Implement ver4 dictionary unigram writing methods.

Bug: 11073222
Change-Id: Ibdb6846fee98919bb5f845170c19d7d571fcb88d

native/jni/Android.mk

@@ -90,6 +90,7 @@ LATIN_IME_CORE_SRC_FILES := \
     $(addprefix suggest/policyimpl/dictionary/structure/v4/, \
         ver4_dict_constants.cpp \
         ver4_patricia_trie_node_reader.cpp \
+        ver4_patricia_trie_node_writer.cpp \
         ver4_patricia_trie_policy.cpp \
         ver4_patricia_trie_reading_utils.cpp ) \
     $(addprefix suggest/policyimpl/dictionary/utils/, \

native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.h

@@ -38,6 +38,28 @@ class ProbabilityDictContent : public SingleDictContent {
         return Ver4PatriciaTrieReadingUtils::getProbability(getBuffer(), terminalId);
     }
 
+    bool setProbability(const int terminalId, const int probability) {
+        if (terminalId < 0 || terminalId > getSize()) {
+            return false;
+        }
+        if (terminalId == getSize()) {
+            // Write new entry.
+            int flagWritingPos = terminalId * (Ver4DictConstants::FLAGS_IN_PROBABILITY_FILE_SIZE
+                    + Ver4DictConstants::PROBABILITY_SIZE);
+            const int dummyFlags = 0;
+            // Write dummy flags.
+            if (!getWritableBuffer()->writeUintAndAdvancePosition(dummyFlags,
+                    Ver4DictConstants::FLAGS_IN_PROBABILITY_FILE_SIZE, &flagWritingPos)) {
+                return false;
+            }
+        }
+        int probabilityWritingPos = terminalId * (Ver4DictConstants::FLAGS_IN_PROBABILITY_FILE_SIZE
+                + Ver4DictConstants::PROBABILITY_SIZE)
+                        + Ver4DictConstants::FLAGS_IN_PROBABILITY_FILE_SIZE;
+        return getWritableBuffer()->writeUintAndAdvancePosition(probability,
+                Ver4DictConstants::PROBABILITY_SIZE, &probabilityWritingPos);
+    }
+
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(ProbabilityDictContent);
 

native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/terminal_position_lookup_table.h

@@ -47,10 +47,28 @@ class TerminalPositionLookupTable : public SingleDictContent {
                 readingPos) - mHeaderRegionSize;
     }
 
+    bool setTerminalPtNodePosition(const int terminalId, const int terminalPtNodePos) {
+        if (terminalId < 0 || terminalId > mSize) {
+            return NOT_A_DICT_POS;
+        }
+        if (terminalId == mSize) {
+            // Use new terminal id.
+            mSize += 1;
+        }
+        int writingPos = terminalId * Ver4DictConstants::TERMINAL_ADDRESS_TABLE_ADDRESS_SIZE;
+        return getWritableBuffer()->writeUintAndAdvancePosition(
+                terminalPtNodePos + mHeaderRegionSize,
+                Ver4DictConstants::TERMINAL_ADDRESS_TABLE_ADDRESS_SIZE, &writingPos);
+    }
+
+    int getNextTerminalId() const {
+        return mSize;
+    }
+
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(TerminalPositionLookupTable);
 
-    const int mSize;
+    int mSize;
     const int mHeaderRegionSize;
 };
 } // namespace latinime

native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_buffers.h

@@ -53,10 +53,19 @@ class Ver4DictBuffers {
         return mDictBuffer.get()->getBufferSize();
     }
 
+
+    AK_FORCE_INLINE TerminalPositionLookupTable *getUpdatableTerminalPositionLookupTable() {
+        return &mTerminalPositionLookupTable;
+    }
+
     AK_FORCE_INLINE const TerminalPositionLookupTable *getTerminalPositionLookupTable() const {
         return &mTerminalPositionLookupTable;
     }
 
+    AK_FORCE_INLINE ProbabilityDictContent *getUpdatableProbabilityDictContent() {
+        return &mProbabilityDictContent;
+    }
+
     AK_FORCE_INLINE const ProbabilityDictContent *getProbabilityDictContent() const {
         return &mProbabilityDictContent;
     }
@@ -69,6 +78,10 @@ class Ver4DictBuffers {
         return &mShortcutDictContent;
     }
 
+    AK_FORCE_INLINE bool isUpdatable() const {
+        return mIsUpdatable;
+    }
+
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(Ver4DictBuffers);
 
@@ -80,13 +93,15 @@ class Ver4DictBuffers {
                       HeaderReadWriteUtils::getHeaderSize(mDictBuffer.get()->getBuffer())),
               mProbabilityDictContent(dictDirPath, isUpdatable),
               mBigramDictContent(dictDirPath, isUpdatable),
-              mShortcutDictContent(dictDirPath, isUpdatable) {}
+              mShortcutDictContent(dictDirPath, isUpdatable),
+              mIsUpdatable(isUpdatable) {}
 
     const MmappedBuffer::MmappedBufferPtr mDictBuffer;
     TerminalPositionLookupTable mTerminalPositionLookupTable;
     ProbabilityDictContent mProbabilityDictContent;
     BigramDictContent mBigramDictContent;
     ShortcutDictContent mShortcutDictContent;
+    const int mIsUpdatable;
 };
 } // namespace latinime
 #endif /* LATINIME_VER4_DICT_BUFFER_H */

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

@@ -34,6 +34,7 @@ const int Ver4DictConstants::NOT_A_TERMINAL_ID = -1;
 const int Ver4DictConstants::PROBABILITY_SIZE = 1;
 const int Ver4DictConstants::FLAGS_IN_PROBABILITY_FILE_SIZE = 1;
 const int Ver4DictConstants::TERMINAL_ADDRESS_TABLE_ADDRESS_SIZE = 3;
+const int Ver4DictConstants::TERMINAL_ID_FIELD_SIZE = 4;
 
 const int Ver4DictConstants::BIGRAM_ADDRESS_TABLE_BLOCK_SIZE = 4;
 const int Ver4DictConstants::BIGRAM_ADDRESS_TABLE_DATA_SIZE = 4;

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

@@ -38,6 +38,7 @@ class Ver4DictConstants {
     static const int PROBABILITY_SIZE;
     static const int FLAGS_IN_PROBABILITY_FILE_SIZE;
     static const int TERMINAL_ADDRESS_TABLE_ADDRESS_SIZE;
+    static const int TERMINAL_ID_FIELD_SIZE;
 
     static const int BIGRAM_ADDRESS_TABLE_BLOCK_SIZE;
     static const int BIGRAM_ADDRESS_TABLE_DATA_SIZE;

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

@@ -0,0 +1,201 @@
+/*
+ * Copyright (C) 2013, 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.
+ */
+
+#include "suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.h"
+
+#include "suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.h"
+#include "suggest/policyimpl/dictionary/shortcut/dynamic_shortcut_list_policy.h"
+#include "suggest/policyimpl/dictionary/structure/v2/patricia_trie_reading_utils.h"
+#include "suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_reader.h"
+#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_reading_utils.h"
+#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_utils.h"
+#include "suggest/policyimpl/dictionary/structure/v4/ver4_dict_buffers.h"
+#include "suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
+
+namespace latinime {
+
+const int Ver4PatriciaTrieNodeWriter::CHILDREN_POSITION_FIELD_SIZE = 3;
+
+bool Ver4PatriciaTrieNodeWriter::markPtNodeAsDeleted(
+        const PtNodeParams *const toBeUpdatedPtNodeParams) {
+    int pos = toBeUpdatedPtNodeParams->getHeadPos();
+    const bool usesAdditionalBuffer = mTrieBuffer->isInAdditionalBuffer(pos);
+    const uint8_t *const dictBuf = mTrieBuffer->getBuffer(usesAdditionalBuffer);
+    if (usesAdditionalBuffer) {
+        pos -= mTrieBuffer->getOriginalBufferSize();
+    }
+    // Read original flags
+    const PatriciaTrieReadingUtils::NodeFlags originalFlags =
+            PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(dictBuf, &pos);
+    const PatriciaTrieReadingUtils::NodeFlags updatedFlags =
+            DynamicPatriciaTrieReadingUtils::updateAndGetFlags(originalFlags, false /* isMoved */,
+                    true /* isDeleted */);
+    int writingPos = toBeUpdatedPtNodeParams->getHeadPos();
+    // Update flags.
+    return DynamicPatriciaTrieWritingUtils::writeFlagsAndAdvancePosition(mTrieBuffer, updatedFlags,
+            &writingPos);
+}
+
+bool Ver4PatriciaTrieNodeWriter::markPtNodeAsMoved(
+        const PtNodeParams *const toBeUpdatedPtNodeParams,
+        const int movedPos, const int bigramLinkedNodePos) {
+    int pos = toBeUpdatedPtNodeParams->getHeadPos();
+    const bool usesAdditionalBuffer = mTrieBuffer->isInAdditionalBuffer(pos);
+    const uint8_t *const dictBuf = mTrieBuffer->getBuffer(usesAdditionalBuffer);
+    if (usesAdditionalBuffer) {
+        pos -= mTrieBuffer->getOriginalBufferSize();
+    }
+    // Read original flags
+    const PatriciaTrieReadingUtils::NodeFlags originalFlags =
+            PatriciaTrieReadingUtils::getFlagsAndAdvancePosition(dictBuf, &pos);
+    const PatriciaTrieReadingUtils::NodeFlags updatedFlags =
+            DynamicPatriciaTrieReadingUtils::updateAndGetFlags(originalFlags, true /* isMoved */,
+                    false /* isDeleted */);
+    int writingPos = toBeUpdatedPtNodeParams->getHeadPos();
+    // Update flags.
+    if (!DynamicPatriciaTrieWritingUtils::writeFlagsAndAdvancePosition(mTrieBuffer, updatedFlags,
+            &writingPos)) {
+        return false;
+    }
+    // Update moved position, which is stored in the parent offset field.
+    if (!DynamicPatriciaTrieWritingUtils::writeParentPosOffsetAndAdvancePosition(
+            mTrieBuffer, movedPos, toBeUpdatedPtNodeParams->getHeadPos(), &writingPos)) {
+        return false;
+    }
+    // Update bigram linked node position, which is stored in the children position field.
+    int childrenPosFieldPos = toBeUpdatedPtNodeParams->getChildrenPosFieldPos();
+    if (!DynamicPatriciaTrieWritingUtils::writeChildrenPositionAndAdvancePosition(
+            mTrieBuffer, bigramLinkedNodePos, &childrenPosFieldPos)) {
+        return false;
+    }
+    if (toBeUpdatedPtNodeParams->hasChildren()) {
+        // Update children's parent position.
+        mReadingHelper.initWithPtNodeArrayPos(toBeUpdatedPtNodeParams->getChildrenPos());
+        while (!mReadingHelper.isEnd()) {
+            const PtNodeParams childPtNodeParams(mReadingHelper.getPtNodeParams());
+            int parentOffsetFieldPos = childPtNodeParams.getHeadPos()
+                    + DynamicPatriciaTrieWritingUtils::NODE_FLAG_FIELD_SIZE;
+            if (!DynamicPatriciaTrieWritingUtils::writeParentPosOffsetAndAdvancePosition(
+                    mTrieBuffer, bigramLinkedNodePos, childPtNodeParams.getHeadPos(),
+                    &parentOffsetFieldPos)) {
+                // Parent offset cannot be written because of a bug or a broken dictionary; thus,
+                // we give up to update dictionary.
+                return false;
+            }
+            mReadingHelper.readNextSiblingNode(childPtNodeParams);
+        }
+    }
+    return true;
+}
+
+bool Ver4PatriciaTrieNodeWriter::updatePtNodeProbability(
+        const PtNodeParams *const toBeUpdatedPtNodeParams, const int newProbability) {
+    if (!toBeUpdatedPtNodeParams->isTerminal()) {
+        return false;
+    }
+    return mBuffers->getUpdatableProbabilityDictContent()->setProbability(
+            toBeUpdatedPtNodeParams->getTerminalId(), newProbability);
+}
+
+bool Ver4PatriciaTrieNodeWriter::updateChildrenPosition(
+        const PtNodeParams *const toBeUpdatedPtNodeParams, const int newChildrenPosition) {
+    int childrenPosFieldPos = toBeUpdatedPtNodeParams->getChildrenPosFieldPos();
+    return DynamicPatriciaTrieWritingUtils::writeChildrenPositionAndAdvancePosition(mTrieBuffer,
+            newChildrenPosition, &childrenPosFieldPos);
+}
+
+bool Ver4PatriciaTrieNodeWriter::writePtNodeAndAdvancePosition(
+        const PtNodeParams *const ptNodeParams, int *const ptNodeWritingPos) {
+    const int nodePos = *ptNodeWritingPos;
+    // Write dummy flags. The Node flags are updated with appropriate flags at the last step of the
+    // PtNode writing.
+    if (!DynamicPatriciaTrieWritingUtils::writeFlagsAndAdvancePosition(mTrieBuffer,
+            0 /* nodeFlags */, ptNodeWritingPos)) {
+        return false;
+    }
+    // Calculate a parent offset and write the offset.
+    if (!DynamicPatriciaTrieWritingUtils::writeParentPosOffsetAndAdvancePosition(mTrieBuffer,
+            ptNodeParams->getParentPos(), nodePos, ptNodeWritingPos)) {
+        return false;
+    }
+    // Write code points
+    if (!DynamicPatriciaTrieWritingUtils::writeCodePointsAndAdvancePosition(mTrieBuffer,
+            ptNodeParams->getCodePoints(), ptNodeParams->getCodePointCount(), ptNodeWritingPos)) {
+        return false;
+    }
+    int terminalId = Ver4DictConstants::NOT_A_TERMINAL_ID;
+    if (ptNodeParams->getTerminalId() != Ver4DictConstants::NOT_A_TERMINAL_ID) {
+        terminalId = ptNodeParams->getTerminalId();
+    } else if (ptNodeParams->getProbability() != NOT_A_PROBABILITY) {
+        // Write terminal information using a new terminal id.
+        // Get a new unused terminal id.
+        terminalId = mBuffers->getTerminalPositionLookupTable()->getNextTerminalId();
+    }
+    const int isTerminal = terminalId != Ver4DictConstants::NOT_A_TERMINAL_ID;
+    if (isTerminal) {
+        // Update the lookup table.
+        if (!mBuffers->getUpdatableTerminalPositionLookupTable()->setTerminalPtNodePosition(
+                terminalId, nodePos)) {
+            return false;
+        }
+        // Write terminal Id.
+        if (!mTrieBuffer->writeUintAndAdvancePosition(terminalId,
+                Ver4DictConstants::TERMINAL_ID_FIELD_SIZE, ptNodeWritingPos)) {
+            return false;
+        }
+        // Write probability.
+        if (!mBuffers->getUpdatableProbabilityDictContent()->setProbability(
+                terminalId, ptNodeParams->getProbability())) {
+            return false;
+        }
+    }
+    // Write children position
+    if (!DynamicPatriciaTrieWritingUtils::writeChildrenPositionAndAdvancePosition(mTrieBuffer,
+            ptNodeParams->getChildrenPos(), ptNodeWritingPos)) {
+        return false;
+    }
+    // TODO: Implement bigram and shortcut writing.
+
+    // Create node flags and write them.
+    PatriciaTrieReadingUtils::NodeFlags nodeFlags =
+            PatriciaTrieReadingUtils::createAndGetFlags(ptNodeParams->isBlacklisted(),
+                    ptNodeParams->isNotAWord(), isTerminal,
+                    false /* hasShortcutTargets */, false /* hasBigrams */,
+                    ptNodeParams->getCodePointCount() > 1 /* hasMultipleChars */,
+                    CHILDREN_POSITION_FIELD_SIZE);
+    int flagsFieldPos = nodePos;
+    if (!DynamicPatriciaTrieWritingUtils::writeFlagsAndAdvancePosition(mTrieBuffer, nodeFlags,
+            &flagsFieldPos)) {
+        return false;
+    }
+    return true;
+}
+
+bool Ver4PatriciaTrieNodeWriter::addNewBigramEntry(
+        const PtNodeParams *const sourcePtNodeParams,
+        const PtNodeParams *const targetPtNodeParam, const int probability,
+        bool *const outAddedNewBigram) {
+    // TODO: Implement.
+    return false;
+}
+
+bool Ver4PatriciaTrieNodeWriter::removeBigramEntry(
+        const PtNodeParams *const sourcePtNodeParams, const PtNodeParams *const targetPtNodeParam) {
+    // TODO: Implement.
+    return false;
+}
+
+}

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

@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2013, 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.
+ */
+
+#ifndef LATINIME_VER4_PATRICIA_TRIE_NODE_WRITER_H
+#define LATINIME_VER4_PATRICIA_TRIE_NODE_WRITER_H
+
+#include <stdint.h>
+
+#include "defines.h"
+#include "suggest/policyimpl/dictionary/structure/pt_common/pt_node_params.h"
+#include "suggest/policyimpl/dictionary/structure/pt_common/pt_node_writer.h"
+#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_reading_helper.h"
+#include "suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_reader.h"
+
+namespace latinime {
+
+class BufferWithExtendableBuffer;
+class Ver4BigramListPolicy;
+class Ver4DictBuffers;
+class Ver4ShortcutListPolicy;
+
+/*
+ * This class is used for helping to writes nodes of ver4 patricia trie.
+ */
+class Ver4PatriciaTrieNodeWriter : public PtNodeWriter {
+ public:
+    Ver4PatriciaTrieNodeWriter(BufferWithExtendableBuffer *const trieBuffer,
+            Ver4DictBuffers *const buffers, const Ver4PatriciaTrieNodeReader *const ptNodeReader,
+            Ver4BigramListPolicy *const bigramPolicy, Ver4ShortcutListPolicy *const shortcutPolicy)
+            : mTrieBuffer(trieBuffer), mBuffers(buffers), mPtNodeReader(ptNodeReader),
+              mReadingHelper(mTrieBuffer, mPtNodeReader),
+              mBigramPolicy(bigramPolicy), mShortcutPolicy(shortcutPolicy) {}
+
+    virtual ~Ver4PatriciaTrieNodeWriter() {}
+
+    virtual bool markPtNodeAsDeleted(const PtNodeParams *const toBeUpdatedPtNodeParams);
+
+    virtual bool markPtNodeAsMoved(const PtNodeParams *const toBeUpdatedPtNodeParams,
+            const int movedPos, const int bigramLinkedNodePos);
+
+    virtual bool updatePtNodeProbability(const PtNodeParams *const toBeUpdatedPtNodeParams,
+            const int newProbability);
+
+    virtual bool updateChildrenPosition(const PtNodeParams *const toBeUpdatedPtNodeParams,
+            const int newChildrenPosition);
+
+    virtual bool writePtNodeAndAdvancePosition(const PtNodeParams *const ptNodeParams,
+            int *const ptNodeWritingPos);
+
+    virtual bool addNewBigramEntry(const PtNodeParams *const sourcePtNodeParams,
+            const PtNodeParams *const targetPtNodeParam, const int probability,
+            bool *const outAddedNewBigram);
+
+    virtual bool removeBigramEntry(const PtNodeParams *const sourcePtNodeParams,
+            const PtNodeParams *const targetPtNodeParam);
+
+ private:
+    DISALLOW_COPY_AND_ASSIGN(Ver4PatriciaTrieNodeWriter);
+
+    static const int CHILDREN_POSITION_FIELD_SIZE;
+
+    BufferWithExtendableBuffer *const mTrieBuffer;
+    Ver4DictBuffers *const mBuffers;
+    const Ver4PatriciaTrieNodeReader *const mPtNodeReader;
+    DynamicPatriciaTrieReadingHelper mReadingHelper;
+    Ver4BigramListPolicy *const mBigramPolicy;
+    Ver4ShortcutListPolicy *const mShortcutPolicy;
+
+};
+} // namespace latinime
+#endif /* LATINIME_VER4_PATRICIA_TRIE_NODE_WRITER_H */

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

@@ -19,12 +19,17 @@
 #include "suggest/core/dicnode/dic_node.h"
 #include "suggest/core/dicnode/dic_node_vector.h"
 #include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_reading_helper.h"
+#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_writing_helper.h"
 #include "suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_reader.h"
 #include "suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h"
 #include "suggest/policyimpl/dictionary/utils/probability_utils.h"
 
 namespace latinime {
 
+const int Ver4PatriciaTriePolicy::MARGIN_TO_REFUSE_DYNAMIC_OPERATIONS = 1024;
+const int Ver4PatriciaTriePolicy::MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS =
+        DynamicPatriciaTrieWritingHelper::MAX_DICTIONARY_SIZE - MARGIN_TO_REFUSE_DYNAMIC_OPERATIONS;
+
 void Ver4PatriciaTriePolicy::createAndGetAllChildDicNodes(const DicNode *const dicNode,
         DicNodeVector *const childDicNodes) const {
     if (!dicNode->hasChildren()) {
@@ -126,8 +131,27 @@ int Ver4PatriciaTriePolicy::getBigramsPositionOfPtNode(const int ptNodePos) cons
 
 bool Ver4PatriciaTriePolicy::addUnigramWord(const int *const word, const int length,
         const int probability) {
-    // TODO: Implement.
+    if (!mBuffers.get()->isUpdatable()) {
-    return false;
+        AKLOGI("Warning: addUnigramWord() 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.");
+        return false;
+    }
+    DynamicPatriciaTrieReadingHelper readingHelper(&mDictBuffer, &mNodeReader);
+    readingHelper.initWithPtNodeArrayPos(getRootPosition());
+    bool addedNewUnigram = false;
+    if (mUpdatingHelper.addUnigramWord(&readingHelper, word, length, probability,
+            &addedNewUnigram)) {
+        if (addedNewUnigram) {
+            mUnigramCount++;
+        }
+        return true;
+    } else {
+        return false;
+    }
 }
 
 bool Ver4PatriciaTriePolicy::addBigramWords(const int *const word0, const int length0,

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

@@ -22,8 +22,10 @@
 #include "suggest/policyimpl/dictionary/bigram/ver4_bigram_list_policy.h"
 #include "suggest/policyimpl/dictionary/header/header_policy.h"
 #include "suggest/policyimpl/dictionary/shortcut/ver4_shortcut_list_policy.h"
+#include "suggest/policyimpl/dictionary/structure/v3/dynamic_patricia_trie_updating_helper.h"
 #include "suggest/policyimpl/dictionary/structure/v4/ver4_dict_buffers.h"
 #include "suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_reader.h"
+#include "suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_node_writer.h"
 #include "suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
 
 namespace latinime {
@@ -44,7 +46,13 @@ class Ver4PatriciaTriePolicy : public DictionaryStructureWithBufferPolicy {
                       mBuffers.get()->getTerminalPositionLookupTable()),
               mShortcutPolicy(mBuffers.get()->getShortcutDictContent(),
                       mBuffers.get()->getTerminalPositionLookupTable()),
-              mNodeReader(&mDictBuffer, mBuffers.get()->getProbabilityDictContent()) {};
+              mNodeReader(&mDictBuffer, mBuffers.get()->getProbabilityDictContent()),
+              mNodeWriter(&mDictBuffer, mBuffers.get(), &mNodeReader, &mBigramPolicy,
+                      &mShortcutPolicy),
+              mUpdatingHelper(&mDictBuffer, &mNodeReader, &mNodeWriter,
+                      mHeaderPolicy.isDecayingDict()),
+              mUnigramCount(mHeaderPolicy.getUnigramCount()),
+              mBigramCount(mHeaderPolicy.getBigramCount()) {};
 
     AK_FORCE_INLINE int getRootPosition() const {
         return 0;
@@ -100,12 +108,21 @@ class Ver4PatriciaTriePolicy : public DictionaryStructureWithBufferPolicy {
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(Ver4PatriciaTriePolicy);
 
-    const Ver4DictBuffers::Ver4DictBuffersPtr mBuffers;
+    // When the dictionary size is near the maximum size, we have to refuse dynamic operations to
+    // prevent the dictionary from overflowing.
+    static const int MARGIN_TO_REFUSE_DYNAMIC_OPERATIONS;
+    static const int MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS;
+
+    Ver4DictBuffers::Ver4DictBuffersPtr mBuffers;
     const HeaderPolicy mHeaderPolicy;
     BufferWithExtendableBuffer mDictBuffer;
-    const Ver4BigramListPolicy mBigramPolicy;
+    Ver4BigramListPolicy mBigramPolicy;
-    const Ver4ShortcutListPolicy mShortcutPolicy;
+    Ver4ShortcutListPolicy mShortcutPolicy;
     Ver4PatriciaTrieNodeReader mNodeReader;
+    Ver4PatriciaTrieNodeWriter mNodeWriter;
+    DynamicPatriciaTrieUpdatingHelper mUpdatingHelper;
+    int mUnigramCount;
+    int mBigramCount;
 };
 } // namespace latinime
 #endif // LATINIME_VER4_PATRICIA_TRIE_POLICY_H

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

@@ -78,7 +78,7 @@ public class Ver4BinaryDictionaryTests extends AndroidTestCase {
 
         final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
                 getDictionaryOptions(TEST_LOCALE, dictVersion));
-        DictEncoder encoder = new Ver4DictEncoder(getContext().getCacheDir());
+        final DictEncoder encoder = new Ver4DictEncoder(getContext().getCacheDir());
         try {
             encoder.writeDictionary(dict, FORMAT_OPTIONS);
         } catch (IOException e) {
@@ -104,7 +104,7 @@ public class Ver4BinaryDictionaryTests extends AndroidTestCase {
         dict.add("aaa", frequency, null, false /* isNotAWord */);
         dict.add("ab", frequency, null, false /* isNotAWord */);
 
-        DictEncoder encoder = new Ver4DictEncoder(getContext().getCacheDir());
+        final DictEncoder encoder = new Ver4DictEncoder(getContext().getCacheDir());
         try {
             encoder.writeDictionary(dict, FORMAT_OPTIONS);
         } catch (IOException e) {
@@ -112,8 +112,8 @@ public class Ver4BinaryDictionaryTests extends AndroidTestCase {
         } catch (UnsupportedFormatException e) {
             Log.e(TAG, "Unsupported format", e);
         }
-        File trieFile = getTrieFile(TEST_LOCALE, dictVersion);
+        final File trieFile = getTrieFile(TEST_LOCALE, dictVersion);
-        BinaryDictionary binaryDictionary = new BinaryDictionary(trieFile.getAbsolutePath(),
+        final BinaryDictionary binaryDictionary = new BinaryDictionary(trieFile.getAbsolutePath(),
                 0 /* offset */, trieFile.length(), true /* useFullEditDistance */,
                 Locale.getDefault(), TEST_LOCALE, true /* isUpdatable */);
         assertTrue(binaryDictionary.isValidDictionary());
@@ -122,7 +122,7 @@ public class Ver4BinaryDictionaryTests extends AndroidTestCase {
         assertEquals(frequency, binaryDictionary.getFrequency("ab"));
     }
 
-    public static int getCalculatedBigramProbabiliy(BinaryDictionary binaryDictionary,
+    public static int getCalculatedBigramProbabiliy(final BinaryDictionary binaryDictionary,
             final int unigramFrequency, final int bigramFrequency) {
         final int bigramFrequencyDiff = BinaryDictEncoderUtils.getBigramFrequencyDiff(
                 unigramFrequency, bigramFrequency);
@@ -146,7 +146,7 @@ public class Ver4BinaryDictionaryTests extends AndroidTestCase {
         dict.setBigram("a", "ab", bigramFrequency1);
         dict.setBigram("aaa", "ab", bigramFrequency2);
 
-        DictEncoder encoder = new Ver4DictEncoder(getContext().getCacheDir());
+        final DictEncoder encoder = new Ver4DictEncoder(getContext().getCacheDir());
         try {
             encoder.writeDictionary(dict, FORMAT_OPTIONS);
         } catch (IOException e) {
@@ -154,8 +154,8 @@ public class Ver4BinaryDictionaryTests extends AndroidTestCase {
         } catch (UnsupportedFormatException e) {
             Log.e(TAG, "Unsupported format", e);
         }
-        File trieFile = getTrieFile(TEST_LOCALE, dictVersion);
+        final File trieFile = getTrieFile(TEST_LOCALE, dictVersion);
-        BinaryDictionary binaryDictionary = new BinaryDictionary(trieFile.getAbsolutePath(),
+        final BinaryDictionary binaryDictionary = new BinaryDictionary(trieFile.getAbsolutePath(),
                 0 /* offset */, trieFile.length(), true /* useFullEditDistance */,
                 Locale.getDefault(), TEST_LOCALE, true /* isUpdatable */);
 
@@ -172,4 +172,38 @@ public class Ver4BinaryDictionaryTests extends AndroidTestCase {
         assertFalse(binaryDictionary.isValidBigram("ab", "a"));
         assertFalse(binaryDictionary.isValidBigram("ab", "aaa"));
     }
+
+    // TODO: Add large tests.
+    public void testWriteUnigrams() {
+        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 probability = 100;
+        binaryDictionary.addUnigramWord("aaa", probability);
+        binaryDictionary.addUnigramWord("abc", probability);
+        binaryDictionary.addUnigramWord("bcd", probability);
+        binaryDictionary.addUnigramWord("x", probability);
+        binaryDictionary.addUnigramWord("y", probability);
+
+        assertEquals(probability, binaryDictionary.getFrequency("aaa"));
+        assertEquals(probability, binaryDictionary.getFrequency("abc"));
+        assertEquals(probability, binaryDictionary.getFrequency("bcd"));
+        assertEquals(probability, binaryDictionary.getFrequency("x"));
+        assertEquals(probability, binaryDictionary.getFrequency("y"));
+    }
+
 }