/*
* Copyright 2001-2013 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.field;
import org.joda.time.DateTimeFieldType;
import org.joda.time.DurationField;
import org.joda.time.DurationFieldType;
/**
* Abstract datetime field class that defines its own DurationField, which
* delegates back into this ImpreciseDateTimeField.
* <p>
* This DateTimeField is useful for defining DateTimeFields that are composed
* of imprecise durations. If both duration fields are precise, then a
* {@link PreciseDateTimeField} should be used instead.
* <p>
* When defining imprecise DateTimeFields where a matching DurationField is
* already available, just extend BaseDateTimeField directly so as not to
* create redundant DurationField instances.
* <p>
* ImpreciseDateTimeField is thread-safe and immutable, and its subclasses must
* be as well.
*
* @author Brian S O'Neill
* @see PreciseDateTimeField
* @since 1.0
*/
public abstract class ImpreciseDateTimeField extends BaseDateTimeField {
@SuppressWarnings("unused")
private static final long serialVersionUID = 7190739608550251860L;
final long iUnitMillis;
private final DurationField iDurationField;
/**
* Constructor.
*
* @param type the field type
* @param unitMillis the average duration unit milliseconds
*/
public ImpreciseDateTimeField(DateTimeFieldType type, long unitMillis) {
super(type);
iUnitMillis = unitMillis;
iDurationField = new LinkedDurationField(type.getDurationType());
}
public abstract int get(long instant);
public abstract long set(long instant, int value);
public abstract long add(long instant, int value);
public abstract long add(long instant, long value);
/**
* Computes the difference between two instants, as measured in the units
* of this field. Any fractional units are dropped from the result. Calling
* getDifference reverses the effect of calling add. In the following code:
*
* <pre>
* long instant = ...
* int v = ...
* int age = getDifference(add(instant, v), instant);
* </pre>
*
* The value 'age' is the same as the value 'v'.
* <p>
* The default implementation call getDifferenceAsLong and converts the
* return value to an int.
*
* @param minuendInstant the milliseconds from 1970-01-01T00:00:00Z to
* subtract from
* @param subtrahendInstant the milliseconds from 1970-01-01T00:00:00Z to
* subtract off the minuend
* @return the difference in the units of this field
*/
public int getDifference(long minuendInstant, long subtrahendInstant) {
return FieldUtils.safeToInt(getDifferenceAsLong(minuendInstant, subtrahendInstant));
}
/**
* Computes the difference between two instants, as measured in the units
* of this field. Any fractional units are dropped from the result. Calling
* getDifference reverses the effect of calling add. In the following code:
*
* <pre>
* long instant = ...
* long v = ...
* long age = getDifferenceAsLong(add(instant, v), instant);
* </pre>
*
* The value 'age' is the same as the value 'v'.
* <p>
* The default implementation performs a guess-and-check algorithm using
* getDurationField().getUnitMillis() and the add() method. Subclasses are
* encouraged to provide a more efficient implementation.
*
* @param minuendInstant the milliseconds from 1970-01-01T00:00:00Z to
* subtract from
* @param subtrahendInstant the milliseconds from 1970-01-01T00:00:00Z to
* subtract off the minuend
* @return the difference in the units of this field
*/
public long getDifferenceAsLong(long minuendInstant, long subtrahendInstant) {
if (minuendInstant < subtrahendInstant) {
return -getDifferenceAsLong(subtrahendInstant, minuendInstant);
}
long difference = (minuendInstant - subtrahendInstant) / iUnitMillis;
if (add(subtrahendInstant, difference) < minuendInstant) {
do {
difference++;
} while (add(subtrahendInstant, difference) <= minuendInstant);
difference--;
} else if (add(subtrahendInstant, difference) > minuendInstant) {
do {
difference--;
} while (add(subtrahendInstant, difference) > minuendInstant);
}
return difference;
}
public final DurationField getDurationField() {
return iDurationField;
}
public abstract DurationField getRangeDurationField();
public abstract long roundFloor(long instant);
protected final long getDurationUnitMillis() {
return iUnitMillis;
}
private final class LinkedDurationField extends BaseDurationField {
private static final long serialVersionUID = -203813474600094134L;
LinkedDurationField(DurationFieldType type) {
super(type);
}
public boolean isPrecise() {
return false;
}
public long getUnitMillis() {
return iUnitMillis;
}
public int getValue(long duration, long instant) {
return ImpreciseDateTimeField.this
.getDifference(instant + duration, instant);
}
public long getValueAsLong(long duration, long instant) {
return ImpreciseDateTimeField.this
.getDifferenceAsLong(instant + duration, instant);
}
public long getMillis(int value, long instant) {
return ImpreciseDateTimeField.this.add(instant, value) - instant;
}
public long getMillis(long value, long instant) {
return ImpreciseDateTimeField.this.add(instant, value) - instant;
}
public long add(long instant, int value) {
return ImpreciseDateTimeField.this.add(instant, value);
}
public long add(long instant, long value) {
return ImpreciseDateTimeField.this.add(instant, value);
}
public int getDifference(long minuendInstant, long subtrahendInstant) {
return ImpreciseDateTimeField.this
.getDifference(minuendInstant, subtrahendInstant);
}
public long getDifferenceAsLong(long minuendInstant, long subtrahendInstant) {
return ImpreciseDateTimeField.this
.getDifferenceAsLong(minuendInstant, subtrahendInstant);
}
}
}