ChronoDateImpl.java

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/*
 * 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.
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 *  * Redistributions in binary form must reproduce the above copyright notice,
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 *  * Neither the name of JSR-310 nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
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package java.time.chrono;

import static java.time.temporal.ChronoField.DAY_OF_MONTH;
import static java.time.temporal.ChronoField.ERA;
import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
import static java.time.temporal.ChronoField.PROLEPTIC_MONTH;
import static java.time.temporal.ChronoField.YEAR_OF_ERA;

import java.io.Serializable;
import java.time.DateTimeException;
import java.time.temporal.ChronoUnit;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalAdjuster;
import java.time.temporal.TemporalUnit;
import java.time.temporal.UnsupportedTemporalTypeException;
import java.time.temporal.ValueRange;
import java.util.Objects;

/**
 * A date expressed in terms of a standard year-month-day calendar system.
 * <p>
 * This class is used by applications seeking to handle dates in non-ISO calendar systems.
 * For example, the Japanese, Minguo, Thai Buddhist and others.
 * <p>
 * {@code ChronoLocalDate} is built on the generic concepts of year, month and day.
 * The calendar system, represented by a {@link java.time.chrono.Chronology}, expresses the relationship between
 * the fields and this class allows the resulting date to be manipulated.
 * <p>
 * Note that not all calendar systems are suitable for use with this class.
 * For example, the Mayan calendar uses a system that bears no relation to years, months and days.
 * <p>
 * The API design encourages the use of {@code LocalDate} for the majority of the application.
 * This includes code to read and write from a persistent data store, such as a database,
 * and to send dates and times across a network. The {@code ChronoLocalDate} instance is then used
 * at the user interface level to deal with localized input/output.
 *
 * <P>Example: </p>
 * <pre>
 *        System.out.printf("Example()%n");
 *        // Enumerate the list of available calendars and print today for each
 *        Set&lt;Chronology&gt; chronos = Chronology.getAvailableChronologies();
 *        for (Chronology chrono : chronos) {
 *            ChronoLocalDate&lt;?&gt; date = chrono.dateNow();
 *            System.out.printf("   %20s: %s%n", chrono.getID(), date.toString());
 *        }
 *
 *        // Print the Hijrah date and calendar
 *        ChronoLocalDate&lt;?&gt; date = Chronology.of("Hijrah").dateNow();
 *        int day = date.get(ChronoField.DAY_OF_MONTH);
 *        int dow = date.get(ChronoField.DAY_OF_WEEK);
 *        int month = date.get(ChronoField.MONTH_OF_YEAR);
 *        int year = date.get(ChronoField.YEAR);
 *        System.out.printf("  Today is %s %s %d-%s-%d%n", date.getChronology().getID(),
 *                dow, day, month, year);

 *        // Print today's date and the last day of the year
 *        ChronoLocalDate&lt;?&gt; now1 = Chronology.of("Hijrah").dateNow();
 *        ChronoLocalDate&lt;?&gt; first = now1.with(ChronoField.DAY_OF_MONTH, 1)
 *                .with(ChronoField.MONTH_OF_YEAR, 1);
 *        ChronoLocalDate&lt;?&gt; last = first.plus(1, ChronoUnit.YEARS)
 *                .minus(1, ChronoUnit.DAYS);
 *        System.out.printf("  Today is %s: start: %s; end: %s%n", last.getChronology().getID(),
 *                first, last);
 * </pre>
 *
 * <h3>Adding Calendars</h3>
 * <p> The set of calendars is extensible by defining a subclass of {@link ChronoLocalDate}
 * to represent a date instance and an implementation of {@code Chronology}
 * to be the factory for the ChronoLocalDate subclass.
 * </p>
 * <p> To permit the discovery of the additional calendar types the implementation of
 * {@code Chronology} must be registered as a Service implementing the {@code Chronology} interface
 * in the {@code META-INF/Services} file as per the specification of {@link java.util.ServiceLoader}.
 * The subclass must function according to the {@code Chronology} class description and must provide its
 * {@link java.time.chrono.Chronology#getId() chronlogy ID} and {@link Chronology#getCalendarType() calendar type}. </p>
 *
 * <h3>Specification for implementors</h3>
 * This abstract 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 <D> the ChronoLocalDate of this date-time
 * @since 1.8
 */
abstract class ChronoDateImpl<D extends ChronoLocalDate<D>>
        implements ChronoLocalDate<D>, Temporal, TemporalAdjuster, Serializable {

    /**
     * Serialization version.
     */
    private static final long serialVersionUID = 6282433883239719096L;

    /**
     * Creates an instance.
     */
    ChronoDateImpl() {
    }

    //-----------------------------------------------------------------------
    @Override
    public D plus(long amountToAdd, TemporalUnit unit) {
        if (unit instanceof ChronoUnit) {
            ChronoUnit f = (ChronoUnit) unit;
            switch (f) {
                case DAYS: return plusDays(amountToAdd);
                case WEEKS: return plusDays(Math.multiplyExact(amountToAdd, 7));
                case MONTHS: return plusMonths(amountToAdd);
                case YEARS: return plusYears(amountToAdd);
                case DECADES: return plusYears(Math.multiplyExact(amountToAdd, 10));
                case CENTURIES: return plusYears(Math.multiplyExact(amountToAdd, 100));
                case MILLENNIA: return plusYears(Math.multiplyExact(amountToAdd, 1000));
                case ERAS: return with(ERA, Math.addExact(getLong(ERA), amountToAdd));
            }
            throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit.getName());
        }
        return ChronoLocalDate.super.plus(amountToAdd, unit);
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this date with the specified period in years added.
     * <p>
     * This adds the specified period in years to the date.
     * In some cases, adding years can cause the resulting date to become invalid.
     * If this occurs, then other fields, typically the day-of-month, will be adjusted to ensure
     * that the result is valid. Typically this will select the last valid day of the month.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param yearsToAdd  the years to add, may be negative
     * @return a date based on this one with the years added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    abstract D plusYears(long yearsToAdd);

    /**
     * Returns a copy of this date with the specified period in months added.
     * <p>
     * This adds the specified period in months to the date.
     * In some cases, adding months can cause the resulting date to become invalid.
     * If this occurs, then other fields, typically the day-of-month, will be adjusted to ensure
     * that the result is valid. Typically this will select the last valid day of the month.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param monthsToAdd  the months to add, may be negative
     * @return a date based on this one with the months added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    abstract D plusMonths(long monthsToAdd);

    /**
     * Returns a copy of this date with the specified period in weeks added.
     * <p>
     * This adds the specified period in weeks to the date.
     * In some cases, adding weeks can cause the resulting date to become invalid.
     * If this occurs, then other fields will be adjusted to ensure that the result is valid.
     * <p>
     * The default implementation uses {@link #plusDays(long)} using a 7 day week.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param weeksToAdd  the weeks to add, may be negative
     * @return a date based on this one with the weeks added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    D plusWeeks(long weeksToAdd) {
        return plusDays(Math.multiplyExact(weeksToAdd, 7));
    }

    /**
     * Returns a copy of this date with the specified number of days added.
     * <p>
     * This adds the specified period in days to the date.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param daysToAdd  the days to add, may be negative
     * @return a date based on this one with the days added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    abstract D plusDays(long daysToAdd);

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this date with the specified period in years subtracted.
     * <p>
     * This subtracts the specified period in years to the date.
     * In some cases, subtracting years can cause the resulting date to become invalid.
     * If this occurs, then other fields, typically the day-of-month, will be adjusted to ensure
     * that the result is valid. Typically this will select the last valid day of the month.
     * <p>
     * The default implementation uses {@link #plusYears(long)}.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param yearsToSubtract  the years to subtract, may be negative
     * @return a date based on this one with the years subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    D minusYears(long yearsToSubtract) {
        return (yearsToSubtract == Long.MIN_VALUE ? ((ChronoDateImpl<D>)plusYears(Long.MAX_VALUE)).plusYears(1) : plusYears(-yearsToSubtract));
    }

    /**
     * Returns a copy of this date with the specified period in months subtracted.
     * <p>
     * This subtracts the specified period in months to the date.
     * In some cases, subtracting months can cause the resulting date to become invalid.
     * If this occurs, then other fields, typically the day-of-month, will be adjusted to ensure
     * that the result is valid. Typically this will select the last valid day of the month.
     * <p>
     * The default implementation uses {@link #plusMonths(long)}.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param monthsToSubtract  the months to subtract, may be negative
     * @return a date based on this one with the months subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    D minusMonths(long monthsToSubtract) {
        return (monthsToSubtract == Long.MIN_VALUE ? ((ChronoDateImpl<D>)plusMonths(Long.MAX_VALUE)).plusMonths(1) : plusMonths(-monthsToSubtract));
    }

    /**
     * Returns a copy of this date with the specified period in weeks subtracted.
     * <p>
     * This subtracts the specified period in weeks to the date.
     * In some cases, subtracting weeks can cause the resulting date to become invalid.
     * If this occurs, then other fields will be adjusted to ensure that the result is valid.
     * <p>
     * The default implementation uses {@link #plusWeeks(long)}.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param weeksToSubtract  the weeks to subtract, may be negative
     * @return a date based on this one with the weeks subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    D minusWeeks(long weeksToSubtract) {
        return (weeksToSubtract == Long.MIN_VALUE ? ((ChronoDateImpl<D>)plusWeeks(Long.MAX_VALUE)).plusWeeks(1) : plusWeeks(-weeksToSubtract));
    }

    /**
     * Returns a copy of this date with the specified number of days subtracted.
     * <p>
     * This subtracts the specified period in days to the date.
     * <p>
     * The default implementation uses {@link #plusDays(long)}.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param daysToSubtract  the days to subtract, may be negative
     * @return a date based on this one with the days subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    D minusDays(long daysToSubtract) {
        return (daysToSubtract == Long.MIN_VALUE ? ((ChronoDateImpl<D>)plusDays(Long.MAX_VALUE)).plusDays(1) : plusDays(-daysToSubtract));
    }

    //-----------------------------------------------------------------------
    /**
     * {@inheritDoc}
     * @throws DateTimeException {@inheritDoc}
     * @throws ArithmeticException {@inheritDoc}
     */
    @Override
    public long periodUntil(Temporal endDateTime, TemporalUnit unit) {
        Objects.requireNonNull(endDateTime, "endDateTime");
        Objects.requireNonNull(unit, "unit");
        if (endDateTime instanceof ChronoLocalDate == false) {
            throw new DateTimeException("Unable to calculate period between objects of two different types");
        }
        ChronoLocalDate<?> end = (ChronoLocalDate<?>) endDateTime;
        if (getChronology().equals(end.getChronology()) == false) {
            throw new DateTimeException("Unable to calculate period between two different chronologies");
        }
        if (unit instanceof ChronoUnit) {
            switch ((ChronoUnit) unit) {
                case DAYS: return daysUntil(end);
                case WEEKS: return daysUntil(end) / 7;
                case MONTHS: return monthsUntil(end);
                case YEARS: return monthsUntil(end) / 12;
                case DECADES: return monthsUntil(end) / 120;
                case CENTURIES: return monthsUntil(end) / 1200;
                case MILLENNIA: return monthsUntil(end) / 12000;
                case ERAS: return end.getLong(ERA) - getLong(ERA);
            }
            throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit.getName());
        }
        return unit.between(this, endDateTime);
    }

    private long daysUntil(ChronoLocalDate<?> end) {
        return end.toEpochDay() - toEpochDay();  // no overflow
    }

    private long monthsUntil(ChronoLocalDate<?> end) {
        ValueRange range = getChronology().range(MONTH_OF_YEAR);
        if (range.getMaximum() != 12) {
            throw new IllegalStateException("ChronoDateImpl only supports Chronologies with 12 months per year");
        }
        long packed1 = getLong(PROLEPTIC_MONTH) * 32L + get(DAY_OF_MONTH);  // no overflow
        long packed2 = end.getLong(PROLEPTIC_MONTH) * 32L + end.get(DAY_OF_MONTH);  // no overflow
        return (packed2 - packed1) / 32;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj instanceof ChronoLocalDate) {
            return compareTo((ChronoLocalDate<?>) obj) == 0;
        }
        return false;
    }

    @Override
    public int hashCode() {
        long epDay = toEpochDay();
        return getChronology().hashCode() ^ ((int) (epDay ^ (epDay >>> 32)));
    }

    @Override
    public String toString() {
        // getLong() reduces chances of exceptions in toString()
        long yoe = getLong(YEAR_OF_ERA);
        long moy = getLong(MONTH_OF_YEAR);
        long dom = getLong(DAY_OF_MONTH);
        StringBuilder buf = new StringBuilder(30);
        buf.append(getChronology().toString())
                .append(" ")
                .append(getEra())
                .append(" ")
                .append(yoe)
                .append(moy < 10 ? "-0" : "-").append(moy)
                .append(dom < 10 ? "-0" : "-").append(dom);
        return buf.toString();
    }

}