/*
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* Copyright (C) 2016 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.server.inputmethod;
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import android.annotation.IntRange;
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import android.annotation.NonNull;
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import android.annotation.Nullable;
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import android.icu.util.ULocale;
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import android.os.LocaleList;
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import android.text.TextUtils;
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import android.util.ArrayMap;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.List;
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import java.util.Locale;
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final class LocaleUtils {
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public interface LocaleExtractor<T> {
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@Nullable
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Locale get(@Nullable T source);
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}
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/**
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* Calculates a matching score for the single desired locale.
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*
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* @see LocaleUtils#filterByLanguage(List, LocaleExtractor, LocaleList, ArrayList)
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*
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* @param supported The locale supported by IME subtype.
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* @param desired The locale preferred by user.
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* @return A score based on the locale matching for the default subtype enabling.
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*/
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@IntRange(from=1, to=3)
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private static byte calculateMatchingSubScore(@NonNull final ULocale supported,
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@NonNull final ULocale desired) {
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// Assuming supported/desired is fully expanded.
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if (supported.equals(desired)) {
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return 3; // Exact match.
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}
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// Skip language matching since it was already done in calculateMatchingScore.
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final String supportedScript = supported.getScript();
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if (supportedScript.isEmpty() || !supportedScript.equals(desired.getScript())) {
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// TODO: Need subscript matching. For example, Hanb should match with Bopo.
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return 1;
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}
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final String supportedCountry = supported.getCountry();
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if (supportedCountry.isEmpty() || !supportedCountry.equals(desired.getCountry())) {
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return 2;
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}
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// Ignore others e.g. variants, extensions.
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return 3;
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}
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private static final class ScoreEntry implements Comparable<ScoreEntry> {
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public int mIndex = -1;
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@NonNull public final byte[] mScore; // matching score of the i-th system languages.
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ScoreEntry(@NonNull byte[] score, int index) {
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mScore = new byte[score.length];
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set(score, index);
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}
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private void set(@NonNull byte[] score, int index) {
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for (int i = 0; i < mScore.length; ++i) {
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mScore[i] = score[i];
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}
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mIndex = index;
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}
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/**
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* Update score and index if the given score is better than this.
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*/
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public void updateIfBetter(@NonNull byte[] score, int index) {
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if (compare(mScore, score) == -1) { // mScore < score
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set(score, index);
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}
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}
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/**
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* Provides comaprison for bytes[].
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*
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* <p> Comparison does as follows. If the first value of {@code left} is larger than the
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* first value of {@code right}, {@code left} is large than {@code right}. If the first
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* value of {@code left} is less than the first value of {@code right}, {@code left} is less
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* than {@code right}. If the first value of {@code left} and the first value of
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* {@code right} is equal, do the same comparison to the next value. Finally if all values
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* in {@code left} and {@code right} are equal, {@code left} and {@code right} is equal.</p>
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*
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* @param left The length must be equal to {@code right}.
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* @param right The length must be equal to {@code left}.
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* @return 1 if {@code left} is larger than {@code right}. -1 if {@code left} is less than
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* {@code right}. 0 if {@code left} and {@code right} is equal.
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*/
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@IntRange(from=-1, to=1)
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private static int compare(@NonNull byte[] left, @NonNull byte[] right) {
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for (int i = 0; i < left.length; ++i) {
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if (left[i] > right[i]) {
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return 1;
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} else if (left[i] < right[i]) {
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return -1;
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}
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}
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return 0;
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}
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@Override
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public int compareTo(final ScoreEntry other) {
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return -1 * compare(mScore, other.mScore); // Order by descending order.
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}
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}
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/**
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* Filters the given items based on language preferences.
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*
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* <p>For each language found in {@code preferredLocales}, this method tries to copy at most
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* one best-match item from {@code source} to {@code dest}. For example, if
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* {@code "en-GB", "ja", "en-AU", "fr-CA", "en-IN"} is specified to {@code preferredLocales},
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* this method tries to copy at most one English locale, at most one Japanese, and at most one
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* French locale from {@code source} to {@code dest}. Here the best matching English locale
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* will be searched from {@code source} based on matching score. For the score design, see
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* {@link LocaleUtils#calculateMatchingSubScore(ULocale, ULocale)}</p>
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*
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* @param sources Source items to be filtered.
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* @param extractor Type converter from the source items to {@link Locale} object.
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* @param preferredLocales Ordered list of locales with which the input items will be
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* filtered.
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* @param dest Destination into which the filtered items will be added.
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* @param <T> Type of the data items.
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*/
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public static <T> void filterByLanguage(
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@NonNull List<T> sources,
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@NonNull LocaleExtractor<T> extractor,
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@NonNull LocaleList preferredLocales,
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@NonNull ArrayList<T> dest) {
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if (preferredLocales.isEmpty()) {
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return;
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}
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final int numPreferredLocales = preferredLocales.size();
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final ArrayMap<String, ScoreEntry> scoreboard = new ArrayMap<>();
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final byte[] score = new byte[numPreferredLocales];
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final ULocale[] preferredULocaleCache = new ULocale[numPreferredLocales];
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final int sourceSize = sources.size();
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for (int i = 0; i < sourceSize; ++i) {
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final Locale locale = extractor.get(sources.get(i));
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if (locale == null) {
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continue;
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}
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boolean canSkip = true;
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for (int j = 0; j < numPreferredLocales; ++j) {
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final Locale preferredLocale = preferredLocales.get(j);
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if (!TextUtils.equals(locale.getLanguage(), preferredLocale.getLanguage())) {
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score[j] = 0;
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continue;
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}
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if (preferredULocaleCache[j] == null) {
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preferredULocaleCache[j] = ULocale.addLikelySubtags(
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ULocale.forLocale(preferredLocale));
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}
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score[j] = calculateMatchingSubScore(
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preferredULocaleCache[j],
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ULocale.addLikelySubtags(ULocale.forLocale(locale)));
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if (canSkip && score[j] != 0) {
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canSkip = false;
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}
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}
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if (canSkip) {
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continue;
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}
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final String lang = locale.getLanguage();
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final ScoreEntry bestScore = scoreboard.get(lang);
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if (bestScore == null) {
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scoreboard.put(lang, new ScoreEntry(score, i));
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} else {
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bestScore.updateIfBetter(score, i);
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}
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}
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final int numEntries = scoreboard.size();
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final ScoreEntry[] result = new ScoreEntry[numEntries];
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for (int i = 0; i < numEntries; ++i) {
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result[i] = scoreboard.valueAt(i);
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}
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Arrays.sort(result);
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for (final ScoreEntry entry : result) {
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dest.add(sources.get(entry.mIndex));
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}
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}
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}
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