Ignore bigrams that are not also listed as unigrams

This is a cherry pick of I14b67e51 on jb-dev

Bug: 6340915
Change-Id: Iaa512abe1b19ca640ea201f9761fd7f1416270ed

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

@@ -159,7 +159,7 @@ abstract public class ExpandableBinaryDictionary extends Dictionary {
     // TODO: Create "cache dictionary" to cache fresh words for frequently updated dictionaries,
     // considering performance regression.
     protected void addWord(final String word, final int frequency) {
-        mFusionDictionary.add(word, frequency, null, null);
+        mFusionDictionary.add(word, frequency, null /* shortcutTargets */);
     }
 
     /**

java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java

@@ -1317,8 +1317,16 @@ public class BinaryDictInputOutput {
                         0 != (optionsFlags & GERMAN_UMLAUT_PROCESSING_FLAG),
                         0 != (optionsFlags & FRENCH_LIGATURE_PROCESSING_FLAG)));
         if (null != dict) {
-            for (Word w : dict) {
+            for (final Word w : dict) {
-                newDict.add(w.mWord, w.mFrequency, w.mShortcutTargets, w.mBigrams);
+                newDict.add(w.mWord, w.mFrequency, w.mShortcutTargets);
+            }
+            for (final Word w : dict) {
+                // By construction a binary dictionary may not have bigrams pointing to
+                // words that are not also registered as unigrams so we don't have to avoid
+                // them explicitly here.
+                for (final WeightedString bigram : w.mBigrams) {
+                    newDict.setBigram(w.mWord, bigram.mWord, bigram.mFrequency);
+                }
             }
         }
 

java/src/com/android/inputmethod/latin/makedict/FusionDictionary.java

@@ -286,7 +286,7 @@ public class FusionDictionary implements Iterable<Word> {
             for (WeightedString word : words) {
                 final CharGroup t = findWordInTree(mRoot, word.mWord);
                 if (null == t) {
-                    add(getCodePoints(word.mWord), 0, null, null);
+                    add(getCodePoints(word.mWord), 0, null);
                 }
             }
         }
@@ -305,12 +305,8 @@ public class FusionDictionary implements Iterable<Word> {
      * @param bigrams a list of bigrams, or null.
      */
     public void add(final String word, final int frequency,
-            final ArrayList<WeightedString> shortcutTargets,
+            final ArrayList<WeightedString> shortcutTargets) {
-            final ArrayList<WeightedString> bigrams) {
+        add(getCodePoints(word), frequency, shortcutTargets);
-        if (null != bigrams) {
-            addNeutralWords(bigrams);
-        }
-        add(getCodePoints(word), frequency, shortcutTargets, bigrams);
     }
 
     /**
@@ -344,7 +340,7 @@ public class FusionDictionary implements Iterable<Word> {
             final CharGroup charGroup2 = findWordInTree(mRoot, word2);
             if (charGroup2 == null) {
                 // TODO: refactor with the identical code in addNeutralWords
-                add(getCodePoints(word2), 0, null, null);
+                add(getCodePoints(word2), 0, null);
             }
             charGroup.addBigram(word2, frequency);
         } else {
@@ -355,17 +351,15 @@ public class FusionDictionary implements Iterable<Word> {
     /**
      * Add a word to this dictionary.
      *
-     * The shortcuts and bigrams, if any, have to be in the dictionary already. If they aren't,
+     * The shortcuts, if any, have to be in the dictionary already. If they aren't,
      * an exception is thrown.
      *
      * @param word the word, as an int array.
      * @param frequency the frequency of the word, in the range [0..255].
      * @param shortcutTargets an optional list of shortcut targets for this word (null if none).
-     * @param bigrams an optional list of bigrams for this word (null if none).
      */
     private void add(final int[] word, final int frequency,
-            final ArrayList<WeightedString> shortcutTargets,
+            final ArrayList<WeightedString> shortcutTargets) {
-            final ArrayList<WeightedString> bigrams) {
         assert(frequency >= 0 && frequency <= 255);
         Node currentNode = mRoot;
         int charIndex = 0;
@@ -390,7 +384,7 @@ public class FusionDictionary implements Iterable<Word> {
             final int insertionIndex = findInsertionIndex(currentNode, word[charIndex]);
             final CharGroup newGroup = new CharGroup(
                     Arrays.copyOfRange(word, charIndex, word.length),
-                    shortcutTargets, bigrams, frequency);
+                    shortcutTargets, null /* bigrams */, frequency);
             currentNode.mData.add(insertionIndex, newGroup);
             checkStack(currentNode);
         } else {
@@ -400,21 +394,21 @@ public class FusionDictionary implements Iterable<Word> {
                     // The new word is a prefix of an existing word, but the node on which it
                     // should end already exists as is. Since the old CharNode was not a terminal, 
                     // make it one by filling in its frequency and other attributes
-                    currentGroup.update(frequency, shortcutTargets, bigrams);
+                    currentGroup.update(frequency, shortcutTargets, null);
                 } else {
                     // The new word matches the full old word and extends past it.
                     // We only have to create a new node and add it to the end of this.
                     final CharGroup newNode = new CharGroup(
                             Arrays.copyOfRange(word, charIndex + differentCharIndex, word.length),
-                                    shortcutTargets, bigrams, frequency);
+                                    shortcutTargets, null /* bigrams */, frequency);
                     currentGroup.mChildren = new Node();
                     currentGroup.mChildren.mData.add(newNode);
                 }
             } else {
                 if (0 == differentCharIndex) {
                     // Exact same word. Update the frequency if higher. This will also add the
-                    // new bigrams to the existing bigram list if it already exists.
+                    // new shortcuts to the existing shortcut list if it already exists.
-                    currentGroup.update(frequency, shortcutTargets, bigrams);
+                    currentGroup.update(frequency, shortcutTargets, null);
                 } else {
                     // Partial prefix match only. We have to replace the current node with a node
                     // containing the current prefix and create two new ones for the tails.
@@ -429,14 +423,14 @@ public class FusionDictionary implements Iterable<Word> {
                     if (charIndex + differentCharIndex >= word.length) {
                         newParent = new CharGroup(
                                 Arrays.copyOfRange(currentGroup.mChars, 0, differentCharIndex),
-                                shortcutTargets, bigrams, frequency, newChildren);
+                                shortcutTargets, null /* bigrams */, frequency, newChildren);
                     } else {
                         newParent = new CharGroup(
                                 Arrays.copyOfRange(currentGroup.mChars, 0, differentCharIndex),
-                                null, null, -1, newChildren);
+                                null /* shortcutTargets */, null /* bigrams */, -1, newChildren);
-                        final CharGroup newWord = new CharGroup(
+                        final CharGroup newWord = new CharGroup(Arrays.copyOfRange(word,
-                                Arrays.copyOfRange(word, charIndex + differentCharIndex,
+                                charIndex + differentCharIndex, word.length),
-                                        word.length), shortcutTargets, bigrams, frequency);
+                                shortcutTargets, null /* bigrams */, frequency);
                         final int addIndex = word[charIndex + differentCharIndex]
                                 > currentGroup.mChars[differentCharIndex] ? 1 : 0;
                         newChildren.mData.add(addIndex, newWord);
@@ -494,7 +488,8 @@ public class FusionDictionary implements Iterable<Word> {
      */
     private static int findInsertionIndex(final Node node, int character) {
         final ArrayList<CharGroup> data = node.mData;
-        final CharGroup reference = new CharGroup(new int[] { character }, null, null, 0);
+        final CharGroup reference = new CharGroup(new int[] { character },
+                null /* shortcutTargets */, null /* bigrams */, 0);
         int result = Collections.binarySearch(data, reference, CHARGROUP_COMPARATOR);
         return result >= 0 ? result : -result - 1;
     }

tools/makedict/src/com/android/inputmethod/latin/makedict/XmlDictInputOutput.java

@@ -72,19 +72,15 @@ public class XmlDictInputOutput {
         int mFreq; // the currently read freq
         String mWord; // the current word
         final HashMap<String, ArrayList<WeightedString>> mShortcutsMap;
-        final HashMap<String, ArrayList<WeightedString>> mBigramsMap;
 
         /**
          * Create the handler.
          *
          * @param shortcuts the shortcuts as a map. This may be empty, but may not be null.
-         * @param bigrams the bigrams as a map. This may be empty, but may not be null.
          */
-        public UnigramHandler(final HashMap<String, ArrayList<WeightedString>> shortcuts,
+        public UnigramHandler(final HashMap<String, ArrayList<WeightedString>> shortcuts) {
-                final HashMap<String, ArrayList<WeightedString>> bigrams) {
             mDictionary = null;
             mShortcutsMap = shortcuts;
-            mBigramsMap = bigrams;
             mWord = "";
             mState = START;
             mFreq = 0;
@@ -94,7 +90,6 @@ public class XmlDictInputOutput {
             final FusionDictionary dict = mDictionary;
             mDictionary = null;
             mShortcutsMap.clear();
-            mBigramsMap.clear();
             mWord = "";
             mState = START;
             mFreq = 0;
@@ -143,7 +138,7 @@ public class XmlDictInputOutput {
         @Override
         public void endElement(String uri, String localName, String qName) {
             if (WORD == mState) {
-                mDictionary.add(mWord, mFreq, mShortcutsMap.get(mWord), mBigramsMap.get(mWord));
+                mDictionary.add(mWord, mFreq, mShortcutsMap.get(mWord));
                 mState = START;
             }
         }
@@ -191,6 +186,7 @@ public class XmlDictInputOutput {
             }
         }
 
+        // This may return an empty map, but will never return null.
         public HashMap<String, ArrayList<WeightedString>> getAssocMap() {
             return mAssocMap;
         }
@@ -211,6 +207,7 @@ public class XmlDictInputOutput {
                     BIGRAM_FREQ_ATTRIBUTE);
         }
 
+        // As per getAssocMap(), this never returns null.
         public HashMap<String, ArrayList<WeightedString>> getBigramMap() {
             return getAssocMap();
         }
@@ -231,6 +228,7 @@ public class XmlDictInputOutput {
                     TARGET_PRIORITY_ATTRIBUTE);
         }
 
+        // As per getAssocMap(), this never returns null.
         public HashMap<String, ArrayList<WeightedString>> getShortcutMap() {
             return getAssocMap();
         }
@@ -260,10 +258,19 @@ public class XmlDictInputOutput {
         if (null != shortcuts) parser.parse(shortcuts, shortcutHandler);
 
         final UnigramHandler unigramHandler =
-                new UnigramHandler(shortcutHandler.getShortcutMap(),
+                new UnigramHandler(shortcutHandler.getShortcutMap());
-                        bigramHandler.getBigramMap());
         parser.parse(unigrams, unigramHandler);
-        return unigramHandler.getFinalDictionary();
+        final FusionDictionary dict = unigramHandler.getFinalDictionary();
+        final HashMap<String, ArrayList<WeightedString>> bigramMap = bigramHandler.getBigramMap();
+        for (final String firstWord : bigramMap.keySet()) {
+            if (!dict.hasWord(firstWord)) continue;
+            final ArrayList<WeightedString> bigramList = bigramMap.get(firstWord);
+            for (final WeightedString bigram : bigramList) {
+                if (!dict.hasWord(bigram.mWord)) continue;
+                dict.setBigram(firstWord, bigram.mWord, bigram.mFrequency);
+            }
+        }
+        return dict;
     }
 
     /**

tools/makedict/tests/com/android/inputmethod/latin/BinaryDictInputOutputTest.java

@@ -43,11 +43,11 @@ public class BinaryDictInputOutputTest extends TestCase {
         final FusionDictionary dict = new FusionDictionary(new Node(),
                 new DictionaryOptions(new HashMap<String, String>(),
                         false /* germanUmlautProcessing */, false /* frenchLigatureProcessing */));
-        dict.add("foo", 1, null, null);
+        dict.add("foo", 1, null);
-        dict.add("fta", 1, null, null);
+        dict.add("fta", 1, null);
-        dict.add("ftb", 1, null, null);
+        dict.add("ftb", 1, null);
-        dict.add("bar", 1, null, null);
+        dict.add("bar", 1, null);
-        dict.add("fool", 1, null, null);
+        dict.add("fool", 1, null);
         final ArrayList<Node> result = BinaryDictInputOutput.flattenTree(dict.mRoot);
         assertEquals(4, result.size());
         while (!result.isEmpty()) {