Add spellcheck and word suggestion to the prediction service

third_party/android_prediction/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.cpp

Index: third_party/android_prediction/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.cpp
diff --git a/third_party/android_prediction/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.cpp b/third_party/android_prediction/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..3ab4ba84b9428df43c8da428ac113b87ade22cdd
--- /dev/null
+++ b/third_party/android_prediction/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.cpp
@@ -0,0 +1,168 @@
+/*
+ * 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 "third_party/android_prediction/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
+
+namespace latinime {
+
+const size_t BufferWithExtendableBuffer::DEFAULT_MAX_ADDITIONAL_BUFFER_SIZE = 1024 * 1024;
+const int BufferWithExtendableBuffer::NEAR_BUFFER_LIMIT_THRESHOLD_PERCENTILE = 90;
+// TODO: Needs to allocate larger memory corresponding to the current vector size.
+const size_t BufferWithExtendableBuffer::EXTEND_ADDITIONAL_BUFFER_SIZE_STEP = 128 * 1024;
+
+uint32_t BufferWithExtendableBuffer::readUint(const int size, const int pos) const {
+    const bool readingPosIsInAdditionalBuffer = isInAdditionalBuffer(pos);
+    const int posInBuffer = readingPosIsInAdditionalBuffer ? pos - mOriginalBuffer.size() : pos;
+    return ByteArrayUtils::readUint(getBuffer(readingPosIsInAdditionalBuffer), size, posInBuffer);
+}
+
+uint32_t BufferWithExtendableBuffer::readUintAndAdvancePosition(const int size,
+        int *const pos) const {
+    const int value = readUint(size, *pos);
+    *pos += size;
+    return value;
+}
+
+void BufferWithExtendableBuffer::readCodePointsAndAdvancePosition(const int maxCodePointCount,
+        int *const outCodePoints, int *outCodePointCount, int *const pos) const {
+    const bool readingPosIsInAdditionalBuffer = isInAdditionalBuffer(*pos);
+    if (readingPosIsInAdditionalBuffer) {
+        *pos -= mOriginalBuffer.size();
+    }
+    *outCodePointCount = ByteArrayUtils::readStringAndAdvancePosition(
+            getBuffer(readingPosIsInAdditionalBuffer), maxCodePointCount, outCodePoints, pos);
+    if (readingPosIsInAdditionalBuffer) {
+        *pos += mOriginalBuffer.size();
+    }
+}
+
+bool BufferWithExtendableBuffer::extend(const int size) {
+    return checkAndPrepareWriting(getTailPosition(), size);
+}
+
+bool BufferWithExtendableBuffer::writeUint(const uint32_t data, const int size, const int pos) {
+    int writingPos = pos;
+    return writeUintAndAdvancePosition(data, size, &writingPos);
+}
+
+bool BufferWithExtendableBuffer::writeUintAndAdvancePosition(const uint32_t data, const int size,
+        int *const pos) {
+    if (!(size >= 1 && size <= 4)) {
+        AKLOGI("writeUintAndAdvancePosition() is called with invalid size: %d", size);
+        ASSERT(false);
+        return false;
+    }
+    if (!checkAndPrepareWriting(*pos, size)) {
+        return false;
+    }
+    const bool usesAdditionalBuffer = isInAdditionalBuffer(*pos);
+    uint8_t *const buffer =
+            usesAdditionalBuffer ? mAdditionalBuffer.data() : mOriginalBuffer.data();
+    if (usesAdditionalBuffer) {
+        *pos -= mOriginalBuffer.size();
+    }
+    ByteArrayUtils::writeUintAndAdvancePosition(buffer, data, size, pos);
+    if (usesAdditionalBuffer) {
+        *pos += mOriginalBuffer.size();
+    }
+    return true;
+}
+
+bool BufferWithExtendableBuffer::writeCodePointsAndAdvancePosition(const int *const codePoints,
+        const int codePointCount, const bool writesTerminator, int *const pos) {
+    const size_t size = ByteArrayUtils::calculateRequiredByteCountToStoreCodePoints(
+            codePoints, codePointCount, writesTerminator);
+    if (!checkAndPrepareWriting(*pos, size)) {
+        return false;
+    }
+    const bool usesAdditionalBuffer = isInAdditionalBuffer(*pos);
+    uint8_t *const buffer =
+            usesAdditionalBuffer ? mAdditionalBuffer.data() : mOriginalBuffer.data();
+    if (usesAdditionalBuffer) {
+        *pos -= mOriginalBuffer.size();
+    }
+    ByteArrayUtils::writeCodePointsAndAdvancePosition(buffer, codePoints, codePointCount,
+            writesTerminator, pos);
+    if (usesAdditionalBuffer) {
+        *pos += mOriginalBuffer.size();
+    }
+    return true;
+}
+
+bool BufferWithExtendableBuffer::extendBuffer(const size_t size) {
+    const size_t extendSize = std::max(EXTEND_ADDITIONAL_BUFFER_SIZE_STEP, size);
+    const size_t sizeAfterExtending =
+            std::min(mAdditionalBuffer.size() + extendSize, mMaxAdditionalBufferSize);
+    if (sizeAfterExtending < mAdditionalBuffer.size() + size) {
+        return false;
+    }
+    mAdditionalBuffer.resize(sizeAfterExtending);
+    return true;
+}
+
+bool BufferWithExtendableBuffer::checkAndPrepareWriting(const int pos, const int size) {
+    if (pos < 0 || size < 0) {
+        // Invalid position or size.
+        return false;
+    }
+    const size_t totalRequiredSize = static_cast<size_t>(pos + size);
+    if (!isInAdditionalBuffer(pos)) {
+        // Here don't need to care about the additional buffer.
+        if (mOriginalBuffer.size() < totalRequiredSize) {
+            // Violate the boundary.
+            return false;
+        }
+        // The buffer has sufficient capacity.
+        return true;
+    }
+    // Hereafter, pos is in the additional buffer.
+    const size_t tailPosition = static_cast<size_t>(getTailPosition());
+    if (totalRequiredSize <= tailPosition) {
+        // The buffer has sufficient capacity.
+        return true;
+    }
+    if (static_cast<size_t>(pos) != tailPosition) {
+        // The additional buffer must be extended from the tail position.
+        return false;
+    }
+    const size_t extendSize = totalRequiredSize -
+            std::min(mAdditionalBuffer.size() + mOriginalBuffer.size(), totalRequiredSize);
+    if (extendSize > 0 && !extendBuffer(extendSize)) {
+        // Failed to extend the buffer.
+        return false;
+    }
+    mUsedAdditionalBufferSize += size;
+    return true;
+}
+
+bool BufferWithExtendableBuffer::copy(const BufferWithExtendableBuffer *const sourceBuffer) {
+    int copyingPos = 0;
+    const int tailPos = sourceBuffer->getTailPosition();
+    const int maxDataChunkSize = sizeof(uint32_t);
+    while (copyingPos < tailPos) {
+        const int remainingSize = tailPos - copyingPos;
+        const int copyingSize = (remainingSize >= maxDataChunkSize) ?
+                maxDataChunkSize : remainingSize;
+        const uint32_t data = sourceBuffer->readUint(copyingSize, copyingPos);
+        if (!writeUint(data, copyingSize, copyingPos)) {
+            return false;
+        }
+        copyingPos += copyingSize;
+    }
+    return true;
+}
+
+}