9342484e8d
Our intention is to have classes of latinime-common under the common package as much as we can. Change-Id: I76efbbbe7bebf1a4aa943715cdff64f91675e20d
106 lines
5.1 KiB
Java
106 lines
5.1 KiB
Java
/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.inputmethod.latin.utils;
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import com.android.inputmethod.latin.NgramContext;
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import com.android.inputmethod.latin.NgramContext.WordInfo;
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import com.android.inputmethod.latin.common.Constants;
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import com.android.inputmethod.latin.settings.SpacingAndPunctuations;
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import java.util.Arrays;
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import java.util.regex.Pattern;
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import javax.annotation.Nonnull;
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public final class NgramContextUtils {
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private NgramContextUtils() {
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// Intentional empty constructor for utility class.
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}
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private static final Pattern SPACE_REGEX = Pattern.compile("\\s+");
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// Get context information from nth word before the cursor. n = 1 retrieves the words
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// immediately before the cursor, n = 2 retrieves the words before that, and so on. This splits
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// on whitespace only.
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// Also, it won't return words that end in a separator (if the nth word before the cursor
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// ends in a separator, it returns information representing beginning-of-sentence).
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// Example (when Constants.MAX_PREV_WORD_COUNT_FOR_N_GRAM is 2):
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// (n = 1) "abc def|" -> abc, def
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// (n = 1) "abc def |" -> abc, def
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// (n = 1) "abc 'def|" -> empty, 'def
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// (n = 1) "abc def. |" -> beginning-of-sentence
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// (n = 1) "abc def . |" -> beginning-of-sentence
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// (n = 2) "abc def|" -> beginning-of-sentence, abc
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// (n = 2) "abc def |" -> beginning-of-sentence, abc
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// (n = 2) "abc 'def|" -> empty. The context is different from "abc def", but we cannot
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// represent this situation using NgramContext. See TODO in the method.
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// TODO: The next example's result should be "abc, def". This have to be fixed before we
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// retrieve the prior context of Beginning-of-Sentence.
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// (n = 2) "abc def. |" -> beginning-of-sentence, abc
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// (n = 2) "abc def . |" -> abc, def
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// (n = 2) "abc|" -> beginning-of-sentence
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// (n = 2) "abc |" -> beginning-of-sentence
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// (n = 2) "abc. def|" -> beginning-of-sentence
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@Nonnull
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public static NgramContext getNgramContextFromNthPreviousWord(final CharSequence prev,
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final SpacingAndPunctuations spacingAndPunctuations, final int n) {
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if (prev == null) return NgramContext.EMPTY_PREV_WORDS_INFO;
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final String[] w = SPACE_REGEX.split(prev);
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final WordInfo[] prevWordsInfo = new WordInfo[Constants.MAX_PREV_WORD_COUNT_FOR_N_GRAM];
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Arrays.fill(prevWordsInfo, WordInfo.EMPTY_WORD_INFO);
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for (int i = 0; i < prevWordsInfo.length; i++) {
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final int focusedWordIndex = w.length - n - i;
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// Referring to the word after the focused word.
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if ((focusedWordIndex + 1) >= 0 && (focusedWordIndex + 1) < w.length) {
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final String wordFollowingTheNthPrevWord = w[focusedWordIndex + 1];
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if (!wordFollowingTheNthPrevWord.isEmpty()) {
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final char firstChar = wordFollowingTheNthPrevWord.charAt(0);
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if (spacingAndPunctuations.isWordConnector(firstChar)) {
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// The word following the focused word is starting with a word connector.
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// TODO: Return meaningful context for this case.
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break;
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}
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}
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}
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// If we can't find (n + i) words, the context is beginning-of-sentence.
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if (focusedWordIndex < 0) {
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prevWordsInfo[i] = WordInfo.BEGINNING_OF_SENTENCE_WORD_INFO;
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break;
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}
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final String focusedWord = w[focusedWordIndex];
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// If the word is, the context is beginning-of-sentence.
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final int length = focusedWord.length();
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if (length <= 0) {
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prevWordsInfo[i] = WordInfo.BEGINNING_OF_SENTENCE_WORD_INFO;
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break;
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}
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// If ends in a sentence separator, the context is beginning-of-sentence.
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final char lastChar = focusedWord.charAt(length - 1);
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if (spacingAndPunctuations.isSentenceSeparator(lastChar)) {
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prevWordsInfo[i] = WordInfo.BEGINNING_OF_SENTENCE_WORD_INFO;
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break;
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}
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// If ends in a word separator or connector, the context is unclear.
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// TODO: Return meaningful context for this case.
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if (spacingAndPunctuations.isWordSeparator(lastChar)
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|| spacingAndPunctuations.isWordConnector(lastChar)) {
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break;
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}
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prevWordsInfo[i] = new WordInfo(focusedWord);
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}
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return new NgramContext(prevWordsInfo);
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}
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}
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