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/*
 * -----------------------------------------------------------------------
 * Copyright © 2013-2014 Meno Hochschild, 
 * -----------------------------------------------------------------------
 * This file (LeapSecondProvider.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.scale;

import net.time4j.base.GregorianDate;

import java.util.Map;


/**
 * This SPI-interface describes when
 * UTC-leapseconds were introduced. 
 *
 * Will be evaluated during loading of the class {@code LeapSeconds}.
 * If any implementation defines no leapseconds then Time4J assumes
 * that leapseconds will generally not be active, effectively resulting
 * in POSIX-time instead of UTC. 
 *
 * @author  Meno Hochschild
 * @doctags.spec    All implementations must have a public no-arg constructor.
 * @since   2.3
 */
/*[deutsch]
 * Dieses SPI-Interface beschreibt, wann
 * UTC-Schaltsekunden eingeführt worden sind. 
 *
 * Wird beim Laden der Klasse {@code LeapSeconds} ausgewertet. Wenn
 * eine Implementierung zum Beispiel per eigener Konfiguration keine
 * Schaltsekunden definiert, so wird angenommen, daß generell
 * keine Schaltsekunden verwendet werden sollen, also die POSIX-Zeit
 * statt UTC. 
 *
 * @author  Meno Hochschild
 * @doctags.spec    All implementations must have a public no-arg constructor.
 * @since   2.3
 */
public interface LeapSecondProvider {

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

    /**
     * Yields all UTC-leapseconds with date and sign. 
     *
     * The switch-over day in the UTC-timezone is considered as
     * map key. The associated value is denotes the sign of the
     * leapsecond. Is the value {@code +1} then it is a positive
     * leapsecond. Is the value {@code -1} then it is a negative
     * leapsecond. Other values are not supported. 
     *
     * @return  map from leap second event day to sign of leap second
     * @since   2.0
     */
    /*[deutsch]
     * Liefert alle UTC-Schaltsekunden mit Datum und Vorzeichen. 
     *
     * Als Schlüssel wird der Umstellungstag in der UTC-Zeitzone
     * genommen. Der zugeordnete Wert bezeichnet das Vorzeichen der
     * Schaltsekunde. Ist der Wert {@code +1}, dann handelt es sich um
     * eine positive Schaltsekunde. Ist der Wert {@code -1}, dann wird
     * eine negative Schaltsekunde angenommen. Andere Werte werden nicht
     * unterstützt. 
     *
     * @return  map from leap second event day to sign of leap second
     * @since   2.0
     */
    Map getLeapSecondTable();

    /**
     * Queries if negative leapseconds are supported. 
     *
     * Until now there has never been any negative leapseconds.
     * As long as this is the case a {@code Provider} is allowed to
     * return {@code false} in order to improve the performance. 
     *
     * @return  {@code true} if supported else {@code false}
     * @since   2.0
     */
    /*[deutsch]
     * Werden auch negative Schaltsekunden unterstützt? 
     *
     * Bis jetzt hat es real noch nie negative Schaltsekunden gegeben.
     * Solange das der Fall ist, darf ein {@code Provider} aus
     * Gründen der besseren Performance hier {@code false}
     * zurückgeben. 
     *
     * @return  {@code true} if supported else {@code false}
     * @since   2.0
     */
    boolean supportsNegativeLS();

    /**
     * Creates the date of a leap second event. 
     *
     * @param   year        proleptic gregorian year >= 1972
     * @param   month       gregorian month
     * @param   dayOfMonth  day of leap second switch
     * @return  immutable date of leap second event
     * @since   2.3
     */
    /*[deutsch]
     * Erzeugt das Datum eines Schaltsekundenereignisses. 
     *
     * @param   year        proleptic gregorian year >= 1972
     * @param   month       gregorian month
     * @param   dayOfMonth  day of leap second switch
     * @return  immutable date of leap second event
     * @since   2.3
     */
    GregorianDate getDateOfEvent(
        int year,
        int month,
        int dayOfMonth
    );

    /**
     * Determines the expiration date of underlying data. 
     *
     * @return  immutable date of expiration
     * @since   2.3
     */
    /*[deutsch]
     * Bestimmt das Verfallsdatum der zugrundeliegenden Daten. 
     *
     * @return  immutable date of expiration
     * @since   2.3
     */
    GregorianDate getDateOfExpiration();

}