Use PrevWordsInfo instead of String in Java side.

Bug: 14119293
Bug: 14425059

Change-Id: I3d5da84881a49a04550180dd9aac2c37da2ed762

17 files changed, 119 insertions, 84 deletions

diff --git a/java/src/com/android/inputmethod/latin/BinaryDictionary.java b/java/src/com/android/inputmethod/latin/BinaryDictionary.java
index 8a6404b1b..b8cf3f89c 100644
--- a/java/src/com/android/inputmethod/latin/BinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/BinaryDictionary.java
@@ -265,7 +265,7 @@ public final class BinaryDictionary extends Dictionary {
 
     @Override
     public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-            final String prevWord, final ProximityInfo proximityInfo,
+            final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
             final boolean blockOffensiveWords, final int[] additionalFeaturesOptions,
             final int sessionId, final float[] inOutLanguageWeight) {
         if (!isValidDictionary()) {
@@ -274,8 +274,8 @@ public final class BinaryDictionary extends Dictionary {
 
         Arrays.fill(mInputCodePoints, Constants.NOT_A_CODE);
         // TODO: toLowerCase in the native code
-        final int[] prevWordCodePointArray = (null == prevWord)
-                ? null : StringUtils.toCodePointArray(prevWord);
+        final int[] prevWordCodePointArray = (null == prevWordsInfo.mPrevWord)
+                ? null : StringUtils.toCodePointArray(prevWordsInfo.mPrevWord);
         final InputPointers inputPointers = composer.getInputPointers();
         final boolean isGesture = composer.isBatchMode();
         final int inputSize;
diff --git a/java/src/com/android/inputmethod/latin/Dictionary.java b/java/src/com/android/inputmethod/latin/Dictionary.java
index 5253cc3dd..aab16653e 100644
--- a/java/src/com/android/inputmethod/latin/Dictionary.java
+++ b/java/src/com/android/inputmethod/latin/Dictionary.java
@@ -69,7 +69,7 @@ public abstract class Dictionary {
      * Searches for suggestions for a given context. For the moment the context is only the
      * previous word.
      * @param composer the key sequence to match with coordinate info, as a WordComposer
-     * @param prevWord the previous word, or null if none
+     * @param prevWordsInfo the information of previous words.
      * @param proximityInfo the object for key proximity. May be ignored by some implementations.
      * @param blockOffensiveWords whether to block potentially offensive words
      * @param additionalFeaturesOptions options about additional features used for the suggestion.
@@ -79,10 +79,8 @@ public abstract class Dictionary {
      * different language weight is used.
      * @return the list of suggestions (possibly null if none)
      */
-    // TODO: pass more context than just the previous word, to enable better suggestions (n-gram
-    // and more)
     abstract public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-            final String prevWord, final ProximityInfo proximityInfo,
+            final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
             final boolean blockOffensiveWords, final int[] additionalFeaturesOptions,
             final int sessionId, final float[] inOutLanguageWeight);
 
@@ -156,7 +154,7 @@ public abstract class Dictionary {
 
         @Override
         public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-                final String prevWord, final ProximityInfo proximityInfo,
+                final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
                 final boolean blockOffensiveWords, final int[] additionalFeaturesOptions,
                 final int sessionId, final float[] inOutLanguageWeight) {
             return null;
diff --git a/java/src/com/android/inputmethod/latin/DictionaryCollection.java b/java/src/com/android/inputmethod/latin/DictionaryCollection.java
index 239fd067a..e6e4e0938 100644
--- a/java/src/com/android/inputmethod/latin/DictionaryCollection.java
+++ b/java/src/com/android/inputmethod/latin/DictionaryCollection.java
@@ -57,7 +57,7 @@ public final class DictionaryCollection extends Dictionary {
 
     @Override
     public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-            final String prevWord, final ProximityInfo proximityInfo,
+            final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
             final boolean blockOffensiveWords, final int[] additionalFeaturesOptions,
             final int sessionId, final float[] inOutLanguageWeight) {
         final CopyOnWriteArrayList<Dictionary> dictionaries = mDictionaries;
@@ -65,13 +65,13 @@ public final class DictionaryCollection extends Dictionary {
         // 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,
-                prevWord, proximityInfo, blockOffensiveWords, additionalFeaturesOptions,
+                prevWordsInfo, proximityInfo, blockOffensiveWords, additionalFeaturesOptions,
                 sessionId, inOutLanguageWeight);
         if (null == suggestions) suggestions = CollectionUtils.newArrayList();
         final int length = dictionaries.size();
         for (int i = 1; i < length; ++ i) {
             final ArrayList<SuggestedWordInfo> sugg = dictionaries.get(i).getSuggestions(composer,
-                    prevWord, proximityInfo, blockOffensiveWords, additionalFeaturesOptions,
+                    prevWordsInfo, proximityInfo, blockOffensiveWords, additionalFeaturesOptions,
                     sessionId, inOutLanguageWeight);
             if (null != sugg) suggestions.addAll(sugg);
         }
diff --git a/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java b/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java
index ddbb196d9..14c8bb6c3 100644
--- a/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java
+++ b/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java
@@ -444,7 +444,7 @@ public class DictionaryFacilitatorForSuggest {
 
     // TODO: Revise the way to fusion suggestion results.
     public SuggestionResults getSuggestionResults(final WordComposer composer,
-            final String prevWord, final ProximityInfo proximityInfo,
+            final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
             final boolean blockOffensiveWords, final int[] additionalFeaturesOptions,
             final int sessionId, final ArrayList<SuggestedWordInfo> rawSuggestions) {
         final Dictionaries dictionaries = mDictionaries;
@@ -455,7 +455,7 @@ public class DictionaryFacilitatorForSuggest {
             final Dictionary dictionary = dictionaries.getDict(dictType);
             if (null == dictionary) continue;
             final ArrayList<SuggestedWordInfo> dictionarySuggestions =
-                    dictionary.getSuggestions(composer, prevWord, proximityInfo,
+                    dictionary.getSuggestions(composer, prevWordsInfo, proximityInfo,
                             blockOffensiveWords, additionalFeaturesOptions, sessionId,
                             languageWeight);
             if (null == dictionarySuggestions) continue;
diff --git a/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java b/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
index 4358f84c2..629f3fd18 100644
--- a/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
@@ -367,7 +367,7 @@ abstract public class ExpandableBinaryDictionary extends Dictionary {
 
     @Override
     public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-            final String prevWord, final ProximityInfo proximityInfo,
+            final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
             final boolean blockOffensiveWords, final int[] additionalFeaturesOptions,
             final int sessionId, final float[] inOutLanguageWeight) {
         reloadDictionaryIfRequired();
@@ -380,7 +380,7 @@ abstract public class ExpandableBinaryDictionary extends Dictionary {
                     return null;
                 }
                 final ArrayList<SuggestedWordInfo> suggestions =
-                        mBinaryDictionary.getSuggestions(composer, prevWord, proximityInfo,
+                        mBinaryDictionary.getSuggestions(composer, prevWordsInfo, proximityInfo,
                                 blockOffensiveWords, additionalFeaturesOptions, sessionId,
                                 inOutLanguageWeight);
                 if (mBinaryDictionary.isCorrupted()) {
diff --git a/java/src/com/android/inputmethod/latin/LatinIME.java b/java/src/com/android/inputmethod/latin/LatinIME.java
index d100d32bb..5e45275f8 100644
--- a/java/src/com/android/inputmethod/latin/LatinIME.java
+++ b/java/src/com/android/inputmethod/latin/LatinIME.java
@@ -1428,8 +1428,8 @@ public class LatinIME extends InputMethodService implements KeyboardActionListen
         if (DEBUG) {
             if (mInputLogic.mWordComposer.isComposingWord()
                     || mInputLogic.mWordComposer.isBatchMode()) {
-                final String previousWord
-                        = mInputLogic.mWordComposer.getPreviousWordForSuggestion();
+                final PrevWordsInfo prevWordsInfo
+                        = mInputLogic.mWordComposer.getPrevWordsInfoForSuggestion();
                 // TODO: this is for checking consistency with older versions. Remove this when
                 // we are confident this is stable.
                 // We're checking the previous word in the text field against the memorized previous
@@ -1438,14 +1438,14 @@ public class LatinIME extends InputMethodService implements KeyboardActionListen
                 final CharSequence rereadPrevWord = mInputLogic.getNthPreviousWordForSuggestion(
                         currentSettings.mSpacingAndPunctuations,
                         mInputLogic.mWordComposer.isComposingWord() ? 2 : 1);
-                if (!TextUtils.equals(previousWord, rereadPrevWord)) {
+                if (!TextUtils.equals(prevWordsInfo.mPrevWord, rereadPrevWord)) {
                     throw new RuntimeException("Unexpected previous word: "
-                            + previousWord + " <> " + rereadPrevWord);
+                            + prevWordsInfo.mPrevWord + " <> " + rereadPrevWord);
                 }
             }
         }
         mInputLogic.mSuggest.getSuggestedWords(mInputLogic.mWordComposer,
-                mInputLogic.mWordComposer.getPreviousWordForSuggestion(),
+                mInputLogic.mWordComposer.getPrevWordsInfoForSuggestion(),
                 keyboard.getProximityInfo(), currentSettings.mBlockPotentiallyOffensive,
                 currentSettings.mCorrectionEnabled, additionalFeaturesOptions, sessionId,
                 sequenceNumber, callback);
diff --git a/java/src/com/android/inputmethod/latin/PrevWordsInfo.java b/java/src/com/android/inputmethod/latin/PrevWordsInfo.java
new file mode 100644
index 000000000..9d8543183
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/PrevWordsInfo.java
@@ -0,0 +1,29 @@
+/*
+ * 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;
+
+public class PrevWordsInfo {
+    // The previous word. May be null after resetting and before starting a new composing word, or
+    // when there is no context like at the start of text for example. It can also be set to null
+    // externally when the user enters a separator that does not let bigrams across, like a period
+    // or a comma.
+    public final String mPrevWord;
+
+    public PrevWordsInfo(final String prevWord) {
+        mPrevWord = prevWord;
+    }
+}
diff --git a/java/src/com/android/inputmethod/latin/ReadOnlyBinaryDictionary.java b/java/src/com/android/inputmethod/latin/ReadOnlyBinaryDictionary.java
index 15b12381b..8f744bef8 100644
--- a/java/src/com/android/inputmethod/latin/ReadOnlyBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/ReadOnlyBinaryDictionary.java
@@ -50,12 +50,12 @@ public final class ReadOnlyBinaryDictionary extends Dictionary {
 
     @Override
     public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-            final String prevWord, final ProximityInfo proximityInfo,
+            final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
             final boolean blockOffensiveWords, final int[] additionalFeaturesOptions,
             final int sessionId, final float[] inOutLanguageWeight) {
         if (mLock.readLock().tryLock()) {
             try {
-                return mBinaryDictionary.getSuggestions(composer, prevWord, proximityInfo,
+                return mBinaryDictionary.getSuggestions(composer, prevWordsInfo, proximityInfo,
                         blockOffensiveWords, additionalFeaturesOptions, sessionId,
                         inOutLanguageWeight);
             } finally {
diff --git a/java/src/com/android/inputmethod/latin/Suggest.java b/java/src/com/android/inputmethod/latin/Suggest.java
index 71355f418..e3759a586 100644
--- a/java/src/com/android/inputmethod/latin/Suggest.java
+++ b/java/src/com/android/inputmethod/latin/Suggest.java
@@ -71,17 +71,17 @@ public final class Suggest {
     }
 
     public void getSuggestedWords(final WordComposer wordComposer,
-            final String prevWordForBigram, final ProximityInfo proximityInfo,
+            final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
             final boolean blockOffensiveWords, final boolean isCorrectionEnabled,
             final int[] additionalFeaturesOptions, final int sessionId, final int sequenceNumber,
             final OnGetSuggestedWordsCallback callback) {
-        LatinImeLogger.onStartSuggestion(prevWordForBigram);
+        LatinImeLogger.onStartSuggestion(prevWordsInfo.mPrevWord);
         if (wordComposer.isBatchMode()) {
-            getSuggestedWordsForBatchInput(wordComposer, prevWordForBigram, proximityInfo,
+            getSuggestedWordsForBatchInput(wordComposer, prevWordsInfo, proximityInfo,
                     blockOffensiveWords, additionalFeaturesOptions, sessionId, sequenceNumber,
                     callback);
         } else {
-            getSuggestedWordsForTypingInput(wordComposer, prevWordForBigram, proximityInfo,
+            getSuggestedWordsForTypingInput(wordComposer, prevWordsInfo, proximityInfo,
                     blockOffensiveWords, isCorrectionEnabled, additionalFeaturesOptions,
                     sequenceNumber, callback);
         }
@@ -90,7 +90,7 @@ public final class Suggest {
     // Retrieves suggestions for the typing input
     // and calls the callback function with the suggestions.
     private void getSuggestedWordsForTypingInput(final WordComposer wordComposer,
-            final String prevWordForBigram, final ProximityInfo proximityInfo,
+            final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
             final boolean blockOffensiveWords, final boolean isCorrectionEnabled,
             final int[] additionalFeaturesOptions, final int sequenceNumber,
             final OnGetSuggestedWordsCallback callback) {
@@ -108,7 +108,7 @@ public final class Suggest {
             rawSuggestions = null;
         }
         final SuggestionResults suggestionResults = mDictionaryFacilitator.getSuggestionResults(
-                wordComposer, prevWordForBigram, proximityInfo, blockOffensiveWords,
+                wordComposer, prevWordsInfo, proximityInfo, blockOffensiveWords,
                 additionalFeaturesOptions, SESSION_TYPING, rawSuggestions);
 
         final boolean isFirstCharCapitalized = wordComposer.isFirstCharCapitalized();
@@ -215,7 +215,7 @@ public final class Suggest {
     // Retrieves suggestions for the batch input
     // and calls the callback function with the suggestions.
     private void getSuggestedWordsForBatchInput(final WordComposer wordComposer,
-            final String prevWordForBigram, final ProximityInfo proximityInfo,
+            final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
             final boolean blockOffensiveWords, final int[] additionalFeaturesOptions,
             final int sessionId, final int sequenceNumber,
             final OnGetSuggestedWordsCallback callback) {
@@ -226,7 +226,7 @@ public final class Suggest {
             rawSuggestions = null;
         }
         final SuggestionResults suggestionResults = mDictionaryFacilitator.getSuggestionResults(
-                wordComposer, prevWordForBigram, proximityInfo, blockOffensiveWords,
+                wordComposer, prevWordsInfo, proximityInfo, blockOffensiveWords,
                 additionalFeaturesOptions, sessionId, rawSuggestions);
         for (SuggestedWordInfo wordInfo : suggestionResults) {
             LatinImeLogger.onAddSuggestedWord(wordInfo.mWord, wordInfo.mSourceDict.mDictType);
diff --git a/java/src/com/android/inputmethod/latin/WordComposer.java b/java/src/com/android/inputmethod/latin/WordComposer.java
index 9cf71c7f4..227b42bde 100644
--- a/java/src/com/android/inputmethod/latin/WordComposer.java
+++ b/java/src/com/android/inputmethod/latin/WordComposer.java
@@ -46,11 +46,9 @@ public final class WordComposer {
     // The list of events that served to compose this string.
     private final ArrayList<Event> mEvents;
     private final InputPointers mInputPointers = new InputPointers(MAX_WORD_LENGTH);
-    // The previous word (before the composing word). Used as context for suggestions. May be null
-    // after resetting and before starting a new composing word, or when there is no context like
-    // at the start of text for example. It can also be set to null externally when the user
-    // enters a separator that does not let bigrams across, like a period or a comma.
-    private String mPreviousWordForSuggestion;
+    // The information of previous words (before the composing word). Must not be null. Used as
+    // context for suggestions.
+    private PrevWordsInfo mPrevWordsInfo;
     private String mAutoCorrection;
     private boolean mIsResumed;
     private boolean mIsBatchMode;
@@ -87,7 +85,7 @@ public final class WordComposer {
         mIsBatchMode = false;
         mCursorPositionWithinWord = 0;
         mRejectedBatchModeSuggestion = null;
-        mPreviousWordForSuggestion = null;
+        mPrevWordsInfo = new PrevWordsInfo(null);
         refreshTypedWordCache();
     }
 
@@ -119,7 +117,7 @@ public final class WordComposer {
         mIsBatchMode = false;
         mCursorPositionWithinWord = 0;
         mRejectedBatchModeSuggestion = null;
-        mPreviousWordForSuggestion = null;
+        mPrevWordsInfo = new PrevWordsInfo(null);
         refreshTypedWordCache();
     }
 
@@ -309,7 +307,7 @@ public final class WordComposer {
                     CoordinateUtils.yFromArray(coordinates, i)));
         }
         mIsResumed = true;
-        mPreviousWordForSuggestion = null == previousWord ? null : previousWord.toString();
+        mPrevWordsInfo = new PrevWordsInfo(null == previousWord ? null : previousWord.toString());
     }
 
     /**
@@ -320,8 +318,8 @@ public final class WordComposer {
         return mTypedWordCache.toString();
     }
 
-    public String getPreviousWordForSuggestion() {
-        return mPreviousWordForSuggestion;
+    public PrevWordsInfo getPrevWordsInfoForSuggestion() {
+        return mPrevWordsInfo;
     }
 
     /**
@@ -379,7 +377,7 @@ public final class WordComposer {
     public void setCapitalizedModeAndPreviousWordAtStartComposingTime(final int mode,
             final CharSequence previousWord) {
         mCapitalizedMode = mode;
-        mPreviousWordForSuggestion = null == previousWord ? null : previousWord.toString();
+        mPrevWordsInfo = new PrevWordsInfo(null == previousWord ? null : previousWord.toString());
     }
 
     /**
@@ -430,7 +428,7 @@ public final class WordComposer {
         mCapsCount = 0;
         mDigitsCount = 0;
         mIsBatchMode = false;
-        mPreviousWordForSuggestion = committedWord.toString();
+        mPrevWordsInfo = new PrevWordsInfo(committedWord.toString());
         mCombinerChain.reset();
         mEvents.clear();
         mCodePointSize = 0;
@@ -448,11 +446,11 @@ public final class WordComposer {
     // when the user inputs a separator that's not whitespace (including the case of the
     // double-space-to-period feature).
     public void discardPreviousWordForSuggestion() {
-        mPreviousWordForSuggestion = null;
+        mPrevWordsInfo = new PrevWordsInfo(null);
     }
 
     public void resumeSuggestionOnLastComposedWord(final LastComposedWord lastComposedWord,
-            final String previousWord) {
+            final PrevWordsInfo prevWordsInfo) {
         mEvents.clear();
         Collections.copy(mEvents, lastComposedWord.mEvents);
         mInputPointers.set(lastComposedWord.mInputPointers);
@@ -463,7 +461,7 @@ public final class WordComposer {
         mCursorPositionWithinWord = mCodePointSize;
         mRejectedBatchModeSuggestion = null;
         mIsResumed = true;
-        mPreviousWordForSuggestion = previousWord;
+        mPrevWordsInfo = prevWordsInfo;
     }
 
     public boolean isBatchMode() {
diff --git a/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerSession.java b/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerSession.java
index ddda52d71..e951f5a89 100644
--- a/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerSession.java
+++ b/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerSession.java
@@ -23,6 +23,7 @@ import android.view.textservice.SentenceSuggestionsInfo;
 import android.view.textservice.SuggestionsInfo;
 import android.view.textservice.TextInfo;
 
+import com.android.inputmethod.latin.PrevWordsInfo;
 import com.android.inputmethod.latin.utils.CollectionUtils;
 
 import java.util.ArrayList;
@@ -57,7 +58,7 @@ public final class AndroidSpellCheckerSession extends AndroidWordLevelSpellCheck
             final int offset = ssi.getOffsetAt(i);
             final int length = ssi.getLengthAt(i);
             final String subText = typedText.substring(offset, offset + length);
-            final String prevWord = currentWord;
+            final PrevWordsInfo prevWordsInfo = new PrevWordsInfo(currentWord);
             currentWord = subText;
             if (!subText.contains(AndroidSpellCheckerService.SINGLE_QUOTE)) {
                 continue;
@@ -73,7 +74,7 @@ public final class AndroidSpellCheckerSession extends AndroidWordLevelSpellCheck
                 if (TextUtils.isEmpty(splitText)) {
                     continue;
                 }
-                if (mSuggestionsCache.getSuggestionsFromCache(splitText, prevWord) == null) {
+                if (mSuggestionsCache.getSuggestionsFromCache(splitText, prevWordsInfo) == null) {
                     continue;
                 }
                 final int newLength = splitText.length();
@@ -148,7 +149,8 @@ public final class AndroidSpellCheckerSession extends AndroidWordLevelSpellCheck
                 } else {
                     prevWord = null;
                 }
-                retval[i] = onGetSuggestionsInternal(textInfos[i], prevWord, suggestionsLimit);
+                final PrevWordsInfo prevWordsInfo = new PrevWordsInfo(prevWord);
+                retval[i] = onGetSuggestionsInternal(textInfos[i], prevWordsInfo, suggestionsLimit);
                 retval[i].setCookieAndSequence(textInfos[i].getCookie(),
                         textInfos[i].getSequence());
             }
diff --git a/java/src/com/android/inputmethod/latin/spellcheck/AndroidWordLevelSpellCheckerSession.java b/java/src/com/android/inputmethod/latin/spellcheck/AndroidWordLevelSpellCheckerSession.java
index 4c23d2210..cf26000d5 100644
--- a/java/src/com/android/inputmethod/latin/spellcheck/AndroidWordLevelSpellCheckerSession.java
+++ b/java/src/com/android/inputmethod/latin/spellcheck/AndroidWordLevelSpellCheckerSession.java
@@ -31,6 +31,7 @@ import com.android.inputmethod.compat.SuggestionsInfoCompatUtils;
 import com.android.inputmethod.keyboard.Keyboard;
 import com.android.inputmethod.latin.Constants;
 import com.android.inputmethod.latin.Dictionary;
+import com.android.inputmethod.latin.PrevWordsInfo;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
 import com.android.inputmethod.latin.WordComposer;
 import com.android.inputmethod.latin.spellcheck.AndroidSpellCheckerService.SuggestionsGatherer;
@@ -71,26 +72,26 @@ public abstract class AndroidWordLevelSpellCheckerSession extends Session {
                 new LruCache<String, SuggestionsParams>(MAX_CACHE_SIZE);
 
         // TODO: Support n-gram input
-        private static String generateKey(String query, String prevWord) {
-            if (TextUtils.isEmpty(query) || TextUtils.isEmpty(prevWord)) {
+        private static String generateKey(final String query, final PrevWordsInfo prevWordsInfo) {
+            if (TextUtils.isEmpty(query) || TextUtils.isEmpty(prevWordsInfo.mPrevWord)) {
                 return query;
             }
-            return query + CHAR_DELIMITER + prevWord;
+            return query + CHAR_DELIMITER + prevWordsInfo.mPrevWord;
         }
 
-        // TODO: Support n-gram input
-        public SuggestionsParams getSuggestionsFromCache(String query, String prevWord) {
-            return mUnigramSuggestionsInfoCache.get(generateKey(query, prevWord));
+        public SuggestionsParams getSuggestionsFromCache(String query,
+                final PrevWordsInfo prevWordsInfo) {
+            return mUnigramSuggestionsInfoCache.get(generateKey(query, prevWordsInfo));
         }
 
-        // TODO: Support n-gram input
         public void putSuggestionsToCache(
-                String query, String prevWord, String[] suggestions, int flags) {
+                final String query, final PrevWordsInfo prevWordsInfo,
+                final String[] suggestions, final int flags) {
             if (suggestions == null || TextUtils.isEmpty(query)) {
                 return;
             }
             mUnigramSuggestionsInfoCache.put(
-                    generateKey(query, prevWord), new SuggestionsParams(suggestions, flags));
+                    generateKey(query, prevWordsInfo), new SuggestionsParams(suggestions, flags));
         }
 
         public void clearCache() {
@@ -259,11 +260,12 @@ public abstract class AndroidWordLevelSpellCheckerSession extends Session {
     }
 
     protected SuggestionsInfo onGetSuggestionsInternal(
-            final TextInfo textInfo, final String prevWord, final int suggestionsLimit) {
+            final TextInfo textInfo, final PrevWordsInfo prevWordsInfo,
+            final int suggestionsLimit) {
         try {
             final String inText = textInfo.getText();
             final SuggestionsParams cachedSuggestionsParams =
-                    mSuggestionsCache.getSuggestionsFromCache(inText, prevWord);
+                    mSuggestionsCache.getSuggestionsFromCache(inText, prevWordsInfo);
             if (cachedSuggestionsParams != null) {
                 if (DBG) {
                     Log.d(TAG, "Cache hit: " + inText + ", " + cachedSuggestionsParams.mFlags);
@@ -325,7 +327,7 @@ public abstract class AndroidWordLevelSpellCheckerSession extends Session {
                 composer.setComposingWord(codePoints, coordinates, null /* previousWord */);
                 // TODO: make a spell checker option to block offensive words or not
                 final ArrayList<SuggestedWordInfo> suggestions =
-                        dictInfo.mDictionary.getSuggestions(composer, prevWord,
+                        dictInfo.mDictionary.getSuggestions(composer, prevWordsInfo,
                                 dictInfo.getProximityInfo(), true /* blockOffensiveWords */,
                                 null /* additionalFeaturesOptions */, 0 /* sessionId */,
                                 null /* inOutLanguageWeight */);
@@ -369,7 +371,8 @@ public abstract class AndroidWordLevelSpellCheckerSession extends Session {
                                     .getValueOf_RESULT_ATTR_HAS_RECOMMENDED_SUGGESTIONS()
                             : 0);
             final SuggestionsInfo retval = new SuggestionsInfo(flags, result.mSuggestions);
-            mSuggestionsCache.putSuggestionsToCache(text, prevWord, result.mSuggestions, flags);
+            mSuggestionsCache.putSuggestionsToCache(text, prevWordsInfo, result.mSuggestions,
+                    flags);
             return retval;
         } catch (RuntimeException e) {
             // Don't kill the keyboard if there is a bug in the spell checker
diff --git a/java/src/com/android/inputmethod/latin/spellcheck/DictionaryPool.java b/java/src/com/android/inputmethod/latin/spellcheck/DictionaryPool.java
index 0be256805..ba2e0c309 100644
--- a/java/src/com/android/inputmethod/latin/spellcheck/DictionaryPool.java
+++ b/java/src/com/android/inputmethod/latin/spellcheck/DictionaryPool.java
@@ -20,6 +20,7 @@ import android.util.Log;
 
 import com.android.inputmethod.keyboard.ProximityInfo;
 import com.android.inputmethod.latin.Dictionary;
+import com.android.inputmethod.latin.PrevWordsInfo;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
 import com.android.inputmethod.latin.WordComposer;
 import com.android.inputmethod.latin.utils.CollectionUtils;
@@ -52,7 +53,7 @@ public final class DictionaryPool extends LinkedBlockingQueue<DictAndKeyboard> {
                 // TODO: this dummy dictionary should be a singleton in the Dictionary class.
                 @Override
                 public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-                        final String prevWord, final ProximityInfo proximityInfo,
+                        final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
                         final boolean blockOffensiveWords, final int[] additionalFeaturesOptions,
                         final int sessionId, final float[] inOutLanguageWeight) {
                     return noSuggestions;
diff --git a/java/src/com/android/inputmethod/latin/spellcheck/SynchronouslyLoadedContactsBinaryDictionary.java b/java/src/com/android/inputmethod/latin/spellcheck/SynchronouslyLoadedContactsBinaryDictionary.java
index 5f6e168b3..75075664f 100644
--- a/java/src/com/android/inputmethod/latin/spellcheck/SynchronouslyLoadedContactsBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/spellcheck/SynchronouslyLoadedContactsBinaryDictionary.java
@@ -20,6 +20,7 @@ import android.content.Context;
 
 import com.android.inputmethod.keyboard.ProximityInfo;
 import com.android.inputmethod.latin.ContactsBinaryDictionary;
+import com.android.inputmethod.latin.PrevWordsInfo;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
 import com.android.inputmethod.latin.WordComposer;
 
@@ -36,11 +37,11 @@ public final class SynchronouslyLoadedContactsBinaryDictionary extends ContactsB
 
     @Override
     public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer codes,
-            final String prevWordForBigrams, final ProximityInfo proximityInfo,
+            final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
             final boolean blockOffensiveWords, final int[] additionalFeaturesOptions,
             final int sessionId, final float[] inOutLanguageWeight) {
         synchronized (mLock) {
-            return super.getSuggestions(codes, prevWordForBigrams, proximityInfo,
+            return super.getSuggestions(codes, prevWordsInfo, proximityInfo,
                     blockOffensiveWords, additionalFeaturesOptions, sessionId, inOutLanguageWeight);
         }
     }
diff --git a/java/src/com/android/inputmethod/latin/spellcheck/SynchronouslyLoadedUserBinaryDictionary.java b/java/src/com/android/inputmethod/latin/spellcheck/SynchronouslyLoadedUserBinaryDictionary.java
index 0499ad234..f2d981a9d 100644
--- a/java/src/com/android/inputmethod/latin/spellcheck/SynchronouslyLoadedUserBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/spellcheck/SynchronouslyLoadedUserBinaryDictionary.java
@@ -19,6 +19,7 @@ package com.android.inputmethod.latin.spellcheck;
 import android.content.Context;
 
 import com.android.inputmethod.keyboard.ProximityInfo;
+import com.android.inputmethod.latin.PrevWordsInfo;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
 import com.android.inputmethod.latin.UserBinaryDictionary;
 import com.android.inputmethod.latin.WordComposer;
@@ -41,11 +42,11 @@ public final class SynchronouslyLoadedUserBinaryDictionary extends UserBinaryDic
 
     @Override
     public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer codes,
-            final String prevWordForBigrams, final ProximityInfo proximityInfo,
+            final PrevWordsInfo prevWordsInfo, final ProximityInfo proximityInfo,
             final boolean blockOffensiveWords, final int[] additionalFeaturesOptions,
             final int sessionId, final float[] inOutLanguageWeight) {
         synchronized (mLock) {
-            return super.getSuggestions(codes, prevWordForBigrams, proximityInfo,
+            return super.getSuggestions(codes, prevWordsInfo, proximityInfo,
                     blockOffensiveWords, additionalFeaturesOptions, sessionId, inOutLanguageWeight);
         }
     }
diff --git a/java/src/com/android/inputmethod/latin/utils/DistracterFilter.java b/java/src/com/android/inputmethod/latin/utils/DistracterFilter.java
index 05387d55b..a21953259 100644
--- a/java/src/com/android/inputmethod/latin/utils/DistracterFilter.java
+++ b/java/src/com/android/inputmethod/latin/utils/DistracterFilter.java
@@ -24,6 +24,7 @@ import android.util.Log;
 
 import com.android.inputmethod.keyboard.Keyboard;
 import com.android.inputmethod.latin.Constants;
+import com.android.inputmethod.latin.PrevWordsInfo;
 import com.android.inputmethod.latin.Suggest;
 import com.android.inputmethod.latin.Suggest.OnGetSuggestedWordsCallback;
 import com.android.inputmethod.latin.SuggestedWords;
@@ -88,13 +89,13 @@ public class DistracterFilter {
     /**
      * Determine whether a word is a distracter to words in dictionaries.
      *
-     * @param prevWord the previous word, or null if none.
+     * @param prevWordsInfo the information of previous words.
      * @param testedWord the word that will be tested to see whether it is a distracter to words
      *                   in dictionaries.
      * @param locale the locale of words.
      * @return true if testedWord is a distracter, otherwise false.
      */
-    public boolean isDistracterToWordsInDictionaries(final String prevWord,
+    public boolean isDistracterToWordsInDictionaries(final PrevWordsInfo prevWordsInfo,
             final String testedWord, final Locale locale) {
         if (mKeyboard == null || locale == null) {
             return false;
@@ -113,7 +114,7 @@ public class DistracterFilter {
         final int[] codePoints = StringUtils.toCodePointArray(testedWord);
         final int[] coordinates;
         coordinates = mKeyboard.getCoordinates(codePoints);
-        composer.setComposingWord(codePoints, coordinates, prevWord);
+        composer.setComposingWord(codePoints, coordinates, prevWordsInfo.mPrevWord);
 
         final int trailingSingleQuotesCount = StringUtils.getTrailingSingleQuotesCount(testedWord);
         final String consideredWord = trailingSingleQuotesCount > 0 ?
@@ -133,7 +134,7 @@ public class DistracterFilter {
                 }
             }
         };
-        mSuggest.getSuggestedWords(composer, prevWord, mKeyboard.getProximityInfo(),
+        mSuggest.getSuggestedWords(composer, prevWordsInfo, mKeyboard.getProximityInfo(),
                 true /* blockOffensiveWords */, true /* isCorrectionEnbaled */,
                 null /* additionalFeaturesOptions */, 0 /* sessionId */,
                 SuggestedWords.NOT_A_SEQUENCE_NUMBER, callback);
diff --git a/java/src/com/android/inputmethod/latin/utils/LanguageModelParam.java b/java/src/com/android/inputmethod/latin/utils/LanguageModelParam.java
index 2d6796e3e..aaf4a4064 100644
--- a/java/src/com/android/inputmethod/latin/utils/LanguageModelParam.java
+++ b/java/src/com/android/inputmethod/latin/utils/LanguageModelParam.java
@@ -20,6 +20,7 @@ import android.util.Log;
 
 import com.android.inputmethod.latin.Dictionary;
 import com.android.inputmethod.latin.DictionaryFacilitatorForSuggest;
+import com.android.inputmethod.latin.PrevWordsInfo;
 import com.android.inputmethod.latin.settings.SpacingAndPunctuations;
 
 import java.util.ArrayList;
@@ -85,7 +86,7 @@ public final class LanguageModelParam {
         final ArrayList<LanguageModelParam> languageModelParams =
                 CollectionUtils.newArrayList();
         final int N = tokens.size();
-        String prevWord = null;
+        PrevWordsInfo prevWordsInfo = new PrevWordsInfo(null);
         for (int i = 0; i < N; ++i) {
             final String tempWord = tokens.get(i);
             if (StringUtils.isEmptyStringOrWhiteSpaces(tempWord)) {
@@ -102,7 +103,7 @@ public final class LanguageModelParam {
                             + tempWord + "\"");
                 }
                 // Sentence terminator found. Split.
-                prevWord = null;
+                prevWordsInfo = new PrevWordsInfo(null);
                 continue;
             }
             if (DEBUG_TOKEN) {
@@ -110,19 +111,19 @@ public final class LanguageModelParam {
             }
             final LanguageModelParam languageModelParam =
                     detectWhetherVaildWordOrNotAndGetLanguageModelParam(
-                            prevWord, tempWord, timestamp, dictionaryFacilitator,
+                            prevWordsInfo, tempWord, timestamp, dictionaryFacilitator,
                             distracterFilter);
             if (languageModelParam == null) {
                 continue;
             }
             languageModelParams.add(languageModelParam);
-            prevWord = languageModelParam.mTargetWord;
+            prevWordsInfo = new PrevWordsInfo(languageModelParam.mTargetWord);
         }
         return languageModelParams;
     }
 
     private static LanguageModelParam detectWhetherVaildWordOrNotAndGetLanguageModelParam(
-            final String prevWord, final String targetWord, final int timestamp,
+            final PrevWordsInfo prevWordsInfo, final String targetWord, final int timestamp,
             final DictionaryFacilitatorForSuggest dictionaryFacilitator,
             final DistracterFilter distracterFilter) {
         final Locale locale = dictionaryFacilitator.getLocale();
@@ -133,14 +134,14 @@ public final class LanguageModelParam {
         // distracterFilter in the following code. If targetWord is a distracter,
         // it should be filtered out.
         if (dictionaryFacilitator.isValidWord(targetWord, false /* ignoreCase */)) {
-            return createAndGetLanguageModelParamOfWord(prevWord, targetWord, timestamp,
+            return createAndGetLanguageModelParamOfWord(prevWordsInfo, targetWord, timestamp,
                     true /* isValidWord */, locale);
         }
 
         final String lowerCaseTargetWord = targetWord.toLowerCase(locale);
         if (dictionaryFacilitator.isValidWord(lowerCaseTargetWord, false /* ignoreCase */)) {
             // Add the lower-cased word.
-            return createAndGetLanguageModelParamOfWord(prevWord, lowerCaseTargetWord,
+            return createAndGetLanguageModelParamOfWord(prevWordsInfo, lowerCaseTargetWord,
                     timestamp, true /* isValidWord */, locale);
         }
 
@@ -150,26 +151,26 @@ public final class LanguageModelParam {
         // Adding such a word to dictonaries would interfere with entering in-dictionary words. For
         // example, adding "mot" to dictionaries might interfere with entering "not".
         // This kind of OOV should be filtered out.
-        if (distracterFilter.isDistracterToWordsInDictionaries(prevWord, targetWord, locale)) {
+        if (distracterFilter.isDistracterToWordsInDictionaries(prevWordsInfo, targetWord, locale)) {
             return null;
         }
-        return createAndGetLanguageModelParamOfWord(prevWord, targetWord, timestamp,
+        return createAndGetLanguageModelParamOfWord(prevWordsInfo, targetWord, timestamp,
                 false /* isValidWord */, locale);
     }
 
     private static LanguageModelParam createAndGetLanguageModelParamOfWord(
-            final String prevWord, final String targetWord, final int timestamp,
+            final PrevWordsInfo prevWordsInfo, final String targetWord, final int timestamp,
             final boolean isValidWord, final Locale locale) {
         final String word;
         if (StringUtils.getCapitalizationType(targetWord) == StringUtils.CAPITALIZE_FIRST
-                && prevWord == null && !isValidWord) {
+                && prevWordsInfo.mPrevWord == null && !isValidWord) {
             word = targetWord.toLowerCase(locale);
         } else {
             word = targetWord;
         }
         final int unigramProbability = isValidWord ?
                 UNIGRAM_PROBABILITY_FOR_VALID_WORD : UNIGRAM_PROBABILITY_FOR_OOV_WORD;
-        if (prevWord == null) {
+        if (prevWordsInfo.mPrevWord == null) {
             if (DEBUG) {
                 Log.d(TAG, "--- add unigram: current("
                         + (isValidWord ? "Valid" : "OOV") + ") = " + word);
@@ -177,12 +178,12 @@ public final class LanguageModelParam {
             return new LanguageModelParam(word, unigramProbability, timestamp);
         }
         if (DEBUG) {
-            Log.d(TAG, "--- add bigram: prev = " + prevWord + ", current("
+            Log.d(TAG, "--- add bigram: prev = " + prevWordsInfo.mPrevWord + ", current("
                     + (isValidWord ? "Valid" : "OOV") + ") = " + word);
         }
         final int bigramProbability = isValidWord ?
                 BIGRAM_PROBABILITY_FOR_VALID_WORD : BIGRAM_PROBABILITY_FOR_OOV_WORD;
-        return new LanguageModelParam(prevWord, word, unigramProbability,
+        return new LanguageModelParam(prevWordsInfo.mPrevWord, word, unigramProbability,
                 bigramProbability, timestamp);
     }
 }