Rename PrevWordsInfo to NgramContext.

Bug: 14425059
Change-Id: Id06a71681fa8b5e589e29fba10fe5c1cfed66984

8 files changed, 151 insertions, 151 deletions

diff --git a/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java b/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
index f3bbe4ad4..8d5d6ccec 100644
--- a/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
+++ b/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
@@ -20,7 +20,7 @@ import android.test.AndroidTestCase;
 import android.test.suitebuilder.annotation.LargeTest;
 import android.util.Pair;
 
-import com.android.inputmethod.latin.PrevWordsInfo.WordInfo;
+import com.android.inputmethod.latin.NgramContext.WordInfo;
 import com.android.inputmethod.latin.makedict.BinaryDictIOUtils;
 import com.android.inputmethod.latin.makedict.CodePointUtils;
 import com.android.inputmethod.latin.makedict.DictDecoder;
@@ -78,13 +78,13 @@ public class BinaryDictionaryDecayingTests extends AndroidTestCase {
 
     private void addBigramWords(final BinaryDictionary binaryDictionary, final String word0,
             final String word1, final int probability) {
-        binaryDictionary.addNgramEntry(new PrevWordsInfo(new WordInfo(word0)), word1, probability,
+        binaryDictionary.addNgramEntry(new NgramContext(new WordInfo(word0)), word1, probability,
                 mCurrentTime /* timestamp */);
     }
 
     private static boolean isValidBigram(final BinaryDictionary binaryDictionary,
             final String word0, final String word1) {
-        return binaryDictionary.isValidNgram(new PrevWordsInfo(new WordInfo(word0)), word1);
+        return binaryDictionary.isValidNgram(new NgramContext(new WordInfo(word0)), word1);
     }
 
     private void forcePassingShortTime(final BinaryDictionary binaryDictionary) {
@@ -661,31 +661,31 @@ public class BinaryDictionaryDecayingTests extends AndroidTestCase {
                 BinaryDictionary.NOT_A_PROBABILITY /* shortcutProbability */,
                 true /* isBeginningOfSentence */, true /* isNotAWord */, false /* isBlacklisted */,
                 mCurrentTime);
-        final PrevWordsInfo prevWordsInfoStartOfSentence = PrevWordsInfo.BEGINNING_OF_SENTENCE;
+        final NgramContext beginningOfSentenceContext = NgramContext.BEGINNING_OF_SENTENCE;
         addUnigramWord(binaryDictionary, "aaa", DUMMY_PROBABILITY);
-        binaryDictionary.addNgramEntry(prevWordsInfoStartOfSentence, "aaa", DUMMY_PROBABILITY,
+        binaryDictionary.addNgramEntry(beginningOfSentenceContext, "aaa", DUMMY_PROBABILITY,
                 mCurrentTime);
-        assertTrue(binaryDictionary.isValidNgram(prevWordsInfoStartOfSentence, "aaa"));
-        binaryDictionary.addNgramEntry(prevWordsInfoStartOfSentence, "aaa", DUMMY_PROBABILITY,
+        assertTrue(binaryDictionary.isValidNgram(beginningOfSentenceContext, "aaa"));
+        binaryDictionary.addNgramEntry(beginningOfSentenceContext, "aaa", DUMMY_PROBABILITY,
                 mCurrentTime);
         addUnigramWord(binaryDictionary, "bbb", DUMMY_PROBABILITY);
-        binaryDictionary.addNgramEntry(prevWordsInfoStartOfSentence, "bbb", DUMMY_PROBABILITY,
+        binaryDictionary.addNgramEntry(beginningOfSentenceContext, "bbb", DUMMY_PROBABILITY,
                 mCurrentTime);
-        assertTrue(binaryDictionary.isValidNgram(prevWordsInfoStartOfSentence, "aaa"));
-        assertTrue(binaryDictionary.isValidNgram(prevWordsInfoStartOfSentence, "bbb"));
+        assertTrue(binaryDictionary.isValidNgram(beginningOfSentenceContext, "aaa"));
+        assertTrue(binaryDictionary.isValidNgram(beginningOfSentenceContext, "bbb"));
 
         forcePassingLongTime(binaryDictionary);
-        assertFalse(binaryDictionary.isValidNgram(prevWordsInfoStartOfSentence, "aaa"));
-        assertFalse(binaryDictionary.isValidNgram(prevWordsInfoStartOfSentence, "bbb"));
+        assertFalse(binaryDictionary.isValidNgram(beginningOfSentenceContext, "aaa"));
+        assertFalse(binaryDictionary.isValidNgram(beginningOfSentenceContext, "bbb"));
 
         addUnigramWord(binaryDictionary, "aaa", DUMMY_PROBABILITY);
-        binaryDictionary.addNgramEntry(prevWordsInfoStartOfSentence, "aaa", DUMMY_PROBABILITY,
+        binaryDictionary.addNgramEntry(beginningOfSentenceContext, "aaa", DUMMY_PROBABILITY,
                 mCurrentTime);
         addUnigramWord(binaryDictionary, "bbb", DUMMY_PROBABILITY);
-        binaryDictionary.addNgramEntry(prevWordsInfoStartOfSentence, "bbb", DUMMY_PROBABILITY,
+        binaryDictionary.addNgramEntry(beginningOfSentenceContext, "bbb", DUMMY_PROBABILITY,
                 mCurrentTime);
-        assertTrue(binaryDictionary.isValidNgram(prevWordsInfoStartOfSentence, "aaa"));
-        assertTrue(binaryDictionary.isValidNgram(prevWordsInfoStartOfSentence, "bbb"));
+        assertTrue(binaryDictionary.isValidNgram(beginningOfSentenceContext, "aaa"));
+        assertTrue(binaryDictionary.isValidNgram(beginningOfSentenceContext, "bbb"));
         binaryDictionary.close();
         dictFile.delete();
     }
diff --git a/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java b/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java
index 4025744f8..e6f00b668 100644
--- a/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java
+++ b/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java
@@ -21,7 +21,7 @@ import android.test.suitebuilder.annotation.LargeTest;
 import android.text.TextUtils;
 import android.util.Pair;
 
-import com.android.inputmethod.latin.PrevWordsInfo.WordInfo;
+import com.android.inputmethod.latin.NgramContext.WordInfo;
 import com.android.inputmethod.latin.makedict.CodePointUtils;
 import com.android.inputmethod.latin.makedict.FormatSpec;
 import com.android.inputmethod.latin.makedict.WeightedString;
@@ -208,45 +208,45 @@ public class BinaryDictionaryTests extends AndroidTestCase {
 
     private static void addBigramWords(final BinaryDictionary binaryDictionary, final String word0,
             final String word1, final int probability) {
-        binaryDictionary.addNgramEntry(new PrevWordsInfo(new WordInfo(word0)), word1, probability,
+        binaryDictionary.addNgramEntry(new NgramContext(new WordInfo(word0)), word1, probability,
                 BinaryDictionary.NOT_A_VALID_TIMESTAMP /* timestamp */);
     }
 
     private static void addTrigramEntry(final BinaryDictionary binaryDictionary, final String word0,
             final String word1, final String word2, final int probability) {
-        final PrevWordsInfo prevWordsInfo =
-                new PrevWordsInfo(new WordInfo[] { new WordInfo(word1), new WordInfo(word0) } );
-        binaryDictionary.addNgramEntry(prevWordsInfo, word2, probability,
+        final NgramContext ngramContext =
+                new NgramContext(new WordInfo[] { new WordInfo(word1), new WordInfo(word0) } );
+        binaryDictionary.addNgramEntry(ngramContext, word2, probability,
                 BinaryDictionary.NOT_A_VALID_TIMESTAMP /* timestamp */);
     }
 
     private static boolean isValidBigram(final BinaryDictionary binaryDictionary,
             final String word0, final String word1) {
-        return binaryDictionary.isValidNgram(new PrevWordsInfo(new WordInfo(word0)), word1);
+        return binaryDictionary.isValidNgram(new NgramContext(new WordInfo(word0)), word1);
     }
 
     private static void removeBigramEntry(final BinaryDictionary binaryDictionary,
             final String word0, final String word1) {
-        binaryDictionary.removeNgramEntry(new PrevWordsInfo(new WordInfo(word0)), word1);
+        binaryDictionary.removeNgramEntry(new NgramContext(new WordInfo(word0)), word1);
     }
 
     private static void removeTrigramEntry(final BinaryDictionary binaryDictionary,
             final String word0, final String word1, final String word2) {
-        final PrevWordsInfo prevWordsInfo =
-                new PrevWordsInfo(new WordInfo[] { new WordInfo(word1), new WordInfo(word0) } );
-        binaryDictionary.removeNgramEntry(prevWordsInfo, word2);
+        final NgramContext ngramContext =
+                new NgramContext(new WordInfo[] { new WordInfo(word1), new WordInfo(word0) } );
+        binaryDictionary.removeNgramEntry(ngramContext, word2);
     }
 
     private static int getBigramProbability(final BinaryDictionary binaryDictionary,
             final String word0,  final String word1) {
-        return binaryDictionary.getNgramProbability(new PrevWordsInfo(new WordInfo(word0)), word1);
+        return binaryDictionary.getNgramProbability(new NgramContext(new WordInfo(word0)), word1);
     }
 
     private static int getTrigramProbability(final BinaryDictionary binaryDictionary,
             final String word0, final String word1, final String word2) {
-        final PrevWordsInfo prevWordsInfo =
-                new PrevWordsInfo(new WordInfo[] { new WordInfo(word1), new WordInfo(word0) } );
-        return binaryDictionary.getNgramProbability(prevWordsInfo, word2);
+        final NgramContext ngramContext =
+                new NgramContext(new WordInfo[] { new WordInfo(word1), new WordInfo(word0) } );
+        return binaryDictionary.getNgramProbability(ngramContext, word2);
     }
 
     public void testAddUnigramWord() {
@@ -1422,7 +1422,7 @@ public class BinaryDictionaryTests extends AndroidTestCase {
         binaryDictionary.addUnigramEntry("ddd", unigramProbability, null /* shortcutTarget */,
                 Dictionary.NOT_A_PROBABILITY, false /* isBeginningOfSentence */,
                 true /* isNotAWord */, true /* isBlacklisted */, 0 /* timestamp */);
-        binaryDictionary.addNgramEntry(PrevWordsInfo.BEGINNING_OF_SENTENCE,
+        binaryDictionary.addNgramEntry(NgramContext.BEGINNING_OF_SENTENCE,
                 "aaa", bigramProbability, 0 /* timestamp */);
         assertEquals(unigramProbability, binaryDictionary.getFrequency("aaa"));
         assertEquals(unigramProbability, binaryDictionary.getFrequency("bbb"));
@@ -1436,7 +1436,7 @@ public class BinaryDictionaryTests extends AndroidTestCase {
         if (canCheckBigramProbability(toFormatVersion)) {
             assertEquals(bigramProbability, getBigramProbability(binaryDictionary, "aaa", "bbb"));
             assertEquals(bigramProbability, binaryDictionary.getNgramProbability(
-                    PrevWordsInfo.BEGINNING_OF_SENTENCE, "aaa"));
+                    NgramContext.BEGINNING_OF_SENTENCE, "aaa"));
         }
         assertTrue(isValidBigram(binaryDictionary, "aaa", "bbb"));
         WordProperty wordProperty = binaryDictionary.getWordProperty("ccc",
@@ -1546,23 +1546,23 @@ public class BinaryDictionaryTests extends AndroidTestCase {
                 0 /* offset */, dictFile.length(), true /* useFullEditDistance */,
                 Locale.getDefault(), TEST_LOCALE, true /* isUpdatable */);
         final int dummyProbability = 0;
-        final PrevWordsInfo prevWordsInfoBeginningOfSentence = PrevWordsInfo.BEGINNING_OF_SENTENCE;
+        final NgramContext beginningOfSentenceContext = NgramContext.BEGINNING_OF_SENTENCE;
         final int bigramProbability = 200;
         addUnigramWord(binaryDictionary, "aaa", dummyProbability);
-        binaryDictionary.addNgramEntry(prevWordsInfoBeginningOfSentence, "aaa", bigramProbability,
+        binaryDictionary.addNgramEntry(beginningOfSentenceContext, "aaa", bigramProbability,
                 BinaryDictionary.NOT_A_VALID_TIMESTAMP /* timestamp */);
         assertEquals(bigramProbability,
-                binaryDictionary.getNgramProbability(prevWordsInfoBeginningOfSentence, "aaa"));
-        binaryDictionary.addNgramEntry(prevWordsInfoBeginningOfSentence, "aaa", bigramProbability,
+                binaryDictionary.getNgramProbability(beginningOfSentenceContext, "aaa"));
+        binaryDictionary.addNgramEntry(beginningOfSentenceContext, "aaa", bigramProbability,
                 BinaryDictionary.NOT_A_VALID_TIMESTAMP /* timestamp */);
         addUnigramWord(binaryDictionary, "bbb", dummyProbability);
-        binaryDictionary.addNgramEntry(prevWordsInfoBeginningOfSentence, "bbb", bigramProbability,
+        binaryDictionary.addNgramEntry(beginningOfSentenceContext, "bbb", bigramProbability,
                 BinaryDictionary.NOT_A_VALID_TIMESTAMP /* timestamp */);
         binaryDictionary.flushWithGC();
         assertEquals(bigramProbability,
-                binaryDictionary.getNgramProbability(prevWordsInfoBeginningOfSentence, "aaa"));
+                binaryDictionary.getNgramProbability(beginningOfSentenceContext, "aaa"));
         assertEquals(bigramProbability,
-                binaryDictionary.getNgramProbability(prevWordsInfoBeginningOfSentence, "bbb"));
+                binaryDictionary.getNgramProbability(beginningOfSentenceContext, "bbb"));
     }
 
     public void testGetMaxFrequencyOfExactMatches() {
diff --git a/tests/src/com/android/inputmethod/latin/NgramContextTests.java b/tests/src/com/android/inputmethod/latin/NgramContextTests.java
new file mode 100644
index 000000000..ecc2c634d
--- /dev/null
+++ b/tests/src/com/android/inputmethod/latin/NgramContextTests.java
@@ -0,0 +1,66 @@
+/*
+ * 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;
+
+import com.android.inputmethod.latin.NgramContext.WordInfo;
+
+import android.test.AndroidTestCase;
+import android.test.suitebuilder.annotation.SmallTest;
+
+@SmallTest
+public class NgramContextTests extends AndroidTestCase {
+    public void testConstruct() {
+        assertEquals(new NgramContext(new WordInfo("a")), new NgramContext(new WordInfo("a")));
+        assertEquals(new NgramContext(WordInfo.BEGINNING_OF_SENTENCE),
+                new NgramContext(WordInfo.BEGINNING_OF_SENTENCE));
+        assertEquals(new NgramContext(WordInfo.EMPTY_WORD_INFO),
+                new NgramContext(WordInfo.EMPTY_WORD_INFO));
+        assertEquals(new NgramContext(WordInfo.EMPTY_WORD_INFO),
+                new NgramContext(WordInfo.EMPTY_WORD_INFO));
+    }
+
+    public void testIsBeginningOfSentenceContext() {
+        assertFalse(new NgramContext().isBeginningOfSentenceContext());
+        assertTrue(new NgramContext(WordInfo.BEGINNING_OF_SENTENCE)
+                .isBeginningOfSentenceContext());
+        assertTrue(NgramContext.BEGINNING_OF_SENTENCE.isBeginningOfSentenceContext());
+        assertFalse(new NgramContext(new WordInfo("a")).isBeginningOfSentenceContext());
+        assertFalse(new NgramContext(new WordInfo("")).isBeginningOfSentenceContext());
+        assertFalse(new NgramContext(WordInfo.EMPTY_WORD_INFO).isBeginningOfSentenceContext());
+        assertTrue(new NgramContext(WordInfo.BEGINNING_OF_SENTENCE, new WordInfo("a"))
+                .isBeginningOfSentenceContext());
+        assertFalse(new NgramContext(new WordInfo("a"), WordInfo.BEGINNING_OF_SENTENCE)
+                .isBeginningOfSentenceContext());
+        assertFalse(new NgramContext(WordInfo.EMPTY_WORD_INFO, WordInfo.BEGINNING_OF_SENTENCE)
+                .isBeginningOfSentenceContext());
+    }
+
+    public void testGetNextNgramContext() {
+        final NgramContext ngramContext_a = new NgramContext(new WordInfo("a"));
+        final NgramContext ngramContext_b_a =
+                ngramContext_a.getNextNgramContext(new WordInfo("b"));
+        assertEquals("b", ngramContext_b_a.getNthPrevWord(1));
+        assertEquals("a", ngramContext_b_a.getNthPrevWord(2));
+        final NgramContext ngramContext_bos_b =
+                ngramContext_b_a.getNextNgramContext(WordInfo.BEGINNING_OF_SENTENCE);
+        assertTrue(ngramContext_bos_b.isBeginningOfSentenceContext());
+        assertEquals("b", ngramContext_bos_b.getNthPrevWord(2));
+        final NgramContext ngramContext_c_bos =
+                ngramContext_b_a.getNextNgramContext(new WordInfo("c"));
+        assertEquals("c", ngramContext_c_bos.getNthPrevWord(1));
+    }
+}
diff --git a/tests/src/com/android/inputmethod/latin/PrevWordsInfoTests.java b/tests/src/com/android/inputmethod/latin/PrevWordsInfoTests.java
deleted file mode 100644
index c571d985d..000000000
--- a/tests/src/com/android/inputmethod/latin/PrevWordsInfoTests.java
+++ /dev/null
@@ -1,66 +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.latin;
-
-import com.android.inputmethod.latin.PrevWordsInfo.WordInfo;
-
-import android.test.AndroidTestCase;
-import android.test.suitebuilder.annotation.SmallTest;
-
-@SmallTest
-public class PrevWordsInfoTests extends AndroidTestCase {
-    public void testConstruct() {
-        assertEquals(new PrevWordsInfo(new WordInfo("a")), new PrevWordsInfo(new WordInfo("a")));
-        assertEquals(new PrevWordsInfo(WordInfo.BEGINNING_OF_SENTENCE),
-                new PrevWordsInfo(WordInfo.BEGINNING_OF_SENTENCE));
-        assertEquals(new PrevWordsInfo(WordInfo.EMPTY_WORD_INFO),
-                new PrevWordsInfo(WordInfo.EMPTY_WORD_INFO));
-        assertEquals(new PrevWordsInfo(WordInfo.EMPTY_WORD_INFO),
-                new PrevWordsInfo(WordInfo.EMPTY_WORD_INFO));
-    }
-
-    public void testIsBeginningOfSentenceContext() {
-        assertFalse(new PrevWordsInfo().isBeginningOfSentenceContext());
-        assertTrue(new PrevWordsInfo(WordInfo.BEGINNING_OF_SENTENCE)
-                .isBeginningOfSentenceContext());
-        assertTrue(PrevWordsInfo.BEGINNING_OF_SENTENCE.isBeginningOfSentenceContext());
-        assertFalse(new PrevWordsInfo(new WordInfo("a")).isBeginningOfSentenceContext());
-        assertFalse(new PrevWordsInfo(new WordInfo("")).isBeginningOfSentenceContext());
-        assertFalse(new PrevWordsInfo(WordInfo.EMPTY_WORD_INFO).isBeginningOfSentenceContext());
-        assertTrue(new PrevWordsInfo(WordInfo.BEGINNING_OF_SENTENCE, new WordInfo("a"))
-                .isBeginningOfSentenceContext());
-        assertFalse(new PrevWordsInfo(new WordInfo("a"), WordInfo.BEGINNING_OF_SENTENCE)
-                .isBeginningOfSentenceContext());
-        assertFalse(new PrevWordsInfo(WordInfo.EMPTY_WORD_INFO, WordInfo.BEGINNING_OF_SENTENCE)
-                .isBeginningOfSentenceContext());
-    }
-
-    public void testGetNextPrevWordsInfo() {
-        final PrevWordsInfo prevWordsInfo_a = new PrevWordsInfo(new WordInfo("a"));
-        final PrevWordsInfo prevWordsInfo_b_a =
-                prevWordsInfo_a.getNextPrevWordsInfo(new WordInfo("b"));
-        assertEquals("b", prevWordsInfo_b_a.getNthPrevWord(1));
-        assertEquals("a", prevWordsInfo_b_a.getNthPrevWord(2));
-        final PrevWordsInfo prevWordsInfo_bos_b =
-                prevWordsInfo_b_a.getNextPrevWordsInfo(WordInfo.BEGINNING_OF_SENTENCE);
-        assertTrue(prevWordsInfo_bos_b.isBeginningOfSentenceContext());
-        assertEquals("b", prevWordsInfo_bos_b.getNthPrevWord(2));
-        final PrevWordsInfo prevWordsInfo_c_bos =
-                prevWordsInfo_b_a.getNextPrevWordsInfo(new WordInfo("c"));
-        assertEquals("c", prevWordsInfo_c_bos.getNthPrevWord(1));
-    }
-}
diff --git a/tests/src/com/android/inputmethod/latin/RichInputConnectionAndTextRangeTests.java b/tests/src/com/android/inputmethod/latin/RichInputConnectionAndTextRangeTests.java
index 2712dc228..7a3233625 100644
--- a/tests/src/com/android/inputmethod/latin/RichInputConnectionAndTextRangeTests.java
+++ b/tests/src/com/android/inputmethod/latin/RichInputConnectionAndTextRangeTests.java
@@ -31,7 +31,7 @@ import android.view.inputmethod.InputConnection;
 import android.view.inputmethod.InputConnectionWrapper;
 
 import com.android.inputmethod.latin.settings.SpacingAndPunctuations;
-import com.android.inputmethod.latin.utils.PrevWordsInfoUtils;
+import com.android.inputmethod.latin.utils.NgramContextUtils;
 import com.android.inputmethod.latin.utils.RunInLocale;
 import com.android.inputmethod.latin.utils.ScriptUtils;
 import com.android.inputmethod.latin.utils.StringUtils;
@@ -157,24 +157,24 @@ public class RichInputConnectionAndTextRangeTests extends AndroidTestCase {
      */
     public void testGetPreviousWord() {
         // If one of the following cases breaks, the bigram suggestions won't work.
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
                 "abc def", mSpacingAndPunctuations, 2).getNthPrevWord(1), "abc");
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
-                "abc", mSpacingAndPunctuations, 2), PrevWordsInfo.BEGINNING_OF_SENTENCE);
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
-                "abc. def", mSpacingAndPunctuations, 2), PrevWordsInfo.BEGINNING_OF_SENTENCE);
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
+                "abc", mSpacingAndPunctuations, 2), NgramContext.BEGINNING_OF_SENTENCE);
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
+                "abc. def", mSpacingAndPunctuations, 2), NgramContext.BEGINNING_OF_SENTENCE);
 
-        assertFalse(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
+        assertFalse(NgramContextUtils.getNgramContextFromNthPreviousWord(
                 "abc def", mSpacingAndPunctuations, 2).isBeginningOfSentenceContext());
-        assertTrue(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
+        assertTrue(NgramContextUtils.getNgramContextFromNthPreviousWord(
                 "abc", mSpacingAndPunctuations, 2).isBeginningOfSentenceContext());
 
         // For n-gram
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
                 "abc def", mSpacingAndPunctuations, 1).getNthPrevWord(1), "def");
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
                 "abc def", mSpacingAndPunctuations, 1).getNthPrevWord(2), "abc");
-        assertTrue(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
+        assertTrue(NgramContextUtils.getNgramContextFromNthPreviousWord(
                 "abc def", mSpacingAndPunctuations, 2).isNthPrevWordBeginningOfSontence(2));
 
         // The following tests reflect the current behavior of the function
@@ -184,33 +184,33 @@ public class RichInputConnectionAndTextRangeTests extends AndroidTestCase {
         // this function if needed - especially since it does not seem very
         // logical. These tests are just there to catch any unintentional
         // changes in the behavior of the RichInputConnection#getPreviousWord method.
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
                 "abc def ", mSpacingAndPunctuations, 2).getNthPrevWord(1), "abc");
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
                 "abc def.", mSpacingAndPunctuations, 2).getNthPrevWord(1), "abc");
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
                 "abc def .", mSpacingAndPunctuations, 2).getNthPrevWord(1), "def");
-        assertTrue(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
+        assertTrue(NgramContextUtils.getNgramContextFromNthPreviousWord(
                 "abc ", mSpacingAndPunctuations, 2).isBeginningOfSentenceContext());
 
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
                 "abc def", mSpacingAndPunctuations, 1).getNthPrevWord(1), "def");
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
                 "abc def ", mSpacingAndPunctuations, 1).getNthPrevWord(1), "def");
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
                 "abc 'def", mSpacingAndPunctuations, 1).getNthPrevWord(1), "'def");
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
-                "abc def.", mSpacingAndPunctuations, 1), PrevWordsInfo.BEGINNING_OF_SENTENCE);
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
-                "abc def .", mSpacingAndPunctuations, 1), PrevWordsInfo.BEGINNING_OF_SENTENCE);
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
-                "abc, def", mSpacingAndPunctuations, 2), PrevWordsInfo.EMPTY_PREV_WORDS_INFO);
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
-                "abc? def", mSpacingAndPunctuations, 2), PrevWordsInfo.EMPTY_PREV_WORDS_INFO);
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
-                "abc! def", mSpacingAndPunctuations, 2), PrevWordsInfo.EMPTY_PREV_WORDS_INFO);
-        assertEquals(PrevWordsInfoUtils.getPrevWordsInfoFromNthPreviousWord(
-                "abc 'def", mSpacingAndPunctuations, 2), PrevWordsInfo.EMPTY_PREV_WORDS_INFO);
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
+                "abc def.", mSpacingAndPunctuations, 1), NgramContext.BEGINNING_OF_SENTENCE);
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
+                "abc def .", mSpacingAndPunctuations, 1), NgramContext.BEGINNING_OF_SENTENCE);
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
+                "abc, def", mSpacingAndPunctuations, 2), NgramContext.EMPTY_PREV_WORDS_INFO);
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
+                "abc? def", mSpacingAndPunctuations, 2), NgramContext.EMPTY_PREV_WORDS_INFO);
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
+                "abc! def", mSpacingAndPunctuations, 2), NgramContext.EMPTY_PREV_WORDS_INFO);
+        assertEquals(NgramContextUtils.getNgramContextFromNthPreviousWord(
+                "abc 'def", mSpacingAndPunctuations, 2), NgramContext.EMPTY_PREV_WORDS_INFO);
     }
 
     public void testGetWordRangeAtCursor() {
diff --git a/tests/src/com/android/inputmethod/latin/makedict/Ver4DictEncoder.java b/tests/src/com/android/inputmethod/latin/makedict/Ver4DictEncoder.java
index 2e5435159..74da93766 100644
--- a/tests/src/com/android/inputmethod/latin/makedict/Ver4DictEncoder.java
+++ b/tests/src/com/android/inputmethod/latin/makedict/Ver4DictEncoder.java
@@ -19,7 +19,7 @@ package com.android.inputmethod.latin.makedict;
 import com.android.inputmethod.annotations.UsedForTesting;
 import com.android.inputmethod.latin.BinaryDictionary;
 import com.android.inputmethod.latin.Dictionary;
-import com.android.inputmethod.latin.PrevWordsInfo;
+import com.android.inputmethod.latin.NgramContext;
 import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
 import com.android.inputmethod.latin.makedict.FusionDictionary.PtNode;
 import com.android.inputmethod.latin.utils.BinaryDictionaryUtils;
@@ -104,12 +104,12 @@ public class Ver4DictEncoder implements DictEncoder {
         for (final WordProperty word0Property : dict) {
             if (null == word0Property.mBigrams) continue;
             for (final WeightedString word1 : word0Property.mBigrams) {
-                final PrevWordsInfo prevWordsInfo =
-                        new PrevWordsInfo(new PrevWordsInfo.WordInfo(word0Property.mWord));
-                if (!binaryDict.addNgramEntry(prevWordsInfo, word1.mWord,
+                final NgramContext ngramContext =
+                        new NgramContext(new NgramContext.WordInfo(word0Property.mWord));
+                if (!binaryDict.addNgramEntry(ngramContext, word1.mWord,
                         word1.getProbability(), 0 /* timestamp */)) {
                     MakedictLog.e("Cannot add n-gram entry for "
-                            + prevWordsInfo + " -> " + word1.mWord);
+                            + ngramContext + " -> " + word1.mWord);
                     return;
                 }
                 if (binaryDict.needsToRunGC(true /* mindsBlockByGC */)) {
diff --git a/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java b/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
index 616209682..290c06752 100644
--- a/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
+++ b/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
@@ -21,8 +21,8 @@ import android.test.suitebuilder.annotation.LargeTest;
 import android.util.Log;
 
 import com.android.inputmethod.latin.ExpandableBinaryDictionary;
-import com.android.inputmethod.latin.PrevWordsInfo;
-import com.android.inputmethod.latin.PrevWordsInfo.WordInfo;
+import com.android.inputmethod.latin.NgramContext;
+import com.android.inputmethod.latin.NgramContext.WordInfo;
 import com.android.inputmethod.latin.utils.BinaryDictionaryUtils;
 import com.android.inputmethod.latin.utils.DistracterFilter;
 import com.android.inputmethod.latin.utils.FileUtils;
@@ -160,12 +160,12 @@ public class UserHistoryDictionaryTests extends AndroidTestCase {
     }
 
     private static void addToDict(final UserHistoryDictionary dict, final List<String> words) {
-        PrevWordsInfo prevWordsInfo = PrevWordsInfo.EMPTY_PREV_WORDS_INFO;
+        NgramContext ngramContext = NgramContext.EMPTY_PREV_WORDS_INFO;
         for (String word : words) {
-            UserHistoryDictionary.addToDictionary(dict, prevWordsInfo, word, true,
+            UserHistoryDictionary.addToDictionary(dict, ngramContext, word, true,
                     (int)TimeUnit.MILLISECONDS.toSeconds(System.currentTimeMillis()),
                     DistracterFilter.EMPTY_DISTRACTER_FILTER);
-            prevWordsInfo = prevWordsInfo.getNextPrevWordsInfo(new WordInfo(word));
+            ngramContext = ngramContext.getNextNgramContext(new WordInfo(word));
         }
     }
 
@@ -288,11 +288,11 @@ public class UserHistoryDictionaryTests extends AndroidTestCase {
         clearHistory(dict);
         final List<String> words = generateWords(numberOfWords, random);
         dict.waitAllTasksForTests();
-        PrevWordsInfo prevWordsInfo = PrevWordsInfo.EMPTY_PREV_WORDS_INFO;
+        NgramContext ngramContext = NgramContext.EMPTY_PREV_WORDS_INFO;
         for (final String word : words) {
-            UserHistoryDictionary.addToDictionary(dict, prevWordsInfo, word, true, mCurrentTime,
+            UserHistoryDictionary.addToDictionary(dict, ngramContext, word, true, mCurrentTime,
                     DistracterFilter.EMPTY_DISTRACTER_FILTER);
-            prevWordsInfo = prevWordsInfo.getNextPrevWordsInfo(new WordInfo(word));
+            ngramContext = ngramContext.getNextNgramContext(new WordInfo(word));
             dict.waitAllTasksForTests();
             assertTrue(dict.isInDictionary(word));
         }
diff --git a/tests/src/com/android/inputmethod/latin/utils/DistracterFilterTest.java b/tests/src/com/android/inputmethod/latin/utils/DistracterFilterTest.java
index 6ed912088..8360d53fb 100644
--- a/tests/src/com/android/inputmethod/latin/utils/DistracterFilterTest.java
+++ b/tests/src/com/android/inputmethod/latin/utils/DistracterFilterTest.java
@@ -24,7 +24,7 @@ import android.test.AndroidTestCase;
 import android.test.suitebuilder.annotation.LargeTest;
 import android.view.inputmethod.InputMethodSubtype;
 
-import com.android.inputmethod.latin.PrevWordsInfo;
+import com.android.inputmethod.latin.NgramContext;
 import com.android.inputmethod.latin.RichInputMethodManager;
 import com.android.inputmethod.latin.utils.DistracterFilter.HandlingType;
 
@@ -58,7 +58,7 @@ public class DistracterFilterTest extends AndroidTestCase {
     }
 
     public void testIsDistracterToWordsInDictionaries() {
-        final PrevWordsInfo EMPTY_PREV_WORDS_INFO = PrevWordsInfo.EMPTY_PREV_WORDS_INFO;
+        final NgramContext EMPTY_PREV_WORDS_INFO = NgramContext.EMPTY_PREV_WORDS_INFO;
 
         final Locale localeEnUs = new Locale("en", "US");
         String typedWord;
@@ -204,7 +204,7 @@ public class DistracterFilterTest extends AndroidTestCase {
 
     public void testGetWordHandlingType() {
         final Locale localeEnUs = new Locale("en", "US");
-        final PrevWordsInfo EMPTY_PREV_WORDS_INFO = PrevWordsInfo.EMPTY_PREV_WORDS_INFO;
+        final NgramContext EMPTY_PREV_WORDS_INFO = NgramContext.EMPTY_PREV_WORDS_INFO;
         int handlingType = 0;
 
         handlingType = mDistracterFilter.getWordHandlingType(EMPTY_PREV_WORDS_INFO,