/*
* Copyright 2001-2005 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.goda.time.chrono;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;
import org.goda.time.Chronology;
import org.goda.time.DateTimeFieldType;
import org.goda.time.DateTimeZone;
import org.goda.time.field.DividedDateTimeField;
import org.goda.time.field.RemainderDateTimeField;
/**
* Implements a chronology that follows the rules of the ISO8601 standard,
* which is compatible with Gregorian for all modern dates.
* When ISO does not define a field, but it can be determined (such as AM/PM)
* it is included.
* <p>
* With the exception of century related fields, ISOChronology is exactly the
* same as {@link GregorianChronology}. In this chronology, centuries and year
* of century are zero based. For all years, the century is determined by
* dropping the last two digits of the year, ignoring sign. The year of century
* is the value of the last two year digits.
* <p>
* ISOChronology is thread-safe and immutable.
*
* @author Stephen Colebourne
* @author Brian S O'Neill
* @since 1.0
*/
public final class ISOChronology extends AssembledChronology {
/** Serialization lock */
private static final long serialVersionUID = -6212696554273812441L;
/** Singleton instance of a UTC ISOChronology */
private static final ISOChronology INSTANCE_UTC;
private static final int FAST_CACHE_SIZE = 64;
/** Fast cache of zone to chronology */
private static final ISOChronology[] cFastCache;
/** Cache of zone to chronology */
private static final Map<DateTimeZone, Chronology> cCache = new HashMap<DateTimeZone, Chronology>();
static {
cFastCache = new ISOChronology[FAST_CACHE_SIZE];
INSTANCE_UTC = new ISOChronology(GregorianChronology.getInstanceUTC());
cCache.put(DateTimeZone.UTC, INSTANCE_UTC);
}
/**
* Gets an instance of the ISOChronology.
* The time zone of the returned instance is UTC.
*
* @return a singleton UTC instance of the chronology
*/
public static ISOChronology getInstanceUTC() {
return INSTANCE_UTC;
}
/**
* Gets an instance of the ISOChronology in the default time zone.
*
* @return a chronology in the default time zone
*/
public static ISOChronology getInstance() {
return getInstance(DateTimeZone.getDefault());
}
/**
* Gets an instance of the ISOChronology 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 ISOChronology getInstance(DateTimeZone zone) {
if (zone == null) {
zone = DateTimeZone.getDefault();
}
int index = System.identityHashCode(zone) & (FAST_CACHE_SIZE - 1);
ISOChronology chrono = cFastCache[index];
if (chrono != null && chrono.getZone() == zone) {
return chrono;
}
synchronized (cCache) {
chrono = (ISOChronology) cCache.get(zone);
if (chrono == null) {
chrono = new ISOChronology(ZonedChronology.getInstance(INSTANCE_UTC, zone));
cCache.put(zone, chrono);
}
}
cFastCache[index] = chrono;
return chrono;
}
// Constructors and instance variables
//-----------------------------------------------------------------------
/**
* Restricted constructor
*/
private ISOChronology(Chronology base) {
super(base, null);
}
// 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);
}
// Output
//-----------------------------------------------------------------------
/**
* Gets a debugging toString.
*
* @return a debugging string
*/
public String toString() {
String str = "ISOChronology";
DateTimeZone zone = getZone();
if (zone != null) {
str = str + '[' + zone.getID() + ']';
}
return str;
}
protected void assemble(Fields fields) {
if (getBase().getZone() == DateTimeZone.UTC) {
// Use zero based century and year of century.
fields.centuryOfEra = new DividedDateTimeField(
ISOYearOfEraDateTimeField.INSTANCE, DateTimeFieldType.centuryOfEra(), 100);
fields.yearOfCentury = new RemainderDateTimeField(
(DividedDateTimeField) fields.centuryOfEra, DateTimeFieldType.yearOfCentury());
fields.weekyearOfCentury = new RemainderDateTimeField(
(DividedDateTimeField) fields.centuryOfEra, DateTimeFieldType.weekyearOfCentury());
fields.centuries = fields.centuryOfEra.getDurationField();
}
}
/**
* Serialize ISOChronology instances using a small stub. This reduces the
* serialized size, and deserialized instances come from the cache.
*/
private Object writeReplace() {
return new Stub(getZone());
}
private static final class Stub implements Serializable {
private static final long serialVersionUID = -6212696554273812441L;
private transient DateTimeZone iZone;
Stub(DateTimeZone zone) {
iZone = zone;
}
private Object readResolve() {
return ISOChronology.getInstance(iZone);
}
// private void writeObject(ObjectOutputStream out) throws IOException {
// out.writeObject(iZone);
// }
//
// private void readObject(ObjectInputStream in)
// throws IOException, ClassNotFoundException
// {
// iZone = (DateTimeZone)in.readObject();
// }
}
}