src/java.base/share/classes/sun/util/locale/provider/LocaleProviderAdapter.java

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package sun.util.locale.provider;

import java.lang.reflect.InvocationTargetException;
import java.text.spi.BreakIteratorProvider;
import java.text.spi.CollatorProvider;
import java.text.spi.DateFormatProvider;
import java.text.spi.DateFormatSymbolsProvider;
import java.text.spi.DecimalFormatSymbolsProvider;
import java.text.spi.NumberFormatProvider;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.ResourceBundle;
import java.util.ServiceConfigurationError;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.spi.CalendarDataProvider;
import java.util.spi.CalendarNameProvider;
import java.util.spi.CurrencyNameProvider;
import java.util.spi.LocaleNameProvider;
import java.util.spi.LocaleServiceProvider;
import java.util.spi.TimeZoneNameProvider;
import sun.text.spi.JavaTimeDateTimePatternProvider;
import sun.util.spi.CalendarProvider;

import static java.lang.System.*;

/**
 * The LocaleProviderAdapter abstract class.
 *
 * @author Naoto Sato
 * @author Masayoshi Okutsu
 */
public abstract class LocaleProviderAdapter {
    /**
     * Adapter type.
     */
    public enum Type {
        JRE("sun.util.locale.provider.JRELocaleProviderAdapter", "sun.util.resources", "sun.text.resources"),
        CLDR("sun.util.cldr.CLDRLocaleProviderAdapter", "sun.util.resources.cldr", "sun.text.resources.cldr"),
        SPI("sun.util.locale.provider.SPILocaleProviderAdapter"),
        HOST("sun.util.locale.provider.HostLocaleProviderAdapter"),
        FALLBACK("sun.util.locale.provider.FallbackLocaleProviderAdapter", "sun.util.resources", "sun.text.resources");

        private final String CLASSNAME;
        private final String UTIL_RESOURCES_PACKAGE;
        private final String TEXT_RESOURCES_PACKAGE;

        Type(String className) {
            this(className, null, null);
        }

        Type(String className, String util, String text) {
            CLASSNAME = className;
            UTIL_RESOURCES_PACKAGE = util;
            TEXT_RESOURCES_PACKAGE = text;
        }

        public String getAdapterClassName() {
            return CLASSNAME;
        }

        public String getUtilResourcesPackage() {
            return UTIL_RESOURCES_PACKAGE;
        }

        public String getTextResourcesPackage() {
            return TEXT_RESOURCES_PACKAGE;
        }
    }

    /**
     * LocaleProviderAdapter preference list.
     */
    private static final List<Type> adapterPreference;

    /**
     * LocaleProviderAdapter instances
     */
    private static final Map<Type, LocaleProviderAdapter> adapterInstances = new ConcurrentHashMap<>();

    /**
     * Adapter lookup cache.
     */
    private static final ConcurrentMap<Class<? extends LocaleServiceProvider>, ConcurrentMap<Locale, LocaleProviderAdapter>>
        adapterCache = new ConcurrentHashMap<>();

    static {
        String order = System.getProperty("java.locale.providers");
        ArrayList<Type> typeList = new ArrayList<>();
        String invalidTypeMessage = null;
        String compatWarningMessage = null;

        // Check user specified adapter preference
        if (order != null && !order.isEmpty()) {
            String[] types = order.split(",");
            for (String type : types) {
                type = type.trim().toUpperCase(Locale.ROOT);
                if (type.equals("COMPAT") || type.equals("JRE")) {
                    compatWarningMessage = "COMPAT locale provider has been removed";
                }
                try {
                    Type aType = Type.valueOf(type.trim().toUpperCase(Locale.ROOT));
                    if (!typeList.contains(aType)) {
                        typeList.add(aType);
                    }
                } catch (IllegalArgumentException e) {
                    // construct a log message.
                    invalidTypeMessage = "Invalid locale provider adapter \"" + type + "\" ignored.";
                }
            }
        }

        if (typeList.isEmpty()) {
            // Default preference list.
            typeList.add(Type.CLDR);
        }

        // always append FALLBACK
        typeList.add(Type.FALLBACK);

        adapterPreference = Collections.unmodifiableList(typeList);

        // Emit logs, if any, after 'adapterPreference' is initialized which is needed
        // for logging.
        if (invalidTypeMessage != null) {
            // could be caused by the user specifying wrong
            // provider name or format in the system property
            getLogger(LocaleProviderAdapter.class.getCanonicalName())
                .log(Logger.Level.INFO, invalidTypeMessage);
        }
        if (compatWarningMessage != null) {
            getLogger(LocaleProviderAdapter.class.getCanonicalName())
                .log(Logger.Level.WARNING, compatWarningMessage);
        }
    }

    /**
     * Returns the singleton instance for each adapter type
     */
    public static LocaleProviderAdapter forType(Type type) {
        switch (type) {
        case JRE:
        case CLDR:
        case SPI:
        case HOST:
        case FALLBACK:
            LocaleProviderAdapter adapter = adapterInstances.get(type);
            if (adapter == null) {
                try {
                    // lazily load adapters here
                    adapter = (LocaleProviderAdapter)Class.forName(type.getAdapterClassName())
                            .getDeclaredConstructor().newInstance();
                    LocaleProviderAdapter cached = adapterInstances.putIfAbsent(type, adapter);
                    if (cached != null) {
                        adapter = cached;
                    }
                } catch (NoSuchMethodException |
                         InvocationTargetException |
                         ClassNotFoundException |
                         IllegalAccessException |
                         InstantiationException |
                         UnsupportedOperationException e) {
                    throw new ServiceConfigurationError("Locale provider adapter \"" +
                            type + "\"cannot be instantiated.", e);
                }
            }
            return adapter;
        default:
            throw new InternalError("unknown locale data adapter type");
        }
    }

    public static LocaleProviderAdapter forJRE() {
        return forType(Type.JRE);
    }

    public static LocaleProviderAdapter getResourceBundleBased() {
        for (Type type : getAdapterPreference()) {
            if (type == Type.JRE || type == Type.CLDR || type == Type.FALLBACK) {
                LocaleProviderAdapter adapter = forType(type);
                if (adapter != null) {
                    return adapter;
                }
            }
        }
        // Shouldn't happen.
        throw new InternalError();
    }

    /**
     * Returns the preference order of LocaleProviderAdapter.Type
     */
    public static List<Type> getAdapterPreference() {
        return adapterPreference;
    }

    /**
     * Returns a LocaleProviderAdapter for the given locale service provider that
     * best matches the given locale. This method returns the LocaleProviderAdapter
     * for JRE if none is found for the given locale.
     *
     * @param providerClass the class for the locale service provider
     * @param locale the desired locale.
     * @return a LocaleProviderAdapter
     */
    public static LocaleProviderAdapter getAdapter(Class<? extends LocaleServiceProvider> providerClass,
                                               Locale locale) {
        LocaleProviderAdapter adapter;

        // cache lookup
        ConcurrentMap<Locale, LocaleProviderAdapter> adapterMap = adapterCache.get(providerClass);
        if (adapterMap != null) {
            if ((adapter = adapterMap.get(locale)) != null) {
                return adapter;
            }
        } else {
            adapterMap = new ConcurrentHashMap<>();
            adapterCache.putIfAbsent(providerClass, adapterMap);
        }

        // Fast look-up for the given locale
        adapter = findAdapter(providerClass, locale);
        if (adapter != null) {
            adapterMap.putIfAbsent(locale, adapter);
            return adapter;
        }

        // Try finding an adapter in the normal candidate locales path of the given locale.
        List<Locale> lookupLocales = ResourceBundle.Control.getControl(ResourceBundle.Control.FORMAT_DEFAULT)
                                        .getCandidateLocales("", locale);
        for (Locale loc : lookupLocales) {
            if (loc.equals(locale)) {
                // We've already done with this loc.
                continue;
            }
            adapter = findAdapter(providerClass, loc);
            if (adapter != null) {
                adapterMap.putIfAbsent(locale, adapter);
                return adapter;
            }
        }

        // returns the adapter for FALLBACK as the last resort
        adapterMap.putIfAbsent(locale, forType(Type.FALLBACK));
        return forType(Type.FALLBACK);
    }

    private static LocaleProviderAdapter findAdapter(Class<? extends LocaleServiceProvider> providerClass,
                                                 Locale locale) {
        for (Type type : getAdapterPreference()) {
            LocaleProviderAdapter adapter = forType(type);
            if (adapter != null) {
                LocaleServiceProvider provider = adapter.getLocaleServiceProvider(providerClass);
                if (provider != null) {
                    if (provider.isSupportedLocale(locale)) {
                        return adapter;
                    }
                }
            }
        }
        return null;
    }

    /**
     * A utility method for implementing the default LocaleServiceProvider.isSupportedLocale
     * for the JRE, CLDR, and FALLBACK adapters.
     */
    public boolean isSupportedProviderLocale(Locale locale,  Set<String> langtags) {
        LocaleProviderAdapter.Type type = getAdapterType();
        assert type == Type.JRE || type == Type.CLDR || type == Type.FALLBACK;
        return false;
    }

    public static Locale[] toLocaleArray(Set<String> tags) {
        return tags.stream()
            .map(t -> switch (t) {
                case "ja-JP-JP" -> JRELocaleConstants.JA_JP_JP;
                case "no-NO-NY" -> JRELocaleConstants.NO_NO_NY;
                case "th-TH-TH" -> JRELocaleConstants.TH_TH_TH;
                default -> Locale.forLanguageTag(t);
            })
            .distinct()
            .toArray(Locale[]::new);
    }

    /**
     * Returns the type of this LocaleProviderAdapter
     */
    public abstract LocaleProviderAdapter.Type getAdapterType();

    /**
     * Getter method for Locale Service Providers.
     */
    public abstract <P extends LocaleServiceProvider> P getLocaleServiceProvider(Class<P> c);

    /**
     * Returns a BreakIteratorProvider for this LocaleProviderAdapter, or null if no
     * BreakIteratorProvider is available.
     *
     * @return a BreakIteratorProvider
     */
    public abstract BreakIteratorProvider getBreakIteratorProvider();

    /**
     * Returns a CollatorProvider for this LocaleProviderAdapter, or null if no
     * CollatorProvider is available.
     *
     * @return a collatorProvider
     */
    public abstract CollatorProvider getCollatorProvider();

    /**
     * Returns a DateFormatProvider for this LocaleProviderAdapter, or null if no
     * DateFormatProvider is available.
     *
     * @return a DateFormatProvider
     */
    public abstract DateFormatProvider getDateFormatProvider();

    /**
     * Returns a DateFormatSymbolsProvider for this LocaleProviderAdapter, or null if no
     * DateFormatSymbolsProvider is available.
     *
     * @return a DateFormatSymbolsProvider
     */
    public abstract DateFormatSymbolsProvider getDateFormatSymbolsProvider();

    /**
     * Returns a DecimalFormatSymbolsProvider for this LocaleProviderAdapter, or null if no
     * DecimalFormatSymbolsProvider is available.
     *
     * @return a DecimalFormatSymbolsProvider
     */
    public abstract DecimalFormatSymbolsProvider getDecimalFormatSymbolsProvider();

    /**
     * Returns a NumberFormatProvider for this LocaleProviderAdapter, or null if no
     * NumberFormatProvider is available.
     *
     * @return a NumberFormatProvider
     */
    public abstract NumberFormatProvider getNumberFormatProvider();

    /*
     * Getter methods for java.util.spi.* providers
     */

    /**
     * Returns a CurrencyNameProvider for this LocaleProviderAdapter, or null if no
     * CurrencyNameProvider is available.
     *
     * @return a CurrencyNameProvider
     */
    public abstract CurrencyNameProvider getCurrencyNameProvider();

    /**
     * Returns a LocaleNameProvider for this LocaleProviderAdapter, or null if no
     * LocaleNameProvider is available.
     *
     * @return a LocaleNameProvider
     */
    public abstract LocaleNameProvider getLocaleNameProvider();

    /**
     * Returns a TimeZoneNameProvider for this LocaleProviderAdapter, or null if no
     * TimeZoneNameProvider is available.
     *
     * @return a TimeZoneNameProvider
     */
    public abstract TimeZoneNameProvider getTimeZoneNameProvider();

    /**
     * Returns a CalendarDataProvider for this LocaleProviderAdapter, or null if no
     * CalendarDataProvider is available.
     *
     * @return a CalendarDataProvider
     */
    public abstract CalendarDataProvider getCalendarDataProvider();

    /**
     * Returns a CalendarNameProvider for this LocaleProviderAdapter, or null if no
     * CalendarNameProvider is available.
     *
     * @return a CalendarNameProvider
     */
    public abstract CalendarNameProvider getCalendarNameProvider();

    /**
     * Returns a CalendarProvider for this LocaleProviderAdapter, or null if no
     * CalendarProvider is available.
     *
     * @return a CalendarProvider
     */
    public abstract CalendarProvider getCalendarProvider();

    /**
     * Returns a JavaTimeDateTimePatternProvider for this LocaleProviderAdapter,
     * or null if no JavaTimeDateTimePatternProvider is available.
     *
     * @return a JavaTimeDateTimePatternProvider
     */
    public abstract JavaTimeDateTimePatternProvider getJavaTimeDateTimePatternProvider();

    public abstract LocaleResources getLocaleResources(Locale locale);

    public abstract Locale[] getAvailableLocales();
}