Implement ver4 dictionary bigram removing methods.

Bug: 11073222
Change-Id: I0c42e283d1ff983dc2c51e91b167bc39cdfd3da8

native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.cpp

@@ -91,6 +91,33 @@ bool Ver4BigramListPolicy::addNewEntry(const int terminalId, const int newTarget
     return mBigramDictContent->copyBigramList(bigramListPos, writingPos);
 }
 
+bool Ver4BigramListPolicy::removeEntry(const int terminalId, const int targetTerminalId) {
+    const int bigramListPos = mBigramDictContent->getBigramListHeadPos(terminalId);
+    if (bigramListPos == NOT_A_DICT_POS) {
+        // Bigram list does't exist.
+        return false;
+    }
+    const int entryPosToUpdate = getEntryPosToUpdate(targetTerminalId, bigramListPos);
+    if (entryPosToUpdate == NOT_A_DICT_POS) {
+        // Bigram entry doesn't exist.
+        return false;
+    }
+    int readingPos = entryPosToUpdate;
+    bool hasNext = false;
+    int probability = NOT_A_PROBABILITY;
+    int originalTargetTerminalId = Ver4DictConstants::NOT_A_TERMINAL_ID;
+    mBigramDictContent->getBigramEntryAndAdvancePosition(&probability, &hasNext,
+            &originalTargetTerminalId, &readingPos);
+    if (targetTerminalId != originalTargetTerminalId) {
+        // Bigram entry doesn't exist.
+        return false;
+    }
+    int writingPos = entryPosToUpdate;
+    // Remove bigram entry by overwriting target terminal Id.
+    return mBigramDictContent->writeBigramEntryAndAdvancePosition(probability, hasNext,
+            Ver4DictConstants::NOT_A_TERMINAL_ID /* targetTerminalId */, &writingPos);
+}
+
 int Ver4BigramListPolicy::getEntryPosToUpdate(const int targetTerminalIdToFind,
         const int bigramListPos) const {
     bool hasNext = true;

native/jni/src/suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.h

@@ -42,6 +42,8 @@ class Ver4BigramListPolicy : public DictionaryBigramsStructurePolicy {
     bool addNewEntry(const int terminalId, const int newTargetTerminalId, const int newProbability,
             bool *const outAddedNewEntry);
 
+    bool removeEntry(const int terminalId, const int targetTerminalId);
+
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(Ver4BigramListPolicy);
 

native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.cpp

@@ -31,9 +31,12 @@ void BigramDictContent::getBigramEntryAndAdvancePosition(int *const outProbabili
     if (outHasNext) {
         *outHasNext = (bigramFlags & Ver4DictConstants::BIGRAM_HAS_NEXT_MASK) != 0;
     }
+    const int targetTerminalId = bigramListBuffer->readUintAndAdvancePosition(
+            Ver4DictConstants::BIGRAM_TARGET_TERMINAL_ID_FIELD_SIZE, bigramEntryPos);
     if (outTargetTerminalId) {
-        *outTargetTerminalId = bigramListBuffer->readUintAndAdvancePosition(
-                Ver4DictConstants::BIGRAM_TARGET_TERMINAL_ID_FIELD_SIZE, bigramEntryPos);
+        *outTargetTerminalId =
+                (targetTerminalId == Ver4DictConstants::INVALID_BIGRAM_TARGET_TERMINAL_ID) ?
+                        Ver4DictConstants::NOT_A_TERMINAL_ID : targetTerminalId;
     }
 }
 
@@ -45,7 +48,10 @@ bool BigramDictContent::writeBigramEntryAndAdvancePosition(const int probability
             Ver4DictConstants::BIGRAM_FLAGS_FIELD_SIZE, entryWritingPos)) {
         return false;
     }
-    return bigramListBuffer->writeUintAndAdvancePosition(targetTerminalId,
+    const int targetTerminalIdToWrite =
+            (targetTerminalId == Ver4DictConstants::NOT_A_TERMINAL_ID) ?
+                    Ver4DictConstants::INVALID_BIGRAM_TARGET_TERMINAL_ID : targetTerminalId;
+    return bigramListBuffer->writeUintAndAdvancePosition(targetTerminalIdToWrite,
             Ver4DictConstants::BIGRAM_TARGET_TERMINAL_ID_FIELD_SIZE, entryWritingPos);
 }
 

native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.cpp

@@ -42,6 +42,10 @@ const int Ver4DictConstants::SHORTCUT_ADDRESS_TABLE_BLOCK_SIZE = 16;
 const int Ver4DictConstants::SHORTCUT_ADDRESS_TABLE_DATA_SIZE = 4;
 
 const int Ver4DictConstants::BIGRAM_TARGET_TERMINAL_ID_FIELD_SIZE = 3;
+// Unsigned int max value of BIGRAM_TARGET_TERMINAL_ID_FIELD_SIZE-byte is used for representing
+// invalid terminal ID in bigram lists.
+const int Ver4DictConstants::INVALID_BIGRAM_TARGET_TERMINAL_ID =
+        (1 << (BIGRAM_TARGET_TERMINAL_ID_FIELD_SIZE * 8)) - 1;
 const int Ver4DictConstants::BIGRAM_FLAGS_FIELD_SIZE = 1;
 const int Ver4DictConstants::BIGRAM_PROBABILITY_MASK = 0x0F;
 const int Ver4DictConstants::BIGRAM_HAS_NEXT_MASK = 0x80;

native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.h

@@ -47,6 +47,7 @@ class Ver4DictConstants {
 
     static const int BIGRAM_FLAGS_FIELD_SIZE;
     static const int BIGRAM_TARGET_TERMINAL_ID_FIELD_SIZE;
+    static const int INVALID_BIGRAM_TARGET_TERMINAL_ID;
     static const int BIGRAM_PROBABILITY_MASK;
     static const int BIGRAM_HAS_NEXT_MASK;
 

native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.cpp

@@ -192,8 +192,8 @@ bool Ver4PatriciaTrieNodeWriter::addNewBigramEntry(
 
 bool Ver4PatriciaTrieNodeWriter::removeBigramEntry(
         const PtNodeParams *const sourcePtNodeParams, const PtNodeParams *const targetPtNodeParam) {
-    // TODO: Implement.
-    return false;
+    return mBigramPolicy->removeEntry(sourcePtNodeParams->getTerminalId(),
+            targetPtNodeParam->getTerminalId());
 }
 
 }

native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp

@@ -188,8 +188,31 @@ bool Ver4PatriciaTriePolicy::addBigramWords(const int *const word0, const int le
 
 bool Ver4PatriciaTriePolicy::removeBigramWords(const int *const word0, const int length0,
         const int *const word1, const int length1) {
-    // TODO: Implement.
-    return false;
+    if (!mBuffers.get()->isUpdatable()) {
+        AKLOGI("Warning: addBigramWords() is called for non-updatable dictionary.");
+        return false;
+    }
+    if (mDictBuffer.getTailPosition() >= MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS) {
+        AKLOGE("The dictionary is too large to dynamically update. Dictionary size: %d",
+                mDictBuffer.getTailPosition());
+        return false;
+    }
+    const int word0Pos = getTerminalPtNodePositionOfWord(word0, length0,
+            false /* forceLowerCaseSearch */);
+    if (word0Pos == NOT_A_DICT_POS) {
+        return false;
+    }
+    const int word1Pos = getTerminalPtNodePositionOfWord(word1, length1,
+            false /* forceLowerCaseSearch */);
+    if (word1Pos == NOT_A_DICT_POS) {
+        return false;
+    }
+    if (mUpdatingHelper.removeBigramWords(word0Pos, word1Pos)) {
+        mBigramCount--;
+        return true;
+    } else {
+        return false;
+    }
 }
 
 void Ver4PatriciaTriePolicy::flush(const char *const filePath) {

tests/src/com/android/inputmethod/latin/Ver4BinaryDictionaryTests.java

@@ -246,4 +246,56 @@ public class Ver4BinaryDictionaryTests extends AndroidTestCase {
         assertEquals(probability, binaryDictionary.getBigramProbability("abb", "aaa"));
         assertEquals(probability, binaryDictionary.getBigramProbability("abb", "bcc"));
     }
+
+    public void testRemoveBigramWords() {
+        final String dictVersion = Long.toString(System.currentTimeMillis());
+        final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
+                getDictionaryOptions(TEST_LOCALE, dictVersion));
+        final DictEncoder encoder = new Ver4DictEncoder(getContext().getCacheDir());
+        try {
+            encoder.writeDictionary(dict, FORMAT_OPTIONS);
+        } catch (IOException e) {
+            Log.e(TAG, "IOException while writing dictionary", e);
+        } catch (UnsupportedFormatException e) {
+            Log.e(TAG, "Unsupported format", e);
+        }
+        final File trieFile = getTrieFile(TEST_LOCALE, dictVersion);
+        final BinaryDictionary binaryDictionary = new BinaryDictionary(trieFile.getAbsolutePath(),
+                0 /* offset */, trieFile.length(), true /* useFullEditDistance */,
+                Locale.getDefault(), TEST_LOCALE, true /* isUpdatable */);
+        assertTrue(binaryDictionary.isValidDictionary());
+
+        final int unigramProbability = 100;
+        final int bigramProbability = 10;
+        binaryDictionary.addUnigramWord("aaa", unigramProbability);
+        binaryDictionary.addUnigramWord("abb", unigramProbability);
+        binaryDictionary.addUnigramWord("bcc", unigramProbability);
+        binaryDictionary.addBigramWords("aaa", "abb", bigramProbability);
+        binaryDictionary.addBigramWords("aaa", "bcc", bigramProbability);
+        binaryDictionary.addBigramWords("abb", "aaa", bigramProbability);
+        binaryDictionary.addBigramWords("abb", "bcc", bigramProbability);
+
+        assertEquals(true, binaryDictionary.isValidBigram("aaa", "abb"));
+        assertEquals(true, binaryDictionary.isValidBigram("aaa", "bcc"));
+        assertEquals(true, binaryDictionary.isValidBigram("abb", "aaa"));
+        assertEquals(true, binaryDictionary.isValidBigram("abb", "bcc"));
+
+        binaryDictionary.removeBigramWords("aaa", "abb");
+        assertEquals(false, binaryDictionary.isValidBigram("aaa", "abb"));
+        binaryDictionary.addBigramWords("aaa", "abb", bigramProbability);
+        assertEquals(true, binaryDictionary.isValidBigram("aaa", "abb"));
+
+        binaryDictionary.removeBigramWords("aaa", "bcc");
+        assertEquals(false, binaryDictionary.isValidBigram("aaa", "bcc"));
+        binaryDictionary.removeBigramWords("abb", "aaa");
+        assertEquals(false, binaryDictionary.isValidBigram("abb", "aaa"));
+        binaryDictionary.removeBigramWords("abb", "bcc");
+        assertEquals(false, binaryDictionary.isValidBigram("abb", "bcc"));
+
+        binaryDictionary.removeBigramWords("aaa", "abb");
+        // Test remove non-existing bigram operation.
+        binaryDictionary.removeBigramWords("aaa", "abb");
+        binaryDictionary.removeBigramWords("bcc", "aaa");
+    }
+
 }