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