);
+        final Keyboard keyboard = getKeyboard();
+        final Drawable icon = (keyboard == null) ? null
+                : key.getIcon(keyboard.mIconsSet, params.mAnimAlpha);
         float labelX = centerX;
         float labelBaseline = centerY;
         final String label = key.getLabel();
@@ -500,8 +502,8 @@
     }
 
     // Draw popup hint "..." at the bottom right corner of the key.
-    protected void drawKeyPopupHint(final Key key, final Canvas canvas, final Paint paint,
-            final KeyDrawParams params) {
+    protected void drawKeyPopupHint(@Nonnull final Key key, @Nonnull final Canvas canvas,
+            @Nonnull final Paint paint, @Nonnull final KeyDrawParams params) {
         if (TextUtils.isEmpty(mKeyPopupHintLetter)) {
             return;
         }
@@ -518,15 +520,15 @@
         canvas.drawText(mKeyPopupHintLetter, hintX, hintY, paint);
     }
 
-    protected static void drawIcon(final Canvas canvas, final Drawable icon, final int x,
-            final int y, final int width, final int height) {
+    protected static void drawIcon(@Nonnull final Canvas canvas,@Nonnull final Drawable icon,
+            final int x, final int y, final int width, final int height) {
         canvas.translate(x, y);
         icon.setBounds(0, 0, width, height);
         icon.draw(canvas);
         canvas.translate(-x, -y);
     }
 
-    public Paint newLabelPaint(final Key key) {
+    public Paint newLabelPaint(@Nullable final Key key) {
         final Paint paint = new Paint();
         paint.setAntiAlias(true);
         if (key == null) {
@@ -560,7 +562,7 @@
      * @see #invalidateAllKeys
      */
     public void invalidateKey(@Nullable final Key key) {
-        if (key == null || mInvalidateAllKeys) {
+        if (mInvalidateAllKeys || key == null) {
             return;
         }
         mInvalidatedKeys.add(key);
diff --git a/java/src/com/android/inputmethod/keyboard/internal/KeyboardBuilder.java b/java/src/com/android/inputmethod/keyboard/internal/KeyboardBuilder.java
index c739bf3..51f89c1 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/KeyboardBuilder.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/KeyboardBuilder.java
@@ -36,7 +36,6 @@
 import com.android.inputmethod.latin.common.Constants;
 import com.android.inputmethod.latin.common.StringUtils;
 import com.android.inputmethod.latin.utils.ResourceUtils;
-import com.android.inputmethod.latin.utils.SubtypeLocaleUtils;
 import com.android.inputmethod.latin.utils.XmlParseUtils;
 import com.android.inputmethod.latin.utils.XmlParseUtils.ParseException;
 
@@ -648,7 +647,7 @@
         try {
             final boolean keyboardLayoutSetMatched = matchString(caseAttr,
                     R.styleable.Keyboard_Case_keyboardLayoutSet,
-                    SubtypeLocaleUtils.getKeyboardLayoutSetName(id.mSubtype));
+                    id.mSubtype.getKeyboardLayoutSetName());
             final boolean keyboardLayoutSetElementMatched = matchTypedValue(caseAttr,
                     R.styleable.Keyboard_Case_keyboardLayoutSetElement, id.mElementId,
                     KeyboardId.elementIdToName(id.mElementId));
diff --git a/java/src/com/android/inputmethod/keyboard/internal/LanguageOnSpacebarHelper.java b/java/src/com/android/inputmethod/keyboard/internal/LanguageOnSpacebarHelper.java
index 2a70ef5..8ed8010 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/LanguageOnSpacebarHelper.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/LanguageOnSpacebarHelper.java
@@ -52,7 +52,7 @@
             return FORMAT_TYPE_MULTIPLE;
         }
         final String keyboardLanguage = locales[0].getLanguage();
-        final String keyboardLayout = SubtypeLocaleUtils.getKeyboardLayoutSetName(subtype);
+        final String keyboardLayout = subtype.getKeyboardLayoutSetName();
         int sameLanguageAndLayoutCount = 0;
         for (final InputMethodSubtype ims : mEnabledSubtypes) {
             final String language = SubtypeLocaleUtils.getSubtypeLocale(ims).getLanguage();
diff --git a/java/src/com/android/inputmethod/latin/AssetFileAddress.java b/java/src/com/android/inputmethod/latin/AssetFileAddress.java
index 923f43c..f8d02d6 100644
--- a/java/src/com/android/inputmethod/latin/AssetFileAddress.java
+++ b/java/src/com/android/inputmethod/latin/AssetFileAddress.java
@@ -62,4 +62,9 @@
     public void deleteUnderlyingFile() {
         FileUtils.deleteRecursively(new File(mFilename));
     }
+
+    @Override
+    public String toString() {
+        return String.format("%s (offset=%d, length=%d)", mFilename, mOffset, mLength);
+    }
 }
diff --git a/java/src/com/android/inputmethod/latin/BinaryDictionaryGetter.java b/java/src/com/android/inputmethod/latin/BinaryDictionaryGetter.java
index 46c8d55..5afb62b 100644
--- a/java/src/com/android/inputmethod/latin/BinaryDictionaryGetter.java
+++ b/java/src/com/android/inputmethod/latin/BinaryDictionaryGetter.java
@@ -284,7 +284,8 @@
                 final AssetFileAddress afa = AssetFileAddress.makeFromFileName(f.getPath());
                 if (null != afa) fileList.add(afa);
             } else {
-                Log.e(TAG, "Found a cached dictionary file but cannot read or use it");
+                Log.e(TAG, "Found a cached dictionary file for " + locale.toString()
+                        + " but cannot read or use it");
             }
         }
 
diff --git a/java/src/com/android/inputmethod/latin/RichInputMethodSubtype.java b/java/src/com/android/inputmethod/latin/RichInputMethodSubtype.java
index 03f6d60..ea8d4a2 100644
--- a/java/src/com/android/inputmethod/latin/RichInputMethodSubtype.java
+++ b/java/src/com/android/inputmethod/latin/RichInputMethodSubtype.java
@@ -135,13 +135,18 @@
 
     public boolean isRtlSubtype() {
         // The subtype is considered RTL if the language of the main subtype is RTL.
-        return SubtypeLocaleUtils.isRtlLanguage(mLocales[0]);
+        return LocaleUtils.isRtlLanguage(mLocales[0]);
     }
 
     // TODO: remove this method
     @Nonnull
     public InputMethodSubtype getRawSubtype() { return mSubtype; }
 
+    @Nonnull
+    public String getKeyboardLayoutSetName() {
+        return SubtypeLocaleUtils.getKeyboardLayoutSetName(mSubtype);
+    }
+
     // Dummy no language QWERTY subtype. See {@link R.xml.method}.
     private static final int SUBTYPE_ID_OF_DUMMY_NO_LANGUAGE_SUBTYPE = 0xdde0bfd3;
     private static final String EXTRA_VALUE_OF_DUMMY_NO_LANGUAGE_SUBTYPE =
diff --git a/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java b/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
index 4ef5048..eba9654 100644
--- a/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
+++ b/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
@@ -179,8 +179,8 @@
     public static final int VERSION403 = 403;
     public static final int VERSION4 = VERSION403;
     public static final int VERSION4_DEV = VERSION403;
-    static final int MINIMUM_SUPPORTED_STATIC_VERSION = VERSION202;
-    static final int MAXIMUM_SUPPORTED_STATIC_VERSION = VERSION202;
+    public static final int MINIMUM_SUPPORTED_STATIC_VERSION = VERSION202;
+    public static final int MAXIMUM_SUPPORTED_STATIC_VERSION = VERSION202;
     static final int MINIMUM_SUPPORTED_DYNAMIC_VERSION = VERSION4;
     static final int MAXIMUM_SUPPORTED_DYNAMIC_VERSION = VERSION4_DEV;
 
diff --git a/java/src/com/android/inputmethod/latin/personalization/PersonalizationHelper.java b/java/src/com/android/inputmethod/latin/personalization/PersonalizationHelper.java
index ac2fc07..8c5eb0a 100644
--- a/java/src/com/android/inputmethod/latin/personalization/PersonalizationHelper.java
+++ b/java/src/com/android/inputmethod/latin/personalization/PersonalizationHelper.java
@@ -28,32 +28,45 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.TimeUnit;
 
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+/**
+ * Helps handle and manage personalized dictionaries such as {@link UserHistoryDictionary} and
+ * {@link PersonalizationDictionary}.
+ */
 public class PersonalizationHelper {
     private static final String TAG = PersonalizationHelper.class.getSimpleName();
     private static final boolean DEBUG = false;
+
     private static final ConcurrentHashMap<String, SoftReference<UserHistoryDictionary>>
             sLangUserHistoryDictCache = new ConcurrentHashMap<>();
     private static final ConcurrentHashMap<String, SoftReference<PersonalizationDictionary>>
             sLangPersonalizationDictCache = new ConcurrentHashMap<>();
 
+    @Nonnull
     public static UserHistoryDictionary getUserHistoryDictionary(
-            final Context context, final Locale locale) {
-        final String localeStr = locale.toString();
+            final Context context, final Locale locale, @Nullable final String accountName) {
+        String lookupStr = locale.toString();
+        if (accountName != null) {
+            lookupStr += "." + accountName;
+        }
         synchronized (sLangUserHistoryDictCache) {
-            if (sLangUserHistoryDictCache.containsKey(localeStr)) {
+            if (sLangUserHistoryDictCache.containsKey(lookupStr)) {
                 final SoftReference<UserHistoryDictionary> ref =
-                        sLangUserHistoryDictCache.get(localeStr);
+                        sLangUserHistoryDictCache.get(lookupStr);
                 final UserHistoryDictionary dict = ref == null ? null : ref.get();
                 if (dict != null) {
                     if (DEBUG) {
-                        Log.w(TAG, "Use cached UserHistoryDictionary for " + locale);
+                        Log.d(TAG, "Use cached UserHistoryDictionary for " + locale +
+                                " & account" + accountName);
                     }
                     dict.reloadDictionaryIfRequired();
                     return dict;
                 }
             }
             final UserHistoryDictionary dict = new UserHistoryDictionary(context, locale);
-            sLangUserHistoryDictCache.put(localeStr, new SoftReference<>(dict));
+            sLangUserHistoryDictCache.put(lookupStr, new SoftReference<>(dict));
             return dict;
         }
     }
diff --git a/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java b/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java
index 58782c6..946835c 100644
--- a/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java
@@ -17,30 +17,73 @@
 package com.android.inputmethod.latin.personalization;
 
 import android.content.Context;
+import android.content.SharedPreferences;
+import android.preference.PreferenceManager;
 
 import com.android.inputmethod.annotations.ExternallyReferenced;
+import com.android.inputmethod.annotations.UsedForTesting;
 import com.android.inputmethod.latin.Dictionary;
 import com.android.inputmethod.latin.ExpandableBinaryDictionary;
 import com.android.inputmethod.latin.NgramContext;
 import com.android.inputmethod.latin.common.Constants;
+import com.android.inputmethod.latin.define.ProductionFlags;
+import com.android.inputmethod.latin.settings.LocalSettingsConstants;
 import com.android.inputmethod.latin.utils.DistracterFilter;
 
 import java.io.File;
 import java.util.Locale;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 
 /**
  * Locally gathers stats about the words user types and various other signals like auto-correction
  * cancellation or manual picks. This allows the keyboard to adapt to the typist over time.
  */
 public class UserHistoryDictionary extends DecayingExpandableBinaryDictionaryBase {
-    /* package */ static final String NAME = UserHistoryDictionary.class.getSimpleName();
+    static final String NAME = UserHistoryDictionary.class.getSimpleName();
 
     // TODO: Make this constructor private
-    /* package */ UserHistoryDictionary(final Context context, final Locale locale) {
-        super(context, getDictName(NAME, locale, null /* dictFile */), locale,
-                Dictionary.TYPE_USER_HISTORY, null /* dictFile */);
+    UserHistoryDictionary(final Context context, final Locale locale) {
+        super(context,
+                getUserHistoryDictName(
+                        NAME,
+                        locale,
+                        null /* dictFile */,
+                        context),
+                locale,
+                Dictionary.TYPE_USER_HISTORY,
+                null /* dictFile */);
+    }
+
+    /**
+     * @returns the name of the {@link UserHistoryDictionary}.
+     */
+    @UsedForTesting
+    static String getUserHistoryDictName(final String name, final Locale locale,
+            @Nullable final File dictFile, final Context context) {
+        if (!ProductionFlags.ENABLE_PER_ACCOUNT_USER_HISTORY_DICTIONARY) {
+            return getDictName(name, locale, dictFile);
+        }
+        return getUserHistoryDictNamePerAccount(name, locale, dictFile, context);
+    }
+
+    /**
+     * Uses the currently signed in account to determine the dictionary name.
+     */
+    private static String getUserHistoryDictNamePerAccount(final String name, final Locale locale,
+            @Nullable final File dictFile, final Context context) {
+        if (dictFile != null) {
+            return dictFile.getName();
+        }
+        final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+        final String account = prefs.getString(LocalSettingsConstants.PREF_ACCOUNT_NAME,
+                null /* default */);
+        String dictName = name + "." + locale.toString();
+        if (account != null) {
+            dictName += "." + account;
+        }
+        return dictName;
     }
 
     // Note: This method is called by {@link DictionaryFacilitator} using Java reflection.
@@ -48,7 +91,14 @@
     @ExternallyReferenced
     public static UserHistoryDictionary getDictionary(final Context context, final Locale locale,
             final File dictFile, final String dictNamePrefix) {
-        return PersonalizationHelper.getUserHistoryDictionary(context, locale);
+        final String account;
+        if (ProductionFlags.ENABLE_PER_ACCOUNT_USER_HISTORY_DICTIONARY) {
+            account = PreferenceManager.getDefaultSharedPreferences(context)
+                    .getString(LocalSettingsConstants.PREF_ACCOUNT_NAME, null /* default */);
+        } else {
+            account = null;
+        }
+        return PersonalizationHelper.getUserHistoryDictionary(context, locale, account);
     }
 
     /**
diff --git a/java/src/com/android/inputmethod/latin/settings/CustomInputStylePreference.java b/java/src/com/android/inputmethod/latin/settings/CustomInputStylePreference.java
index 01398f4..b749aa5 100644
--- a/java/src/com/android/inputmethod/latin/settings/CustomInputStylePreference.java
+++ b/java/src/com/android/inputmethod/latin/settings/CustomInputStylePreference.java
@@ -346,8 +346,10 @@
             super(context, android.R.layout.simple_spinner_item);
             setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
 
+            final String[] predefinedKeyboardLayoutSet = context.getResources().getStringArray(
+                    R.array.predefined_layouts);
             // TODO: Should filter out already existing combinations of locale and layout.
-            for (final String layout : SubtypeLocaleUtils.getPredefinedKeyboardLayoutSet()) {
+            for (final String layout : predefinedKeyboardLayoutSet) {
                 // This is a dummy subtype with NO_LANGUAGE, only for display.
                 final InputMethodSubtype subtype =
                         AdditionalSubtypeUtils.createDummyAdditionalSubtype(
diff --git a/java/src/com/android/inputmethod/latin/suggestions/SuggestionStripLayoutHelper.java b/java/src/com/android/inputmethod/latin/suggestions/SuggestionStripLayoutHelper.java
index 27a0f62..7991a24 100644
--- a/java/src/com/android/inputmethod/latin/suggestions/SuggestionStripLayoutHelper.java
+++ b/java/src/com/android/inputmethod/latin/suggestions/SuggestionStripLayoutHelper.java
@@ -50,10 +50,10 @@
 import com.android.inputmethod.latin.R;
 import com.android.inputmethod.latin.SuggestedWords;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
+import com.android.inputmethod.latin.common.LocaleUtils;
 import com.android.inputmethod.latin.settings.Settings;
 import com.android.inputmethod.latin.settings.SettingsValues;
 import com.android.inputmethod.latin.utils.ResourceUtils;
-import com.android.inputmethod.latin.utils.SubtypeLocaleUtils;
 import com.android.inputmethod.latin.utils.ViewLayoutUtils;
 
 import java.util.ArrayList;
@@ -570,8 +570,7 @@
             final boolean isRtlLanguage = (ViewCompat.getLayoutDirection(addToDictionaryStrip)
                     == ViewCompat.LAYOUT_DIRECTION_RTL);
             final String arrow = isRtlLanguage ? RIGHTWARDS_ARROW : LEFTWARDS_ARROW;
-            final boolean isRtlSystem = SubtypeLocaleUtils.isRtlLanguage(
-                    res.getConfiguration().locale);
+            final boolean isRtlSystem = LocaleUtils.isRtlLanguage(res.getConfiguration().locale);
             final CharSequence hint = res.getText(R.string.hint_add_to_dictionary);
             hintText = (isRtlLanguage == isRtlSystem) ? (arrow + hint) : (hint + arrow);
             hintWidth = width - wordWidth;
diff --git a/java/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtils.java b/java/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtils.java
index b36168b..013f024 100644
--- a/java/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtils.java
+++ b/java/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtils.java
@@ -27,11 +27,9 @@
 import android.view.inputmethod.InputMethodSubtype;
 
 import com.android.inputmethod.latin.R;
-import com.android.inputmethod.latin.RichInputMethodSubtype;
 import com.android.inputmethod.latin.common.LocaleUtils;
 import com.android.inputmethod.latin.common.StringUtils;
 
-import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Locale;
 
@@ -56,7 +54,6 @@
     private static volatile boolean sInitialized = false;
     private static final Object sInitializeLock = new Object();
     private static Resources sResources;
-    private static String[] sPredefinedKeyboardLayoutSet;
     // Keyboard layout to its display name map.
     private static final HashMap<String, String> sKeyboardLayoutToDisplayNameMap = new HashMap<>();
     // Keyboard layout to subtype name resource id map.
@@ -103,7 +100,6 @@
         sResources = res;
 
         final String[] predefinedLayoutSet = res.getStringArray(R.array.predefined_layouts);
-        sPredefinedKeyboardLayoutSet = predefinedLayoutSet;
         final String[] layoutDisplayNames = res.getStringArray(
                 R.array.predefined_layout_display_names);
         for (int i = 0; i < predefinedLayoutSet.length; i++) {
@@ -152,10 +148,6 @@
         }
     }
 
-    public static String[] getPredefinedKeyboardLayoutSet() {
-        return sPredefinedKeyboardLayoutSet;
-    }
-
     public static boolean isExceptionalLocale(final String localeString) {
         return sExceptionalLocaleToNameIdsMap.containsKey(localeString);
     }
@@ -334,10 +326,6 @@
     }
 
     @Nonnull
-    public static String getKeyboardLayoutSetName(@Nonnull final RichInputMethodSubtype subtype) {
-        return getKeyboardLayoutSetName(subtype.getRawSubtype());
-    }
-
     public static String getKeyboardLayoutSetName(final InputMethodSubtype subtype) {
         String keyboardLayoutSet = subtype.getExtraValueOf(KEYBOARD_LAYOUT_SET);
         if (keyboardLayoutSet == null) {
@@ -357,22 +345,6 @@
         return keyboardLayoutSet;
     }
 
-    // TODO: Get this information from the framework instead of maintaining here by ourselves.
-    // Sorted list of known Right-To-Left language codes.
-    private static final String[] SORTED_RTL_LANGUAGES = {
-        "ar", // Arabic
-        "fa", // Persian
-        "iw", // Hebrew
-    };
-    static {
-        Arrays.sort(SORTED_RTL_LANGUAGES);
-    }
-
-    public static boolean isRtlLanguage(final Locale locale) {
-        final String language = locale.getLanguage();
-        return Arrays.binarySearch(SORTED_RTL_LANGUAGES, language) >= 0;
-    }
-
     public static String getCombiningRulesExtraValue(final InputMethodSubtype subtype) {
         return subtype.getExtraValueOf(COMBINING_RULES);
     }
diff --git a/native/dicttoolkit/NativeFileList.mk b/native/dicttoolkit/NativeFileList.mk
index 925ec45..d2c8c3a 100644
--- a/native/dicttoolkit/NativeFileList.mk
+++ b/native/dicttoolkit/NativeFileList.mk
@@ -22,8 +22,22 @@
         help_executor.cpp \
         info_executor.cpp \
         makedict_executor.cpp) \
-    utils/command_utils.cpp
+    $(addprefix offdevice_intermediate_dict/, \
+        offdevice_intermediate_dict.cpp) \
+    $(addprefix utils/, \
+        arguments_parser.cpp \
+        command_utils.cpp \
+        utf8_utils.cpp)
 
 LATIN_IME_DICT_TOOLKIT_TEST_FILES := \
+    $(addprefix command_executors/, \
+        diff_executor_test.cpp \
+        header_executor_test.cpp \
+        info_executor_test.cpp \
+        makedict_executor_test.cpp) \
     dict_toolkit_defines_test.cpp \
-    utils/command_utils_test.cpp
+    $(addprefix offdevice_intermediate_dict/, \
+        offdevice_intermediate_dict_test.cpp) \
+    $(addprefix utils/, \
+        command_utils_test.cpp \
+        utf8_utils_test.cpp)
diff --git a/native/dicttoolkit/src/command_executors/diff_executor.cpp b/native/dicttoolkit/src/command_executors/diff_executor.cpp
index 077a400..bf68306 100644
--- a/native/dicttoolkit/src/command_executors/diff_executor.cpp
+++ b/native/dicttoolkit/src/command_executors/diff_executor.cpp
@@ -30,8 +30,19 @@
 
 /* static */ void DiffExecutor::printUsage() {
     printf("*** %s\n", COMMAND_NAME);
-    printf("Usage: %s\n", COMMAND_NAME);
-    printf("Shows differences between two dictionaries.\n\n");
+    getArgumentsParser().printUsage(COMMAND_NAME, "Shows differences between two dictionaries.");
+}
+
+/* static */ const ArgumentsParser DiffExecutor::getArgumentsParser() {
+    std::unordered_map<std::string, OptionSpec> optionSpecs;
+    optionSpecs["p"] = OptionSpec::switchOption("(plumbing) produce output suitable for a script");
+
+    const std::vector<ArgumentSpec> argumentSpecs = {
+        ArgumentSpec::singleArgument("dict1", "dictionary file"),
+        ArgumentSpec::singleArgument("dict2", "dictionary file")
+    };
+
+    return ArgumentsParser(std::move(optionSpecs), std::move(argumentSpecs));
 }
 
 } // namespace dicttoolkit
diff --git a/native/dicttoolkit/src/command_executors/diff_executor.h b/native/dicttoolkit/src/command_executors/diff_executor.h
index fc8dc0d..f92ae49 100644
--- a/native/dicttoolkit/src/command_executors/diff_executor.h
+++ b/native/dicttoolkit/src/command_executors/diff_executor.h
@@ -18,6 +18,7 @@
 #define LATINIME_DICT_TOOLKIT_DIFF_EXECUTOR_H
 
 #include "dict_toolkit_defines.h"
+#include "utils/arguments_parser.h"
 
 namespace latinime {
 namespace dicttoolkit {
@@ -28,6 +29,7 @@
 
     static int run(const int argc, char **argv);
     static void printUsage();
+    static const ArgumentsParser getArgumentsParser();
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(DiffExecutor);
diff --git a/native/dicttoolkit/src/command_executors/header_executor.cpp b/native/dicttoolkit/src/command_executors/header_executor.cpp
index 068a62c..b3d273b 100644
--- a/native/dicttoolkit/src/command_executors/header_executor.cpp
+++ b/native/dicttoolkit/src/command_executors/header_executor.cpp
@@ -30,9 +30,19 @@
 
 /* static */ void HeaderExecutor::printUsage() {
     printf("*** %s\n", COMMAND_NAME);
-    printf("Usage: %s\n", COMMAND_NAME);
-    printf("Prints the header contents of a dictionary file.\n\n");
+    getArgumentsParser().printUsage(COMMAND_NAME,
+            "Prints the header contents of a dictionary file.");
 }
 
+/* static */ const ArgumentsParser HeaderExecutor::getArgumentsParser() {
+    std::unordered_map<std::string, OptionSpec> optionSpecs;
+    optionSpecs["p"] = OptionSpec::switchOption("(plumbing) produce output suitable for a script");
+
+    const std::vector<ArgumentSpec> argumentSpecs = {
+        ArgumentSpec::singleArgument("dict", "prints the header contents of a dictionary file")
+    };
+
+    return ArgumentsParser(std::move(optionSpecs), std::move(argumentSpecs));
+}
 } // namespace dicttoolkit
 } // namespace latinime
diff --git a/native/dicttoolkit/src/command_executors/header_executor.h b/native/dicttoolkit/src/command_executors/header_executor.h
index 4cdeb1a..44cc9cf 100644
--- a/native/dicttoolkit/src/command_executors/header_executor.h
+++ b/native/dicttoolkit/src/command_executors/header_executor.h
@@ -18,6 +18,7 @@
 #define LATINIME_DICT_TOOLKIT_HEADER_EXECUTOR_H
 
 #include "dict_toolkit_defines.h"
+#include "utils/arguments_parser.h"
 
 namespace latinime {
 namespace dicttoolkit {
@@ -28,6 +29,7 @@
 
     static int run(const int argc, char **argv);
     static void printUsage();
+    static const ArgumentsParser getArgumentsParser();
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(HeaderExecutor);
diff --git a/native/dicttoolkit/src/command_executors/info_executor.cpp b/native/dicttoolkit/src/command_executors/info_executor.cpp
index c4d84ca..351da4a 100644
--- a/native/dicttoolkit/src/command_executors/info_executor.cpp
+++ b/native/dicttoolkit/src/command_executors/info_executor.cpp
@@ -17,6 +17,9 @@
 #include "command_executors/info_executor.h"
 
 #include <cstdio>
+#include <string>
+#include <unordered_map>
+#include <vector>
 
 namespace latinime {
 namespace dicttoolkit {
@@ -30,8 +33,21 @@
 
 /* static */ void InfoExecutor::printUsage() {
     printf("*** %s\n", COMMAND_NAME);
-    printf("Usage: %s\n", COMMAND_NAME);
-    printf("Prints various information about a dictionary file.\n\n");
+    getArgumentsParser().printUsage(COMMAND_NAME,
+            "Prints various information about a dictionary file.");
+}
+
+/* static */const ArgumentsParser InfoExecutor::getArgumentsParser() {
+    std::unordered_map<std::string, OptionSpec> optionSpecs;
+    optionSpecs["p"] = OptionSpec::switchOption("(plumbing) produce output suitable for a script");
+
+    const std::vector<ArgumentSpec> argumentSpecs = {
+        ArgumentSpec::singleArgument("dict", "dictionary file name"),
+        ArgumentSpec::variableLengthArguments("word", 0 /* minCount */,
+                ArgumentSpec::UNLIMITED_COUNT, "word to show information")
+    };
+
+    return ArgumentsParser(std::move(optionSpecs), std::move(argumentSpecs));
 }
 
 } // namespace dicttoolkit
diff --git a/native/dicttoolkit/src/command_executors/info_executor.h b/native/dicttoolkit/src/command_executors/info_executor.h
index 4ffa74f..d4106d5 100644
--- a/native/dicttoolkit/src/command_executors/info_executor.h
+++ b/native/dicttoolkit/src/command_executors/info_executor.h
@@ -18,6 +18,7 @@
 #define LATINIME_DICT_TOOLKIT_INFO_EXECUTOR_H
 
 #include "dict_toolkit_defines.h"
+#include "utils/arguments_parser.h"
 
 namespace latinime {
 namespace dicttoolkit {
@@ -28,6 +29,7 @@
 
     static int run(const int argc, char **argv);
     static void printUsage();
+    static const ArgumentsParser getArgumentsParser();
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(InfoExecutor);
diff --git a/native/dicttoolkit/src/command_executors/makedict_executor.cpp b/native/dicttoolkit/src/command_executors/makedict_executor.cpp
index ea62e3c..8a84e80 100644
--- a/native/dicttoolkit/src/command_executors/makedict_executor.cpp
+++ b/native/dicttoolkit/src/command_executors/makedict_executor.cpp
@@ -30,10 +30,25 @@
 
 /* static */ void MakedictExecutor::printUsage() {
     printf("*** %s\n", COMMAND_NAME);
-    printf("Usage: %s\n", COMMAND_NAME);
-    printf("Converts a source dictionary file to one or several outputs.\n"
+    getArgumentsParser().printUsage(COMMAND_NAME,
+            "Converts a source dictionary file to one or several outputs.\n"
             "Source can be a binary dictionary file or a combined format file.\n"
-            "Binary version 2 (Jelly Bean), 4, and combined format outputs are supported.\n\n");
+            "Binary version 2 (Jelly Bean), 4, and combined format outputs are supported.");
+}
+
+/* static */const ArgumentsParser MakedictExecutor::getArgumentsParser() {
+    std::unordered_map<std::string, OptionSpec> optionSpecs;
+    optionSpecs["o"] = OptionSpec::keyValueOption("format", "2",
+            "output format version: 2/4/combined");
+    optionSpecs["t"] = OptionSpec::keyValueOption("mode", "off",
+            "code point table switch: on/off/auto");
+
+    const std::vector<ArgumentSpec> argumentSpecs = {
+        ArgumentSpec::singleArgument("src_dict", "source dictionary file"),
+        ArgumentSpec::singleArgument("dest_dict", "output dictionary file")
+    };
+
+    return ArgumentsParser(std::move(optionSpecs), std::move(argumentSpecs));
 }
 
 } // namespace dicttoolkit
diff --git a/native/dicttoolkit/src/command_executors/makedict_executor.h b/native/dicttoolkit/src/command_executors/makedict_executor.h
index ae1309f..c3de977 100644
--- a/native/dicttoolkit/src/command_executors/makedict_executor.h
+++ b/native/dicttoolkit/src/command_executors/makedict_executor.h
@@ -18,6 +18,7 @@
 #define LATINIME_DICT_TOOLKIT_MAKEDICT_EXECUTOR_H
 
 #include "dict_toolkit_defines.h"
+#include "utils/arguments_parser.h"
 
 namespace latinime {
 namespace dicttoolkit {
@@ -28,6 +29,7 @@
 
     static int run(const int argc, char **argv);
     static void printUsage();
+    static const ArgumentsParser getArgumentsParser();
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(MakedictExecutor);
diff --git a/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict.cpp b/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict.cpp
new file mode 100644
index 0000000..af28131
--- /dev/null
+++ b/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict.cpp
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include "offdevice_intermediate_dict/offdevice_intermediate_dict.h"
+
+#include "offdevice_intermediate_dict/offdevice_intermediate_dict_pt_node.h"
+
+namespace latinime {
+namespace dicttoolkit {
+
+bool OffdeviceIntermediateDict::addWord(const WordProperty &wordProperty) {
+    const CodePointArrayView codePoints = wordProperty.getCodePoints();
+    if (codePoints.empty() || codePoints.size() > MAX_WORD_LENGTH) {
+        return false;
+    }
+    return addWordInner(codePoints, wordProperty, mRootPtNodeArray);
+}
+
+bool OffdeviceIntermediateDict::addWordInner(const CodePointArrayView codePoints,
+        const WordProperty &wordProperty, OffdeviceIntermediateDictPtNodeArray &ptNodeArray) {
+    auto ptNodeList = ptNodeArray.getMutablePtNodeList();
+    auto ptNodeIt = ptNodeList->begin();
+    for (; ptNodeIt != ptNodeList->end(); ++ptNodeIt) {
+        const auto &ptNode = *ptNodeIt;
+        const CodePointArrayView ptNodeCodePoints = ptNode->getPtNodeCodePoints();
+        if (codePoints[0] < ptNodeCodePoints[0]) {
+            continue;
+        }
+        if (codePoints[0] > ptNodeCodePoints[0]) {
+            break;
+        }
+        size_t i = 1;
+        for (; i < codePoints.size(); ++i) {
+            if (i >= ptNodeCodePoints.size()) {
+                // Add new child.
+                return addWordInner(codePoints.skip(i), wordProperty,
+                        ptNode->getChildrenPtNodeArray());
+            }
+            if (codePoints[i] != ptNodeCodePoints[i]) {
+                break;
+            }
+        }
+        if (codePoints.size() == i && codePoints.size() == ptNodeCodePoints.size()) {
+            // All code points matched.
+            if (ptNode->getWordProperty()) {
+                //  Adding the same word multiple times is not supported.
+                return false;
+            }
+            ptNodeList->insert(ptNodeIt,
+                    std::make_shared<OffdeviceIntermediateDictPtNode>(wordProperty, *ptNode));
+            ptNodeList->erase(ptNodeIt);
+            return true;
+        }
+        // The (i+1)-th elements are different.
+        // Create and Add new parent ptNode for the common part.
+        auto newPtNode = codePoints.size() == i
+                ? std::make_shared<OffdeviceIntermediateDictPtNode>(codePoints, wordProperty)
+                : std::make_shared<OffdeviceIntermediateDictPtNode>(codePoints.limit(i));
+        ptNodeList->insert(ptNodeIt, newPtNode);
+        OffdeviceIntermediateDictPtNodeArray &childrenPtNodeArray =
+                newPtNode->getChildrenPtNodeArray();
+        // Add new child for the existing ptNode.
+        childrenPtNodeArray.getMutablePtNodeList()->push_back(
+                std::make_shared<OffdeviceIntermediateDictPtNode>(
+                        ptNodeCodePoints.skip(i), *ptNode));
+        ptNodeList->erase(ptNodeIt);
+        if (codePoints.size() != i) {
+            // Add a child for the new word.
+            return addWordInner(codePoints.skip(i), wordProperty, childrenPtNodeArray);
+        }
+        return true;
+    }
+    ptNodeList->insert(ptNodeIt,
+            std::make_shared<OffdeviceIntermediateDictPtNode>(codePoints, wordProperty));
+    return true;
+}
+
+const WordProperty *OffdeviceIntermediateDict::getWordProperty(
+        const CodePointArrayView codePoints) const {
+    const OffdeviceIntermediateDictPtNodeArray *ptNodeArray = &mRootPtNodeArray;
+    for (size_t i = 0; i < codePoints.size();) {
+        bool foundNext = false;
+        for (const auto ptNode : ptNodeArray->getPtNodeList()) {
+            const CodePointArrayView ptNodeCodePoints = ptNode->getPtNodeCodePoints();
+            if (codePoints[i] < ptNodeCodePoints[0]) {
+                continue;
+            }
+            if (codePoints[i] > ptNodeCodePoints[0]
+                     || codePoints.size() < ptNodeCodePoints.size()) {
+                return nullptr;
+            }
+            for (size_t j = 1; j < ptNodeCodePoints.size(); ++j) {
+                if (codePoints[i + j] != ptNodeCodePoints[j]) {
+                    return nullptr;
+                }
+            }
+            i += ptNodeCodePoints.size();
+            if (i == codePoints.size()) {
+                return ptNode->getWordProperty();
+            }
+            ptNodeArray = &ptNode->getChildrenPtNodeArray();
+            foundNext = true;
+            break;
+        }
+        if (!foundNext) {
+            break;
+        }
+    }
+    return nullptr;
+}
+
+} // namespace dicttoolkit
+} // namespace latinime
diff --git a/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict.h b/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict.h
new file mode 100644
index 0000000..13d26ba
--- /dev/null
+++ b/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2014 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_DICT_TOOLKIT_OFFDEVICE_INTERMEDIATE_DICT_H
+#define LATINIME_DICT_TOOLKIT_OFFDEVICE_INTERMEDIATE_DICT_H
+
+#include "dict_toolkit_defines.h"
+#include "offdevice_intermediate_dict/offdevice_intermediate_dict_header.h"
+#include "offdevice_intermediate_dict/offdevice_intermediate_dict_pt_node_array.h"
+#include "suggest/core/dictionary/property/word_property.h"
+#include "utils/int_array_view.h"
+
+namespace latinime {
+namespace dicttoolkit {
+
+/**
+ * On memory patricia trie to represent a dictionary.
+ */
+class OffdeviceIntermediateDict final {
+ public:
+    OffdeviceIntermediateDict(const OffdeviceIntermediateDictHeader &header)
+            : mHeader(header), mRootPtNodeArray() {}
+
+    bool addWord(const WordProperty &wordProperty);
+    // The returned value will be invalid after modifying the dictionary. e.g. calling addWord().
+    const WordProperty *getWordProperty(const CodePointArrayView codePoints) const;
+    const OffdeviceIntermediateDictHeader &getHeader() const { return mHeader; }
+
+ private:
+    DISALLOW_ASSIGNMENT_OPERATOR(OffdeviceIntermediateDict);
+
+    const OffdeviceIntermediateDictHeader mHeader;
+    OffdeviceIntermediateDictPtNodeArray mRootPtNodeArray;
+
+    bool addWordInner(const CodePointArrayView codePoints, const WordProperty &wordProperty,
+            OffdeviceIntermediateDictPtNodeArray &ptNodeArray);
+};
+
+} // namespace dicttoolkit
+} // namespace latinime
+#endif // LATINIME_DICT_TOOLKIT_OFFDEVICE_INTERMEDIATE_DICT_H
diff --git a/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict_header.h b/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict_header.h
new file mode 100644
index 0000000..440627a
--- /dev/null
+++ b/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict_header.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2014 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_DICT_TOOLKIT_OFFDEVICE_INTERMEDIATE_DICT_HEADER_H
+#define LATINIME_DICT_TOOLKIT_OFFDEVICE_INTERMEDIATE_DICT_HEADER_H
+
+#include <map>
+#include <vector>
+
+#include "dict_toolkit_defines.h"
+
+namespace latinime {
+namespace dicttoolkit {
+
+class OffdeviceIntermediateDictHeader final {
+ public:
+    using AttributeMap = std::map<std::vector<int>, std::vector<int>>;
+
+    OffdeviceIntermediateDictHeader(const AttributeMap &attributesMap)
+            : mAttributeMap(attributesMap) {}
+
+ private:
+    DISALLOW_DEFAULT_CONSTRUCTOR(OffdeviceIntermediateDictHeader);
+    DISALLOW_ASSIGNMENT_OPERATOR(OffdeviceIntermediateDictHeader);
+
+    const AttributeMap mAttributeMap;
+};
+
+} // namespace dicttoolkit
+} // namespace latinime
+#endif // LATINIME_DICT_TOOLKIT_OFFDEVICE_INTERMEDIATE_DICT_HEADER_H
diff --git a/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict_pt_node.h b/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict_pt_node.h
new file mode 100644
index 0000000..721ccd7
--- /dev/null
+++ b/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict_pt_node.h
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2014 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_DICT_TOOLKIT_OFFDEVICE_INTERMEDIATE_DICT_PT_NODE_H
+#define LATINIME_DICT_TOOLKIT_OFFDEVICE_INTERMEDIATE_DICT_PT_NODE_H
+
+#include <memory>
+
+#include "dict_toolkit_defines.h"
+#include "offdevice_intermediate_dict/offdevice_intermediate_dict_pt_node_array.h"
+#include "suggest/core/dictionary/property/word_property.h"
+#include "utils/int_array_view.h"
+
+namespace latinime {
+namespace dicttoolkit {
+
+class OffdeviceIntermediateDictPtNode final {
+ public:
+    // Non-terminal
+    OffdeviceIntermediateDictPtNode(const CodePointArrayView ptNodeCodePoints)
+            : mPtNodeCodePoints(ptNodeCodePoints.toVector()), mChildrenPtNodeArray(),
+              mWortProperty(nullptr) {}
+
+    // Terminal
+    OffdeviceIntermediateDictPtNode(const CodePointArrayView ptNodeCodePoints,
+            const WordProperty &wordProperty)
+             : mPtNodeCodePoints(ptNodeCodePoints.toVector()), mChildrenPtNodeArray(),
+               mWortProperty(new WordProperty(wordProperty)) {}
+
+    // Replacing PtNodeCodePoints.
+    OffdeviceIntermediateDictPtNode(const CodePointArrayView ptNodeCodePoints,
+            const OffdeviceIntermediateDictPtNode &ptNode)
+            : mPtNodeCodePoints(ptNodeCodePoints.toVector()),
+              mChildrenPtNodeArray(ptNode.mChildrenPtNodeArray),
+              mWortProperty(new WordProperty(*ptNode.mWortProperty)) {}
+
+    // Replacing WordProperty.
+    OffdeviceIntermediateDictPtNode(const WordProperty &wordProperty,
+            const OffdeviceIntermediateDictPtNode &ptNode)
+            : mPtNodeCodePoints(ptNode.mPtNodeCodePoints),
+              mChildrenPtNodeArray(ptNode.mChildrenPtNodeArray),
+              mWortProperty(new WordProperty(wordProperty)) {}
+
+    const WordProperty *getWordProperty() const {
+        return mWortProperty.get();
+    }
+
+    const CodePointArrayView getPtNodeCodePoints() const {
+        return CodePointArrayView(mPtNodeCodePoints);
+    }
+
+    OffdeviceIntermediateDictPtNodeArray &getChildrenPtNodeArray() {
+        return mChildrenPtNodeArray;
+    }
+
+ private:
+    DISALLOW_COPY_AND_ASSIGN(OffdeviceIntermediateDictPtNode);
+
+    const std::vector<int> mPtNodeCodePoints;
+    OffdeviceIntermediateDictPtNodeArray mChildrenPtNodeArray;
+    const std::unique_ptr<WordProperty> mWortProperty;
+};
+
+} // namespace dicttoolkit
+} // namespace latinime
+#endif // LATINIME_DICT_TOOLKIT_OFFDEVICE_INTERMEDIATE_DICT_PT_NODE_H
diff --git a/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict_pt_node_array.h b/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict_pt_node_array.h
new file mode 100644
index 0000000..f87456c
--- /dev/null
+++ b/native/dicttoolkit/src/offdevice_intermediate_dict/offdevice_intermediate_dict_pt_node_array.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2014 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_DICT_TOOLKIT_OFFDEVICE_INTERMEDIATE_DICT_PT_NODE_ARRAY_H
+#define LATINIME_DICT_TOOLKIT_OFFDEVICE_INTERMEDIATE_DICT_PT_NODE_ARRAY_H
+
+#include <list>
+#include <memory>
+
+#include "dict_toolkit_defines.h"
+
+namespace latinime {
+namespace dicttoolkit {
+
+class OffdeviceIntermediateDictPtNode;
+
+class OffdeviceIntermediateDictPtNodeArray final {
+ public:
+    const std::list<std::shared_ptr<OffdeviceIntermediateDictPtNode>> &getPtNodeList() const {
+        return mPtNodes;
+    }
+
+    std::list<std::shared_ptr<OffdeviceIntermediateDictPtNode>> *getMutablePtNodeList() {
+        return &mPtNodes;
+    }
+
+ private:
+    DISALLOW_ASSIGNMENT_OPERATOR(OffdeviceIntermediateDictPtNodeArray);
+
+    std::list<std::shared_ptr<OffdeviceIntermediateDictPtNode>> mPtNodes;
+};
+
+} // namespace dicttoolkit
+} // namespace latinime
+#endif // LATINIME_DICT_TOOLKIT_OFFDEVICE_INTERMEDIATE_DICT_PT_NODE_ARRAY_H
diff --git a/native/dicttoolkit/src/utils/arguments_and_options.h b/native/dicttoolkit/src/utils/arguments_and_options.h
new file mode 100644
index 0000000..d8f5985
--- /dev/null
+++ b/native/dicttoolkit/src/utils/arguments_and_options.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2014 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_DICT_TOOLKIT_ARGUMENTS_AND_OPTIONS_H
+#define LATINIME_DICT_TOOLKIT_ARGUMENTS_AND_OPTIONS_H
+
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "dict_toolkit_defines.h"
+
+namespace latinime {
+namespace dicttoolkit {
+
+class ArgumentsAndOptions {
+ public:
+    ArgumentsAndOptions() : mIsValid(false), mOptions(), mArguments() {}
+
+    ArgumentsAndOptions(std::unordered_map<std::string, std::string> &&options,
+            std::unordered_map<std::string, std::vector<std::string>> &&arguments)
+            : mIsValid(true), mOptions(std::move(options)), mArguments(std::move(arguments)) {}
+
+    bool isValid() const {
+        return mIsValid;
+    }
+
+    bool hasOption(const std::string &optionName) const {
+        return mOptions.find(optionName) != mOptions.end();
+    }
+
+ private:
+    DISALLOW_ASSIGNMENT_OPERATOR(ArgumentsAndOptions);
+
+    const bool mIsValid;
+    const std::unordered_map<std::string, std::string> mOptions;
+    const std::unordered_map<std::string, std::vector<std::string>> mArguments;
+};
+} // namespace dicttoolkit
+} // namespace latinime
+#endif // LATINIME_DICT_TOOLKIT_ARGUMENTS_AND_OPTIONS_H
diff --git a/native/dicttoolkit/src/utils/arguments_parser.cpp b/native/dicttoolkit/src/utils/arguments_parser.cpp
new file mode 100644
index 0000000..039dae3
--- /dev/null
+++ b/native/dicttoolkit/src/utils/arguments_parser.cpp
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include "utils/arguments_parser.h"
+
+namespace latinime {
+namespace dicttoolkit {
+
+const int ArgumentSpec::UNLIMITED_COUNT = -1;
+
+bool ArgumentsParser::validateSpecs() const {
+    for (size_t i = 0; i < mArgumentSpecs.size() ; ++i) {
+        if (mArgumentSpecs[i].getMinCount() != mArgumentSpecs[i].getMaxCount()
+                && i != mArgumentSpecs.size() - 1) {
+            AKLOGE("Variable length argument must be at the end.");
+            return false;
+        }
+    }
+    return true;
+}
+
+void ArgumentsParser::printUsage(const std::string &commandName,
+        const std::string &description) const {
+    printf("Usage: %s", commandName.c_str());
+    for (const auto &option : mOptionSpecs) {
+        const std::string &optionName = option.first;
+        const OptionSpec &spec = option.second;
+        printf(" [-%s", optionName.c_str());
+        if (spec.takeValue()) {
+            printf(" <%s>", spec.getValueName().c_str());
+        }
+        printf("]");
+    }
+    for (const auto &argSpec : mArgumentSpecs) {
+        if (argSpec.getMinCount() == 0 && argSpec.getMaxCount() == 1) {
+            printf(" [<%s>]", argSpec.getName().c_str());
+        } else if (argSpec.getMinCount() == 1 && argSpec.getMaxCount() == 1) {
+            printf(" <%s>", argSpec.getName().c_str());
+        } else if (argSpec.getMinCount() == 0) {
+            printf(" [<%s>...]", argSpec.getName().c_str());
+        } else if (argSpec.getMinCount() == 1) {
+            printf(" <%s>...", argSpec.getName().c_str());
+        }
+    }
+    printf("\n%s\n\n", description.c_str());
+    for (const auto &option : mOptionSpecs) {
+        const std::string &optionName = option.first;
+        const OptionSpec &spec = option.second;
+        printf(" -%s", optionName.c_str());
+        if (spec.takeValue()) {
+            printf(" <%s>", spec.getValueName().c_str());
+        }
+        printf("\t\t\t%s", spec.getDescription().c_str());
+        if (spec.takeValue() && !spec.getDefaultValue().empty()) {
+            printf("\tdefault: %s", spec.getDefaultValue().c_str());
+        }
+        printf("\n");
+    }
+    for (const auto &argSpec : mArgumentSpecs) {
+        printf(" <%s>\t\t\t%s\n", argSpec.getName().c_str(), argSpec.getDescription().c_str());
+    }
+    printf("\n\n");
+}
+
+const ArgumentsAndOptions ArgumentsParser::parseArguments(const int argc, char **argv) const {
+    // TODO: Implement
+    return ArgumentsAndOptions();
+}
+
+} // namespace dicttoolkit
+} // namespace latinime
diff --git a/native/dicttoolkit/src/utils/arguments_parser.h b/native/dicttoolkit/src/utils/arguments_parser.h
new file mode 100644
index 0000000..be2dd87
--- /dev/null
+++ b/native/dicttoolkit/src/utils/arguments_parser.h
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2014 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_DICT_TOOLKIT_ARGUMENTS_PARSER_H
+#define LATINIME_DICT_TOOLKIT_ARGUMENTS_PARSER_H
+
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "dict_toolkit_defines.h"
+#include "utils/arguments_and_options.h"
+
+namespace latinime {
+namespace dicttoolkit {
+
+class OptionSpec {
+ public:
+    // Default constructor and assignment operator is enabled to be used with std::unordered_map.
+    OptionSpec() = default;
+    OptionSpec &operator=(const OptionSpec &) = default;
+
+    static OptionSpec keyValueOption(const std::string &valueName, const std::string &defaultValue,
+            const std::string &description) {
+        return OptionSpec(true /* takeValue */, valueName, defaultValue, description);
+    }
+
+    static OptionSpec switchOption(const std::string &description) {
+        return OptionSpec(false /* takeValue */, "" /* valueName */, "" /* defaultValue */,
+                description);
+    }
+
+    bool takeValue() const { return mTakeValue; }
+    const std::string &getValueName() const { return mValueName; }
+    const std::string &getDefaultValue() const { return mDefaultValue; }
+    const std::string &getDescription() const { return mDescription; }
+
+ private:
+    OptionSpec(const bool takeValue, const std::string &valueName, const std::string &defaultValue,
+            const std::string &description)
+            : mTakeValue(takeValue), mValueName(valueName), mDefaultValue(defaultValue),
+              mDescription(description) {}
+
+    // Whether the option have to be used with a value or just a switch.
+    // e.g. 'f' in "command -f /path/to/file" is mTakeValue == true.
+    //      'f' in "command -f -t" is mTakeValue == false.
+    bool mTakeValue;
+    // Name of the value used to show usage.
+    std::string mValueName;
+    std::string mDefaultValue;
+    std::string mDescription;
+};
+
+class ArgumentSpec {
+ public:
+    static const int UNLIMITED_COUNT;
+
+    static ArgumentSpec singleArgument(const std::string &name, const std::string &description) {
+        return ArgumentSpec(name, 1 /* minCount */, 1 /* maxCount */, description);
+    }
+
+    static ArgumentSpec variableLengthArguments(const std::string &name, const int minCount,
+            const int maxCount, const std::string &description) {
+        return ArgumentSpec(name, minCount, maxCount, description);
+    }
+
+    const std::string &getName() const { return mName; }
+    int getMinCount() const { return mMinCount; }
+    int getMaxCount() const { return mMaxCount; }
+    const std::string &getDescription() const { return mDescription; }
+
+ private:
+    DISALLOW_DEFAULT_CONSTRUCTOR(ArgumentSpec);
+
+    ArgumentSpec(const std::string &name, const int minCount, const int maxCount,
+            const std::string &description)
+            : mName(name), mMinCount(minCount), mMaxCount(maxCount), mDescription(description) {}
+
+    const std::string mName;
+    const int mMinCount;
+    const int mMaxCount;
+    const std::string mDescription;
+};
+
+class ArgumentsParser {
+ public:
+    ArgumentsParser(std::unordered_map<std::string, OptionSpec> &&optionSpecs,
+            std::vector<ArgumentSpec> &&argumentSpecs)
+            : mOptionSpecs(std::move(optionSpecs)), mArgumentSpecs(std::move(argumentSpecs)) {}
+
+    const ArgumentsAndOptions parseArguments(const int argc, char **argv) const;
+    bool validateSpecs() const;
+    void printUsage(const std::string &commandName, const std::string &description) const;
+
+ private:
+    DISALLOW_DEFAULT_CONSTRUCTOR(ArgumentsParser);
+    DISALLOW_ASSIGNMENT_OPERATOR(ArgumentsParser);
+
+    const std::unordered_map<std::string, OptionSpec> mOptionSpecs;
+    const std::vector<ArgumentSpec> mArgumentSpecs;
+};
+
+} // namespace dicttoolkit
+} // namespace latinime
+#endif // LATINIME_DICT_TOOLKIT_ARGUMENTS_PARSER_H
diff --git a/native/dicttoolkit/src/utils/utf8_utils.cpp b/native/dicttoolkit/src/utils/utf8_utils.cpp
new file mode 100644
index 0000000..0f349f5
--- /dev/null
+++ b/native/dicttoolkit/src/utils/utf8_utils.cpp
@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include "utils/utf8_utils.h"
+
+#include "utils/char_utils.h"
+
+namespace latinime {
+namespace dicttoolkit {
+
+const size_t Utf8Utils::MAX_SEQUENCE_SIZE_FOR_A_CODE_POINT = 4;
+const uint8_t Utf8Utils::FIRST_BYTE_MARKER_MASKS[] = {0, 0x80, 0xE0, 0xF0, 0xF8};
+const uint8_t Utf8Utils::FIRST_BYTE_MARKERS[] = {0, 0x00, 0xC0, 0xE0, 0xF0};
+const uint8_t Utf8Utils::FIRST_BYTE_CODE_POINT_BITS_MASKS[] = {0, 0x7F, 0x1F, 0x0F, 0x03};
+const int Utf8Utils::MAX_ENCODED_CODE_POINT_VALUES[] = {-1, 0x7F, 0x7FF, 0xFFFF, 0x10FFFF};
+
+const uint8_t Utf8Utils::TRAILING_BYTE_CODE_POINT_BITS_MASK = 0x3F;
+const uint8_t Utf8Utils::TRAILING_BYTE_MARKER = 0x80;
+const size_t Utf8Utils::CODE_POINT_BIT_COUNT_IN_TRAILING_BYTE = 6;
+
+/* static */ std::vector<int> Utf8Utils::getCodePoints(const std::string &utf8Str) {
+    std::vector<int> codePoints;
+    int remainingByteCountForCurrentCodePoint = 0;
+    int currentCodePointSequenceSize = 0;
+    int codePoint = 0;
+    for (const char c : utf8Str) {
+        if (remainingByteCountForCurrentCodePoint == 0) {
+            currentCodePointSequenceSize = getSequenceSizeByCheckingFirstByte(c);
+            if (currentCodePointSequenceSize <= 0) {
+                AKLOGE("%x is an invalid utf8 first byte value.", c);
+                return std::vector<int>();
+            }
+            remainingByteCountForCurrentCodePoint = currentCodePointSequenceSize;
+            codePoint = maskFirstByte(c, remainingByteCountForCurrentCodePoint);
+        } else {
+            codePoint <<= CODE_POINT_BIT_COUNT_IN_TRAILING_BYTE;
+            codePoint += maskTrailingByte(c);
+        }
+        remainingByteCountForCurrentCodePoint--;
+        if (remainingByteCountForCurrentCodePoint == 0) {
+            if (codePoint <= MAX_ENCODED_CODE_POINT_VALUES[currentCodePointSequenceSize - 1]) {
+                AKLOGE("%d bytes encode for codePoint(%x) is a redundant UTF-8 sequence.",
+                        currentCodePointSequenceSize,  codePoint);
+                return std::vector<int>();
+            }
+            codePoints.push_back(codePoint);
+        }
+    }
+    return codePoints;
+}
+
+/* static */ int Utf8Utils::getSequenceSizeByCheckingFirstByte(const uint8_t firstByte) {
+    for (size_t i = 1; i <= MAX_SEQUENCE_SIZE_FOR_A_CODE_POINT; ++i) {
+        if ((firstByte & FIRST_BYTE_MARKER_MASKS[i]) == FIRST_BYTE_MARKERS[i]) {
+            return i;
+        }
+    }
+    // Not a valid utf8 char first byte.
+    return -1;
+}
+
+/* static */ AK_FORCE_INLINE int Utf8Utils::maskFirstByte(const uint8_t firstByte,
+        const int sequenceSize) {
+    return firstByte & FIRST_BYTE_CODE_POINT_BITS_MASKS[sequenceSize];
+}
+
+/* static */ AK_FORCE_INLINE int Utf8Utils::maskTrailingByte(const uint8_t secondOrLaterByte) {
+    return secondOrLaterByte & TRAILING_BYTE_CODE_POINT_BITS_MASK;
+}
+
+/* static */ std::string Utf8Utils::getUtf8String(const CodePointArrayView codePoints) {
+    std::string utf8String;
+    for (const int codePoint : codePoints) {
+        const int sequenceSize = getSequenceSizeToEncodeCodePoint(codePoint);
+        if (sequenceSize <= 0) {
+            AKLOGE("Cannot encode code point (%d).", codePoint);
+            return std::string();
+        }
+        const int trailingByteCount = sequenceSize - 1;
+        // Output first byte.
+        const int value = codePoint >> (trailingByteCount * CODE_POINT_BIT_COUNT_IN_TRAILING_BYTE);
+        utf8String.push_back(static_cast<char>(value | FIRST_BYTE_MARKERS[sequenceSize]));
+        // Output second and later bytes.
+        for (int i = 1; i < sequenceSize; ++i) {
+            const int shiftAmount = (trailingByteCount - i) * CODE_POINT_BIT_COUNT_IN_TRAILING_BYTE;
+            const int value = (codePoint >> shiftAmount) & TRAILING_BYTE_CODE_POINT_BITS_MASK;
+            utf8String.push_back(static_cast<char>(value | TRAILING_BYTE_MARKER));
+        }
+    }
+    return utf8String;
+}
+
+/* static */ int Utf8Utils::getSequenceSizeToEncodeCodePoint(const int codePoint) {
+    if (codePoint < 0) {
+        return -1;
+    }
+    for (size_t i = 1; i <= MAX_SEQUENCE_SIZE_FOR_A_CODE_POINT; ++i) {
+        if (codePoint <= MAX_ENCODED_CODE_POINT_VALUES[i]) {
+            return i;
+        }
+    }
+    return -1;
+}
+
+} // namespace dicttoolkit
+} // namespace latinime
diff --git a/native/dicttoolkit/src/utils/utf8_utils.h b/native/dicttoolkit/src/utils/utf8_utils.h
new file mode 100644
index 0000000..35818e5
--- /dev/null
+++ b/native/dicttoolkit/src/utils/utf8_utils.h
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2014 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_DICT_TOOLKIT_UTF8_UTILS_H
+#define LATINIME_DICT_TOOLKIT_UTF8_UTILS_H
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+#include "dict_toolkit_defines.h"
+#include "utils/int_array_view.h"
+
+namespace latinime {
+namespace dicttoolkit {
+
+class Utf8Utils {
+public:
+    static std::vector<int> getCodePoints(const std::string &utf8Str);
+    static std::string getUtf8String(const CodePointArrayView codePoints);
+
+private:
+    DISALLOW_IMPLICIT_CONSTRUCTORS(Utf8Utils);
+
+    // Values indexed by sequence size.
+    static const size_t MAX_SEQUENCE_SIZE_FOR_A_CODE_POINT;
+    static const uint8_t FIRST_BYTE_MARKER_MASKS[];
+    static const uint8_t FIRST_BYTE_MARKERS[];
+    static const uint8_t FIRST_BYTE_CODE_POINT_BITS_MASKS[];
+    static const int MAX_ENCODED_CODE_POINT_VALUES[];
+
+    static const uint8_t TRAILING_BYTE_CODE_POINT_BITS_MASK;
+    static const uint8_t TRAILING_BYTE_MARKER;
+    static const size_t CODE_POINT_BIT_COUNT_IN_TRAILING_BYTE;
+
+    static int getSequenceSizeByCheckingFirstByte(const uint8_t firstByte);
+    static int maskFirstByte(const uint8_t firstByte, const int encodeSize);
+    static int maskTrailingByte(const uint8_t secondOrLaterByte);
+    static int getSequenceSizeToEncodeCodePoint(const int codePoint);
+};
+} // namespace dicttoolkit
+} // namespace latinime
+#endif // LATINIME_DICT_TOOLKIT_UTF8_UTILS_H
diff --git a/native/dicttoolkit/tests/command_executors/diff_executor_test.cpp b/native/dicttoolkit/tests/command_executors/diff_executor_test.cpp
new file mode 100644
index 0000000..4441414
--- /dev/null
+++ b/native/dicttoolkit/tests/command_executors/diff_executor_test.cpp
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include "command_executors/diff_executor.h"
+
+#include <gtest/gtest.h>
+
+namespace latinime {
+namespace dicttoolkit {
+namespace {
+
+TEST(DiffExecutorTests, TestArguemntSpecs) {
+    EXPECT_TRUE(DiffExecutor::getArgumentsParser().validateSpecs());
+}
+
+} // namespace
+} // namespace dicttoolkit
+} // namespace latinime
diff --git a/native/dicttoolkit/tests/command_executors/header_executor_test.cpp b/native/dicttoolkit/tests/command_executors/header_executor_test.cpp
new file mode 100644
index 0000000..a94150b
--- /dev/null
+++ b/native/dicttoolkit/tests/command_executors/header_executor_test.cpp
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include "command_executors/header_executor.h"
+
+#include <gtest/gtest.h>
+
+namespace latinime {
+namespace dicttoolkit {
+namespace {
+
+TEST(HeaderExecutorTests, TestArguemntSpecs) {
+    EXPECT_TRUE(HeaderExecutor::getArgumentsParser().validateSpecs());
+}
+
+} // namespace
+} // namespace dicttoolkit
+} // namespace latinime
diff --git a/native/dicttoolkit/tests/command_executors/info_executor_test.cpp b/native/dicttoolkit/tests/command_executors/info_executor_test.cpp
new file mode 100644
index 0000000..debe8c6
--- /dev/null
+++ b/native/dicttoolkit/tests/command_executors/info_executor_test.cpp
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include "command_executors/info_executor.h"
+
+#include <gtest/gtest.h>
+
+namespace latinime {
+namespace dicttoolkit {
+namespace {
+
+TEST(InfoExecutorTests, TestArguemntSpecs) {
+    EXPECT_TRUE(InfoExecutor::getArgumentsParser().validateSpecs());
+}
+
+} // namespace
+} // namespace dicttoolkit
+} // namespace latinime
diff --git a/native/dicttoolkit/tests/command_executors/makedict_executor_test.cpp b/native/dicttoolkit/tests/command_executors/makedict_executor_test.cpp
new file mode 100644
index 0000000..44eb3dc
--- /dev/null
+++ b/native/dicttoolkit/tests/command_executors/makedict_executor_test.cpp
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include "command_executors/makedict_executor.h"
+
+#include <gtest/gtest.h>
+
+namespace latinime {
+namespace dicttoolkit {
+namespace {
+
+TEST(MakedictExecutorTests, TestArguemntSpecs) {
+    EXPECT_TRUE(MakedictExecutor::getArgumentsParser().validateSpecs());
+}
+
+} // namespace
+} // namespace dicttoolkit
+} // namespace latinime
diff --git a/native/dicttoolkit/tests/offdevice_intermediate_dict/offdevice_intermediate_dict_test.cpp b/native/dicttoolkit/tests/offdevice_intermediate_dict/offdevice_intermediate_dict_test.cpp
new file mode 100644
index 0000000..f2e24ab
--- /dev/null
+++ b/native/dicttoolkit/tests/offdevice_intermediate_dict/offdevice_intermediate_dict_test.cpp
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include "offdevice_intermediate_dict/offdevice_intermediate_dict.h"
+
+#include <gtest/gtest.h>
+
+#include <vector>
+
+#include "suggest/core/dictionary/property/word_property.h"
+#include "utils/int_array_view.h"
+
+namespace latinime {
+namespace dicttoolkit {
+namespace {
+
+const std::vector<int> getCodePointVector(const char *str) {
+    std::vector<int> codePoints;
+    while (*str) {
+        codePoints.push_back(*str);
+        ++str;
+    }
+    return codePoints;
+}
+
+const WordProperty getDummpWordProperty(const std::vector<int> &&codePoints) {
+    return WordProperty(std::move(codePoints), UnigramProperty(), std::vector<NgramProperty>());
+}
+
+TEST(OffdeviceIntermediateDictTest, TestAddWordProperties) {
+    OffdeviceIntermediateDict dict = OffdeviceIntermediateDict(
+            OffdeviceIntermediateDictHeader(OffdeviceIntermediateDictHeader::AttributeMap()));
+    EXPECT_EQ(nullptr, dict.getWordProperty(CodePointArrayView()));
+
+    const WordProperty wordProperty0 = getDummpWordProperty(getCodePointVector("abcd"));
+    EXPECT_TRUE(dict.addWord(wordProperty0));
+    EXPECT_NE(nullptr, dict.getWordProperty(wordProperty0.getCodePoints()));
+
+    const WordProperty wordProperty1 = getDummpWordProperty(getCodePointVector("efgh"));
+    EXPECT_TRUE(dict.addWord(wordProperty1));
+    EXPECT_NE(nullptr, dict.getWordProperty(wordProperty1.getCodePoints()));
+
+    const WordProperty wordProperty2 = getDummpWordProperty(getCodePointVector("ab"));
+    EXPECT_TRUE(dict.addWord(wordProperty2));
+    EXPECT_NE(nullptr, dict.getWordProperty(wordProperty2.getCodePoints()));
+
+    const WordProperty wordProperty3 = getDummpWordProperty(getCodePointVector("abcdefg"));
+    EXPECT_TRUE(dict.addWord(wordProperty3));
+    EXPECT_NE(nullptr, dict.getWordProperty(wordProperty3.getCodePoints()));
+
+    const WordProperty wordProperty4 = getDummpWordProperty(getCodePointVector("efef"));
+    EXPECT_TRUE(dict.addWord(wordProperty4));
+    EXPECT_NE(nullptr, dict.getWordProperty(wordProperty4.getCodePoints()));
+
+    const WordProperty wordProperty5 = getDummpWordProperty(getCodePointVector("ef"));
+    EXPECT_TRUE(dict.addWord(wordProperty5));
+    EXPECT_NE(nullptr, dict.getWordProperty(wordProperty5.getCodePoints()));
+
+    const WordProperty wordProperty6 = getDummpWordProperty(getCodePointVector("abcd"));
+    EXPECT_FALSE(dict.addWord(wordProperty6)) << "Adding the same word multiple times should fail.";
+
+    EXPECT_NE(nullptr, dict.getWordProperty(wordProperty0.getCodePoints()));
+    EXPECT_NE(nullptr, dict.getWordProperty(wordProperty1.getCodePoints()));
+    EXPECT_NE(nullptr, dict.getWordProperty(wordProperty2.getCodePoints()));
+    EXPECT_NE(nullptr, dict.getWordProperty(wordProperty3.getCodePoints()));
+    EXPECT_NE(nullptr, dict.getWordProperty(wordProperty4.getCodePoints()));
+    EXPECT_NE(nullptr, dict.getWordProperty(wordProperty5.getCodePoints()));
+}
+
+} // namespace
+} // namespace dicttoolkit
+} // namespace latinime
diff --git a/native/dicttoolkit/tests/utils/utf8_utils_test.cpp b/native/dicttoolkit/tests/utils/utf8_utils_test.cpp
new file mode 100644
index 0000000..9c59a8b
--- /dev/null
+++ b/native/dicttoolkit/tests/utils/utf8_utils_test.cpp
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include "utils/utf8_utils.h"
+
+#include <gtest/gtest.h>
+
+#include <vector>
+
+#include "utils/int_array_view.h"
+
+namespace latinime {
+namespace dicttoolkit {
+namespace {
+
+TEST(Utf8UtilsTests, TestGetCodePoints) {
+    {
+        const std::vector<int> codePoints = Utf8Utils::getCodePoints("");
+        EXPECT_EQ(0u, codePoints.size());
+    }
+    {
+        const std::vector<int> codePoints = Utf8Utils::getCodePoints("test");
+        EXPECT_EQ(4u, codePoints.size());
+        EXPECT_EQ('t', codePoints[0]);
+        EXPECT_EQ('e', codePoints[1]);
+        EXPECT_EQ('s', codePoints[2]);
+        EXPECT_EQ('t', codePoints[3]);
+    }
+    {
+        const std::vector<int> codePoints = Utf8Utils::getCodePoints(u8"\u3042a\u03C2\u0410");
+        EXPECT_EQ(4u, codePoints.size());
+        EXPECT_EQ(0x3042, codePoints[0]); // HIRAGANA LETTER A
+        EXPECT_EQ('a', codePoints[1]);
+        EXPECT_EQ(0x03C2, codePoints[2]); // CYRILLIC CAPITAL LETTER A
+        EXPECT_EQ(0x0410, codePoints[3]); // GREEK SMALL LETTER FINAL SIGMA
+    }
+    {
+        const std::vector<int> codePoints = Utf8Utils::getCodePoints(u8"\U0001F36A?\U0001F752");
+        EXPECT_EQ(3u, codePoints.size());
+        EXPECT_EQ(0x1F36A, codePoints[0]); // COOKIE
+        EXPECT_EQ('?', codePoints[1]);
+        EXPECT_EQ(0x1F752, codePoints[2]); // ALCHEMICAL SYMBOL FOR STARRED TRIDENT
+    }
+
+    // Redundant UTF-8 sequences must be rejected.
+    EXPECT_TRUE(Utf8Utils::getCodePoints("\xC0\xAF").empty());
+    EXPECT_TRUE(Utf8Utils::getCodePoints("\xE0\x80\xAF").empty());
+    EXPECT_TRUE(Utf8Utils::getCodePoints("\xF0\x80\x80\xAF").empty());
+}
+
+TEST(Utf8UtilsTests, TestGetUtf8String) {
+    {
+        const std::vector<int> codePoints = {'t', 'e', 's', 't'};
+        EXPECT_EQ("test", Utf8Utils::getUtf8String(CodePointArrayView(codePoints)));
+    }
+    {
+        const std::vector<int> codePoints = {
+                0x00E0 /* LATIN SMALL LETTER A WITH GRAVE */,
+                0x03C2 /* GREEK SMALL LETTER FINAL SIGMA */,
+                0x0430 /* CYRILLIC SMALL LETTER A */,
+                0x3042 /* HIRAGANA LETTER A */,
+                0x1F36A /* COOKIE */,
+                0x1F752 /* ALCHEMICAL SYMBOL FOR STARRED TRIDENT */
+        };
+        EXPECT_EQ(u8"\u00E0\u03C2\u0430\u3042\U0001F36A\U0001F752",
+                Utf8Utils::getUtf8String(CodePointArrayView(codePoints)));
+    }
+}
+
+} // namespace
+} // namespace dicttoolkit
+} // namespace latinime
diff --git a/native/jni/src/utils/int_array_view.h b/native/jni/src/utils/int_array_view.h
index 4083731..e0f6710 100644
--- a/native/jni/src/utils/int_array_view.h
+++ b/native/jni/src/utils/int_array_view.h
@@ -133,6 +133,29 @@
         return std::vector<int>(begin(), end());
     }
 
+    std::vector<IntArrayView> split(const int separator, const int limit = S_INT_MAX) const {
+        if (limit <= 0) {
+            return std::vector<IntArrayView>();
+        }
+        std::vector<IntArrayView> result;
+        if (limit == 1) {
+            result.emplace_back(mPtr, mSize);
+            return result;
+        }
+        size_t startIndex = 0;
+        for (size_t i = 0; i < mSize; ++i) {
+            if (mPtr[i] == separator) {
+                result.emplace_back(mPtr + startIndex, i - startIndex);
+                startIndex = i + 1;
+                if (result.size() >= static_cast<size_t>(limit - 1)) {
+                    break;
+                }
+            }
+        }
+        result.emplace_back(mPtr + startIndex, mSize - startIndex);
+        return result;
+    }
+
  private:
     DISALLOW_ASSIGNMENT_OPERATOR(IntArrayView);
 
diff --git a/native/jni/tests/utils/int_array_view_test.cpp b/native/jni/tests/utils/int_array_view_test.cpp
index 4757a41..2fce633 100644
--- a/native/jni/tests/utils/int_array_view_test.cpp
+++ b/native/jni/tests/utils/int_array_view_test.cpp
@@ -151,5 +151,52 @@
     EXPECT_EQ(std::vector<int>(), CodePointArrayView().toVector());
 }
 
+TEST(IntArrayViewTest, TestSplit) {
+    EXPECT_TRUE(IntArrayView().split(0, 0).empty());
+    {
+        const auto intArrayViews = IntArrayView().split(0, 1);
+        EXPECT_EQ(1u, intArrayViews.size());
+        EXPECT_TRUE(intArrayViews[0].empty());
+    }
+    {
+        const auto intArrayViews = IntArrayView().split(0, 100);
+        EXPECT_EQ(1u, intArrayViews.size());
+        EXPECT_TRUE(intArrayViews[0].empty());
+    }
+
+    const std::vector<int> intVector = {1, 2, 3, 3, 2, 3};
+    const IntArrayView intArrayView(intVector);
+    {
+        const auto intArrayViews = intArrayView.split(2);
+        EXPECT_EQ(3u, intArrayViews.size());
+        EXPECT_EQ(std::vector<int>({1}), intArrayViews[0].toVector());
+        EXPECT_EQ(std::vector<int>({3, 3}), intArrayViews[1].toVector());
+        EXPECT_EQ(std::vector<int>({3}), intArrayViews[2].toVector());
+    }
+    {
+        const auto intArrayViews = intArrayView.split(2, 2);
+        EXPECT_EQ(2u, intArrayViews.size());
+        EXPECT_EQ(std::vector<int>({1}), intArrayViews[0].toVector());
+        EXPECT_EQ(std::vector<int>({3, 3, 2, 3}), intArrayViews[1].toVector());
+    }
+    {
+        const auto intArrayViews = intArrayView.split(2, 1);
+        EXPECT_EQ(1u, intArrayViews.size());
+        EXPECT_EQ(intVector, intArrayViews[0].toVector());
+    }
+    {
+        const auto intArrayViews = intArrayView.split(2, 0);
+        EXPECT_EQ(0u, intArrayViews.size());
+    }
+    {
+        const auto intArrayViews = intArrayView.split(3);
+        EXPECT_EQ(4u, intArrayViews.size());
+        EXPECT_EQ(std::vector<int>({1, 2}), intArrayViews[0].toVector());
+        EXPECT_EQ(std::vector<int>(), intArrayViews[1].toVector());
+        EXPECT_EQ(std::vector<int>({2}), intArrayViews[2].toVector());
+        EXPECT_EQ(std::vector<int>(), intArrayViews[3].toVector());
+    }
+}
+
 }  // namespace
 }  // namespace latinime
diff --git a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
index 6c60fdc..d833b97 100644
--- a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
+++ b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
@@ -26,7 +26,6 @@
 import com.android.inputmethod.latin.common.CodePointUtils;
 import com.android.inputmethod.latin.makedict.BinaryDictDecoderUtils.CharEncoding;
 import com.android.inputmethod.latin.makedict.BinaryDictDecoderUtils.DictBuffer;
-import com.android.inputmethod.latin.makedict.FormatSpec.DictionaryOptions;
 import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
 import com.android.inputmethod.latin.makedict.FusionDictionary.PtNode;
 import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
diff --git a/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java b/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
index 813a712..a84df28 100644
--- a/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
+++ b/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
@@ -16,6 +16,8 @@
 
 package com.android.inputmethod.latin.personalization;
 
+import android.content.SharedPreferences;
+import android.preference.PreferenceManager;
 import android.test.AndroidTestCase;
 import android.test.suitebuilder.annotation.LargeTest;
 import android.util.Log;
@@ -24,6 +26,7 @@
 import com.android.inputmethod.latin.NgramContext;
 import com.android.inputmethod.latin.NgramContext.WordInfo;
 import com.android.inputmethod.latin.common.FileUtils;
+import com.android.inputmethod.latin.settings.LocalSettingsConstants;
 import com.android.inputmethod.latin.utils.BinaryDictionaryUtils;
 import com.android.inputmethod.latin.utils.DistracterFilter;
 
@@ -36,6 +39,8 @@
 import java.util.Random;
 import java.util.concurrent.TimeUnit;
 
+import javax.annotation.Nullable;
+
 /**
  * Unit tests for UserHistoryDictionary
  */
@@ -44,6 +49,7 @@
     private static final String TAG = UserHistoryDictionaryTests.class.getSimpleName();
     private static final int WAIT_FOR_WRITING_FILE_IN_MILLISECONDS = 3000;
     private static final String TEST_LOCALE_PREFIX = "test_";
+    private static final String TEST_ACCOUNT = "account@example.com";
 
     private static final String[] CHARACTERS = {
         "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",
@@ -52,15 +58,18 @@
 
     private int mCurrentTime = 0;
 
+    private SharedPreferences mPrefs;
+    private String mLastKnownAccount = null;
+
     private void removeAllTestDictFiles() {
         final Locale dummyLocale = new Locale(TEST_LOCALE_PREFIX);
-        final String dictName = ExpandableBinaryDictionary.getDictName(
-                UserHistoryDictionary.NAME, dummyLocale, null /* dictFile */);
+        final String dictName = UserHistoryDictionary.getUserHistoryDictName(
+                UserHistoryDictionary.NAME, dummyLocale, null /* dictFile */, getContext());
         final File dictFile = ExpandableBinaryDictionary.getDictFile(
                 mContext, dictName, null /* dictFile */);
         final FilenameFilter filenameFilter = new FilenameFilter() {
             @Override
-            public boolean accept(File dir, String filename) {
+            public boolean accept(final File dir, final String filename) {
                 return filename.startsWith(UserHistoryDictionary.NAME + "." + TEST_LOCALE_PREFIX);
             }
         };
@@ -99,6 +108,12 @@
     @Override
     protected void setUp() throws Exception {
         super.setUp();
+
+        mPrefs = PreferenceManager.getDefaultSharedPreferences(getContext());
+        // Keep track of the current account so that we restore it when the test finishes.
+        mLastKnownAccount = mPrefs.getString(LocalSettingsConstants.PREF_ACCOUNT_NAME, null);
+        updateAccountName(TEST_ACCOUNT);
+
         resetCurrentTimeForTestMode();
         removeAllTestDictFiles();
     }
@@ -107,6 +122,10 @@
     protected void tearDown() throws Exception {
         removeAllTestDictFiles();
         stopTestModeInNativeCode();
+
+        // Restore the account that was present before running the test.
+        updateAccountName(mLastKnownAccount);
+
         super.tearDown();
     }
 
@@ -115,6 +134,14 @@
         setCurrentTimeForTestMode(mCurrentTime);
     }
 
+    private void updateAccountName(@Nullable final String accountName) {
+        if (accountName == null) {
+            mPrefs.edit().remove(LocalSettingsConstants.PREF_ACCOUNT_NAME).apply();
+        } else {
+            mPrefs.edit().putString(LocalSettingsConstants.PREF_ACCOUNT_NAME, accountName).apply();
+        }
+    }
+
     private void forcePassingShortTime() {
         // 3 days.
         final int timeToElapse = (int)TimeUnit.DAYS.toSeconds(3);
@@ -142,7 +169,7 @@
      */
     private static String generateWord(final int value) {
         final int lengthOfChars = CHARACTERS.length;
-        StringBuilder builder = new StringBuilder();
+        final StringBuilder builder = new StringBuilder();
         long lvalue = Math.abs((long)value);
         while (lvalue > 0) {
             builder.append(CHARACTERS[(int)(lvalue % lengthOfChars)]);
@@ -162,7 +189,7 @@
     private static void addToDict(final UserHistoryDictionary dict, final List<String> words,
             final int timestamp) {
         NgramContext ngramContext = NgramContext.EMPTY_PREV_WORDS_INFO;
-        for (String word : words) {
+        for (final String word : words) {
             UserHistoryDictionary.addToDictionary(dict, ngramContext, word, true, timestamp,
                     DistracterFilter.EMPTY_DISTRACTER_FILTER);
             ngramContext = ngramContext.getNextNgramContext(new WordInfo(word));
@@ -204,12 +231,12 @@
         Log.d(TAG, "This test can be used for profiling.");
         Log.d(TAG, "Usage: please set UserHistoryDictionary.PROFILE_SAVE_RESTORE to true.");
         final Locale dummyLocale = getDummyLocale("random_words");
-        final String dictName = ExpandableBinaryDictionary.getDictName(
-                UserHistoryDictionary.NAME, dummyLocale, null /* dictFile */);
+        final String dictName = UserHistoryDictionary.getUserHistoryDictName(
+                UserHistoryDictionary.NAME, dummyLocale, null /* dictFile */, getContext());
         final File dictFile = ExpandableBinaryDictionary.getDictFile(
                 mContext, dictName, null /* dictFile */);
         final UserHistoryDictionary dict = PersonalizationHelper.getUserHistoryDictionary(
-                getContext(), dummyLocale);
+                getContext(), dummyLocale, TEST_ACCOUNT);
 
         final int numberOfWords = 1000;
         final Random random = new Random(123456);
@@ -232,12 +259,12 @@
             // Create filename suffixes for this test.
             for (int i = 0; i < numberOfLanguages; i++) {
                 final Locale dummyLocale = getDummyLocale("switching_languages" + i);
-                final String dictName = ExpandableBinaryDictionary.getDictName(
-                        UserHistoryDictionary.NAME, dummyLocale, null /* dictFile */);
+                final String dictName = UserHistoryDictionary.getUserHistoryDictName(
+                        UserHistoryDictionary.NAME, dummyLocale, null /* dictFile */, getContext());
                 dictFiles[i] = ExpandableBinaryDictionary.getDictFile(
                         mContext, dictName, null /* dictFile */);
                 dicts[i] = PersonalizationHelper.getUserHistoryDictionary(getContext(),
-                        dummyLocale);
+                        dummyLocale, TEST_ACCOUNT);
                 clearHistory(dicts[i]);
             }
 
@@ -262,14 +289,14 @@
 
     public void testAddManyWords() {
         final Locale dummyLocale = getDummyLocale("many_random_words");
-        final String dictName = ExpandableBinaryDictionary.getDictName(
-                UserHistoryDictionary.NAME, dummyLocale, null /* dictFile */);
+        final String dictName = UserHistoryDictionary.getUserHistoryDictName(
+                UserHistoryDictionary.NAME, dummyLocale, null /* dictFile */, getContext());
         final File dictFile = ExpandableBinaryDictionary.getDictFile(
                 mContext, dictName, null /* dictFile */);
         final int numberOfWords = 10000;
         final Random random = new Random(123456);
         final UserHistoryDictionary dict = PersonalizationHelper.getUserHistoryDictionary(
-                getContext(), dummyLocale);
+                getContext(), dummyLocale, TEST_ACCOUNT);
         clearHistory(dict);
         try {
             addAndWriteRandomWords(dict, numberOfWords, random, true /* checksContents */);
@@ -281,7 +308,7 @@
     public void testDecaying() {
         final Locale dummyLocale = getDummyLocale("decaying");
         final UserHistoryDictionary dict = PersonalizationHelper.getUserHistoryDictionary(
-                getContext(), dummyLocale);
+                getContext(), dummyLocale, TEST_ACCOUNT);
         final int numberOfWords = 5000;
         final Random random = new Random(123456);
         resetCurrentTimeForTestMode();
@@ -309,4 +336,9 @@
             assertFalse(dict.isInDictionary(word));
         }
     }
-}
+
+    public void testRandomWords_NullAccount() {
+        updateAccountName(null);
+        testRandomWords();
+    }
+}
\ No newline at end of file
diff --git a/tests/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtilsTests.java b/tests/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtilsTests.java
index 54f478f..03dcdfc 100644
--- a/tests/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtilsTests.java
+++ b/tests/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtilsTests.java
@@ -434,8 +434,8 @@
     // locale layout         |  display name
     // ------ -------------- - ----------------------
     //  sr    south_slavic   F  Српски
-    //  sr_ZZ serbian_qwertz F  српски (латиница)
-    //  sr_ZZ qwerty         T  српски (QWERTY)
+    //  sr_ZZ serbian_qwertz F  Српски (латиница)
+    //  sr_ZZ qwerty         T  Српски (QWERTY)
 
     public void testSerbianLatinSubtypesInSerbianSystemLocale() {
         final RunInLocale<Void> tests = new RunInLocale<Void>() {
@@ -445,12 +445,10 @@
                         SubtypeLocaleUtils.getSubtypeDisplayNameInSystemLocale(SR));
                 // These are preliminary subtypes and may not exist.
                 if (SR_LATN != null) {
-                    // TODO: Uncommented because of the current translation of these strings
-                    // in Seriban are described in Latin script.
-//                    assertEquals("sr_ZZ", "српски (латиница)",
-//                            SubtypeLocaleUtils.getSubtypeDisplayNameInSystemLocale(SR_LATN));
-//                    assertEquals("sr_ZZ", "српски (QWERTY)",
-//                            SubtypeLocaleUtils.getSubtypeDisplayNameInSystemLocale(SR_LATN_QWERTY));
+                    assertEquals("sr_ZZ", "Српски (латиница)",
+                            SubtypeLocaleUtils.getSubtypeDisplayNameInSystemLocale(SR_LATN));
+                    assertEquals("sr_ZZ", "Српски (QWERTY)",
+                            SubtypeLocaleUtils.getSubtypeDisplayNameInSystemLocale(SR_LATN_QWERTY));
                 }
                 return null;
             }
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 3ec28f3..84c3956 100644
--- a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/BinaryDictOffdeviceUtils.java
+++ b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/BinaryDictOffdeviceUtils.java
@@ -186,9 +186,7 @@
                 throw new UnsupportedFormatException("Header too large");
             }
             final byte[] headerBuffer = new byte[totalHeaderSize - tmpBuffer.length];
-            if (headerBuffer.length != input.read(headerBuffer)) {
-                throw new UnsupportedFormatException("File shorter than specified in the header");
-            }
+            readStreamExhaustively(input, headerBuffer);
             final HashMap<String, String> attributes =
                     BinaryDictDecoderUtils.decodeHeaderAttributes(headerBuffer);
             return new DictionaryHeader(totalHeaderSize, new DictionaryOptions(attributes),
@@ -196,6 +194,20 @@
         }
     }
 
+    private static void readStreamExhaustively(final InputStream inputStream,
+            final byte[] outBuffer) throws IOException, UnsupportedFormatException {
+        int readBytes = 0;
+        int readBytesLastCycle = -1;
+        while (readBytes != outBuffer.length) {
+            readBytesLastCycle = inputStream.read(outBuffer, readBytes,
+                    outBuffer.length - readBytes);
+            if (readBytesLastCycle == -1)
+                throw new UnsupportedFormatException("File shorter than specified in the header"
+                        + " (expected " + outBuffer.length + ", read " + readBytes + ")");
+            readBytes += readBytesLastCycle;
+        }
+    }
+
     public static void copy(final InputStream input, final OutputStream output) throws IOException {
         final byte[] buffer = new byte[COPY_BUFFER_SIZE];
         for (int readBytes = input.read(buffer); readBytes >= 0; readBytes = input.read(buffer)) {
diff --git a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Header.java b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Header.java
index 51efdec..ba96c0a 100644
--- a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Header.java
+++ b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Header.java
@@ -62,6 +62,7 @@
         System.out.println("Dictionary : " + dictFile.getAbsolutePath());
         System.out.println("Size : " + dictFile.length() + " bytes");
         System.out.println("Format : Binary dictionary format");
+        System.out.println("Format version : " + header.mFormatOptions.mVersion);
         System.out.println("Packaging : " + spec.describeChain());
         System.out.println("Header attributes :");
         System.out.print(header.mDictionaryOptions.toString(2 /* indentCount */, plumbing));
diff --git a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Package.java b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Package.java
index 4e5c074..3efa10a 100644
--- a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Package.java
+++ b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/Package.java
@@ -16,6 +16,8 @@
 
 package com.android.inputmethod.latin.dicttool;
 
+import com.android.inputmethod.latin.makedict.DictionaryHeader;
+
 import java.io.BufferedOutputStream;
 import java.io.File;
 import java.io.FileNotFoundException;
@@ -77,16 +79,16 @@
             if (mArgs.length != 2) {
                 throw new RuntimeException("Too many/too few arguments for command " + COMMAND);
             }
-            final BinaryDictOffdeviceUtils.DecoderChainSpec<File> decodedSpec =
-                    BinaryDictOffdeviceUtils.getRawDictionaryOrNull(new File(mArgs[0]));
+            final BinaryDictOffdeviceUtils.DecoderChainSpec<DictionaryHeader> decodedSpec =
+                    BinaryDictOffdeviceUtils.decodeDictionaryForProcess(new File(mArgs[0]),
+                            new BinaryDictOffdeviceUtils.HeaderReaderProcessor());
             if (null == decodedSpec) {
                 System.out.println(mArgs[0] + " does not seem to be a dictionary");
                 return;
             }
             System.out.println("Packaging : " + decodedSpec.describeChain());
-            System.out.println("Uncompressed size : " + decodedSpec.mResult.length());
             try (
-                final InputStream input = getFileInputStream(decodedSpec.mResult);
+                final InputStream input = decodedSpec.getStream(new File(mArgs[0]));
                 final OutputStream output = new BufferedOutputStream(
                         getFileOutputStreamOrStdOut(mArgs[1]))
             ) {