jdk/src/share/classes/java/time/temporal/Chrono.java
changeset 15658 55b829ca2334
parent 15657 c588664d547e
child 15659 e575dab44ff5
--- a/jdk/src/share/classes/java/time/temporal/Chrono.java	Tue Feb 12 16:02:14 2013 +0400
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,858 +0,0 @@
-/*
- * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.  Oracle designates this
- * particular file as subject to the "Classpath" exception as provided
- * by Oracle in the LICENSE file that accompanied this code.
- *
- * This code 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
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-/*
- * This file is available under and governed by the GNU General Public
- * License version 2 only, as published by the Free Software Foundation.
- * However, the following notice accompanied the original version of this
- * file:
- *
- * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
- *
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- *  * Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- *
- *  * Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- *
- *  * Neither the name of JSR-310 nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
- * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
- * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-package java.time.temporal;
-
-import java.io.DataInput;
-import java.io.DataOutput;
-import java.io.IOException;
-import java.io.InvalidObjectException;
-import java.io.ObjectStreamException;
-import java.time.Clock;
-import java.time.DateTimeException;
-import java.time.Instant;
-import java.time.LocalDate;
-import java.time.LocalTime;
-import java.time.ZoneId;
-import java.time.calendar.HijrahChrono;
-import java.time.calendar.JapaneseChrono;
-import java.time.calendar.MinguoChrono;
-import java.time.calendar.ThaiBuddhistChrono;
-import java.time.format.DateTimeFormatterBuilder;
-import java.time.format.TextStyle;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Locale;
-import java.util.Objects;
-import java.util.ServiceLoader;
-import java.util.Set;
-import java.util.concurrent.ConcurrentHashMap;
-
-/**
- * A calendar system, used to organize and identify dates.
- * <p>
- * The main date and time API is built on the ISO calendar system.
- * This class operates behind the scenes to represent the general concept of a calendar system.
- * For example, the Japanese, Minguo, Thai Buddhist and others.
- * <p>
- * Most other calendar systems also operate on the shared concepts of year, month and day,
- * linked to the cycles of the Earth around the Sun, and the Moon around the Earth.
- * These shared concepts are defined by {@link ChronoField} and are availalbe
- * for use by any {@code Chrono} implementation:
- * <pre>
- *   LocalDate isoDate = ...
- *   ChronoLocalDate&lt;ThaiBuddhistChrono&gt; thaiDate = ...
- *   int isoYear = isoDate.get(ChronoField.YEAR);
- *   int thaiYear = thaiDate.get(ChronoField.YEAR);
- * </pre>
- * As shown, although the date objects are in different calendar systems, represented by different
- * {@code Chrono} instances, both can be queried using the same constant on {@code ChronoField}.
- * For a full discussion of the implications of this, see {@link ChronoLocalDate}.
- * In general, the advice is to use the known ISO-based {@code LocalDate}, rather than
- * {@code ChronoLocalDate}.
- * <p>
- * While a {@code Chrono} object typically uses {@code ChronoField} and is based on
- * an era, year-of-era, month-of-year, day-of-month model of a date, this is not required.
- * A {@code Chrono} instance may represent a totally different kind of calendar system,
- * such as the Mayan.
- * <p>
- * In practical terms, the {@code Chrono} instance also acts as a factory.
- * The {@link #of(String)} method allows an instance to be looked up by identifier,
- * while the {@link #ofLocale(Locale)} method allows lookup by locale.
- * <p>
- * The {@code Chrono} instance provides a set of methods to create {@code ChronoLocalDate} instances.
- * The date classes are used to manipulate specific dates.
- * <p><ul>
- * <li> {@link #dateNow() dateNow()}
- * <li> {@link #dateNow(Clock) dateNow(clock)}
- * <li> {@link #dateNow(ZoneId) dateNow(zone)}
- * <li> {@link #date(int, int, int) date(yearProleptic, month, day)}
- * <li> {@link #date(Era, int, int, int) date(era, yearOfEra, month, day)}
- * <li> {@link #dateYearDay(int, int) dateYearDay(yearProleptic, dayOfYear)}
- * <li> {@link #dateYearDay(Era, int, int) dateYearDay(era, yearOfEra, dayOfYear)}
- * <li> {@link #date(TemporalAccessor) date(TemporalAccessor)}
- * </ul><p>
- *
- * <p id="addcalendars">Adding New Calendars</p>
- * The set of available chronologies can be extended by applications.
- * Adding a new calendar system requires the writing of an implementation of
- * {@code Chrono}, {@code ChronoLocalDate} and {@code Era}.
- * The majority of the logic specific to the calendar system will be in
- * {@code ChronoLocalDate}. The {@code Chrono} subclass acts as a factory.
- * <p>
- * To permit the discovery of additional chronologies, the {@link java.util.ServiceLoader ServiceLoader}
- * is used. A file must be added to the {@code META-INF/services} directory with the
- * name 'java.time.temporal.Chrono' listing the implementation classes.
- * See the ServiceLoader for more details on service loading.
- * For lookup by id or calendarType, the system provided calendars are found
- * first followed by application provided calendars.
- * <p>
- * Each chronology must define a chronology ID that is unique within the system.
- * If the chronology represents a calendar system defined by the
- * <em>Unicode Locale Data Markup Language (LDML)</em> specification then that
- * calendar type should also be specified.
- *
- * <h3>Specification for implementors</h3>
- * This class must be implemented with care to ensure other classes operate correctly.
- * All implementations that can be instantiated must be final, immutable and thread-safe.
- * Subclasses should be Serializable wherever possible.
- *
- * @param <C> the type of the implementing subclass
- * @since 1.8
- */
-public abstract class Chrono<C extends Chrono<C>> implements Comparable<Chrono<?>> {
-
-    /**
-     * Map of available calendars by ID.
-     */
-    private static final ConcurrentHashMap<String, Chrono<?>> CHRONOS_BY_ID = new ConcurrentHashMap<>();
-    /**
-     * Map of available calendars by calendar type.
-     */
-    private static final ConcurrentHashMap<String, Chrono<?>> CHRONOS_BY_TYPE = new ConcurrentHashMap<>();
-
-    /**
-     * Register a Chrono by ID and type for lookup by {@link #of(java.lang.String)}.
-     * Chronos must not be registered until they are completely constructed.
-     * Specifically, not in the constructor of Chrono.
-     * @param chrono the chronology to register; not null
-     */
-    private static void registerChrono(Chrono chrono) {
-        Chrono<?> prev = CHRONOS_BY_ID.putIfAbsent(chrono.getId(), chrono);
-        if (prev == null) {
-            String type = chrono.getCalendarType();
-            if (type != null) {
-                CHRONOS_BY_TYPE.putIfAbsent(type, chrono);
-            }
-        }
-    }
-
-    /**
-     * Initialization of the maps from id and type to Chrono.
-     * The ServiceLoader is used to find and register any implementations
-     * of {@link javax.time.temporal.Chrono} found in the bootclass loader.
-     * The built-in chronologies are registered explicitly.
-     * Calendars configured via the Thread's context classloader are local
-     * to that thread and are ignored.
-     * <p>
-     * The initialization is done only once using the registration
-     * of the ISOChrono as the test and the final step.
-     * Multiple threads may perform the initialization concurrently.
-     * Only the first registration of each Chrono is retained by the
-     * ConcurrentHashMap.
-     * @return true if the cache was initialized
-     */
-    private static boolean initCache() {
-        if (CHRONOS_BY_ID.get("ISO") == null) {
-            // Initialization is incomplete
-            @SuppressWarnings("rawtypes")
-            ServiceLoader<Chrono> loader =  ServiceLoader.load(Chrono.class, null);
-            for (Chrono<?> chrono : loader) {
-                registerChrono(chrono);
-            }
-
-            // Register these calendars; the ServiceLoader configuration is not used
-            registerChrono(HijrahChrono.INSTANCE);
-            registerChrono(JapaneseChrono.INSTANCE);
-            registerChrono(MinguoChrono.INSTANCE);
-            registerChrono(ThaiBuddhistChrono.INSTANCE);
-
-            // finally, register ISOChrono to mark initialization is complete
-            registerChrono(ISOChrono.INSTANCE);
-            return true;
-        }
-        return false;
-    }
-
-    //-----------------------------------------------------------------------
-    /**
-     * Obtains an instance of {@code Chrono} from a temporal object.
-     * <p>
-     * A {@code TemporalAccessor} represents some form of date and time information.
-     * This factory converts the arbitrary temporal object to an instance of {@code Chrono}.
-     * If the specified temporal object does not have a chronology, {@link ISOChrono} is returned.
-     * <p>
-     * The conversion will obtain the chronology using {@link Queries#chrono()}.
-     * <p>
-     * This method matches the signature of the functional interface {@link TemporalQuery}
-     * allowing it to be used in queries via method reference, {@code Chrono::from}.
-     *
-     * @param temporal  the temporal to convert, not null
-     * @return the chronology, not null
-     * @throws DateTimeException if unable to convert to an {@code Chrono}
-     */
-    public static Chrono<?> from(TemporalAccessor temporal) {
-        Objects.requireNonNull(temporal, "temporal");
-        Chrono<?> obj = temporal.query(Queries.chrono());
-        return (obj != null ? obj : ISOChrono.INSTANCE);
-    }
-
-    //-----------------------------------------------------------------------
-    /**
-     * Obtains an instance of {@code Chrono} from a locale.
-     * <p>
-     * The locale can be used to identify a calendar.
-     * This uses {@link Locale#getUnicodeLocaleType(String)} to obtain the "ca" key
-     * to identify the calendar system.
-     * <p>
-     * If the locale does not contain calendar system information, the standard
-     * ISO calendar system is used.
-     *
-     * @param locale  the locale to use to obtain the calendar system, not null
-     * @return the calendar system associated with the locale, not null
-     * @throws DateTimeException if the locale-specified calendar cannot be found
-     */
-    public static Chrono<?> ofLocale(Locale locale) {
-        Objects.requireNonNull(locale, "locale");
-        String type = locale.getUnicodeLocaleType("ca");
-        if (type == null) {
-            return ISOChrono.INSTANCE;
-        } else if ("iso".equals(type) || "iso8601".equals(type)) {
-            return ISOChrono.INSTANCE;
-        } else {
-            Chrono<?> chrono = CHRONOS_BY_TYPE.get(type);
-            if (chrono == null) {
-                throw new DateTimeException("Unknown calendar system: " + type);
-            }
-            return chrono;
-        }
-    }
-
-    //-----------------------------------------------------------------------
-    /**
-     * Obtains an instance of {@code Chrono} from a chronology ID or
-     * calendar system type.
-     * <p>
-     * This returns a chronology based on either the ID or the type.
-     * The {@link #getId() chronology ID} uniquely identifies the chronology.
-     * The {@link #getCalendarType() calendar system type} is defined by the LDML specification.
-     * <p>
-     * The chronology may be a system chronology or a chronology
-     * provided by the application via ServiceLoader configuration.
-     * <p>
-     * Since some calendars can be customized, the ID or type typically refers
-     * to the default customization. For example, the Gregorian calendar can have multiple
-     * cutover dates from the Julian, but the lookup only provides the default cutover date.
-     *
-     * @param id  the chronology ID or calendar system type, not null
-     * @return the chronology with the identifier requested, not null
-     * @throws DateTimeException if the chronology cannot be found
-     */
-    public static Chrono<?> of(String id) {
-        Objects.requireNonNull(id, "id");
-        do {
-            Chrono chrono = of0(id);
-            if (chrono != null) {
-                return chrono;
-            }
-            // If not found, do the initialization (once) and repeat the lookup
-        } while (initCache());
-
-        // Look for a Chrono using ServiceLoader of the Thread's ContextClassLoader
-        // Application provided Chronologies must not be cached
-        @SuppressWarnings("rawtypes")
-        ServiceLoader<Chrono> loader = ServiceLoader.load(Chrono.class);
-        for (Chrono<?> chrono : loader) {
-            if (id.equals(chrono.getId()) || id.equals(chrono.getCalendarType())) {
-                return chrono;
-            }
-        }
-        throw new DateTimeException("Unknown chronology: " + id);
-    }
-
-    /**
-     * Obtains an instance of {@code Chrono} from a chronology ID or
-     * calendar system type.
-     *
-     * @param id  the chronology ID or calendar system type, not null
-     * @return the chronology with the identifier requested, or {@code null} if not found
-     */
-    private static Chrono<?> of0(String id) {
-        Chrono<?> chrono = CHRONOS_BY_ID.get(id);
-        if (chrono == null) {
-            chrono = CHRONOS_BY_TYPE.get(id);
-        }
-        return chrono;
-    }
-
-    /**
-     * Returns the available chronologies.
-     * <p>
-     * Each returned {@code Chrono} is available for use in the system.
-     * The set of chronologies includes the system chronologies and
-     * any chronologies provided by the application via ServiceLoader
-     * configuration.
-     *
-     * @return the independent, modifiable set of the available chronology IDs, not null
-     */
-    public static Set<Chrono<?>> getAvailableChronologies() {
-        initCache();       // force initialization
-        HashSet<Chrono<?>> chronos = new HashSet<>(CHRONOS_BY_ID.values());
-
-        /// Add in Chronologies from the ServiceLoader configuration
-        @SuppressWarnings("rawtypes")
-        ServiceLoader<Chrono> loader = ServiceLoader.load(Chrono.class);
-        for (Chrono<?> chrono : loader) {
-            chronos.add(chrono);
-        }
-        return chronos;
-    }
-
-    //-----------------------------------------------------------------------
-    /**
-     * Obtains a local date-time from the a date and time.
-     * <p>
-     * This combines a {@link ChronoLocalDate}, which provides the {@code Chrono},
-     * with a {@link LocalTime} to produce a {@link ChronoLocalDateTime}.
-     * <p>
-     * This method is intended for chronology implementations.
-     * It uses a standard implementation that is shared for all chronologies.
-     *
-     * @param <R>  the chronology of the date
-     * @param date  the date, not null
-     * @param time  the time, not null
-     * @return the local date-time combining the input date and time, not null
-     */
-    public static <R extends Chrono<R>> ChronoLocalDateTime<R> dateTime(ChronoLocalDate<R> date, LocalTime time) {
-        return ChronoLocalDateTimeImpl.of(date, time);
-    }
-
-    //-----------------------------------------------------------------------
-    /**
-     * Creates an instance.
-     */
-    protected Chrono() {
-    }
-
-    //-----------------------------------------------------------------------
-    /**
-     * Casts the {@code Temporal} to {@code ChronoLocalDate} with the same chronology.
-     *
-     * @param temporal  a date-time to cast, not null
-     * @return the date-time checked and cast to {@code ChronoLocalDate}, not null
-     * @throws ClassCastException if the date-time cannot be cast to ChronoLocalDate
-     *  or the chronology is not equal this Chrono
-     */
-    ChronoLocalDate<C> ensureChronoLocalDate(Temporal temporal) {
-        @SuppressWarnings("unchecked")
-        ChronoLocalDate<C> other = (ChronoLocalDate<C>) temporal;
-        if (this.equals(other.getChrono()) == false) {
-            throw new ClassCastException("Chrono mismatch, expected: " + getId() + ", actual: " + other.getChrono().getId());
-        }
-        return other;
-    }
-
-    /**
-     * Casts the {@code Temporal} to {@code ChronoLocalDateTime} with the same chronology.
-     *
-     * @param temporal   a date-time to cast, not null
-     * @return the date-time checked and cast to {@code ChronoLocalDateTime}, not null
-     * @throws ClassCastException if the date-time cannot be cast to ChronoLocalDateTimeImpl
-     *  or the chronology is not equal this Chrono
-     */
-    ChronoLocalDateTimeImpl<C> ensureChronoLocalDateTime(Temporal temporal) {
-        @SuppressWarnings("unchecked")
-        ChronoLocalDateTimeImpl<C> other = (ChronoLocalDateTimeImpl<C>) temporal;
-        if (this.equals(other.getDate().getChrono()) == false) {
-            throw new ClassCastException("Chrono mismatch, required: " + getId()
-                    + ", supplied: " + other.getDate().getChrono().getId());
-        }
-        return other;
-    }
-
-    /**
-     * Casts the {@code Temporal} to {@code ChronoZonedDateTimeImpl} with the same chronology.
-     *
-     * @param temporal  a date-time to cast, not null
-     * @return the date-time checked and cast to {@code ChronoZonedDateTimeImpl}, not null
-     * @throws ClassCastException if the date-time cannot be cast to ChronoZonedDateTimeImpl
-     *  or the chronology is not equal this Chrono
-     */
-    ChronoZonedDateTimeImpl<C> ensureChronoZonedDateTime(Temporal temporal) {
-        @SuppressWarnings("unchecked")
-        ChronoZonedDateTimeImpl<C> other = (ChronoZonedDateTimeImpl<C>) temporal;
-        if (this.equals(other.getDate().getChrono()) == false) {
-            throw new ClassCastException("Chrono mismatch, required: " + getId()
-                    + ", supplied: " + other.getDate().getChrono().getId());
-        }
-        return other;
-    }
-
-    //-----------------------------------------------------------------------
-    /**
-     * Gets the ID of the chronology.
-     * <p>
-     * The ID uniquely identifies the {@code Chrono}.
-     * It can be used to lookup the {@code Chrono} using {@link #of(String)}.
-     *
-     * @return the chronology ID, not null
-     * @see #getCalendarType()
-     */
-    public abstract String getId();
-
-    /**
-     * Gets the calendar type of the underlying calendar system.
-     * <p>
-     * The calendar type is an identifier defined by the
-     * <em>Unicode Locale Data Markup Language (LDML)</em> specification.
-     * It can be used to lookup the {@code Chrono} using {@link #of(String)}.
-     * It can also be used as part of a locale, accessible via
-     * {@link Locale#getUnicodeLocaleType(String)} with the key 'ca'.
-     *
-     * @return the calendar system type, null if the calendar is not defined by LDML
-     * @see #getId()
-     */
-    public abstract String getCalendarType();
-
-    //-----------------------------------------------------------------------
-    /**
-     * Obtains a local date in this chronology from the era, year-of-era,
-     * month-of-year and day-of-month fields.
-     *
-     * @param era  the era of the correct type for the chronology, not null
-     * @param yearOfEra  the chronology year-of-era
-     * @param month  the chronology month-of-year
-     * @param dayOfMonth  the chronology day-of-month
-     * @return the local date in this chronology, not null
-     * @throws DateTimeException if unable to create the date
-     */
-    public ChronoLocalDate<C> date(Era<C> era, int yearOfEra, int month, int dayOfMonth) {
-        return date(prolepticYear(era, yearOfEra), month, dayOfMonth);
-    }
-
-    /**
-     * Obtains a local date in this chronology from the proleptic-year,
-     * month-of-year and day-of-month fields.
-     *
-     * @param prolepticYear  the chronology proleptic-year
-     * @param month  the chronology month-of-year
-     * @param dayOfMonth  the chronology day-of-month
-     * @return the local date in this chronology, not null
-     * @throws DateTimeException if unable to create the date
-     */
-    public abstract ChronoLocalDate<C> date(int prolepticYear, int month, int dayOfMonth);
-
-    /**
-     * Obtains a local date in this chronology from the era, year-of-era and
-     * day-of-year fields.
-     *
-     * @param era  the era of the correct type for the chronology, not null
-     * @param yearOfEra  the chronology year-of-era
-     * @param dayOfYear  the chronology day-of-year
-     * @return the local date in this chronology, not null
-     * @throws DateTimeException if unable to create the date
-     */
-    public ChronoLocalDate<C> dateYearDay(Era<C> era, int yearOfEra, int dayOfYear) {
-        return dateYearDay(prolepticYear(era, yearOfEra), dayOfYear);
-    }
-
-    /**
-     * Obtains a local date in this chronology from the proleptic-year and
-     * day-of-year fields.
-     *
-     * @param prolepticYear  the chronology proleptic-year
-     * @param dayOfYear  the chronology day-of-year
-     * @return the local date in this chronology, not null
-     * @throws DateTimeException if unable to create the date
-     */
-    public abstract ChronoLocalDate<C> dateYearDay(int prolepticYear, int dayOfYear);
-
-    /**
-     * Obtains a local date in this chronology from another temporal object.
-     * <p>
-     * This creates a date in this chronology based on the specified {@code TemporalAccessor}.
-     * <p>
-     * The standard mechanism for conversion between date types is the
-     * {@link ChronoField#EPOCH_DAY local epoch-day} field.
-     *
-     * @param temporal  the temporal object to convert, not null
-     * @return the local date in this chronology, not null
-     * @throws DateTimeException if unable to create the date
-     */
-    public abstract ChronoLocalDate<C> date(TemporalAccessor temporal);
-
-    //-----------------------------------------------------------------------
-    /**
-     * Obtains the current local date in this chronology from the system clock in the default time-zone.
-     * <p>
-     * This will query the {@link Clock#systemDefaultZone() system clock} in the default
-     * time-zone to obtain the current date.
-     * <p>
-     * Using this method will prevent the ability to use an alternate clock for testing
-     * because the clock is hard-coded.
-     * <p>
-     * This implementation uses {@link #dateNow(Clock)}.
-     *
-     * @return the current local date using the system clock and default time-zone, not null
-     * @throws DateTimeException if unable to create the date
-     */
-    public ChronoLocalDate<C> dateNow() {
-        return dateNow(Clock.systemDefaultZone());
-    }
-
-    /**
-     * Obtains the current local date in this chronology from the system clock in the specified time-zone.
-     * <p>
-     * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current date.
-     * Specifying the time-zone avoids dependence on the default time-zone.
-     * <p>
-     * Using this method will prevent the ability to use an alternate clock for testing
-     * because the clock is hard-coded.
-     *
-     * @param zone  the zone ID to use, not null
-     * @return the current local date using the system clock, not null
-     * @throws DateTimeException if unable to create the date
-     */
-    public ChronoLocalDate<C> dateNow(ZoneId zone) {
-        return dateNow(Clock.system(zone));
-    }
-
-    /**
-     * Obtains the current local date in this chronology from the specified clock.
-     * <p>
-     * This will query the specified clock to obtain the current date - today.
-     * Using this method allows the use of an alternate clock for testing.
-     * The alternate clock may be introduced using {@link Clock dependency injection}.
-     *
-     * @param clock  the clock to use, not null
-     * @return the current local date, not null
-     * @throws DateTimeException if unable to create the date
-     */
-    public ChronoLocalDate<C> dateNow(Clock clock) {
-        Objects.requireNonNull(clock, "clock");
-        return date(LocalDate.now(clock));
-    }
-
-    //-----------------------------------------------------------------------
-    /**
-     * Obtains a local date-time in this chronology from another temporal object.
-     * <p>
-     * This creates a date-time in this chronology based on the specified {@code TemporalAccessor}.
-     * <p>
-     * The date of the date-time should be equivalent to that obtained by calling
-     * {@link #date(TemporalAccessor)}.
-     * The standard mechanism for conversion between time types is the
-     * {@link ChronoField#NANO_OF_DAY nano-of-day} field.
-     *
-     * @param temporal  the temporal object to convert, not null
-     * @return the local date-time in this chronology, not null
-     * @throws DateTimeException if unable to create the date-time
-     */
-    public ChronoLocalDateTime<C> localDateTime(TemporalAccessor temporal) {
-        try {
-            return date(temporal).atTime(LocalTime.from(temporal));
-        } catch (DateTimeException ex) {
-            throw new DateTimeException("Unable to obtain ChronoLocalDateTime from TemporalAccessor: " + temporal.getClass(), ex);
-        }
-    }
-
-    /**
-     * Obtains a zoned date-time in this chronology from another temporal object.
-     * <p>
-     * This creates a date-time in this chronology based on the specified {@code TemporalAccessor}.
-     * <p>
-     * This should obtain a {@code ZoneId} using {@link ZoneId#from(TemporalAccessor)}.
-     * The date-time should be obtained by obtaining an {@code Instant}.
-     * If that fails, the local date-time should be used.
-     *
-     * @param temporal  the temporal object to convert, not null
-     * @return the zoned date-time in this chronology, not null
-     * @throws DateTimeException if unable to create the date-time
-     */
-    public ChronoZonedDateTime<C> zonedDateTime(TemporalAccessor temporal) {
-        try {
-            ZoneId zone = ZoneId.from(temporal);
-            try {
-                Instant instant = Instant.from(temporal);
-                return zonedDateTime(instant, zone);
-
-            } catch (DateTimeException ex1) {
-                ChronoLocalDateTimeImpl<C> cldt = ensureChronoLocalDateTime(localDateTime(temporal));
-                return ChronoZonedDateTimeImpl.ofBest(cldt, zone, null);
-            }
-        } catch (DateTimeException ex) {
-            throw new DateTimeException("Unable to obtain ChronoZonedDateTime from TemporalAccessor: " + temporal.getClass(), ex);
-        }
-    }
-
-    /**
-     * Obtains a zoned date-time in this chronology from an {@code Instant}.
-     * <p>
-     * This creates a zoned date-time with the same instant as that specified.
-     *
-     * @param instant  the instant to create the date-time from, not null
-     * @param zone  the time-zone, not null
-     * @return the zoned date-time, not null
-     * @throws DateTimeException if the result exceeds the supported range
-     */
-    public ChronoZonedDateTime<C> zonedDateTime(Instant instant, ZoneId zone) {
-        return ChronoZonedDateTimeImpl.ofInstant(this, instant, zone);
-    }
-
-    //-----------------------------------------------------------------------
-    /**
-     * Checks if the specified year is a leap year.
-     * <p>
-     * A leap-year is a year of a longer length than normal.
-     * The exact meaning is determined by the chronology according to the following constraints.
-     * <p><ul>
-     * <li>a leap-year must imply a year-length longer than a non leap-year.
-     * <li>a chronology that does not support the concept of a year must return false.
-     * </ul><p>
-     *
-     * @param prolepticYear  the proleptic-year to check, not validated for range
-     * @return true if the year is a leap year
-     */
-    public abstract boolean isLeapYear(long prolepticYear);
-
-    /**
-     * Calculates the proleptic-year given the era and year-of-era.
-     * <p>
-     * This combines the era and year-of-era into the single proleptic-year field.
-     *
-     * @param era  the era of the correct type for the chronology, not null
-     * @param yearOfEra  the chronology year-of-era
-     * @return the proleptic-year
-     * @throws DateTimeException if unable to convert
-     */
-    public abstract int prolepticYear(Era<C> era, int yearOfEra);
-
-    /**
-     * Creates the chronology era object from the numeric value.
-     * <p>
-     * The era is, conceptually, the largest division of the time-line.
-     * Most calendar systems have a single epoch dividing the time-line into two eras.
-     * However, some have multiple eras, such as one for the reign of each leader.
-     * The exact meaning is determined by the chronology according to the following constraints.
-     * <p>
-     * The era in use at 1970-01-01 must have the value 1.
-     * Later eras must have sequentially higher values.
-     * Earlier eras must have sequentially lower values.
-     * Each chronology must refer to an enum or similar singleton to provide the era values.
-     * <p>
-     * This method returns the singleton era of the correct type for the specified era value.
-     *
-     * @param eraValue  the era value
-     * @return the calendar system era, not null
-     * @throws DateTimeException if unable to create the era
-     */
-    public abstract Era<C> eraOf(int eraValue);
-
-    /**
-     * Gets the list of eras for the chronology.
-     * <p>
-     * Most calendar systems have an era, within which the year has meaning.
-     * If the calendar system does not support the concept of eras, an empty
-     * list must be returned.
-     *
-     * @return the list of eras for the chronology, may be immutable, not null
-     */
-    public abstract List<Era<C>> eras();
-
-    //-----------------------------------------------------------------------
-    /**
-     * Gets the range of valid values for the specified field.
-     * <p>
-     * All fields can be expressed as a {@code long} integer.
-     * This method returns an object that describes the valid range for that value.
-     * <p>
-     * Note that the result only describes the minimum and maximum valid values
-     * and it is important not to read too much into them. For example, there
-     * could be values within the range that are invalid for the field.
-     * <p>
-     * This method will return a result whether or not the chronology supports the field.
-     *
-     * @param field  the field to get the range for, not null
-     * @return the range of valid values for the field, not null
-     * @throws DateTimeException if the range for the field cannot be obtained
-     */
-    public abstract ValueRange range(ChronoField field);
-
-    //-----------------------------------------------------------------------
-    /**
-     * Gets the textual representation of this chronology.
-     * <p>
-     * This returns the textual name used to identify the chronology.
-     * The parameters control the style of the returned text and the locale.
-     *
-     * @param style  the style of the text required, not null
-     * @param locale  the locale to use, not null
-     * @return the text value of the chronology, not null
-     */
-    public String getText(TextStyle style, Locale locale) {
-        return new DateTimeFormatterBuilder().appendChronoText(style).toFormatter(locale).print(new TemporalAccessor() {
-            @Override
-            public boolean isSupported(TemporalField field) {
-                return false;
-            }
-            @Override
-            public long getLong(TemporalField field) {
-                throw new DateTimeException("Unsupported field: " + field);
-            }
-            @SuppressWarnings("unchecked")
-            @Override
-            public <R> R query(TemporalQuery<R> query) {
-                if (query == Queries.chrono()) {
-                    return (R) Chrono.this;
-                }
-                return TemporalAccessor.super.query(query);
-            }
-        });
-    }
-
-    //-----------------------------------------------------------------------
-    /**
-     * Compares this chronology to another chronology.
-     * <p>
-     * The comparison order first by the chronology ID string, then by any
-     * additional information specific to the subclass.
-     * It is "consistent with equals", as defined by {@link Comparable}.
-     * <p>
-     * The default implementation compares the chronology ID.
-     * Subclasses must compare any additional state that they store.
-     *
-     * @param other  the other chronology to compare to, not null
-     * @return the comparator value, negative if less, positive if greater
-     */
-    @Override
-    public int compareTo(Chrono<?> other) {
-        return getId().compareTo(other.getId());
-    }
-
-    /**
-     * Checks if this chronology is equal to another chronology.
-     * <p>
-     * The comparison is based on the entire state of the object.
-     * <p>
-     * The default implementation checks the type and calls {@link #compareTo(Chrono)}.
-     *
-     * @param obj  the object to check, null returns false
-     * @return true if this is equal to the other chronology
-     */
-    @Override
-    public boolean equals(Object obj) {
-        if (this == obj) {
-           return true;
-        }
-        if (obj instanceof Chrono) {
-            return compareTo((Chrono<?>) obj) == 0;
-        }
-        return false;
-    }
-
-    /**
-     * A hash code for this chronology.
-     * <p>
-     * The default implementation is based on the ID and class.
-     * Subclasses should add any additional state that they store.
-     *
-     * @return a suitable hash code
-     */
-    @Override
-    public int hashCode() {
-        return getClass().hashCode() ^ getId().hashCode();
-    }
-
-    //-----------------------------------------------------------------------
-    /**
-     * Outputs this chronology as a {@code String}, using the ID.
-     *
-     * @return a string representation of this chronology, not null
-     */
-    @Override
-    public String toString() {
-        return getId();
-    }
-
-    //-----------------------------------------------------------------------
-    /**
-     * Writes the object using a
-     * <a href="../../../serialized-form.html#java.time.temporal.Ser">dedicated serialized form</a>.
-     * <pre>
-     *  out.writeByte(7);  // identifies this as a Chrono
-     * out.writeUTF(chronoId);
-     * </pre>
-     *
-     * @return the instance of {@code Ser}, not null
-     */
-    private Object writeReplace() {
-        return new Ser(Ser.CHRONO_TYPE, this);
-    }
-
-    /**
-     * Defend against malicious streams.
-     * @return never
-     * @throws InvalidObjectException always
-     */
-    private Object readResolve() throws ObjectStreamException {
-        throw new InvalidObjectException("Deserialization via serialization delegate");
-    }
-
-    void writeExternal(DataOutput out) throws IOException {
-        out.writeUTF(getId());
-    }
-
-    static Chrono<?> readExternal(DataInput in) throws IOException {
-        String id = in.readUTF();
-        return Chrono.of(id);
-    }
-
-}