diff --git a/common/src/com/android/inputmethod/latin/common/ComposedData.java b/common/src/com/android/inputmethod/latin/common/ComposedData.java
new file mode 100644
index 0000000..0508d49
--- /dev/null
+++ b/common/src/com/android/inputmethod/latin/common/ComposedData.java
@@ -0,0 +1,61 @@
+/*
+ * 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.
+ */
+
+package com.android.inputmethod.latin.common;
+
+/**
+ * An immutable class that encapsulates a snapshot of word composition data.
+ */
+public class ComposedData {
+    public final InputPointers mInputPointers;
+    public final boolean mIsBatchMode;
+    public final String mTypedWord;
+    public ComposedData(final InputPointers inputPointers, final boolean isBatchMode,
+            final String typedWord) {
+        mInputPointers = inputPointers;
+        mIsBatchMode = isBatchMode;
+        mTypedWord = typedWord;
+    }
+
+    /**
+     * Copy the code points in the typed word to a destination array of ints.
+     *
+     * If the array is too small to hold the code points in the typed word, nothing is copied and
+     * -1 is returned.
+     *
+     * @param destination the array of ints.
+     * @return the number of copied code points.
+     */
+    public int copyCodePointsExceptTrailingSingleQuotesAndReturnCodePointCount(
+            final int[] destination) {
+        // lastIndex is exclusive
+        final int lastIndex = mTypedWord.length()
+                - StringUtils.getTrailingSingleQuotesCount(mTypedWord);
+        if (lastIndex <= 0) {
+            // The string is empty or contains only single quotes.
+            return 0;
+        }
+
+        // The following function counts the number of code points in the text range which begins
+        // at index 0 and extends to the character at lastIndex.
+        final int codePointSize = Character.codePointCount(mTypedWord, 0, lastIndex);
+        if (codePointSize > destination.length) {
+            return -1;
+        }
+        return StringUtils.copyCodePointsAndReturnCodePointCount(destination, mTypedWord, 0,
+                lastIndex, true /* downCase */);
+    }
+}
diff --git a/java/src/com/android/inputmethod/latin/BinaryDictionary.java b/java/src/com/android/inputmethod/latin/BinaryDictionary.java
index 8e9b5c6..b5d0b44 100644
--- a/java/src/com/android/inputmethod/latin/BinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/BinaryDictionary.java
@@ -21,8 +21,8 @@
 import android.util.SparseArray;
 
 import com.android.inputmethod.annotations.UsedForTesting;
-import com.android.inputmethod.keyboard.ProximityInfo;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
+import com.android.inputmethod.latin.common.ComposedData;
 import com.android.inputmethod.latin.common.Constants;
 import com.android.inputmethod.latin.common.InputPointers;
 import com.android.inputmethod.latin.common.StringUtils;
@@ -262,8 +262,8 @@
     }
 
     @Override
-    public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-            final NgramContext ngramContext, final ProximityInfo proximityInfo,
+    public ArrayList<SuggestedWordInfo> getSuggestions(final ComposedData composedData,
+            final NgramContext ngramContext, final long proximityInfoHandle,
             final SettingsValuesForSuggestion settingsValuesForSuggestion,
             final int sessionId, final float weightForLocale,
             final float[] inOutWeightOfLangModelVsSpatialModel) {
@@ -274,12 +274,13 @@
         Arrays.fill(session.mInputCodePoints, Constants.NOT_A_CODE);
         ngramContext.outputToArray(session.mPrevWordCodePointArrays,
                 session.mIsBeginningOfSentenceArray);
-        final InputPointers inputPointers = composer.getInputPointers();
-        final boolean isGesture = composer.isBatchMode();
+        final InputPointers inputPointers = composedData.mInputPointers;
+        final boolean isGesture = composedData.mIsBatchMode;
         final int inputSize;
         if (!isGesture) {
-            inputSize = composer.copyCodePointsExceptTrailingSingleQuotesAndReturnCodePointCount(
-                    session.mInputCodePoints);
+            inputSize =
+                    composedData.copyCodePointsExceptTrailingSingleQuotesAndReturnCodePointCount(
+                        session.mInputCodePoints);
             if (inputSize < 0) {
                 return null;
             }
@@ -303,7 +304,7 @@
                     Dictionary.NOT_A_WEIGHT_OF_LANG_MODEL_VS_SPATIAL_MODEL;
         }
         // TOOD: Pass multiple previous words information for n-gram.
-        getSuggestionsNative(mNativeDict, proximityInfo.getNativeProximityInfo(),
+        getSuggestionsNative(mNativeDict, proximityInfoHandle,
                 getTraverseSession(sessionId).getSession(), inputPointers.getXCoordinates(),
                 inputPointers.getYCoordinates(), inputPointers.getTimes(),
                 inputPointers.getPointerIds(), session.mInputCodePoints, inputSize,
diff --git a/java/src/com/android/inputmethod/latin/Dictionary.java b/java/src/com/android/inputmethod/latin/Dictionary.java
index 28a62b2..7d7ed77 100644
--- a/java/src/com/android/inputmethod/latin/Dictionary.java
+++ b/java/src/com/android/inputmethod/latin/Dictionary.java
@@ -17,8 +17,8 @@
 package com.android.inputmethod.latin;
 
 import com.android.inputmethod.annotations.UsedForTesting;
-import com.android.inputmethod.keyboard.ProximityInfo;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
+import com.android.inputmethod.latin.common.ComposedData;
 import com.android.inputmethod.latin.settings.SettingsValuesForSuggestion;
 
 import java.util.ArrayList;
@@ -87,9 +87,9 @@
 
     /**
      * Searches for suggestions for a given context.
-     * @param composer the key sequence to match with coordinate info, as a WordComposer
+     * @param composedData the key sequence to match with coordinate info
      * @param ngramContext the context for n-gram.
-     * @param proximityInfo the object for key proximity. May be ignored by some implementations.
+     * @param proximityInfoHandle the handle for key proximity. Is ignored by some implementations.
      * @param settingsValuesForSuggestion the settings values used for the suggestion.
      * @param sessionId the session id.
      * @param weightForLocale the weight given to this locale, to multiply the output scores for
@@ -99,8 +99,8 @@
      * a float array that has only one element. This can be updated when a different value is used.
      * @return the list of suggestions (possibly null if none)
      */
-    abstract public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-            final NgramContext ngramContext, final ProximityInfo proximityInfo,
+    abstract public ArrayList<SuggestedWordInfo> getSuggestions(final ComposedData composedData,
+            final NgramContext ngramContext, final long proximityInfoHandle,
             final SettingsValuesForSuggestion settingsValuesForSuggestion,
             final int sessionId, final float weightForLocale,
             final float[] inOutWeightOfLangModelVsSpatialModel);
@@ -203,8 +203,8 @@
         }
 
         @Override
-        public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-                final NgramContext ngramContext, final ProximityInfo proximityInfo,
+        public ArrayList<SuggestedWordInfo> getSuggestions(final ComposedData composedData,
+                final NgramContext ngramContext, final long proximityInfoHandle,
                 final SettingsValuesForSuggestion settingsValuesForSuggestion,
                 final int sessionId, final float weightForLocale,
                 final float[] inOutWeightOfLangModelVsSpatialModel) {
diff --git a/java/src/com/android/inputmethod/latin/DictionaryCollection.java b/java/src/com/android/inputmethod/latin/DictionaryCollection.java
index a6d7205..96575f6 100644
--- a/java/src/com/android/inputmethod/latin/DictionaryCollection.java
+++ b/java/src/com/android/inputmethod/latin/DictionaryCollection.java
@@ -18,8 +18,8 @@
 
 import android.util.Log;
 
-import com.android.inputmethod.keyboard.ProximityInfo;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
+import com.android.inputmethod.latin.common.ComposedData;
 import com.android.inputmethod.latin.settings.SettingsValuesForSuggestion;
 
 import java.util.ArrayList;
@@ -59,8 +59,8 @@
     }
 
     @Override
-    public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-            final NgramContext ngramContext, final ProximityInfo proximityInfo,
+    public ArrayList<SuggestedWordInfo> getSuggestions(final ComposedData composedData,
+            final NgramContext ngramContext, final long proximityInfoHandle,
             final SettingsValuesForSuggestion settingsValuesForSuggestion,
             final int sessionId, final float weightForLocale,
             final float[] inOutWeightOfLangModelVsSpatialModel) {
@@ -68,15 +68,15 @@
         if (dictionaries.isEmpty()) return null;
         // To avoid creating unnecessary objects, we get the list out of the first
         // dictionary and add the rest to it if not null, hence the get(0)
-        ArrayList<SuggestedWordInfo> suggestions = dictionaries.get(0).getSuggestions(composer,
-                ngramContext, proximityInfo, settingsValuesForSuggestion, sessionId,
+        ArrayList<SuggestedWordInfo> suggestions = dictionaries.get(0).getSuggestions(composedData,
+                ngramContext, proximityInfoHandle, settingsValuesForSuggestion, sessionId,
                 weightForLocale, inOutWeightOfLangModelVsSpatialModel);
         if (null == suggestions) suggestions = new ArrayList<>();
         final int length = dictionaries.size();
         for (int i = 1; i < length; ++ i) {
-            final ArrayList<SuggestedWordInfo> sugg = dictionaries.get(i).getSuggestions(composer,
-                    ngramContext, proximityInfo, settingsValuesForSuggestion, sessionId,
-                    weightForLocale, inOutWeightOfLangModelVsSpatialModel);
+            final ArrayList<SuggestedWordInfo> sugg = dictionaries.get(i).getSuggestions(
+                    composedData, ngramContext, proximityInfoHandle, settingsValuesForSuggestion,
+                    sessionId, weightForLocale, inOutWeightOfLangModelVsSpatialModel);
             if (null != sugg) suggestions.addAll(sugg);
         }
         return suggestions;
diff --git a/java/src/com/android/inputmethod/latin/DictionaryFacilitator.java b/java/src/com/android/inputmethod/latin/DictionaryFacilitator.java
index 4a22cde..d23639a 100644
--- a/java/src/com/android/inputmethod/latin/DictionaryFacilitator.java
+++ b/java/src/com/android/inputmethod/latin/DictionaryFacilitator.java
@@ -23,7 +23,6 @@
 import android.view.inputmethod.InputMethodSubtype;
 
 import com.android.inputmethod.annotations.UsedForTesting;
-import com.android.inputmethod.keyboard.ProximityInfo;
 import com.android.inputmethod.latin.ExpandableBinaryDictionary.UpdateEntriesForInputEventsCallback;
 import com.android.inputmethod.latin.NgramContext.WordInfo;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
@@ -683,7 +682,7 @@
 
     // TODO: Revise the way to fusion suggestion results.
     public SuggestionResults getSuggestionResults(final WordComposer composer,
-            final NgramContext ngramContext, final ProximityInfo proximityInfo,
+            final NgramContext ngramContext, final long proximityInfoHandle,
             final SettingsValuesForSuggestion settingsValuesForSuggestion, final int sessionId) {
         final DictionaryGroup[] dictionaryGroups = mDictionaryGroups;
         final SuggestionResults suggestionResults = new SuggestionResults(
@@ -698,8 +697,8 @@
                         ? dictionaryGroup.mWeightForGesturingInLocale
                         : dictionaryGroup.mWeightForTypingInLocale;
                 final ArrayList<SuggestedWordInfo> dictionarySuggestions =
-                        dictionary.getSuggestions(composer, ngramContext, proximityInfo,
-                                settingsValuesForSuggestion, sessionId,
+                        dictionary.getSuggestions(composer.getComposedDataSnapshot(), ngramContext,
+                                proximityInfoHandle, settingsValuesForSuggestion, sessionId,
                                 weightForLocale, weightOfLangModelVsSpatialModel);
                 if (null == dictionarySuggestions) continue;
                 suggestionResults.addAll(dictionarySuggestions);
diff --git a/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java b/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
index 702d153..bbffece 100644
--- a/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
@@ -20,8 +20,8 @@
 import android.util.Log;
 
 import com.android.inputmethod.annotations.UsedForTesting;
-import com.android.inputmethod.keyboard.ProximityInfo;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
+import com.android.inputmethod.latin.common.ComposedData;
 import com.android.inputmethod.latin.common.Constants;
 import com.android.inputmethod.latin.makedict.DictionaryHeader;
 import com.android.inputmethod.latin.makedict.FormatSpec;
@@ -480,8 +480,8 @@
     }
 
     @Override
-    public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-            final NgramContext ngramContext, final ProximityInfo proximityInfo,
+    public ArrayList<SuggestedWordInfo> getSuggestions(final ComposedData composedData,
+            final NgramContext ngramContext, final long proximityInfoHandle,
             final SettingsValuesForSuggestion settingsValuesForSuggestion, final int sessionId,
             final float weightForLocale, final float[] inOutWeightOfLangModelVsSpatialModel) {
         reloadDictionaryIfRequired();
@@ -494,9 +494,9 @@
                     return null;
                 }
                 final ArrayList<SuggestedWordInfo> suggestions =
-                        mBinaryDictionary.getSuggestions(composer, ngramContext, proximityInfo,
-                                settingsValuesForSuggestion, sessionId, weightForLocale,
-                                inOutWeightOfLangModelVsSpatialModel);
+                        mBinaryDictionary.getSuggestions(composedData, ngramContext,
+                                proximityInfoHandle, settingsValuesForSuggestion, sessionId,
+                                weightForLocale, inOutWeightOfLangModelVsSpatialModel);
                 if (mBinaryDictionary.isCorrupted()) {
                     Log.i(TAG, "Dictionary (" + mDictName +") is corrupted. "
                             + "Remove and regenerate it.");
diff --git a/java/src/com/android/inputmethod/latin/ReadOnlyBinaryDictionary.java b/java/src/com/android/inputmethod/latin/ReadOnlyBinaryDictionary.java
index bc8bd83..7b1a53a 100644
--- a/java/src/com/android/inputmethod/latin/ReadOnlyBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/ReadOnlyBinaryDictionary.java
@@ -16,8 +16,8 @@
 
 package com.android.inputmethod.latin;
 
-import com.android.inputmethod.keyboard.ProximityInfo;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
+import com.android.inputmethod.latin.common.ComposedData;
 import com.android.inputmethod.latin.settings.SettingsValuesForSuggestion;
 
 import java.util.ArrayList;
@@ -50,16 +50,16 @@
     }
 
     @Override
-    public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-            final NgramContext ngramContext, final ProximityInfo proximityInfo,
+    public ArrayList<SuggestedWordInfo> getSuggestions(final ComposedData composedData,
+            final NgramContext ngramContext, final long proximityInfoHandle,
             final SettingsValuesForSuggestion settingsValuesForSuggestion,
             final int sessionId, final float weightForLocale,
             final float[] inOutWeightOfLangModelVsSpatialModel) {
         if (mLock.readLock().tryLock()) {
             try {
-                return mBinaryDictionary.getSuggestions(composer, ngramContext, proximityInfo,
-                        settingsValuesForSuggestion, sessionId, weightForLocale,
-                        inOutWeightOfLangModelVsSpatialModel);
+                return mBinaryDictionary.getSuggestions(composedData, ngramContext,
+                        proximityInfoHandle, settingsValuesForSuggestion, sessionId,
+                        weightForLocale, inOutWeightOfLangModelVsSpatialModel);
             } finally {
                 mLock.readLock().unlock();
             }
diff --git a/java/src/com/android/inputmethod/latin/Suggest.java b/java/src/com/android/inputmethod/latin/Suggest.java
index 430f765..9b4619d 100644
--- a/java/src/com/android/inputmethod/latin/Suggest.java
+++ b/java/src/com/android/inputmethod/latin/Suggest.java
@@ -140,8 +140,8 @@
                 : typedWord;
 
         final SuggestionResults suggestionResults = mDictionaryFacilitator.getSuggestionResults(
-                wordComposer, ngramContext, proximityInfo, settingsValuesForSuggestion,
-                SESSION_ID_TYPING);
+                wordComposer, ngramContext, proximityInfo.getNativeProximityInfo(),
+                settingsValuesForSuggestion, SESSION_ID_TYPING);
         final ArrayList<SuggestedWordInfo> suggestionsContainer =
                 getTransformedSuggestedWordInfoList(wordComposer, suggestionResults,
                         trailingSingleQuotesCount,
@@ -247,8 +247,8 @@
             final int inputStyle, final int sequenceNumber,
             final OnGetSuggestedWordsCallback callback) {
         final SuggestionResults suggestionResults = mDictionaryFacilitator.getSuggestionResults(
-                wordComposer, ngramContext, proximityInfo, settingsValuesForSuggestion,
-                SESSION_ID_GESTURE);
+                wordComposer, ngramContext, proximityInfo.getNativeProximityInfo(),
+                settingsValuesForSuggestion, SESSION_ID_GESTURE);
         // For transforming words that don't come from a dictionary, because it's our best bet
         final Locale defaultLocale = mDictionaryFacilitator.getMostProbableLocale();
         final ArrayList<SuggestedWordInfo> suggestionsContainer =
diff --git a/java/src/com/android/inputmethod/latin/WordComposer.java b/java/src/com/android/inputmethod/latin/WordComposer.java
index 0b77f2c..fa55319 100644
--- a/java/src/com/android/inputmethod/latin/WordComposer.java
+++ b/java/src/com/android/inputmethod/latin/WordComposer.java
@@ -19,6 +19,7 @@
 import com.android.inputmethod.event.CombinerChain;
 import com.android.inputmethod.event.Event;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
+import com.android.inputmethod.latin.common.ComposedData;
 import com.android.inputmethod.latin.common.Constants;
 import com.android.inputmethod.latin.common.InputPointers;
 import com.android.inputmethod.latin.common.StringUtils;
@@ -90,6 +91,10 @@
         refreshTypedWordCache();
     }
 
+    public ComposedData getComposedDataSnapshot() {
+        return new ComposedData(getInputPointers(), isBatchMode(), mTypedWordCache.toString());
+    }
+
     /**
      * Restart the combiners, possibly with a new spec.
      * @param combiningSpec The spec string for combining. This is found in the extra value.
@@ -134,38 +139,6 @@
         return mCodePointSize;
     }
 
-    /**
-     * Copy the code points in the typed word to a destination array of ints.
-     *
-     * If the array is too small to hold the code points in the typed word, nothing is copied and
-     * -1 is returned.
-     *
-     * @param destination the array of ints.
-     * @return the number of copied code points.
-     */
-    public int copyCodePointsExceptTrailingSingleQuotesAndReturnCodePointCount(
-            final int[] destination) {
-        // This method can be called on a separate thread and mTypedWordCache can change while we
-        // are executing this method.
-        final String typedWord = mTypedWordCache.toString();
-        // lastIndex is exclusive
-        final int lastIndex = typedWord.length()
-                - StringUtils.getTrailingSingleQuotesCount(typedWord);
-        if (lastIndex <= 0) {
-            // The string is empty or contains only single quotes.
-            return 0;
-        }
-
-        // The following function counts the number of code points in the text range which begins
-        // at index 0 and extends to the character at lastIndex.
-        final int codePointSize = Character.codePointCount(typedWord, 0, lastIndex);
-        if (codePointSize > destination.length) {
-            return -1;
-        }
-        return StringUtils.copyCodePointsAndReturnCodePointCount(destination, typedWord, 0,
-                lastIndex, true /* downCase */);
-    }
-
     public boolean isSingleLetter() {
         return size() == 1;
     }
diff --git a/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerService.java b/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerService.java
index 315e369..bcf7bbf 100644
--- a/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerService.java
+++ b/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerService.java
@@ -168,7 +168,8 @@
             DictionaryFacilitator dictionaryFacilitatorForLocale =
                     mDictionaryFacilitatorCache.get(locale);
             return dictionaryFacilitatorForLocale.getSuggestionResults(composer, ngramContext,
-                    proximityInfo, mSettingsValuesForSuggestion, sessionId);
+                    proximityInfo.getNativeProximityInfo(), mSettingsValuesForSuggestion,
+                    sessionId);
         } finally {
             if (sessionId != null) {
                 mSessionIdPool.add(sessionId);
diff --git a/java/src/com/android/inputmethod/latin/utils/CollectionUtils.java b/java/src/com/android/inputmethod/latin/utils/CollectionUtils.java
index f9839eb..01f5e10 100644
--- a/java/src/com/android/inputmethod/latin/utils/CollectionUtils.java
+++ b/java/src/com/android/inputmethod/latin/utils/CollectionUtils.java
@@ -22,16 +22,27 @@
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
+/**
+ * Utility methods for working with collections.
+ */
 public final class CollectionUtils {
     private CollectionUtils() {
         // This utility class is not publicly instantiable.
     }
 
+    /**
+     * Converts a sub-range of the given array to an ArrayList of the appropriate type.
+     * @param array Array to be converted.
+     * @param start First index inclusive to be converted.
+     * @param end Last index exclusive to be converted.
+     * @throws IllegalArgumentException if start or end are out of range or start &gt; end.
+     */
     @Nonnull
     public static <E> ArrayList<E> arrayAsList(@Nonnull final E[] array, final int start,
             final int end) {
         if (start < 0 || start > end || end > array.length) {
-            throw new IllegalArgumentException();
+            throw new IllegalArgumentException("Invalid start: " + start + " end: " + end
+                    + " with array.length: " + array.length);
         }
 
         final ArrayList<E> list = new ArrayList<>(end - start);
diff --git a/java/src/com/android/inputmethod/latin/utils/DistracterFilterCheckingExactMatchesAndSuggestions.java b/java/src/com/android/inputmethod/latin/utils/DistracterFilterCheckingExactMatchesAndSuggestions.java
index 56c8249..9c6a948 100644
--- a/java/src/com/android/inputmethod/latin/utils/DistracterFilterCheckingExactMatchesAndSuggestions.java
+++ b/java/src/com/android/inputmethod/latin/utils/DistracterFilterCheckingExactMatchesAndSuggestions.java
@@ -250,8 +250,9 @@
         composer.setComposingWord(codePoints, coordinates);
         final SuggestionResults suggestionResults;
         synchronized (mLock) {
-            suggestionResults = dictionaryFacilitator.getSuggestionResults(
-                    composer, NgramContext.EMPTY_PREV_WORDS_INFO, keyboard.getProximityInfo(),
+            suggestionResults = dictionaryFacilitator.getSuggestionResults(composer,
+                    NgramContext.EMPTY_PREV_WORDS_INFO,
+                    keyboard.getProximityInfo().getNativeProximityInfo(),
                     settingsValuesForSuggestion, 0 /* sessionId */);
         }
         if (suggestionResults.isEmpty()) {
diff --git a/tests/src/com/android/inputmethod/latin/utils/CollectionUtilsTests.java b/tests/src/com/android/inputmethod/latin/utils/CollectionUtilsTests.java
index a5979c3..dc4e2e4 100644
--- a/tests/src/com/android/inputmethod/latin/utils/CollectionUtilsTests.java
+++ b/tests/src/com/android/inputmethod/latin/utils/CollectionUtilsTests.java
@@ -29,14 +29,45 @@
 @SmallTest
 public class CollectionUtilsTests extends AndroidTestCase {
     /**
+     * Tests that {@link CollectionUtils#arrayAsList(Object[],int,int)} fails as expected
+     * with some invalid inputs.
+     */
+    public void testArrayAsListFailure() {
+        final String[] array = { "0", "1" };
+        // Negative start
+        try {
+            CollectionUtils.arrayAsList(array, -1, 1);
+            fail("Failed to catch start < 0");
+        } catch (final IllegalArgumentException e) {
+            assertEquals("Invalid start: -1 end: 1 with array.length: 2", e.getMessage());
+        }
+        // start > end
+        try {
+            CollectionUtils.arrayAsList(array, 1, -1);
+            fail("Failed to catch start > end");
+        } catch (final IllegalArgumentException e) {
+            assertEquals("Invalid start: 1 end: -1 with array.length: 2", e.getMessage());
+        }
+        // end > array.length
+        try {
+            CollectionUtils.arrayAsList(array, 1, 3);
+            fail("Failed to catch end > array.length");
+        } catch (final IllegalArgumentException e) {
+            assertEquals("Invalid start: 1 end: 3 with array.length: 2", e.getMessage());
+        }
+    }
+
+    /**
      * Tests that {@link CollectionUtils#arrayAsList(Object[],int,int)} gives the expected
      * results for a few valid inputs.
      */
     public void testArrayAsList() {
-        final String[] array = { "0", "1", "2", "3", "4" };
         final ArrayList<String> empty = new ArrayList<>();
+        assertEquals(empty, CollectionUtils.arrayAsList(new String[] { }, 0, 0));
+        final String[] array = { "0", "1", "2", "3", "4" };
         assertEquals(empty, CollectionUtils.arrayAsList(array, 0, 0));
         assertEquals(empty, CollectionUtils.arrayAsList(array, 1, 1));
+        assertEquals(empty, CollectionUtils.arrayAsList(array, array.length, array.length));
         final ArrayList<String> expected123 = new ArrayList<>(Arrays.asList("1", "2", "3"));
         assertEquals(expected123, CollectionUtils.arrayAsList(array, 1, 4));
     }
diff --git a/tools/dicttool/Android.mk b/tools/dicttool/Android.mk
index 81c0706..4265925 100644
--- a/tools/dicttool/Android.mk
+++ b/tools/dicttool/Android.mk
@@ -42,15 +42,11 @@
 # a significant part of the dependencies are mocked in the compat/ directory, with empty or
 # nearly-empty implementations, for parts that we don't use in Dicttool.
 LATINIME_SRC_FILES_FOR_DICTTOOL := \
-        event/Combiner.java \
-        event/Event.java \
         latin/BinaryDictionary.java \
         latin/DicTraverseSession.java \
         latin/Dictionary.java \
-        latin/LastComposedWord.java \
         latin/NgramContext.java \
         latin/SuggestedWords.java \
-        latin/WordComposer.java \
         latin/settings/NativeSuggestOptions.java \
         latin/settings/SettingsValuesForSuggestion.java \
         latin/utils/BinaryDictionaryUtils.java \
diff --git a/tools/dicttool/compat/com/android/inputmethod/event/CombinerChain.java b/tools/dicttool/compat/com/android/inputmethod/event/CombinerChain.java
deleted file mode 100644
index c4457a1..0000000
--- a/tools/dicttool/compat/com/android/inputmethod/event/CombinerChain.java
+++ /dev/null
@@ -1,54 +0,0 @@
-/*
- * 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.
- */
-
-package com.android.inputmethod.event;
-
-import java.util.ArrayList;
-
-/**
- * Compatibility class that stands in for the combiner chain in LatinIME.
- *
- * This is not used by dicttool, it's just needed by the dependency chain.
- */
-// TODO: there should not be a dependency to this in dicttool, so there
-// should be a sensible way to separate them cleanly.
-public class CombinerChain {
-    private StringBuilder mComposingWord;
-    public CombinerChain(final String initialText, final Combiner... combinerList) {
-        mComposingWord = new StringBuilder(initialText);
-    }
-
-    public Event processEvent(final ArrayList<Event> previousEvents, final Event newEvent) {
-        return newEvent;
-    }
-
-    public void applyProcessedEvent(final Event event) {
-        mComposingWord.append(event.getTextToCommit());
-    }
-
-    public CharSequence getComposingWordWithCombiningFeedback() {
-        return mComposingWord;
-    }
-
-    public void reset() {
-        mComposingWord.setLength(0);
-    }
-
-    public static Combiner[] createCombiners(final String spec) {
-        // Dicttool never uses a combiner at all, so we just return a zero-sized array.
-        return new Combiner[0];
-    }
-}