1 /* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef LATINIME_MULTI_BIGRAM_MAP_H 18 #define LATINIME_MULTI_BIGRAM_MAP_H 19 20 #include <cstring> 21 #include <stdint.h> 22 23 #include "defines.h" 24 #include "binary_format.h" 25 #include "hash_map_compat.h" 26 27 namespace latinime { 28 29 // Class for caching bigram maps for multiple previous word contexts. This is useful since the 30 // algorithm needs to look up the set of bigrams for every word pair that occurs in every 31 // multi-word suggestion. 32 class MultiBigramMap { 33 public: MultiBigramMap()34 MultiBigramMap() : mBigramMaps() {} ~MultiBigramMap()35 ~MultiBigramMap() {} 36 37 // Look up the bigram probability for the given word pair from the cached bigram maps. 38 // Also caches the bigrams if there is space remaining and they have not been cached already. getBigramProbability(const uint8_t * const dicRoot,const int wordPosition,const int nextWordPosition,const int unigramProbability)39 int getBigramProbability(const uint8_t *const dicRoot, const int wordPosition, 40 const int nextWordPosition, const int unigramProbability) { 41 hash_map_compat<int, BigramMap>::const_iterator mapPosition = 42 mBigramMaps.find(wordPosition); 43 if (mapPosition != mBigramMaps.end()) { 44 return mapPosition->second.getBigramProbability(nextWordPosition, unigramProbability); 45 } 46 if (mBigramMaps.size() < MAX_CACHED_PREV_WORDS_IN_BIGRAM_MAP) { 47 addBigramsForWordPosition(dicRoot, wordPosition); 48 return mBigramMaps[wordPosition].getBigramProbability( 49 nextWordPosition, unigramProbability); 50 } 51 return BinaryFormat::getBigramProbability( 52 dicRoot, wordPosition, nextWordPosition, unigramProbability); 53 } 54 clear()55 void clear() { 56 mBigramMaps.clear(); 57 } 58 59 private: 60 DISALLOW_COPY_AND_ASSIGN(MultiBigramMap); 61 62 class BigramMap { 63 public: BigramMap()64 BigramMap() : mBigramMap(DEFAULT_HASH_MAP_SIZE_FOR_EACH_BIGRAM_MAP) {} ~BigramMap()65 ~BigramMap() {} 66 init(const uint8_t * const dicRoot,int position)67 void init(const uint8_t *const dicRoot, int position) { 68 BinaryFormat::fillBigramProbabilityToHashMap(dicRoot, position, &mBigramMap); 69 } 70 getBigramProbability(const int nextWordPosition,const int unigramProbability)71 inline int getBigramProbability(const int nextWordPosition, const int unigramProbability) 72 const { 73 return BinaryFormat::getBigramProbabilityFromHashMap( 74 nextWordPosition, &mBigramMap, unigramProbability); 75 } 76 77 private: 78 // Note: Default copy constructor needed for use in hash_map. 79 hash_map_compat<int, int> mBigramMap; 80 }; 81 addBigramsForWordPosition(const uint8_t * const dicRoot,const int position)82 void addBigramsForWordPosition(const uint8_t *const dicRoot, const int position) { 83 mBigramMaps[position].init(dicRoot, position); 84 } 85 86 hash_map_compat<int, BigramMap> mBigramMaps; 87 }; 88 } // namespace latinime 89 #endif // LATINIME_MULTI_BIGRAM_MAP_H 90