org.joda.time.chrono.IslamicChronology Maven / Gradle / Ivy
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/*
* Copyright 2001-2014 Stephen Colebourne
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.joda.time.chrono;
import java.io.Serializable;
import java.util.concurrent.ConcurrentHashMap;
import org.joda.time.Chronology;
import org.joda.time.DateTime;
import org.joda.time.DateTimeConstants;
import org.joda.time.DateTimeField;
import org.joda.time.DateTimeZone;
/**
* Implements the Islamic, or Hijri, calendar system using arithmetic rules.
*
* This calendar is a lunar calendar with a shorter year than ISO.
* Year 1 in the Islamic calendar began on July 16, 622 CE (Julian), thus
* Islamic years do not begin at the same time as Julian years. This chronology
* is not proleptic, as it does not allow dates before the first Islamic year.
*
* There are two basic forms of the Islamic calendar, the tabular and the
* observed. The observed form cannot easily be used by computers as it
* relies on human observation of the new moon.
* The tabular calendar, implemented here, is an arithmetical approximation
* of the observed form that follows relatively simple rules.
*
* The tabular form of the calendar defines 12 months of alternately
* 30 and 29 days. The last month is extended to 30 days in a leap year.
* Leap years occur according to a 30 year cycle. There are four recognised
* patterns of leap years in the 30 year cycle:
*
* Years 2, 5, 7, 10, 13, 15, 18, 21, 24, 26 & 29 - 15-based, used by Microsoft
* Years 2, 5, 7, 10, 13, 16, 18, 21, 24, 26 & 29 - 16-based, most commonly used
* Years 2, 5, 8, 10, 13, 16, 19, 21, 24, 27 & 29 - Indian
* Years 2, 5, 8, 11, 13, 16, 19, 21, 24, 27 & 30 - Habash al-Hasib
*
* You can select which pattern to use via the factory methods, or use the
* default (16-based).
*
* This implementation defines a day as midnight to midnight exactly as per
* the ISO chronology. This correct start of day is at sunset on the previous
* day, however this cannot readily be modelled and has been ignored.
*
* IslamicChronology is thread-safe and immutable.
*
* @see Wikipedia
*
* @author Stephen Colebourne
* @since 1.2
*/
public final class IslamicChronology extends BasicChronology {
/** Serialization lock */
private static final long serialVersionUID = -3663823829888L;
/**
* Constant value for 'Anno Hegirae', equivalent
* to the value returned for AD/CE.
*/
public static final int AH = DateTimeConstants.CE;
/** A singleton era field. */
private static final DateTimeField ERA_FIELD = new BasicSingleEraDateTimeField("AH");
/** Leap year 15-based pattern. */
public static final LeapYearPatternType LEAP_YEAR_15_BASED = new LeapYearPatternType(0, 623158436);
/** Leap year 16-based pattern. */
public static final LeapYearPatternType LEAP_YEAR_16_BASED = new LeapYearPatternType(1, 623191204);
/** Leap year Indian pattern. */
public static final LeapYearPatternType LEAP_YEAR_INDIAN = new LeapYearPatternType(2, 690562340);
/** Leap year Habash al-Hasib pattern. */
public static final LeapYearPatternType LEAP_YEAR_HABASH_AL_HASIB = new LeapYearPatternType(3, 153692453);
/** The lowest year that can be fully supported. */
private static final int MIN_YEAR = -292269337;
/**
* The highest year that can be fully supported.
* Although calculateFirstDayOfYearMillis can go higher without
* overflowing, the getYear method overflows when it adds the
* approximate millis at the epoch.
*/
private static final int MAX_YEAR = 292271022;
/** The days in a pair of months. */
private static final int MONTH_PAIR_LENGTH = 59;
/** The length of the long month. */
private static final int LONG_MONTH_LENGTH = 30;
/** The length of the short month. */
private static final int SHORT_MONTH_LENGTH = 29;
/** The length of the long month in millis. */
private static final long MILLIS_PER_MONTH_PAIR = 59L * DateTimeConstants.MILLIS_PER_DAY;
/** The length of the long month in millis. */
private static final long MILLIS_PER_MONTH = (long) (29.53056 * DateTimeConstants.MILLIS_PER_DAY);
/** The length of the long month in millis. */
private static final long MILLIS_PER_LONG_MONTH = 30L * DateTimeConstants.MILLIS_PER_DAY;
/** The typical millis per year. */
private static final long MILLIS_PER_YEAR = (long) (354.36667 * DateTimeConstants.MILLIS_PER_DAY);
/** The typical millis per year. */
private static final long MILLIS_PER_SHORT_YEAR = 354L * DateTimeConstants.MILLIS_PER_DAY;
/** The typical millis per year. */
private static final long MILLIS_PER_LONG_YEAR = 355L * DateTimeConstants.MILLIS_PER_DAY;
/** The millis of 0001-01-01. */
private static final long MILLIS_YEAR_1 = -42521587200000L;
// -42520809600000L;
// long start = 0L - 278L * DateTimeConstants.MILLIS_PER_DAY;
// long cy = 46L * MILLIS_PER_CYCLE; // 1381-01-01
// long rem = 5L * MILLIS_PER_SHORT_YEAR +
// 3L * MILLIS_PER_LONG_YEAR; // 1389-01-01
/** The length of the cycle of leap years. */
private static final int CYCLE = 30;
/** The millis of a 30 year cycle. */
private static final long MILLIS_PER_CYCLE = ((19L * 354L + 11L * 355L) * DateTimeConstants.MILLIS_PER_DAY);
/** Cache of zone to chronology arrays */
private static final ConcurrentHashMap cCache = new ConcurrentHashMap();
/** Singleton instance of a UTC IslamicChronology */
private static final IslamicChronology INSTANCE_UTC;
static {
// init after static fields
INSTANCE_UTC = getInstance(DateTimeZone.UTC);
}
/** The leap years to use. */
private final LeapYearPatternType iLeapYears;
//-----------------------------------------------------------------------
/**
* Gets an instance of the IslamicChronology.
* The time zone of the returned instance is UTC.
*
* @return a singleton UTC instance of the chronology
*/
public static IslamicChronology getInstanceUTC() {
return INSTANCE_UTC;
}
/**
* Gets an instance of the IslamicChronology in the default time zone.
*
* @return a chronology in the default time zone
*/
public static IslamicChronology getInstance() {
return getInstance(DateTimeZone.getDefault(), LEAP_YEAR_16_BASED);
}
/**
* Gets an instance of the IslamicChronology in the given time zone.
*
* @param zone the time zone to get the chronology in, null is default
* @return a chronology in the specified time zone
*/
public static IslamicChronology getInstance(DateTimeZone zone) {
return getInstance(zone, LEAP_YEAR_16_BASED);
}
/**
* Gets an instance of the IslamicChronology in the given time zone.
*
* @param zone the time zone to get the chronology in, null is default
* @param leapYears the type defining the leap year pattern
* @return a chronology in the specified time zone
*/
public static IslamicChronology getInstance(DateTimeZone zone, LeapYearPatternType leapYears) {
if (zone == null) {
zone = DateTimeZone.getDefault();
}
IslamicChronology chrono;
IslamicChronology[] chronos = cCache.get(zone);
if (chronos == null) {
chronos = new IslamicChronology[4];
IslamicChronology[] oldChronos = cCache.putIfAbsent(zone, chronos);
if (oldChronos != null) {
chronos = oldChronos;
}
}
chrono = chronos[leapYears.index];
if (chrono == null) {
synchronized (chronos) {
chrono = chronos[leapYears.index];
if (chrono == null) {
if (zone == DateTimeZone.UTC) {
// First create without a lower limit.
chrono = new IslamicChronology(null, null, leapYears);
// Impose lower limit and make another IslamicChronology.
DateTime lowerLimit = new DateTime(1, 1, 1, 0, 0, 0, 0, chrono);
chrono = new IslamicChronology(
LimitChronology.getInstance(chrono, lowerLimit, null),
null, leapYears);
} else {
chrono = getInstance(DateTimeZone.UTC, leapYears);
chrono = new IslamicChronology
(ZonedChronology.getInstance(chrono, zone), null, leapYears);
}
chronos[leapYears.index] = chrono;
}
}
}
return chrono;
}
// Constructors and instance variables
//-----------------------------------------------------------------------
/**
* Restricted constructor.
*/
IslamicChronology(Chronology base, Object param, LeapYearPatternType leapYears) {
super(base, param, 4);
this.iLeapYears = leapYears;
}
/**
* Serialization singleton.
*/
private Object readResolve() {
Chronology base = getBase();
return base == null ? getInstanceUTC() : getInstance(base.getZone());
}
//-----------------------------------------------------------------------
/**
* Gets the leap year pattern type.
*
* @return the pattern type
*/
public LeapYearPatternType getLeapYearPatternType() {
return iLeapYears;
}
// Conversion
//-----------------------------------------------------------------------
/**
* Gets the Chronology in the UTC time zone.
*
* @return the chronology in UTC
*/
public Chronology withUTC() {
return INSTANCE_UTC;
}
/**
* Gets the Chronology in a specific time zone.
*
* @param zone the zone to get the chronology in, null is default
* @return the chronology
*/
public Chronology withZone(DateTimeZone zone) {
if (zone == null) {
zone = DateTimeZone.getDefault();
}
if (zone == getZone()) {
return this;
}
return getInstance(zone);
}
//-----------------------------------------------------------------------
/**
* Checks if this chronology instance equals another.
*
* @param obj the object to compare to
* @return true if equal
* @since 2.3
*/
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj instanceof IslamicChronology) {
IslamicChronology chrono = (IslamicChronology) obj;
return getLeapYearPatternType().index == chrono.getLeapYearPatternType().index &&
super.equals(obj);
}
return false;
}
/**
* A suitable hash code for the chronology.
*
* @return the hash code
* @since 1.6
*/
public int hashCode() {
return super.hashCode() * 13 + getLeapYearPatternType().hashCode();
}
//-----------------------------------------------------------------------
int getYear(long instant) {
long millisIslamic = instant - MILLIS_YEAR_1;
long cycles = millisIslamic / MILLIS_PER_CYCLE;
long cycleRemainder = millisIslamic % MILLIS_PER_CYCLE;
int year = (int) ((cycles * CYCLE) + 1L);
long yearMillis = (isLeapYear(year) ? MILLIS_PER_LONG_YEAR : MILLIS_PER_SHORT_YEAR);
while (cycleRemainder >= yearMillis) {
cycleRemainder -= yearMillis;
yearMillis = (isLeapYear(++year) ? MILLIS_PER_LONG_YEAR : MILLIS_PER_SHORT_YEAR);
}
return year;
}
long setYear(long instant, int year) {
// optimsed implementation of set, due to fixed months
int thisYear = getYear(instant);
int dayOfYear = getDayOfYear(instant, thisYear);
int millisOfDay = getMillisOfDay(instant);
// Current year is leap, and day is leap.
if (dayOfYear > 354 && !isLeapYear(year)) {
// Moving to a non-leap year, leap day doesn't exist.
dayOfYear--;
}
instant = getYearMonthDayMillis(year, 1, dayOfYear);
instant += millisOfDay;
return instant;
}
//-----------------------------------------------------------------------
long getYearDifference(long minuendInstant, long subtrahendInstant) {
// optimsed implementation of getDifference, due to fixed months
int minuendYear = getYear(minuendInstant);
int subtrahendYear = getYear(subtrahendInstant);
// Inlined remainder method to avoid duplicate calls to get.
long minuendRem = minuendInstant - getYearMillis(minuendYear);
long subtrahendRem = subtrahendInstant - getYearMillis(subtrahendYear);
int difference = minuendYear - subtrahendYear;
if (minuendRem < subtrahendRem) {
difference--;
}
return difference;
}
//-----------------------------------------------------------------------
long getTotalMillisByYearMonth(int year, int month) {
if (--month % 2 == 1) {
month /= 2;
return month * MILLIS_PER_MONTH_PAIR + MILLIS_PER_LONG_MONTH;
} else {
month /= 2;
return month * MILLIS_PER_MONTH_PAIR;
}
}
//-----------------------------------------------------------------------
int getDayOfMonth(long millis) {
// optimised for simple months
int doy = getDayOfYear(millis) - 1;
if (doy == 354) {
return 30;
}
return (doy % MONTH_PAIR_LENGTH) % LONG_MONTH_LENGTH + 1;
}
//-----------------------------------------------------------------------
boolean isLeapYear(int year) {
return iLeapYears.isLeapYear(year);
}
//-----------------------------------------------------------------------
int getDaysInYearMax() {
return 355;
}
//-----------------------------------------------------------------------
int getDaysInYear(int year) {
return isLeapYear(year) ? 355 : 354;
}
//-----------------------------------------------------------------------
int getDaysInYearMonth(int year, int month) {
if (month == 12 && isLeapYear(year)) {
return LONG_MONTH_LENGTH;
}
return (--month % 2 == 0 ? LONG_MONTH_LENGTH : SHORT_MONTH_LENGTH);
}
//-----------------------------------------------------------------------
int getDaysInMonthMax() {
return LONG_MONTH_LENGTH;
}
//-----------------------------------------------------------------------
int getDaysInMonthMax(int month) {
if (month == 12) {
return LONG_MONTH_LENGTH;
}
return (--month % 2 == 0 ? LONG_MONTH_LENGTH : SHORT_MONTH_LENGTH);
}
//-----------------------------------------------------------------------
int getMonthOfYear(long millis, int year) {
int doyZeroBased = (int) ((millis - getYearMillis(year)) / DateTimeConstants.MILLIS_PER_DAY);
if (doyZeroBased == 354) {
return 12;
}
return ((doyZeroBased * 2) / MONTH_PAIR_LENGTH) + 1;
// return (int) (doyZeroBased / 29.9f) + 1;
//
// int monthPairZeroBased = doyZeroBased / MONTH_PAIR_LENGTH;
// int monthPairRemainder = doyZeroBased % MONTH_PAIR_LENGTH;
// return (monthPairZeroBased * 2) + 1 + (monthPairRemainder >= LONG_MONTH_LENGTH ? 1 : 0);
}
//-----------------------------------------------------------------------
long getAverageMillisPerYear() {
return MILLIS_PER_YEAR;
}
//-----------------------------------------------------------------------
long getAverageMillisPerYearDividedByTwo() {
return MILLIS_PER_YEAR / 2;
}
//-----------------------------------------------------------------------
long getAverageMillisPerMonth() {
return MILLIS_PER_MONTH;
}
//-----------------------------------------------------------------------
long calculateFirstDayOfYearMillis(int year) {
if (year > MAX_YEAR) {
throw new ArithmeticException("Year is too large: " + year + " > " + MAX_YEAR);
}
if (year < MIN_YEAR) {
throw new ArithmeticException("Year is too small: " + year + " < " + MIN_YEAR);
}
// Java epoch is 1970-01-01 Gregorian which is 0622-07-16 Islamic.
// 0001-01-01 Islamic is -42520809600000L
// would prefer to calculate against year zero, but leap year
// can be in that year so it doesn't work
year--;
long cycle = year / CYCLE;
long millis = MILLIS_YEAR_1 + cycle * MILLIS_PER_CYCLE;
int cycleRemainder = (year % CYCLE) + 1;
for (int i = 1; i < cycleRemainder; i++) {
millis += (isLeapYear(i) ? MILLIS_PER_LONG_YEAR : MILLIS_PER_SHORT_YEAR);
}
return millis;
}
//-----------------------------------------------------------------------
int getMinYear() {
return 1; //MIN_YEAR;
}
//-----------------------------------------------------------------------
int getMaxYear() {
return MAX_YEAR;
}
//-----------------------------------------------------------------------
long getApproxMillisAtEpochDividedByTwo() {
// Epoch 1970-01-01 ISO = 1389-10-22 Islamic
return (-MILLIS_YEAR_1) / 2;
}
//-----------------------------------------------------------------------
protected void assemble(Fields fields) {
if (getBase() == null) {
super.assemble(fields);
fields.era = ERA_FIELD;
fields.monthOfYear = new BasicMonthOfYearDateTimeField(this, 12);
fields.months = fields.monthOfYear.getDurationField();
}
}
//-----------------------------------------------------------------------
/**
* Opaque object describing a leap year pattern for the Islamic Chronology.
*
* @since 1.2
*/
public static class LeapYearPatternType implements Serializable {
/** Serialization lock */
private static final long serialVersionUID = 26581275372698L;
// /** Leap year raw data encoded into bits. */
// private static final int[][] LEAP_YEARS = {
// {2, 5, 7, 10, 13, 15, 18, 21, 24, 26, 29}, // 623158436
// {2, 5, 7, 10, 13, 16, 18, 21, 24, 26, 29}, // 623191204
// {2, 5, 8, 10, 13, 16, 19, 21, 24, 27, 29}, // 690562340
// {0, 2, 5, 8, 11, 13, 16, 19, 21, 24, 27}, // 153692453
// };
/** The index. */
final byte index;
/** The leap year pattern, a bit-based 1=true pattern. */
final int pattern;
/**
* Constructor.
* This constructor takes a bit pattern where bits 0-29 correspond
* to years 0-29 in the 30 year Islamic cycle of years. This allows
* a highly efficient lookup by bit-matching.
*
* @param index the index
* @param pattern the bit pattern
*/
LeapYearPatternType(int index, int pattern) {
super();
this.index = (byte) index;
this.pattern = pattern;
}
/**
* Is the year a leap year.
* @param year the year to query
* @return true if leap
*/
boolean isLeapYear(int year) {
int key = 1 << (year % 30);
return ((pattern & key) > 0);
}
/**
* Ensure a singleton is returned if possible.
* @return the singleton instance
*/
private Object readResolve() {
switch (index) {
case 0:
return LEAP_YEAR_15_BASED;
case 1:
return LEAP_YEAR_16_BASED;
case 2:
return LEAP_YEAR_INDIAN;
case 3:
return LEAP_YEAR_HABASH_AL_HASIB;
default:
return this;
}
}
@Override
public boolean equals(Object obj) {
if (obj instanceof LeapYearPatternType) {
return index == ((LeapYearPatternType) obj).index;
}
return false;
}
@Override
public int hashCode() {
return index;
}
}
}