96 lines
3.8 KiB
C++
96 lines
3.8 KiB
C++
/*
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* Copyright (C) 2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "dictionary/structure/pt_common/bigram/bigram_list_read_write_utils.h"
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#include "dictionary/utils/byte_array_utils.h"
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#include "dictionary/utils/buffer_with_extendable_buffer.h"
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namespace latinime {
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const BigramListReadWriteUtils::BigramFlags BigramListReadWriteUtils::MASK_ATTRIBUTE_ADDRESS_TYPE =
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0x30;
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const BigramListReadWriteUtils::BigramFlags
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BigramListReadWriteUtils::FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE = 0x10;
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const BigramListReadWriteUtils::BigramFlags
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BigramListReadWriteUtils::FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES = 0x20;
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const BigramListReadWriteUtils::BigramFlags
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BigramListReadWriteUtils::FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES = 0x30;
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const BigramListReadWriteUtils::BigramFlags
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BigramListReadWriteUtils::FLAG_ATTRIBUTE_OFFSET_NEGATIVE = 0x40;
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// Flag for presence of more attributes
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const BigramListReadWriteUtils::BigramFlags BigramListReadWriteUtils::FLAG_ATTRIBUTE_HAS_NEXT =
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0x80;
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// Mask for attribute probability, stored on 4 bits inside the flags byte.
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const BigramListReadWriteUtils::BigramFlags
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BigramListReadWriteUtils::MASK_ATTRIBUTE_PROBABILITY = 0x0F;
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/* static */ bool BigramListReadWriteUtils::getBigramEntryPropertiesAndAdvancePosition(
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const ReadOnlyByteArrayView buffer, BigramFlags *const outBigramFlags,
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int *const outTargetPtNodePos, int *const bigramEntryPos) {
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if (static_cast<int>(buffer.size()) <= *bigramEntryPos) {
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AKLOGE("Read invalid pos in getBigramEntryPropertiesAndAdvancePosition(). bufSize: %zd, "
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"bigramEntryPos: %d.", buffer.size(), *bigramEntryPos);
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return false;
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}
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const BigramFlags bigramFlags = ByteArrayUtils::readUint8AndAdvancePosition(buffer.data(),
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bigramEntryPos);
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if (outBigramFlags) {
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*outBigramFlags = bigramFlags;
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}
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const int targetPos = getBigramAddressAndAdvancePosition(buffer, bigramFlags, bigramEntryPos);
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if (outTargetPtNodePos) {
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*outTargetPtNodePos = targetPos;
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}
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return true;
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}
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/* static */ bool BigramListReadWriteUtils::skipExistingBigrams(const ReadOnlyByteArrayView buffer,
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int *const bigramListPos) {
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BigramFlags flags;
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do {
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if (!getBigramEntryPropertiesAndAdvancePosition(buffer, &flags, 0 /* outTargetPtNodePos */,
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bigramListPos)) {
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return false;
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}
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} while(hasNext(flags));
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return true;
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}
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/* static */ int BigramListReadWriteUtils::getBigramAddressAndAdvancePosition(
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const ReadOnlyByteArrayView buffer, const BigramFlags flags, int *const pos) {
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int offset = 0;
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const int origin = *pos;
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switch (MASK_ATTRIBUTE_ADDRESS_TYPE & flags) {
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case FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE:
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offset = ByteArrayUtils::readUint8AndAdvancePosition(buffer.data(), pos);
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break;
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case FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES:
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offset = ByteArrayUtils::readUint16AndAdvancePosition(buffer.data(), pos);
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break;
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case FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES:
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offset = ByteArrayUtils::readUint24AndAdvancePosition(buffer.data(), pos);
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break;
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}
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if (isOffsetNegative(flags)) {
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return origin - offset;
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} else {
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return origin + offset;
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}
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}
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} // namespace latinime
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