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/* LocaleHelper.java -- helper routines for localization

   Copyright (C) 2004, 2005 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2, or (at your option)

any later version.

GNU Classpath is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License

along with GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301 USA.

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

conditions of the GNU General Public License cover the whole

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version. */

package gnu.java.locale;

import java.text.Collator;

import java.util.Locale;

/**

 * This class provides common helper methods

 * for handling localized data.

 *

 * @author Andrew John Hughes (gnu_andrew@member.fsf.org)

 *

 * @see java.util.Locale

 * @see java.util.ResourceBundle

 */

public class LocaleHelper

{

  /**

   * <p>

   * This method is used by the localized name lookup methods to

   * retrieve the next locale to try.  The next locale is derived

   * from the supplied locale by applying the first applicable

   * rule from the following:

   * </p>

   * <ol>

   * <li>If the variant contains a <code>'_'</code>, then

   * this and everything following it is trimmed.</li>

   * <li>If the variant is non-empty, it is converted to

   * an empty string.</li>

   * <li>If the country is non-empty, it is converted to

   * an empty string.</li>

   * <li>If the language is non-empty, it is converted to

   * an empty string (forming {@link java.util.Locale#ROOT})</li>

   * </ol>

   * <p>

   * The base fallback locale is {@link java.util.Locale#ROOT}.

   * </p>

   *

   * @param locale the locale for which a localized piece of

   *               data could not be obtained.

   * @return the next fallback locale to try.

   */

  public static Locale getFallbackLocale(Locale locale)

  {

    String language = locale.getLanguage();

    String country = locale.getCountry();

    String variant = locale.getVariant();

    int uscore = variant.indexOf('_');

    if (uscore != -1)

      return new Locale(language, country,

                        variant.substring(0, uscore));

    if (!variant.isEmpty())

      return new Locale(language, country, "");

    if (!country.isEmpty())

      return new Locale(language, "", "");

    return Locale.ROOT;

  }

  /**

   * Return an array of all the locales for which there is a

   * {@link Collator} instance.  A new array is returned each time.

   */

  public static Locale[] getCollatorLocales()

  {

    // For now we don't bother caching.  This is probably

    // not called very frequently.  And, we would have to

    // clone the array anyway.

    if (LocaleData.collatorLocaleNames.length == 0)

      return new Locale[] { Locale.US };

    Locale[] result = new Locale[LocaleData.collatorLocaleNames.length];

    for (int i = 0; i < result.length; ++i)

      {

        String language;

        String region = "";

        String variant = "";

        String name = LocaleData.collatorLocaleNames[i];

        language = name.substring(0, 2);

        if (name.length() > 2)

          region = name.substring(3);

        int index = region.indexOf("_");

        if (index > 0)

          {

            variant = region.substring(index + 1);

            region = region.substring(0, index - 1);

          }

        result[i] = new Locale(language, region, variant);

      }

    return result;

  }

  /**

   * Return the number of locales we know of.

   */

  public static int getLocaleCount()

  {

    return LocaleData.localeNames.length;

  }

  /**

   * Return the Nth locale name.

   */

  public static String getLocaleName(int n)

  {

    return LocaleData.localeNames[n];

  }

}