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/*
* Copyright (C) 2014 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.
*/
package com.android.inputmethod.latin;
import android.text.TextUtils;
import com.android.inputmethod.latin.utils.StringUtils;
import java.util.Arrays;
/**
* Class to represent information of previous words. This class is used to add n-gram entries
* into binary dictionaries, to get predictions, and to get suggestions.
*/
public class PrevWordsInfo {
public static final PrevWordsInfo EMPTY_PREV_WORDS_INFO =
new PrevWordsInfo(WordInfo.EMPTY_WORD_INFO);
public static final PrevWordsInfo BEGINNING_OF_SENTENCE =
new PrevWordsInfo(WordInfo.BEGINNING_OF_SENTENCE);
/**
* Word information used to represent previous words information.
*/
public static class WordInfo {
public static final WordInfo EMPTY_WORD_INFO = new WordInfo(null);
public static final WordInfo BEGINNING_OF_SENTENCE = new WordInfo();
// This is an empty char sequence when mIsBeginningOfSentence is true.
public final CharSequence mWord;
// TODO: Have sentence separator.
// Whether the current context is beginning of sentence or not. This is true when composing
// at the beginning of an input field or composing a word after a sentence separator.
public final boolean mIsBeginningOfSentence;
// Beginning of sentence.
public WordInfo() {
mWord = "";
mIsBeginningOfSentence = true;
}
public WordInfo(final CharSequence word) {
mWord = word;
mIsBeginningOfSentence = false;
}
public boolean isValid() {
return mWord != null;
}
@Override
public int hashCode() {
return Arrays.hashCode(new Object[] { mWord, mIsBeginningOfSentence } );
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof WordInfo)) return false;
final WordInfo wordInfo = (WordInfo)o;
if (mWord == null || wordInfo.mWord == null) {
return mWord == wordInfo.mWord
&& mIsBeginningOfSentence == wordInfo.mIsBeginningOfSentence;
}
return TextUtils.equals(mWord, wordInfo.mWord)
&& mIsBeginningOfSentence == wordInfo.mIsBeginningOfSentence;
}
}
// The words immediately before the considered word. EMPTY_WORD_INFO element means we don't
// have any context for that previous word including the "beginning of sentence context" - we
// just don't know what to predict using the information. An example of that is after a comma.
// For simplicity of implementation, elements may also be EMPTY_WORD_INFO transiently after the
// WordComposer was reset and before starting a new composing word, but we should never be
// calling getSuggetions* in this situation.
public final WordInfo[] mPrevWordsInfo;
// Construct from the previous word information.
public PrevWordsInfo(final WordInfo prevWordInfo) {
mPrevWordsInfo = new WordInfo[] { prevWordInfo };
}
// Construct from WordInfo array. n-th element represents (n+1)-th previous word's information.
public PrevWordsInfo(final WordInfo[] prevWordsInfo) {
mPrevWordsInfo = prevWordsInfo;
}
// Create next prevWordsInfo using current prevWordsInfo.
public PrevWordsInfo getNextPrevWordsInfo(final WordInfo wordInfo) {
final int nextPrevWordCount = Math.min(Constants.MAX_PREV_WORD_COUNT_FOR_N_GRAM,
mPrevWordsInfo.length + 1);
final WordInfo[] prevWordsInfo = new WordInfo[nextPrevWordCount];
prevWordsInfo[0] = wordInfo;
System.arraycopy(mPrevWordsInfo, 0, prevWordsInfo, 1, prevWordsInfo.length - 1);
return new PrevWordsInfo(prevWordsInfo);
}
public boolean isValid() {
return mPrevWordsInfo.length > 0 && mPrevWordsInfo[0].isValid();
}
public void outputToArray(final int[][] codePointArrays,
final boolean[] isBeginningOfSentenceArray) {
for (int i = 0; i < mPrevWordsInfo.length; i++) {
final WordInfo wordInfo = mPrevWordsInfo[i];
if (wordInfo == null || !wordInfo.isValid()) {
codePointArrays[i] = new int[0];
isBeginningOfSentenceArray[i] = false;
continue;
}
codePointArrays[i] = StringUtils.toCodePointArray(wordInfo.mWord);
isBeginningOfSentenceArray[i] = wordInfo.mIsBeginningOfSentence;
}
}
public int getPrevWordCount() {
return mPrevWordsInfo.length;
}
@Override
public int hashCode() {
return Arrays.hashCode(mPrevWordsInfo);
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof PrevWordsInfo)) return false;
final PrevWordsInfo prevWordsInfo = (PrevWordsInfo)o;
return Arrays.equals(mPrevWordsInfo, prevWordsInfo.mPrevWordsInfo);
}
@Override
public String toString() {
final StringBuffer builder = new StringBuffer();
for (int i = 0; i < mPrevWordsInfo.length; i++) {
final WordInfo wordInfo = mPrevWordsInfo[i];
builder.append("PrevWord[");
builder.append(i);
builder.append("]: ");
if (wordInfo == null || !wordInfo.isValid()) {
builder.append("Empty. ");
continue;
}
builder.append(wordInfo.mWord);
builder.append(", isBeginningOfSentence: ");
builder.append(wordInfo.mIsBeginningOfSentence);
builder.append(". ");
}
return builder.toString();
}
}
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