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 27 import java.util.ArrayList; 28 import java.util.Arrays; 29 import java.util.HashMap; 30 import java.util.List; 31 import java.util.Locale; 32 33 public final class LocaleUtils { 34 35 @VisibleForTesting 36 public interface LocaleExtractor<T> { 37 @Nullable 38 Locale get(@Nullable T source); 39 } 40 41 /** 42 * Calculates a matching score for the single desired locale. 43 * 44 * @see LocaleUtils#calculateMatchingScore(ULocale, LocaleList, byte[]) 45 * 46 * @param supported The locale supported by IME subtype. 47 * @param desired The locale preferred by user. 48 * @return A score based on the locale matching for the default subtype enabling. 49 */ 50 @IntRange(from=1, to=3) 51 private static byte calculateMatchingSubScore(@NonNull final ULocale supported, 52 @NonNull final ULocale desired) { 53 // Assuming supported/desired is fully expanded. 54 if (supported.equals(desired)) { 55 return 3; // Exact match. 56 } 57 58 // Skip language matching since it was already done in calculateMatchingScore. 59 60 final String supportedScript = supported.getScript(); 61 if (supportedScript.isEmpty() || !supportedScript.equals(desired.getScript())) { 62 // TODO: Need subscript matching. For example, Hanb should match with Bopo. 63 return 1; 64 } 65 66 final String supportedCountry = supported.getCountry(); 67 if (supportedCountry.isEmpty() || !supportedCountry.equals(desired.getCountry())) { 68 return 2; 69 } 70 71 // Ignore others e.g. variants, extensions. 72 return 3; 73 } 74 75 /** 76 * Calculates a matching score for the desired locale list. 77 * 78 * <p>The supported locale gets a matching score of 3 if all language, script and country of the 79 * supported locale matches with the desired locale. The supported locale gets a matching 80 * score of 2 if the language and script of the supported locale matches with the desired 81 * locale. The supported locale gets a matching score of 1 if only language of the supported 82 * locale matches with the desired locale. The supported locale gets a matching score of 0 if 83 * the language of the supported locale doesn't match with the desired locale.</p> 84 * 85 * @param supported The locale supported by IME subtyle. 86 * @param desired The locale list preferred by user. Typically system locale list. 87 * @param out The output buffer to be stored the individual score for the desired language list. 88 * The length of {@code out} must be same as the length of {@code desired} language list. 89 * @return {@code false} if supported locale doesn't match with any desired locale list. 90 * Otherwise {@code true}. 91 */ 92 private static boolean calculateMatchingScore(@NonNull final ULocale supported, 93 @NonNull final LocaleList desired, @NonNull byte[] out) { 94 if (desired.isEmpty()) { 95 return false; 96 } 97 98 boolean allZeros = true; 99 final int N = desired.size(); 100 for (int i = 0; i < N; ++i) { 101 final Locale locale = desired.get(i); 102 103 if (!locale.getLanguage().equals(supported.getLanguage())) { 104 // TODO: cache the result of addLikelySubtags if it is slow. 105 out[i] = 0; 106 } else { 107 out[i] = calculateMatchingSubScore( 108 supported, ULocale.addLikelySubtags(ULocale.forLocale(locale))); 109 if (allZeros && out[i] != 0) { 110 allZeros = false; 111 } 112 } 113 } 114 return !allZeros; 115 } 116 117 private static final class ScoreEntry implements Comparable<ScoreEntry> { 118 public int mIndex = -1; 119 @NonNull public final byte[] mScore; // matching score of the i-th system languages. 120 121 ScoreEntry(@NonNull byte[] score, int index) { 122 mScore = new byte[score.length]; 123 set(score, index); 124 } 125 126 private void set(@NonNull byte[] score, int index) { 127 for (int i = 0; i < mScore.length; ++i) { 128 mScore[i] = score[i]; 129 } 130 mIndex = index; 131 } 132 133 /** 134 * Update score and index if the given score is better than this. 135 */ 136 public void updateIfBetter(@NonNull byte[] score, int index) { 137 if (compare(mScore, score) == -1) { // mScore < score 138 set(score, index); 139 } 140 } 141 142 /** 143 * Provides comaprison for bytes[]. 144 * 145 * <p> Comparison does as follows. If the first value of {@code left} is larger than the 146 * first value of {@code right}, {@code left} is large than {@code right}. If the first 147 * value of {@code left} is less than the first value of {@code right}, {@code left} is less 148 * than {@code right}. If the first value of {@code left} and the first value of 149 * {@code right} is equal, do the same comparison to the next value. Finally if all values 150 * in {@code left} and {@code right} are equal, {@code left} and {@code right} is equal.</p> 151 * 152 * @param left The length must be equal to {@code right}. 153 * @param right The length must be equal to {@code left}. 154 * @return 1 if {@code left} is larger than {@code right}. -1 if {@code left} is less than 155 * {@code right}. 0 if {@code left} and {@code right} is equal. 156 */ 157 @IntRange(from=-1, to=1) 158 private static int compare(@NonNull byte[] left, @NonNull byte[] right) { 159 for (int i = 0; i < left.length; ++i) { 160 if (left[i] > right[i]) { 161 return 1; 162 } else if (left[i] < right[i]) { 163 return -1; 164 } 165 } 166 return 0; 167 } 168 169 @Override 170 public int compareTo(final ScoreEntry other) { 171 return -1 * compare(mScore, other.mScore); // Order by descending order. 172 } 173 } 174 175 /** 176 * Filters the given items based on language preferences. 177 * 178 * <p>For each language found in {@code preferredLanguages}, this method tries to copy at most 179 * one best-match item from {@code source} to {@code dest}. For example, if 180 * {@code "en-GB", "ja", "en-AU", "fr-CA", "en-IN"} is specified to {@code preferredLanguages}, 181 * this method tries to copy at most one English locale, at most one Japanese, and at most one 182 * French locale from {@code source} to {@code dest}. Here the best matching English locale 183 * will be searched from {@code source} based on matching score. For the score design, see 184 * {@link LocaleUtils#calculateMatchingScore(ULocale, LocaleList, byte[])}</p> 185 * 186 * @param sources Source items to be filtered. 187 * @param extractor Type converter from the source items to {@link Locale} object. 188 * @param preferredLanguages Ordered list of locales with which the input items will be 189 * filtered. 190 * @param dest Destination into which the filtered items will be added. 191 * @param <T> Type of the data items. 192 */ 193 @VisibleForTesting 194 public static <T> void filterByLanguage( 195 @NonNull List<T> sources, 196 @NonNull LocaleExtractor<T> extractor, 197 @NonNull LocaleList preferredLanguages, 198 @NonNull ArrayList<T> dest) { 199 final HashMap<String, ScoreEntry> scoreboard = new HashMap<>(); 200 final byte[] score = new byte[preferredLanguages.size()]; 201 202 final int sourceSize = sources.size(); 203 for (int i = 0; i < sourceSize; ++i) { 204 final Locale locale = extractor.get(sources.get(i)); 205 if (locale == null || 206 !calculateMatchingScore(ULocale.addLikelySubtags(ULocale.forLocale(locale)), 207 preferredLanguages, score)) { 208 continue; 209 } 210 211 final String lang = locale.getLanguage(); 212 final ScoreEntry bestScore = scoreboard.get(lang); 213 if (bestScore == null) { 214 scoreboard.put(lang, new ScoreEntry(score, i)); 215 } else { 216 bestScore.updateIfBetter(score, i); 217 } 218 } 219 220 final ScoreEntry[] result = scoreboard.values().toArray(new ScoreEntry[scoreboard.size()]); 221 Arrays.sort(result); 222 for (final ScoreEntry entry : result) { 223 dest.add(sources.get(entry.mIndex)); 224 } 225 } 226 } 227
