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 package com.android.inputmethod.latin; 18 19 import android.text.TextUtils; 20 21 import com.android.inputmethod.latin.utils.StringUtils; 22 23 import java.util.Arrays; 24 25 /** 26 * Class to represent information of previous words. This class is used to add n-gram entries 27 * into binary dictionaries, to get predictions, and to get suggestions. 28 */ 29 public class PrevWordsInfo { 30 public static final PrevWordsInfo EMPTY_PREV_WORDS_INFO = 31 new PrevWordsInfo(WordInfo.EMPTY_WORD_INFO); 32 public static final PrevWordsInfo BEGINNING_OF_SENTENCE = 33 new PrevWordsInfo(WordInfo.BEGINNING_OF_SENTENCE); 34 35 /** 36 * Word information used to represent previous words information. 37 */ 38 public static class WordInfo { 39 public static final WordInfo EMPTY_WORD_INFO = new WordInfo(null); 40 public static final WordInfo BEGINNING_OF_SENTENCE = new WordInfo(); 41 42 // This is an empty char sequence when mIsBeginningOfSentence is true. 43 public final CharSequence mWord; 44 // TODO: Have sentence separator. 45 // Whether the current context is beginning of sentence or not. This is true when composing 46 // at the beginning of an input field or composing a word after a sentence separator. 47 public final boolean mIsBeginningOfSentence; 48 49 // Beginning of sentence. 50 public WordInfo() { 51 mWord = ""; 52 mIsBeginningOfSentence = true; 53 } 54 55 public WordInfo(final CharSequence word) { 56 mWord = word; 57 mIsBeginningOfSentence = false; 58 } 59 60 public boolean isValid() { 61 return mWord != null; 62 } 63 64 @Override 65 public int hashCode() { 66 return Arrays.hashCode(new Object[] { mWord, mIsBeginningOfSentence } ); 67 } 68 69 @Override 70 public boolean equals(Object o) { 71 if (this == o) return true; 72 if (!(o instanceof WordInfo)) return false; 73 final WordInfo wordInfo = (WordInfo)o; 74 if (mWord == null || wordInfo.mWord == null) { 75 return mWord == wordInfo.mWord 76 && mIsBeginningOfSentence == wordInfo.mIsBeginningOfSentence; 77 } 78 return TextUtils.equals(mWord, wordInfo.mWord) 79 && mIsBeginningOfSentence == wordInfo.mIsBeginningOfSentence; 80 } 81 } 82 83 // The words immediately before the considered word. EMPTY_WORD_INFO element means we don't 84 // have any context for that previous word including the "beginning of sentence context" - we 85 // just don't know what to predict using the information. An example of that is after a comma. 86 // For simplicity of implementation, elements may also be EMPTY_WORD_INFO transiently after the 87 // WordComposer was reset and before starting a new composing word, but we should never be 88 // calling getSuggetions* in this situation. 89 public WordInfo[] mPrevWordsInfo = new WordInfo[Constants.MAX_PREV_WORD_COUNT_FOR_N_GRAM]; 90 91 // Construct from the previous word information. 92 public PrevWordsInfo(final WordInfo prevWordInfo) { 93 mPrevWordsInfo[0] = prevWordInfo; 94 } 95 96 // Construct from WordInfo array. n-th element represents (n+1)-th previous word's information. 97 public PrevWordsInfo(final WordInfo[] prevWordsInfo) { 98 for (int i = 0; i < Constants.MAX_PREV_WORD_COUNT_FOR_N_GRAM; i++) { 99 mPrevWordsInfo[i] = 100 (prevWordsInfo.length > i) ? prevWordsInfo[i] : WordInfo.EMPTY_WORD_INFO; 101 } 102 } 103 104 // Create next prevWordsInfo using current prevWordsInfo. 105 public PrevWordsInfo getNextPrevWordsInfo(final WordInfo wordInfo) { 106 final WordInfo[] prevWordsInfo = new WordInfo[Constants.MAX_PREV_WORD_COUNT_FOR_N_GRAM]; 107 prevWordsInfo[0] = wordInfo; 108 for (int i = 1; i < prevWordsInfo.length; i++) { 109 prevWordsInfo[i] = mPrevWordsInfo[i - 1]; 110 } 111 return new PrevWordsInfo(prevWordsInfo); 112 } 113 114 public boolean isValid() { 115 return mPrevWordsInfo[0].isValid(); 116 } 117 118 public void outputToArray(final int[][] codePointArrays, 119 final boolean[] isBeginningOfSentenceArray) { 120 for (int i = 0; i < mPrevWordsInfo.length; i++) { 121 final WordInfo wordInfo = mPrevWordsInfo[i]; 122 if (wordInfo == null || !wordInfo.isValid()) { 123 codePointArrays[i] = new int[0]; 124 isBeginningOfSentenceArray[i] = false; 125 continue; 126 } 127 codePointArrays[i] = StringUtils.toCodePointArray(wordInfo.mWord); 128 isBeginningOfSentenceArray[i] = wordInfo.mIsBeginningOfSentence; 129 } 130 } 131 132 @Override 133 public int hashCode() { 134 return Arrays.hashCode(mPrevWordsInfo); 135 } 136 137 @Override 138 public boolean equals(Object o) { 139 if (this == o) return true; 140 if (!(o instanceof PrevWordsInfo)) return false; 141 final PrevWordsInfo prevWordsInfo = (PrevWordsInfo)o; 142 return Arrays.equals(mPrevWordsInfo, prevWordsInfo.mPrevWordsInfo); 143 } 144 145 @Override 146 public String toString() { 147 final StringBuffer builder = new StringBuffer(); 148 for (int i = 0; i < mPrevWordsInfo.length; i++) { 149 final WordInfo wordInfo = mPrevWordsInfo[i]; 150 builder.append("PrevWord["); 151 builder.append(i); 152 builder.append("]: "); 153 if (wordInfo == null || !wordInfo.isValid()) { 154 builder.append("Empty. "); 155 continue; 156 } 157 builder.append(wordInfo.mWord); 158 builder.append(", isBeginningOfSentence: "); 159 builder.append(wordInfo.mIsBeginningOfSentence); 160 builder.append(". "); 161 } 162 return builder.toString(); 163 } 164 } 165