1 /* 2 * Copyright (C) 2016 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.internal.inputmethod; 18 19 import com.android.internal.annotations.VisibleForTesting; 20 21 import android.annotation.IntRange; 22 import android.annotation.NonNull; 23 import android.annotation.Nullable; 24 import android.icu.util.ULocale; 25 import android.os.LocaleList; 26 import android.text.TextUtils; 27 28 import java.util.ArrayList; 29 import java.util.Arrays; 30 import java.util.HashMap; 31 import java.util.List; 32 import java.util.Locale; 33 34 public final class LocaleUtils { 35 36 @VisibleForTesting 37 public interface LocaleExtractor<T> { 38 @Nullable 39 Locale get(@Nullable T source); 40 } 41 42 /** 43 * Calculates a matching score for the single desired locale. 44 * 45 * @see LocaleUtils#filterByLanguage(List, LocaleExtractor, LocaleList, ArrayList) 46 * 47 * @param supported The locale supported by IME subtype. 48 * @param desired The locale preferred by user. 49 * @return A score based on the locale matching for the default subtype enabling. 50 */ 51 @IntRange(from=1, to=3) 52 private static byte calculateMatchingSubScore(@NonNull final ULocale supported, 53 @NonNull final ULocale desired) { 54 // Assuming supported/desired is fully expanded. 55 if (supported.equals(desired)) { 56 return 3; // Exact match. 57 } 58 59 // Skip language matching since it was already done in calculateMatchingScore. 60 61 final String supportedScript = supported.getScript(); 62 if (supportedScript.isEmpty() || !supportedScript.equals(desired.getScript())) { 63 // TODO: Need subscript matching. For example, Hanb should match with Bopo. 64 return 1; 65 } 66 67 final String supportedCountry = supported.getCountry(); 68 if (supportedCountry.isEmpty() || !supportedCountry.equals(desired.getCountry())) { 69 return 2; 70 } 71 72 // Ignore others e.g. variants, extensions. 73 return 3; 74 } 75 76 private static final class ScoreEntry implements Comparable<ScoreEntry> { 77 public int mIndex = -1; 78 @NonNull public final byte[] mScore; // matching score of the i-th system languages. 79 80 ScoreEntry(@NonNull byte[] score, int index) { 81 mScore = new byte[score.length]; 82 set(score, index); 83 } 84 85 private void set(@NonNull byte[] score, int index) { 86 for (int i = 0; i < mScore.length; ++i) { 87 mScore[i] = score[i]; 88 } 89 mIndex = index; 90 } 91 92 /** 93 * Update score and index if the given score is better than this. 94 */ 95 public void updateIfBetter(@NonNull byte[] score, int index) { 96 if (compare(mScore, score) == -1) { // mScore < score 97 set(score, index); 98 } 99 } 100 101 /** 102 * Provides comaprison for bytes[]. 103 * 104 * <p> Comparison does as follows. If the first value of {@code left} is larger than the 105 * first value of {@code right}, {@code left} is large than {@code right}. If the first 106 * value of {@code left} is less than the first value of {@code right}, {@code left} is less 107 * than {@code right}. If the first value of {@code left} and the first value of 108 * {@code right} is equal, do the same comparison to the next value. Finally if all values 109 * in {@code left} and {@code right} are equal, {@code left} and {@code right} is equal.</p> 110 * 111 * @param left The length must be equal to {@code right}. 112 * @param right The length must be equal to {@code left}. 113 * @return 1 if {@code left} is larger than {@code right}. -1 if {@code left} is less than 114 * {@code right}. 0 if {@code left} and {@code right} is equal. 115 */ 116 @IntRange(from=-1, to=1) 117 private static int compare(@NonNull byte[] left, @NonNull byte[] right) { 118 for (int i = 0; i < left.length; ++i) { 119 if (left[i] > right[i]) { 120 return 1; 121 } else if (left[i] < right[i]) { 122 return -1; 123 } 124 } 125 return 0; 126 } 127 128 @Override 129 public int compareTo(final ScoreEntry other) { 130 return -1 * compare(mScore, other.mScore); // Order by descending order. 131 } 132 } 133 134 /** 135 * Filters the given items based on language preferences. 136 * 137 * <p>For each language found in {@code preferredLocales}, this method tries to copy at most 138 * one best-match item from {@code source} to {@code dest}. For example, if 139 * {@code "en-GB", "ja", "en-AU", "fr-CA", "en-IN"} is specified to {@code preferredLocales}, 140 * this method tries to copy at most one English locale, at most one Japanese, and at most one 141 * French locale from {@code source} to {@code dest}. Here the best matching English locale 142 * will be searched from {@code source} based on matching score. For the score design, see 143 * {@link LocaleUtils#calculateMatchingSubScore(ULocale, ULocale)}</p> 144 * 145 * @param sources Source items to be filtered. 146 * @param extractor Type converter from the source items to {@link Locale} object. 147 * @param preferredLocales Ordered list of locales with which the input items will be 148 * filtered. 149 * @param dest Destination into which the filtered items will be added. 150 * @param <T> Type of the data items. 151 */ 152 @VisibleForTesting 153 public static <T> void filterByLanguage( 154 @NonNull List<T> sources, 155 @NonNull LocaleExtractor<T> extractor, 156 @NonNull LocaleList preferredLocales, 157 @NonNull ArrayList<T> dest) { 158 if (preferredLocales.isEmpty()) { 159 return; 160 } 161 162 final int numPreferredLocales = preferredLocales.size(); 163 final HashMap<String, ScoreEntry> scoreboard = new HashMap<>(); 164 final byte[] score = new byte[numPreferredLocales]; 165 final ULocale[] preferredULocaleCache = new ULocale[numPreferredLocales]; 166 167 final int sourceSize = sources.size(); 168 for (int i = 0; i < sourceSize; ++i) { 169 final Locale locale = extractor.get(sources.get(i)); 170 if (locale == null) { 171 continue; 172 } 173 174 boolean canSkip = true; 175 for (int j = 0; j < numPreferredLocales; ++j) { 176 final Locale preferredLocale = preferredLocales.get(j); 177 if (!TextUtils.equals(locale.getLanguage(), preferredLocale.getLanguage())) { 178 score[j] = 0; 179 continue; 180 } 181 if (preferredULocaleCache[j] == null) { 182 preferredULocaleCache[j] = ULocale.addLikelySubtags( 183 ULocale.forLocale(preferredLocale)); 184 } 185 score[j] = calculateMatchingSubScore( 186 preferredULocaleCache[j], 187 ULocale.addLikelySubtags(ULocale.forLocale(locale))); 188 if (canSkip && score[j] != 0) { 189 canSkip = false; 190 } 191 } 192 if (canSkip) { 193 continue; 194 } 195 196 final String lang = locale.getLanguage(); 197 final ScoreEntry bestScore = scoreboard.get(lang); 198 if (bestScore == null) { 199 scoreboard.put(lang, new ScoreEntry(score, i)); 200 } else { 201 bestScore.updateIfBetter(score, i); 202 } 203 } 204 205 final ScoreEntry[] result = scoreboard.values().toArray(new ScoreEntry[scoreboard.size()]); 206 Arrays.sort(result); 207 for (final ScoreEntry entry : result) { 208 dest.add(sources.get(entry.mIndex)); 209 } 210 } 211 } 212
