DiscordianChronology.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:
*
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* 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
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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
* without specific prior written permission.
*
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package org.threeten.extra.chrono;
import java.io.Serializable;
import java.time.Clock;
import java.time.DateTimeException;
import java.time.Instant;
import java.time.ZoneId;
import java.time.chrono.AbstractChronology;
import java.time.chrono.ChronoLocalDateTime;
import java.time.chrono.ChronoZonedDateTime;
import java.time.chrono.Chronology;
import java.time.chrono.Era;
import java.time.format.ResolverStyle;
import java.time.temporal.ChronoField;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalField;
import java.time.temporal.ValueRange;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
/**
* The Discordian calendar system.
* <p>
* This chronology defines the rules of the proleptic Discordian calendar system.
* The Discordian differs from the Gregorian in terms of month and week lengths, with an offset year.
* Dates are aligned such that each Discordian year starts with each ISO year, with an offset index.
* <p>
* This class is not proleptic. It implements Discordian rules only since YOLD 1 (ISO BCE 1166).
* <p>
* The fields are defined as follows:
* <ul>
* <li>era - There is one era, the current 'Year of Our Lady of Discord' (YOLD).
* <li>year-of-era - The year-of-era for the current era increases uniformly from the epoch at year one.
* <li>proleptic-year - The proleptic year is the same as the year-of-era for the current era.
* <li>month-of-year - There are 5 months in a Discordian year, numbered from 1 to 5.
* <li>day-of-week - There are 5 days in a Discordian week, numbered from 1 to 5.
* <li>day-of-month - There are 73 days in each Discordian month, numbered from 1 to 73.
* <li>day-of-year - There are 365 days in a standard Discordian year and 366 in a leap year.
* The days are numbered from 1 to 365 or 1 to 366.
* <li>leap-year - Leap years occur in sync with ISO leap-years; that is, they occur every 4 ISO years, excepting when that ISO year is divisible by 100 but not 400.
* <li>St. Tib's Day - St. Tib's Day occurs each leap-year, and is inserted between the 59th and 60th day of the first month.
* St. Tib's Day is not part of any month, nor is it part of the Discordian week. It is aligned with the ISO calendar leap-day (February 29th).
* </ul>
*
* <h3>Implementation Requirements</h3>
* This class is immutable and thread-safe.
*/
public final class DiscordianChronology
extends AbstractChronology
implements Serializable {
/**
* Singleton instance for the Discordian chronology.
*/
public static final DiscordianChronology INSTANCE = new DiscordianChronology();
/**
* Serialization version.
*/
private static final long serialVersionUID = 1075529146344250850L;
/**
* Offset from ISO 0
*/
static final int OFFSET_FROM_ISO_0000 = 1166;
/**
* Days in a regular month.
*/
static final int DAYS_IN_MONTH = 73;
/**
* Days in a regular week.
*/
static final int DAYS_IN_WEEK = 5;
/**
* Months in a regular year.
*/
static final int MONTHS_IN_YEAR = 5;
/**
* Weeks in a regular year.
*/
static final int WEEKS_IN_YEAR = 73;
/**
* Range of proleptic-year.
*/
static final ValueRange YEAR_RANGE = ValueRange.of(1, 999_999);
/**
* Range of month-of-year.
*/
static final ValueRange MONTH_OF_YEAR_RANGE = ValueRange.of(0, 1, MONTHS_IN_YEAR, MONTHS_IN_YEAR);
/**
* Range of day-of-month.
*/
static final ValueRange DAY_OF_MONTH_RANGE = ValueRange.of(0, 1, 0, DAYS_IN_MONTH);
/**
* Range of epoch day.
*/
static final ValueRange EPOCH_DAY_RANGE = ValueRange.of(-1_145_400, 999_999 * 365L + 242_499);
/**
* Range of proleptic month.
*/
private static final ValueRange PROLEPTIC_MONTH_RANGE = ValueRange.of(0, (long) 999_999 * MONTHS_IN_YEAR + MONTHS_IN_YEAR - 1);
/**
* Range of day-of-week.
*/
private static final ValueRange DAY_OF_WEEK_RANGE = ValueRange.of(0, 1, 0, DAYS_IN_WEEK);
/**
* Range of aligned day-of-week of year.
*/
private static final ValueRange ALIGNED_DOW_OF_YEAR_RANGE = ValueRange.of(0, 1, DAYS_IN_WEEK, DAYS_IN_WEEK);
/**
* Range of week-of-month.
*/
private static final ValueRange WEEK_OF_MONTH_RANGE = ValueRange.of(0, 1, 0, 15);
/**
* Range of week-of-year.
*/
private static final ValueRange WEEK_OF_YEAR_RANGE = ValueRange.of(0, 1, WEEKS_IN_YEAR, WEEKS_IN_YEAR);
/**
* Range of eras.
*/
private static final ValueRange ERA_RANGE = ValueRange.of(1, 1);
/**
* Private constructor, that is public to satisfy the {@code ServiceLoader}.
* @deprecated Use the singleton {@link #INSTANCE} instead.
*/
@Deprecated
public DiscordianChronology() {
}
/**
* Resolve singleton.
*
* @return the singleton instance, not null
*/
private Object readResolve() {
return INSTANCE;
}
//-----------------------------------------------------------------------
/**
* Gets the ID of the chronology - 'Discordian'.
* <p>
* The ID uniquely identifies the {@code Chronology}.
* It can be used to lookup the {@code Chronology} using {@link Chronology#of(String)}.
*
* @return the chronology ID - 'Discordian'
* @see #getCalendarType()
*/
@Override
public String getId() {
return "Discordian";
}
/**
* Gets the calendar type of the underlying calendar system - 'discordian'.
* <p>
* The <em>Unicode Locale Data Markup Language (LDML)</em> specification
* does not define an identifier for the Discordian calendar, but were it to
* do so, 'discordian' is highly likely to be chosen.
*
* @return the calendar system type - 'discordian'
* @see #getId()
*/
@Override
public String getCalendarType() {
return "discordian";
}
//-----------------------------------------------------------------------
/**
* Obtains a local date in Discordian calendar system from the
* era, year-of-era, month-of-year and day-of-month fields.
*
* @param era the Discordian era, not null
* @param yearOfEra the year-of-era
* @param month the month-of-year
* @param dayOfMonth the day-of-month
* @return the Discordian local date, not null
* @throws DateTimeException if unable to create the date
* @throws ClassCastException if the {@code era} is not a {@code DiscordianEra}
*/
@Override
public DiscordianDate date(Era era, int yearOfEra, int month, int dayOfMonth) {
return date(prolepticYear(era, yearOfEra), month, dayOfMonth);
}
/**
* Obtains a local date in Discordian calendar system from the
* proleptic-year, month-of-year and day-of-month fields.
*
* @param prolepticYear the proleptic-year
* @param month the month-of-year
* @param dayOfMonth the day-of-month
* @return the Discordian local date, not null
* @throws DateTimeException if unable to create the date
*/
@Override
public DiscordianDate date(int prolepticYear, int month, int dayOfMonth) {
return DiscordianDate.of(prolepticYear, month, dayOfMonth);
}
/**
* Obtains a local date in Discordian calendar system from the
* era, year-of-era and day-of-year fields.
*
* @param era the Discordian era, not null
* @param yearOfEra the year-of-era
* @param dayOfYear the day-of-year
* @return the Discordian local date, not null
* @throws DateTimeException if unable to create the date
* @throws ClassCastException if the {@code era} is not a {@code DiscordianEra}
*/
@Override
public DiscordianDate dateYearDay(Era era, int yearOfEra, int dayOfYear) {
return dateYearDay(prolepticYear(era, yearOfEra), dayOfYear);
}
/**
* Obtains a local date in the Discordian calendar system from the
* proleptic-year and day-of-year fields.
*
* @param prolepticYear the proleptic-year
* @param dayOfYear the day-of-year
* @return the Discordian local date, not null
* @throws DateTimeException if unable to create the date
*/
@Override
public DiscordianDate dateYearDay(int prolepticYear, int dayOfYear) {
return DiscordianDate.ofYearDay(prolepticYear, dayOfYear);
}
/**
* Obtains a local date in the Discordian calendar system from the epoch-day.
*
* @param epochDay the epoch day
* @return the Discordian local date, not null
* @throws DateTimeException if unable to create the date
*/
@Override // override with covariant return type
public DiscordianDate dateEpochDay(long epochDay) {
return DiscordianDate.ofEpochDay(epochDay);
}
//-------------------------------------------------------------------------
/**
* Obtains the current Discordian local date 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.
*
* @return the current Discordian local date using the system clock and default time-zone, not null
* @throws DateTimeException if unable to create the date
*/
@Override // override with covariant return type
public DiscordianDate dateNow() {
return DiscordianDate.now();
}
/**
* Obtains the current Discordian local date 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 Discordian local date using the system clock, not null
* @throws DateTimeException if unable to create the date
*/
@Override // override with covariant return type
public DiscordianDate dateNow(ZoneId zone) {
return DiscordianDate.now(zone);
}
/**
* Obtains the current Discordian local date 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 Discordian local date, not null
* @throws DateTimeException if unable to create the date
*/
@Override // override with covariant return type
public DiscordianDate dateNow(Clock clock) {
return DiscordianDate.now(clock);
}
//-------------------------------------------------------------------------
/**
* Obtains a Discordian local date from another date-time object.
*
* @param temporal the date-time object to convert, not null
* @return the Discordian local date, not null
* @throws DateTimeException if unable to create the date
*/
@Override
public DiscordianDate date(TemporalAccessor temporal) {
return DiscordianDate.from(temporal);
}
/**
* Obtains a Discordian local date-time from another date-time object.
*
* @param temporal the date-time object to convert, not null
* @return the Discordian local date-time, not null
* @throws DateTimeException if unable to create the date-time
*/
@Override
@SuppressWarnings("unchecked")
public ChronoLocalDateTime<DiscordianDate> localDateTime(TemporalAccessor temporal) {
return (ChronoLocalDateTime<DiscordianDate>) super.localDateTime(temporal);
}
/**
* Obtains a Discordian zoned date-time from another date-time object.
*
* @param temporal the date-time object to convert, not null
* @return the Discordian zoned date-time, not null
* @throws DateTimeException if unable to create the date-time
*/
@Override
@SuppressWarnings("unchecked")
public ChronoZonedDateTime<DiscordianDate> zonedDateTime(TemporalAccessor temporal) {
return (ChronoZonedDateTime<DiscordianDate>) super.zonedDateTime(temporal);
}
/**
* Obtains a Discordian zoned date-time in this chronology from an {@code Instant}.
*
* @param instant the instant to create the date-time from, not null
* @param zone the time-zone, not null
* @return the Discordian zoned date-time, not null
* @throws DateTimeException if the result exceeds the supported range
*/
@Override
@SuppressWarnings("unchecked")
public ChronoZonedDateTime<DiscordianDate> zonedDateTime(Instant instant, ZoneId zone) {
return (ChronoZonedDateTime<DiscordianDate>) super.zonedDateTime(instant, zone);
}
//-----------------------------------------------------------------------
/**
* Checks if the specified year is a leap year.
* <p>
* A Discordian proleptic-year is leap if the remainder after division by four equals zero.
* There are two special cases.
* If the year minus 1166 is divisible by 100 it is not a leap year, unless
* it is also divisible by 400, when it is a leap year.
* These rules produce leap days on the same dates as the ISO-8601 calendar system.
*
* @param prolepticYear the proleptic-year to check, not validated for range
* @return true if the year is a leap year
*/
@Override
public boolean isLeapYear(long prolepticYear) {
long offsetYear = prolepticYear - OFFSET_FROM_ISO_0000;
return (offsetYear % 4 == 0) && ((offsetYear % 400 == 0) || (offsetYear % 100 != 0));
}
@Override
public int prolepticYear(Era era, int yearOfEra) {
if (!DiscordianEra.YOLD.equals(era)) {
throw new ClassCastException("Era must be DiscordianEra.YOLD");
}
return YEAR_RANGE.checkValidIntValue(yearOfEra, ChronoField.YEAR_OF_ERA);
}
@Override
public DiscordianEra eraOf(int era) {
return DiscordianEra.of(era);
}
@Override
public List<Era> eras() {
return Arrays.<Era>asList(DiscordianEra.values());
}
//-----------------------------------------------------------------------
@Override
public ValueRange range(ChronoField field) {
switch (field) {
case ALIGNED_DAY_OF_WEEK_IN_YEAR:
return ALIGNED_DOW_OF_YEAR_RANGE;
case ALIGNED_DAY_OF_WEEK_IN_MONTH:
case DAY_OF_WEEK:
return DAY_OF_WEEK_RANGE;
case ALIGNED_WEEK_OF_MONTH:
return WEEK_OF_MONTH_RANGE;
case ALIGNED_WEEK_OF_YEAR:
return WEEK_OF_YEAR_RANGE;
case DAY_OF_MONTH:
return DAY_OF_MONTH_RANGE;
case EPOCH_DAY:
return EPOCH_DAY_RANGE;
case ERA:
return ERA_RANGE;
case MONTH_OF_YEAR:
return MONTH_OF_YEAR_RANGE;
case PROLEPTIC_MONTH:
return PROLEPTIC_MONTH_RANGE;
case YEAR_OF_ERA:
case YEAR:
return YEAR_RANGE;
default:
break;
}
return field.range();
}
//-----------------------------------------------------------------------
@Override // override for return type
public DiscordianDate resolveDate(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
return (DiscordianDate) super.resolveDate(fieldValues, resolverStyle);
}
}