1 /* 2 * Copyright (C) 2014, 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_NGRAM_UTILS_H 18 #define LATINIME_NGRAM_UTILS_H 19 20 #include "defines.h" 21 22 namespace latinime { 23 24 enum class NgramType : int { 25 Unigram = 0, 26 Bigram = 1, 27 Trigram = 2, 28 Quadgram = 3, 29 NotANgramType = -1, 30 }; 31 32 namespace AllNgramTypes { 33 // Use anonymous namespace to avoid ODR (One Definition Rule) violation. 34 namespace { 35 36 const NgramType ASCENDING[] = { 37 NgramType::Unigram, NgramType::Bigram, NgramType::Trigram 38 }; 39 40 const NgramType DESCENDING[] = { 41 NgramType::Trigram, NgramType::Bigram, NgramType::Unigram 42 }; 43 44 } // namespace 45 } // namespace AllNgramTypes 46 47 class NgramUtils final { 48 public: 49 static AK_FORCE_INLINE NgramType getNgramTypeFromWordCount(const int wordCount) { 50 // Max supported ngram is (MAX_PREV_WORD_COUNT_FOR_N_GRAM + 1)-gram. 51 if (wordCount <= 0 || wordCount > MAX_PREV_WORD_COUNT_FOR_N_GRAM + 1) { 52 return NgramType::NotANgramType; 53 } 54 // Convert word count to 0-origin enum value. 55 return static_cast<NgramType>(wordCount - 1); 56 } 57 58 private: 59 DISALLOW_IMPLICIT_CONSTRUCTORS(NgramUtils); 60 61 }; 62 } 63 #endif /* LATINIME_NGRAM_UTILS_H */ 64
