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/*
 * -----------------------------------------------------------------------
 * Copyright © 2013-2016 Meno Hochschild, 
 * -----------------------------------------------------------------------
 * This file (NumberSymbolProvider.java) is part of project Time4J.
 *
 * Time4J is free software: You can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * Time4J 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with Time4J. If not, see .
 * -----------------------------------------------------------------------
 */

package net.time4j.format;

import java.text.DecimalFormatSymbols;
import java.util.Locale;


/**
 * This SPI-interface enables the access to localized
 * number properties like zero digits and is instantiated via a
 * {@code ServiceLoader}-mechanism. 
 *
 * If there is no external {@code NumberSymbolProvider} then Time4J will
 * just delegate to the internal resources or to the JDK. 
 *
 * @author  Meno Hochschild
 * @since   2.1
 * @see     java.util.ServiceLoader
 * @see     java.text.DecimalFormatSymbols#getZeroDigit
 * @doctags.spec    Implementations must have a public no-arg constructor.
 */
/*[deutsch]
 * Dieses SPI-Interface ermöglicht den Zugriff
 * auf {@code Locale}-abhängige Zahleigenschaften wie Nullziffern
 * und wird über einen {@code ServiceLoader}-Mechanismus instanziert. 
 *
 * Wird kein externer {@code NumberSymbolProvider} gefunden, wird intern
 * eine Instanz erzeugt, die an die internen Ressourcen oder das JDK delegiert. 
 *
 * @author  Meno Hochschild
 * @since   2.1
 * @see     java.util.ServiceLoader
 * @see     java.text.DecimalFormatSymbols#getZeroDigit
 * @doctags.spec    Implementations must have a public no-arg constructor.
 */
public interface NumberSymbolProvider {

    //~ Statische Felder/Initialisierungen --------------------------------

    /**
     * Default provider which delegates to standard JVM resources. 
     *
     * @see     DecimalFormatSymbols
     */
    /*[deutsch]
     * Standardimplementierung, die an die Ressourcen der JVM delegiert. 
     *
     * @see     DecimalFormatSymbols
     */
    NumberSymbolProvider DEFAULT =
        new NumberSymbolProvider() {
            @Override
            public Locale[] getAvailableLocales() {
                return DecimalFormatSymbols.getAvailableLocales();
            }

            @Override
            public char getZeroDigit(Locale locale) {
                return getSymbols(locale).getZeroDigit();
            }

            @Override
            public char getDecimalSeparator(Locale locale) {
                return getSymbols(locale).getDecimalSeparator();
            }

            @Override
            public String getPlusSign(Locale locale) {
                if (locale.getLanguage().equals("ar")) {
                    return "\u200F+";
                }
                return String.valueOf('+');
            }

            @Override
            public String getMinusSign(Locale locale) {
                if (locale.getLanguage().equals("ar")) {
                    return "\u200F\u002D";
                }
                return String.valueOf(getSymbols(locale).getMinusSign());
            }

            private DecimalFormatSymbols getSymbols(Locale loc) {
                return DecimalFormatSymbols.getInstance(loc);
            }
        };

    //~ Methoden ----------------------------------------------------------

    /**
     * Yields the supported languages. 
     *
     * @return  Locale-array
     */
    /*[deutsch]
     * Gibt die unterstützten Sprachen an. 
     *
     * @return  Locale-array
     */
    Locale[] getAvailableLocales();

    /**
     * Returns the localized zero digit. 
     *
     * @param   locale      language and country setting
     * @return  zero digit of associated numbering system
     */
    /*[deutsch]
     * Liefert die lokalisierte Nullziffer. 
     *
     * @param   locale      language and country setting
     * @return  zero digit of associated numbering system
     */
    char getZeroDigit(Locale locale);

    /**
     * Returns the localized decimal separator. 
     *
     * @param   locale      language and country setting
     * @return  localized decimal separator
     */
    /*[deutsch]
     * Liefert das lokalisierte Dezimaltrennzeichen. 
     *
     * @param   locale      language and country setting
     * @return  localized decimal separator
     */
    char getDecimalSeparator(Locale locale);

    /**
     * Returns the localized plus sign. 
     *
     * @param   locale      language and country setting
     * @return  localized plus sign, possibly including RLM- or LRM-markers
     * @since   3.13/4.10
     */
    /*[deutsch]
     * Liefert das lokalisierte Plus-Zeichen. 
     *
     * @param   locale      language and country setting
     * @return  localized plus sign, possibly including RLM- or LRM-markers
     * @since   3.13/4.10
     */
    default String getPlusSign(Locale locale) {
        return String.valueOf('+');
    }

    /**
     * Returns the localized minus sign. 
     *
     * @param   locale      language and country setting
     * @return  localized minus sign, possibly including RLM- or LRM-markers
     */
    /*[deutsch]
     * Liefert das lokalisierte Minus-Zeichen. 
     *
     * @param   locale      language and country setting
     * @return  localized minus sign, possibly including RLM- or LRM-markers
     */
    String getMinusSign(Locale locale);

    /**
     * Obtains the standard number system for given locale. 
     *
     * @param   locale      language and country setting
     * @return  default number system
     * @since   3.23/4.19
     */
    /*[deutsch]
     * Ermitelt das Standardzahlsystem für die angegebene Sprache. 
     *
     * @param   locale      language and country setting
     * @return  default number system
     * @since   3.23/4.19
     */
    default NumberSystem getDefaultNumberSystem(Locale locale) {

        return NumberSystem.ARABIC; // worldwide standard

    }

}