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/*
* 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_MULTI_BIGRAM_MAP_H
#define LATINIME_MULTI_BIGRAM_MAP_H
#include <cstring>
#include <stdint.h>
#include "defines.h"
#include "binary_format.h"
#include "hash_map_compat.h"
namespace latinime {
// Class for caching bigram maps for multiple previous word contexts. This is useful since the
// algorithm needs to look up the set of bigrams for every word pair that occurs in every
// multi-word suggestion.
class MultiBigramMap {
public:
MultiBigramMap() : mBigramMaps() {}
~MultiBigramMap() {}
// Look up the bigram probability for the given word pair from the cached bigram maps.
// Also caches the bigrams if there is space remaining and they have not been cached already.
int getBigramProbability(const uint8_t *const dicRoot, const int wordPosition,
const int nextWordPosition, const int unigramProbability) {
hash_map_compat<int, BigramMap>::const_iterator mapPosition =
mBigramMaps.find(wordPosition);
if (mapPosition != mBigramMaps.end()) {
return mapPosition->second.getBigramProbability(nextWordPosition, unigramProbability);
}
if (mBigramMaps.size() < MAX_CACHED_PREV_WORDS_IN_BIGRAM_MAP) {
addBigramsForWordPosition(dicRoot, wordPosition);
return mBigramMaps[wordPosition].getBigramProbability(
nextWordPosition, unigramProbability);
}
return BinaryFormat::getBigramProbability(
dicRoot, wordPosition, nextWordPosition, unigramProbability);
}
void clear() {
mBigramMaps.clear();
}
private:
DISALLOW_COPY_AND_ASSIGN(MultiBigramMap);
class BigramMap {
public:
BigramMap() : mBigramMap(DEFAULT_HASH_MAP_SIZE_FOR_EACH_BIGRAM_MAP) {}
~BigramMap() {}
void init(const uint8_t *const dicRoot, int position) {
BinaryFormat::fillBigramProbabilityToHashMap(dicRoot, position, &mBigramMap);
}
inline int getBigramProbability(const int nextWordPosition, const int unigramProbability)
const {
return BinaryFormat::getBigramProbabilityFromHashMap(
nextWordPosition, &mBigramMap, unigramProbability);
}
private:
// Note: Default copy constructor needed for use in hash_map.
hash_map_compat<int, int> mBigramMap;
};
void addBigramsForWordPosition(const uint8_t *const dicRoot, const int position) {
mBigramMaps[position].init(dicRoot, position);
}
hash_map_compat<int, BigramMap> mBigramMaps;
};
} // namespace latinime
#endif // LATINIME_MULTI_BIGRAM_MAP_H
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