Use BinaryDicitonary.MAX_PREV_WORD_COUNT_FOR_NGRAM for D2 dictioanries.

Fixes the UserHistoryDictionaryTests

Change-Id: I49776f53298ced3cd7e771cfe77a940b80b01f20

java/src/com/android/inputmethod/latin/BinaryDictionary.java

@@ -58,7 +58,8 @@ public final class BinaryDictionary extends Dictionary {
     // Must be equal to CONFIDENCE_TO_AUTO_COMMIT in native/jni/src/defines.h
     private static final int CONFIDENCE_TO_AUTO_COMMIT = 1000000;
 
-    static final int DICTIONARY_MAX_WORD_LENGTH = 48;
+    public static final int DICTIONARY_MAX_WORD_LENGTH = 48;
+    public static final int MAX_PREV_WORD_COUNT_FOR_N_GRAM = 3;
 
     @UsedForTesting
     public static final String UNIGRAM_COUNT_QUERY = "UNIGRAM_COUNT";

java/src/com/android/inputmethod/latin/ContactsBinaryDictionary.java

@@ -125,7 +125,8 @@ public class ContactsBinaryDictionary extends ExpandableBinaryDictionary
      */
     private void addNameLocked(final String name) {
         int len = StringUtils.codePointCount(name);
-        NgramContext ngramContext = NgramContext.EMPTY_PREV_WORDS_INFO;
+        NgramContext ngramContext = NgramContext.getEmptyPrevWordsContext(
+                BinaryDictionary.MAX_PREV_WORD_COUNT_FOR_N_GRAM);
         // TODO: Better tokenization for non-Latin writing systems
         for (int i = 0; i < len; i++) {
             if (Character.isLetter(name.codePointAt(i))) {

java/src/com/android/inputmethod/latin/NgramContext.java

@@ -43,6 +43,10 @@ public class NgramContext {
 
     public static final String CONTEXT_SEPARATOR = " ";
 
+    public static NgramContext getEmptyPrevWordsContext(int maxPrevWordCount) {
+        return new NgramContext(maxPrevWordCount, WordInfo.EMPTY_WORD_INFO);
+    }
+
     /**
      * Word information used to represent previous words information.
      */
@@ -102,10 +106,17 @@ public class NgramContext {
     private final WordInfo[] mPrevWordsInfo;
     private final int mPrevWordsCount;
 
+    private final int mMaxPrevWordCount;
+
     // Construct from the previous word information.
     public NgramContext(final WordInfo... prevWordsInfo) {
+        this(DecoderSpecificConstants.MAX_PREV_WORD_COUNT_FOR_N_GRAM, prevWordsInfo);
+    }
+
+    public NgramContext(final int maxPrevWordCount, final WordInfo... prevWordsInfo) {
         mPrevWordsInfo = prevWordsInfo;
         mPrevWordsCount = prevWordsInfo.length;
+        mMaxPrevWordCount = maxPrevWordCount;
     }
 
     /**
@@ -113,8 +124,7 @@ public class NgramContext {
      */
     @Nonnull
     public NgramContext getNextNgramContext(final WordInfo wordInfo) {
-        final int nextPrevWordCount = Math.min(
+        final int nextPrevWordCount = Math.min(mMaxPrevWordCount, mPrevWordsCount + 1);
-                DecoderSpecificConstants.MAX_PREV_WORD_COUNT_FOR_N_GRAM, mPrevWordsCount + 1);
         final WordInfo[] prevWordsInfo = new WordInfo[nextPrevWordCount];
         prevWordsInfo[0] = wordInfo;
         System.arraycopy(mPrevWordsInfo, 0, prevWordsInfo, 1, nextPrevWordCount - 1);

java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java

@@ -20,6 +20,7 @@ import android.content.Context;
 
 import com.android.inputmethod.annotations.ExternallyReferenced;
 import com.android.inputmethod.annotations.UsedForTesting;
+import com.android.inputmethod.latin.BinaryDictionary;
 import com.android.inputmethod.latin.Dictionary;
 import com.android.inputmethod.latin.ExpandableBinaryDictionary;
 import com.android.inputmethod.latin.NgramContext;
@@ -98,7 +99,7 @@ public class UserHistoryDictionary extends ExpandableBinaryDictionary {
     public static void addToDictionary(final ExpandableBinaryDictionary userHistoryDictionary,
             @Nonnull final NgramContext ngramContext, final String word, final boolean isValid,
             final int timestamp) {
-        if (word.length() > DecoderSpecificConstants.DICTIONARY_MAX_WORD_LENGTH) {
+        if (word.length() > BinaryDictionary.DICTIONARY_MAX_WORD_LENGTH) {
             return;
         }
         userHistoryDictionary.updateEntriesForWord(ngramContext, word,

tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTestsHelper.java

@@ -18,6 +18,7 @@ package com.android.inputmethod.latin.personalization;
 
 import android.content.Context;
 
+import com.android.inputmethod.latin.BinaryDictionary;
 import com.android.inputmethod.latin.NgramContext;
 import com.android.inputmethod.latin.NgramContext.WordInfo;
 import com.android.inputmethod.latin.common.FileUtils;
@@ -98,7 +99,8 @@ public class UserHistoryDictionaryTestsHelper {
 
     private static void addWordsToDictionary(final UserHistoryDictionary dict,
             final List<String> words, final int timestamp) {
-        NgramContext ngramContext = NgramContext.EMPTY_PREV_WORDS_INFO;
+        NgramContext ngramContext = NgramContext.getEmptyPrevWordsContext(
+                BinaryDictionary.MAX_PREV_WORD_COUNT_FOR_N_GRAM);
         for (final String word : words) {
             UserHistoryDictionary.addToDictionary(dict, ngramContext, word, true, timestamp);
             ngramContext = ngramContext.getNextNgramContext(new WordInfo(word));