bp/chrono/Chronology.java

/*
 * Copyright (c) 2007-present, 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,
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package org.threeten.bp.chrono;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectStreamException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.ServiceLoader;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

import org.threeten.bp.Clock;
import org.threeten.bp.DateTimeException;
import org.threeten.bp.Instant;
import org.threeten.bp.LocalDate;
import org.threeten.bp.LocalTime;
import org.threeten.bp.ZoneId;
import org.threeten.bp.format.DateTimeFormatterBuilder;
import org.threeten.bp.format.ResolverStyle;
import org.threeten.bp.format.TextStyle;
import org.threeten.bp.jdk8.DefaultInterfaceTemporalAccessor;
import org.threeten.bp.jdk8.Jdk8Methods;
import org.threeten.bp.temporal.ChronoField;
import org.threeten.bp.temporal.Temporal;
import org.threeten.bp.temporal.TemporalAccessor;
import org.threeten.bp.temporal.TemporalField;
import org.threeten.bp.temporal.TemporalQueries;
import org.threeten.bp.temporal.TemporalQuery;
import org.threeten.bp.temporal.UnsupportedTemporalTypeException;
import org.threeten.bp.temporal.ValueRange;

/**
 * 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 Chronology} implementation:
 * <pre>
 *   LocalDate isoDate = ...
 *   ChronoLocalDate&lt;ThaiBuddhistChrono&gt; minguoDate = ...
 *   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 Chronology} 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 Chronology} 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 Chronology} instance may represent a totally different kind of calendar system,
 * such as the Mayan.
 * <p>
 * In practical terms, the {@code Chronology} 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 Chronology} 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 Chronology}, {@code ChronoLocalDate} and {@code Era}.
 * The majority of the logic specific to the calendar system will be in
 * {@code ChronoLocalDate}. The {@code Chronology} 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 'org.threeten.bp.chrono.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.
 * <p>
 * In JDK 8, this is an interface with default methods.
 * Since there are no default methods in JDK 7, an abstract class is used.
 */
public abstract class Chronology implements Comparable<Chronology> {

    /**
     * Simulate JDK 8 method reference Chronology::from.
     */
    public static final TemporalQuery<Chronology> FROM = new TemporalQuery<Chronology>() {
        @Override
        public Chronology queryFrom(TemporalAccessor temporal) {
            return Chronology.from(temporal);
        }
    };

    /**
     * Map of available calendars by ID.
     */
    private static final ConcurrentHashMap<String, Chronology> CHRONOS_BY_ID = new ConcurrentHashMap<String, Chronology>();
    /**
     * Map of available calendars by calendar type.
     */
    private static final ConcurrentHashMap<String, Chronology> CHRONOS_BY_TYPE = new ConcurrentHashMap<String, Chronology>();
    /**
     * Access JDK 7 method if on JDK 7.
     */
    private static final Method LOCALE_METHOD;
    static {
        Method method = null;
        try {
            method = Locale.class.getMethod("getUnicodeLocaleType", String.class);
        } catch (Throwable ex) {
            // ignore
        }
        LOCALE_METHOD = method;
    }

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of {@code Chronology} 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 Chronology}.
     * If the specified temporal object does not have a chronology, {@link IsoChronology} is returned.
     * <p>
     * The conversion will obtain the chronology using {@link TemporalQueries#chronology()}.
     * <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 Chronology}
     */
    public static Chronology from(TemporalAccessor temporal) {
        Jdk8Methods.requireNonNull(temporal, "temporal");
        Chronology obj = temporal.query(TemporalQueries.chronology());
        return (obj != null ? obj : IsoChronology.INSTANCE);
    }

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of {@code Chronology} from a locale.
     * <p>
     * This returns a {@code Chronology} based on the specified locale,
     * typically returning {@code IsoChronology}. Other calendar systems
     * are only returned if they are explicitly selected within the locale.
     * <p>
     * The {@link Locale} class provide access to a range of information useful
     * for localizing an application. This includes the language and region,
     * such as "en-GB" for English as used in Great Britain.
     * <p>
     * The {@code Locale} class also supports an extension mechanism that
     * can be used to identify a calendar system. The mechanism is a form
     * of key-value pairs, where the calendar system has the key "ca".
     * For example, the locale "en-JP-u-ca-japanese" represents the English
     * language as used in Japan with the Japanese calendar system.
     * <p>
     * This method finds the desired calendar system by in a manner equivalent
     * to passing "ca" to {@link Locale#getUnicodeLocaleType(String)}.
     * If the "ca" key is not present, then {@code IsoChronology} is returned.
     * <p>
     * Note that the behavior of this method differs from the older
     * {@link java.util.Calendar#getInstance(Locale)} method.
     * If that method receives a locale of "th_TH" it will return {@code BuddhistCalendar}.
     * By contrast, this method will return {@code IsoChronology}.
     * Passing the locale "th-TH-u-ca-buddhist" into either method will
     * result in the Thai Buddhist calendar system and is therefore the
     * recommended approach going forward for Thai calendar system localization.
     * <p>
     * A similar, but simpler, situation occurs for the Japanese calendar system.
     * The locale "jp_JP_JP" has previously been used to access the calendar.
     * However, unlike the Thai locale, "ja_JP_JP" is automatically converted by
     * {@code Locale} to the modern and recommended form of "ja-JP-u-ca-japanese".
     * Thus, there is no difference in behavior between this method and
     * {@code Calendar#getInstance(Locale)}.
     *
     * @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 Chronology ofLocale(Locale locale) {
        init();
        Jdk8Methods.requireNonNull(locale, "locale");
        String type = "iso";
        if (LOCALE_METHOD != null) {
            // JDK 7: locale.getUnicodeLocaleType("ca");
            try {
                type = (String) LOCALE_METHOD.invoke(locale, "ca");
            } catch (IllegalArgumentException ex) {
                // ignore
            } catch (IllegalAccessException ex) {
                // ignore
            } catch (InvocationTargetException ex) {
                // ignore
            }
        } else if (locale.equals(JapaneseChronology.LOCALE)) {
            type = "japanese";
        }
        if (type == null || "iso".equals(type) || "iso8601".equals(type)) {
            return IsoChronology.INSTANCE;
        } else {
            Chronology chrono = CHRONOS_BY_TYPE.get(type);
            if (chrono == null) {
                throw new DateTimeException("Unknown calendar system: " + type);
            }
            return chrono;
        }
    }

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of {@code Chronology} 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 Chronology of(String id) {
        init();
        Chronology chrono = CHRONOS_BY_ID.get(id);
        if (chrono != null) {
            return chrono;
        }
        chrono = CHRONOS_BY_TYPE.get(id);
        if (chrono != null) {
            return chrono;
        }
        throw new DateTimeException("Unknown chronology: " + id);
    }

    /**
     * Returns the available chronologies.
     * <p>
     * Each returned {@code Chronology} is available for use in the system.
     *
     * @return the independent, modifiable set of the available chronology IDs, not null
     */
    public static Set<Chronology> getAvailableChronologies() {
        init();
        return new HashSet<Chronology>(CHRONOS_BY_ID.values());
    }

    private static void init() {
        if (CHRONOS_BY_ID.isEmpty()) {
            register(IsoChronology.INSTANCE);
            register(ThaiBuddhistChronology.INSTANCE);
            register(MinguoChronology.INSTANCE);
            register(JapaneseChronology.INSTANCE);
            register(HijrahChronology.INSTANCE);
            CHRONOS_BY_ID.putIfAbsent("Hijrah", HijrahChronology.INSTANCE);
            CHRONOS_BY_TYPE.putIfAbsent("islamic", HijrahChronology.INSTANCE);
            ServiceLoader<Chronology> loader =  ServiceLoader.load(Chronology.class, Chronology.class.getClassLoader());
            for (Chronology chrono : loader) {
                CHRONOS_BY_ID.putIfAbsent(chrono.getId(), chrono);
                String type = chrono.getCalendarType();
                if (type != null) {
                    CHRONOS_BY_TYPE.putIfAbsent(type, chrono);
                }
            }
        }
    }

    private static void register(Chronology chrono) {
        CHRONOS_BY_ID.putIfAbsent(chrono.getId(), chrono);
        String type = chrono.getCalendarType();
        if (type != null) {
            CHRONOS_BY_TYPE.putIfAbsent(type, chrono);
        }
    }

    //-----------------------------------------------------------------------
    /**
     * Creates an instance.
     */
    protected Chronology() {
    }

    //-----------------------------------------------------------------------
    /**
     * 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
     */
    <D extends ChronoLocalDate> D ensureChronoLocalDate(Temporal temporal) {
        @SuppressWarnings("unchecked")
        D other = (D) temporal;
        if (this.equals(other.getChronology()) == false) {
            throw new ClassCastException("Chrono mismatch, expected: " + getId() + ", actual: " + other.getChronology().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
     */
    <D extends ChronoLocalDate> ChronoLocalDateTimeImpl<D> ensureChronoLocalDateTime(Temporal temporal) {
        @SuppressWarnings("unchecked")
        ChronoLocalDateTimeImpl<D> other = (ChronoLocalDateTimeImpl<D>) temporal;
        if (this.equals(other.toLocalDate().getChronology()) == false) {
            throw new ClassCastException("Chrono mismatch, required: " + getId()
                    + ", supplied: " + other.toLocalDate().getChronology().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
     */
    <D extends ChronoLocalDate> ChronoZonedDateTimeImpl<D> ensureChronoZonedDateTime(Temporal temporal) {
        @SuppressWarnings("unchecked")
        ChronoZonedDateTimeImpl<D> other = (ChronoZonedDateTimeImpl<D>) temporal;
        if (this.equals(other.toLocalDate().getChronology()) == false) {
            throw new ClassCastException("Chrono mismatch, required: " + getId()
                    + ", supplied: " + other.toLocalDate().getChronology().getId());
        }
        return other;
    }

    //-----------------------------------------------------------------------
    /**
     * Gets the ID of the chronology.
     * <p>
     * The ID uniquely identifies the {@code Chronology}.
     * It can be used to lookup the {@code Chronology} 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 Chronology} 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
     * @throws ClassCastException if the {@code era} is not of the correct type for the chronology
     */
    public ChronoLocalDate date(Era 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 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
     * @throws ClassCastException if the {@code era} is not of the correct type for the chronology
     */
    public ChronoLocalDate dateYearDay(Era 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 dateYearDay(int prolepticYear, int dayOfYear);

    /**
     * Obtains a local date in this chronology from the epoch-day.
     * <p>
     * The definition of {@link ChronoField#EPOCH_DAY EPOCH_DAY} is the same
     * for all calendar systems, thus it can be used for conversion.
     *
     * @param epochDay  the epoch day
     * @return the local date in this chronology, not null
     * @throws DateTimeException if unable to create the date
     */
    public abstract ChronoLocalDate dateEpochDay(long epochDay);

    /**
     * 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 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 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 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 dateNow(Clock clock) {
        Jdk8Methods.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<?> localDateTime(TemporalAccessor temporal) {
        try {
            ChronoLocalDate date = date(temporal);
            return date.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
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public ChronoZonedDateTime<?> zonedDateTime(TemporalAccessor temporal) {
        try {
            ZoneId zone = ZoneId.from(temporal);
            try {
                Instant instant = Instant.from(temporal);
                return zonedDateTime(instant, zone);

            } catch (DateTimeException ex1) {
                ChronoLocalDateTime cldt = localDateTime(temporal);
                ChronoLocalDateTimeImpl cldtImpl = ensureChronoLocalDateTime(cldt);
                return ChronoZonedDateTimeImpl.ofBest(cldtImpl, 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<?> zonedDateTime(Instant instant, ZoneId zone) {
        ChronoZonedDateTime<? extends ChronoLocalDate> result = ChronoZonedDateTimeImpl.ofInstant(this, instant, zone);
        return result;
    }

    //-----------------------------------------------------------------------
    /**
     * Obtains a period for this chronology based on years, months and days.
     * <p>
     * This returns a period tied to this chronology using the specified
     * years, months and days.  All supplied chronologies use periods
     * based on years, months and days, however the {@code ChronoPeriod} API
     * allows the period to be represented using other units.
     * <p>
     * The default implementation returns an implementation class suitable
     * for most calendar systems. It is based solely on the three units.
     * Normalization, addition and subtraction derive the number of months
     * in a year from the {@link #range(ChronoField)}. If the number of
     * months within a year is fixed, then the calculation approach for
     * addition, subtraction and normalization is slightly different.
     * <p>
     * If implementing an unusual calendar system that is not based on
     * years, months and days, or where you want direct control, then
     * the {@code ChronoPeriod} interface must be directly implemented.
     * <p>
     * The returned period is immutable and thread-safe.
     *
     * @param years  the number of years, may be negative
     * @param months  the number of years, may be negative
     * @param days  the number of years, may be negative
     * @return the period in terms of this chronology, not null
     */
    public ChronoPeriod period(int years, int months, int days) {
        return new ChronoPeriodImpl(this, years, months, days);
    }

    //-----------------------------------------------------------------------
    /**
     * 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
     * @throws ClassCastException if the {@code era} is not of the correct type for the chronology
     */
    public abstract int prolepticYear(Era 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 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> 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 getDisplayName(TextStyle style, Locale locale) {
        return new DateTimeFormatterBuilder().appendChronologyText(style).toFormatter(locale).format(new DefaultInterfaceTemporalAccessor() {
            @Override
            public boolean isSupported(TemporalField field) {
                return false;
            }
            @Override
            public long getLong(TemporalField field) {
                throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
            }
            @SuppressWarnings("unchecked")
            @Override
            public <R> R query(TemporalQuery<R> query) {
                if (query == TemporalQueries.chronology()) {
                    return (R) Chronology.this;
                }
                return super.query(query);
            }
        });
    }

    //-----------------------------------------------------------------------
    /**
     * Resolves parsed {@code ChronoField} values into a date during parsing.
     * <p>
     * Most {@code TemporalField} implementations are resolved using the
     * resolve method on the field. By contrast, the {@code ChronoField} class
     * defines fields that only have meaning relative to the chronology.
     * As such, {@code ChronoField} date fields are resolved here in the
     * context of a specific chronology.
     * <p>
     * The default implementation, which explains typical resolve behaviour,
     * is provided in {@link AbstractChronology}.
     *
     * @param fieldValues  the map of fields to values, which can be updated, not null
     * @param resolverStyle  the requested type of resolve, not null
     * @return the resolved date, null if insufficient information to create a date
     * @throws DateTimeException if the date cannot be resolved, typically
     *  because of a conflict in the input data
     */
    public abstract ChronoLocalDate resolveDate(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle);

    /**
     * Updates the map of field-values during resolution.
     *
     * @param field  the field to update, not null
     * @param value  the value to update, not null
     * @throws DateTimeException if a conflict occurs
     */
    void updateResolveMap(Map<TemporalField, Long> fieldValues, ChronoField field, long value) {
        Long current = fieldValues.get(field);
        if (current != null && current.longValue() != value) {
            throw new DateTimeException("Invalid state, field: " + field + " " + current + " conflicts with " + field + " " + value);
        }
        fieldValues.put(field, value);
    }

    //-----------------------------------------------------------------------
    /**
     * 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(Chronology 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(Chronology)}.
     *
     * @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 Chronology) {
            return compareTo((Chronology) 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();
    }

    //-----------------------------------------------------------------------
    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 Chronology readExternal(DataInput in) throws IOException {
        String id = in.readUTF();
        return Chronology.of(id);
    }

}