/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.core.os;
import static androidx.annotation.RestrictTo.Scope.LIBRARY_GROUP;
import android.os.Build;
import androidx.annotation.GuardedBy;
import androidx.annotation.IntRange;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RestrictTo;
import androidx.annotation.Size;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashSet;
import java.util.Locale;
/**
* LocaleListHelper is an immutable list of Locales, typically used to keep an ordered list of user
* preferences for locales.
*
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
final class LocaleListHelper {
private final Locale[] mList;
// This is a comma-separated list of the locales in the LocaleListHelper created at construction
// time, basically the result of running each locale's toLanguageTag() method and concatenating
// them with commas in between.
@NonNull
private final String mStringRepresentation;
private static final Locale[] sEmptyList = new Locale[0];
private static final LocaleListHelper sEmptyLocaleList = new LocaleListHelper();
/**
* Retrieves the {@link Locale} at the specified index.
*
* @param index The position to retrieve.
* @return The {@link Locale} in the given index.
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
Locale get(int index) {
return (0 <= index && index < mList.length) ? mList[index] : null;
}
/**
* Returns whether the {@link LocaleListHelper} contains no {@link Locale} items.
*
* @return {@code true} if this {@link LocaleListHelper} has no {@link Locale} items,
* {@code false} otherwise.
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
boolean isEmpty() {
return mList.length == 0;
}
/**
* Returns the number of {@link Locale} items in this {@link LocaleListHelper}.
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
@IntRange(from = 0)
int size() {
return mList.length;
}
/**
* Searches this {@link LocaleListHelper} for the specified {@link Locale} and returns the index
* of the first occurrence.
*
* @param locale The {@link Locale} to search for.
* @return The index of the first occurrence of the {@link Locale} or {@code -1} if the item
* wasn't found.
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
@IntRange(from = -1)
int indexOf(Locale locale) {
for (int i = 0; i < mList.length; i++) {
if (mList[i].equals(locale)) {
return i;
}
}
return -1;
}
@Override
public boolean equals(Object other) {
if (other == this) {
return true;
}
if (!(other instanceof LocaleListHelper)) {
return false;
}
final Locale[] otherList = ((LocaleListHelper) other).mList;
if (mList.length != otherList.length) {
return false;
}
for (int i = 0; i < mList.length; i++) {
if (!mList[i].equals(otherList[i])) {
return false;
}
}
return true;
}
@Override
public int hashCode() {
int result = 1;
for (int i = 0; i < mList.length; i++) {
result = 31 * result + mList[i].hashCode();
}
return result;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("[");
for (int i = 0; i < mList.length; i++) {
sb.append(mList[i]);
if (i < mList.length - 1) {
sb.append(',');
}
}
sb.append("]");
return sb.toString();
}
/**
* Retrieves a String representation of the language tags in this list.
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
@NonNull
String toLanguageTags() {
return mStringRepresentation;
}
/**
* Creates a new {@link LocaleListHelper}.
*
* <p>For empty lists of {@link Locale} items it is better to use {@link #getEmptyLocaleList()},
* which returns a pre-constructed empty list.</p>
*
* @throws NullPointerException if any of the input locales is <code>null</code>.
* @throws IllegalArgumentException if any of the input locales repeat.
*
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
LocaleListHelper(@NonNull Locale... list) {
if (list.length == 0) {
mList = sEmptyList;
mStringRepresentation = "";
} else {
final Locale[] localeList = new Locale[list.length];
final HashSet<Locale> seenLocales = new HashSet<Locale>();
final StringBuilder sb = new StringBuilder();
for (int i = 0; i < list.length; i++) {
final Locale l = list[i];
if (l == null) {
throw new NullPointerException("list[" + i + "] is null");
} else if (seenLocales.contains(l)) {
throw new IllegalArgumentException("list[" + i + "] is a repetition");
} else {
final Locale localeClone = (Locale) l.clone();
localeList[i] = localeClone;
sb.append(LocaleHelper.toLanguageTag(localeClone));
if (i < list.length - 1) {
sb.append(',');
}
seenLocales.add(localeClone);
}
}
mList = localeList;
mStringRepresentation = sb.toString();
}
}
/**
* Constructs a locale list, with the topLocale moved to the front if it already is
* in otherLocales, or added to the front if it isn't.
*
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
LocaleListHelper(@NonNull Locale topLocale, LocaleListHelper otherLocales) {
if (topLocale == null) {
throw new NullPointerException("topLocale is null");
}
final int inputLength = (otherLocales == null) ? 0 : otherLocales.mList.length;
int topLocaleIndex = -1;
for (int i = 0; i < inputLength; i++) {
if (topLocale.equals(otherLocales.mList[i])) {
topLocaleIndex = i;
break;
}
}
final int outputLength = inputLength + (topLocaleIndex == -1 ? 1 : 0);
final Locale[] localeList = new Locale[outputLength];
localeList[0] = (Locale) topLocale.clone();
if (topLocaleIndex == -1) {
// topLocale was not in otherLocales
for (int i = 0; i < inputLength; i++) {
localeList[i + 1] = (Locale) otherLocales.mList[i].clone();
}
} else {
for (int i = 0; i < topLocaleIndex; i++) {
localeList[i + 1] = (Locale) otherLocales.mList[i].clone();
}
for (int i = topLocaleIndex + 1; i < inputLength; i++) {
localeList[i] = (Locale) otherLocales.mList[i].clone();
}
}
final StringBuilder sb = new StringBuilder();
for (int i = 0; i < outputLength; i++) {
sb.append(LocaleHelper.toLanguageTag(localeList[i]));
if (i < outputLength - 1) {
sb.append(',');
}
}
mList = localeList;
mStringRepresentation = sb.toString();
}
/**
* Retrieve an empty instance of {@link LocaleListHelper}.
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
@NonNull
static LocaleListHelper getEmptyLocaleList() {
return sEmptyLocaleList;
}
/**
* Generates a new LocaleListHelper with the given language tags.
*
* @param list The language tags to be included as a single {@link String} separated by commas.
* @return A new instance with the {@link Locale} items identified by the given tags.
*
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
@NonNull
static LocaleListHelper forLanguageTags(@Nullable String list) {
if (list == null || list.isEmpty()) {
return getEmptyLocaleList();
} else {
final String[] tags = list.split(",", -1);
final Locale[] localeArray = new Locale[tags.length];
for (int i = 0; i < localeArray.length; i++) {
localeArray[i] = LocaleHelper.forLanguageTag(tags[i]);
}
return new LocaleListHelper(localeArray);
}
}
private static String getLikelyScript(Locale locale) {
if (Build.VERSION.SDK_INT >= 21) {
final String script = locale.getScript();
if (!script.isEmpty()) {
return script;
} else {
return "";
}
}
return "";
}
private static final String STRING_EN_XA = "en-XA";
private static final String STRING_AR_XB = "ar-XB";
private static final Locale LOCALE_EN_XA = new Locale("en", "XA");
private static final Locale LOCALE_AR_XB = new Locale("ar", "XB");
private static final int NUM_PSEUDO_LOCALES = 2;
private static boolean isPseudoLocale(String locale) {
return STRING_EN_XA.equals(locale) || STRING_AR_XB.equals(locale);
}
private static boolean isPseudoLocale(Locale locale) {
return LOCALE_EN_XA.equals(locale) || LOCALE_AR_XB.equals(locale);
}
@IntRange(from = 0, to = 1)
private static int matchScore(Locale supported, Locale desired) {
if (supported.equals(desired)) {
return 1; // return early so we don't do unnecessary computation
}
if (!supported.getLanguage().equals(desired.getLanguage())) {
return 0;
}
if (isPseudoLocale(supported) || isPseudoLocale(desired)) {
// The locales are not the same, but the languages are the same, and one of the locales
// is a pseudo-locale. So this is not a match.
return 0;
}
final String supportedScr = getLikelyScript(supported);
if (supportedScr.isEmpty()) {
// If we can't guess a script, we don't know enough about the locales' language to find
// if the locales match. So we fall back to old behavior of matching, which considered
// locales with different regions different.
final String supportedRegion = supported.getCountry();
return (supportedRegion.isEmpty() || supportedRegion.equals(desired.getCountry()))
? 1
: 0;
}
final String desiredScr = getLikelyScript(desired);
// There is no match if the two locales use different scripts. This will most imporantly
// take care of traditional vs simplified Chinese.
return supportedScr.equals(desiredScr) ? 1 : 0;
}
private int findFirstMatchIndex(Locale supportedLocale) {
for (int idx = 0; idx < mList.length; idx++) {
final int score = matchScore(supportedLocale, mList[idx]);
if (score > 0) {
return idx;
}
}
return Integer.MAX_VALUE;
}
private static final Locale EN_LATN = LocaleHelper.forLanguageTag("en-Latn");
private int computeFirstMatchIndex(Collection<String> supportedLocales,
boolean assumeEnglishIsSupported) {
if (mList.length == 1) { // just one locale, perhaps the most common scenario
return 0;
}
if (mList.length == 0) { // empty locale list
return -1;
}
int bestIndex = Integer.MAX_VALUE;
// Try English first, so we can return early if it's in the LocaleListHelper
if (assumeEnglishIsSupported) {
final int idx = findFirstMatchIndex(EN_LATN);
if (idx == 0) { // We have a match on the first locale, which is good enough
return 0;
} else if (idx < bestIndex) {
bestIndex = idx;
}
}
for (String languageTag : supportedLocales) {
final Locale supportedLocale = LocaleHelper.forLanguageTag(languageTag);
// We expect the average length of locale lists used for locale resolution to be
// smaller than three, so it's OK to do this as an O(mn) algorithm.
final int idx = findFirstMatchIndex(supportedLocale);
if (idx == 0) { // We have a match on the first locale, which is good enough
return 0;
} else if (idx < bestIndex) {
bestIndex = idx;
}
}
if (bestIndex == Integer.MAX_VALUE) {
// no match was found, so we fall back to the first locale in the locale list
return 0;
} else {
return bestIndex;
}
}
private Locale computeFirstMatch(Collection<String> supportedLocales,
boolean assumeEnglishIsSupported) {
int bestIndex = computeFirstMatchIndex(supportedLocales, assumeEnglishIsSupported);
return bestIndex == -1 ? null : mList[bestIndex];
}
/**
* Returns the first match in the locale list given an unordered array of supported locales
* in BCP 47 format.
*
* @return The first {@link Locale} from this list that appears in the given array, or
* {@code null} if the {@link LocaleListHelper} is empty.
*
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
@Nullable
Locale getFirstMatch(String[] supportedLocales) {
return computeFirstMatch(Arrays.asList(supportedLocales),
false /* assume English is not supported */);
}
/**
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
int getFirstMatchIndex(String[] supportedLocales) {
return computeFirstMatchIndex(Arrays.asList(supportedLocales),
false /* assume English is not supported */);
}
/**
* Same as getFirstMatch(), but with English assumed to be supported, even if it's not.
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
@Nullable
Locale getFirstMatchWithEnglishSupported(String[] supportedLocales) {
return computeFirstMatch(Arrays.asList(supportedLocales),
true /* assume English is supported */);
}
/**
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
int getFirstMatchIndexWithEnglishSupported(Collection<String> supportedLocales) {
return computeFirstMatchIndex(supportedLocales, true /* assume English is supported */);
}
/**
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
int getFirstMatchIndexWithEnglishSupported(String[] supportedLocales) {
return getFirstMatchIndexWithEnglishSupported(Arrays.asList(supportedLocales));
}
/**
* Returns true if the collection of locale tags only contains empty locales and pseudolocales.
* Assumes that there is no repetition in the input.
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
static boolean isPseudoLocalesOnly(@Nullable String[] supportedLocales) {
if (supportedLocales == null) {
return true;
}
if (supportedLocales.length > NUM_PSEUDO_LOCALES + 1) {
// This is for optimization. Since there's no repetition in the input, if we have more
// than the number of pseudo-locales plus one for the empty string, it's guaranteed
// that we have some meaninful locale in the collection, so the list is not "practically
// empty".
return false;
}
for (String locale : supportedLocales) {
if (!locale.isEmpty() && !isPseudoLocale(locale)) {
return false;
}
}
return true;
}
/** Lock for mutable static fields */
private final static Object sLock = new Object();
@GuardedBy("sLock")
private static LocaleListHelper sLastExplicitlySetLocaleList = null;
@GuardedBy("sLock")
private static LocaleListHelper sDefaultLocaleList = null;
@GuardedBy("sLock")
private static LocaleListHelper sDefaultAdjustedLocaleList = null;
@GuardedBy("sLock")
private static Locale sLastDefaultLocale = null;
/**
* The result is guaranteed to include the default Locale returned by Locale.getDefault(), but
* not necessarily at the top of the list. The default locale not being at the top of the list
* is an indication that the system has set the default locale to one of the user's other
* preferred locales, having concluded that the primary preference is not supported but a
* secondary preference is.
*
* <p>Note that the default LocaleListHelper would change if Locale.setDefault() is called. This
* method takes that into account by always checking the output of Locale.getDefault() and
* recalculating the default LocaleListHelper if needed.</p>
*
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
@NonNull @Size(min = 1)
static LocaleListHelper getDefault() {
final Locale defaultLocale = Locale.getDefault();
synchronized (sLock) {
if (!defaultLocale.equals(sLastDefaultLocale)) {
sLastDefaultLocale = defaultLocale;
// It's either the first time someone has asked for the default locale list, or
// someone has called Locale.setDefault() since we last set or adjusted the default
// locale list. So let's recalculate the locale list.
if (sDefaultLocaleList != null
&& defaultLocale.equals(sDefaultLocaleList.get(0))) {
// The default Locale has changed, but it happens to be the first locale in the
// default locale list, so we don't need to construct a new locale list.
return sDefaultLocaleList;
}
sDefaultLocaleList = new LocaleListHelper(
defaultLocale, sLastExplicitlySetLocaleList);
sDefaultAdjustedLocaleList = sDefaultLocaleList;
}
// sDefaultLocaleList can't be null, since it can't be set to null by
// LocaleListHelper.setDefault(), and if getDefault() is called before a call to
// setDefault(), sLastDefaultLocale would be null and the check above would set
// sDefaultLocaleList.
return sDefaultLocaleList;
}
}
/**
* Returns the default locale list, adjusted by moving the default locale to its first
* position.
*/
@NonNull @Size(min = 1)
static LocaleListHelper getAdjustedDefault() {
getDefault(); // to recalculate the default locale list, if necessary
synchronized (sLock) {
return sDefaultAdjustedLocaleList;
}
}
/**
* Also sets the default locale by calling Locale.setDefault() with the first locale in the
* list.
*
* @throws NullPointerException if the input is <code>null</code>.
* @throws IllegalArgumentException if the input is empty.
*
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
static void setDefault(@NonNull @Size(min = 1) LocaleListHelper locales) {
setDefault(locales, 0);
}
/**
* This may be used directly by system processes to set the default locale list for apps. For
* such uses, the default locale list would always come from the user preferences, but the
* default locale may have been chosen to be a locale other than the first locale in the locale
* list (based on the locales the app supports).
*
* @hide
*/
@RestrictTo(LIBRARY_GROUP)
static void setDefault(@NonNull @Size(min = 1) LocaleListHelper locales,
int localeIndex) {
if (locales == null) {
throw new NullPointerException("locales is null");
}
if (locales.isEmpty()) {
throw new IllegalArgumentException("locales is empty");
}
synchronized (sLock) {
sLastDefaultLocale = locales.get(localeIndex);
Locale.setDefault(sLastDefaultLocale);
sLastExplicitlySetLocaleList = locales;
sDefaultLocaleList = locales;
if (localeIndex == 0) {
sDefaultAdjustedLocaleList = sDefaultLocaleList;
} else {
sDefaultAdjustedLocaleList = new LocaleListHelper(
sLastDefaultLocale, sDefaultLocaleList);
}
}
}
}