001/*
002 *  Copyright 2001-2005 Stephen Colebourne
003 *
004 *  Licensed under the Apache License, Version 2.0 (the "License");
005 *  you may not use this file except in compliance with the License.
006 *  You may obtain a copy of the License at
007 *
008 *      http://www.apache.org/licenses/LICENSE-2.0
009 *
010 *  Unless required by applicable law or agreed to in writing, software
011 *  distributed under the License is distributed on an "AS IS" BASIS,
012 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 *  See the License for the specific language governing permissions and
014 *  limitations under the License.
015 */
016package org.joda.time.field;
017
018import org.joda.time.DurationFieldType;
019
020/**
021 * Duration field class representing a field with a fixed unit length.
022 * <p>
023 * PreciseDurationField is thread-safe and immutable.
024 * 
025 * @author Stephen Colebourne
026 * @author Brian S O'Neill
027 * @since 1.0
028 */
029public class PreciseDurationField extends BaseDurationField {
030    
031    private static final long serialVersionUID = -8346152187724495365L;
032
033    /** The size of the unit */
034    private final long iUnitMillis;
035
036    /**
037     * Constructor.
038     * 
039     * @param type  the field type
040     * @param unitMillis  the unit milliseconds
041     */    
042    public PreciseDurationField(DurationFieldType type, long unitMillis) {
043        super(type);
044        iUnitMillis = unitMillis;
045    }
046    
047    //------------------------------------------------------------------------
048    /**
049     * This field is precise.
050     * 
051     * @return true always
052     */
053    public final boolean isPrecise() {
054        return true;
055    }
056    
057    /**
058     * Returns the amount of milliseconds per unit value of this field.
059     *
060     * @return the unit size of this field, in milliseconds
061     */
062    public final long getUnitMillis() {
063        return iUnitMillis;
064    }
065
066    //------------------------------------------------------------------------
067    /**
068     * Get the value of this field from the milliseconds.
069     * 
070     * @param duration  the milliseconds to query, which may be negative
071     * @param instant  ignored
072     * @return the value of the field, in the units of the field, which may be
073     * negative
074     */
075    public long getValueAsLong(long duration, long instant) {
076        return duration / iUnitMillis;  // safe
077    }
078
079    /**
080     * Get the millisecond duration of this field from its value.
081     * 
082     * @param value  the value of the field, which may be negative
083     * @param instant  ignored
084     * @return the milliseconds that the field represents, which may be
085     * negative
086     */
087    public long getMillis(int value, long instant) {
088        return value * iUnitMillis;  // safe
089    }
090
091    /**
092     * Get the millisecond duration of this field from its value.
093     * 
094     * @param value  the value of the field, which may be negative
095     * @param instant  ignored
096     * @return the milliseconds that the field represents, which may be
097     * negative
098     */
099    public long getMillis(long value, long instant) {
100        return FieldUtils.safeMultiply(value, iUnitMillis);
101    }
102
103    public long add(long instant, int value) {
104        long addition = value * iUnitMillis;  // safe
105        return FieldUtils.safeAdd(instant, addition);
106    }
107
108    public long add(long instant, long value) {
109        long addition = FieldUtils.safeMultiply(value, iUnitMillis);
110        return FieldUtils.safeAdd(instant, addition);
111    }
112
113    public long getDifferenceAsLong(long minuendInstant, long subtrahendInstant) {
114        long difference = FieldUtils.safeSubtract(minuendInstant, subtrahendInstant);
115        return difference / iUnitMillis;
116    }
117
118    //-----------------------------------------------------------------------
119    /**
120     * Compares this duration field to another.
121     * Two fields are equal if of the same type and duration.
122     * 
123     * @param obj  the object to compare to
124     * @return if equal
125     */
126    public boolean equals(Object obj) {
127        if (this == obj) {
128            return true;
129        } else if (obj instanceof PreciseDurationField) {
130            PreciseDurationField other = (PreciseDurationField) obj;
131            return (getType() == other.getType()) && (iUnitMillis == other.iUnitMillis);
132        }
133        return false;
134    }
135
136    /**
137     * Gets a hash code for this instance.
138     * 
139     * @return a suitable hashcode
140     */
141    public int hashCode() {
142        long millis = iUnitMillis;
143        int hash = (int) (millis ^ (millis >>> 32));
144        hash += getType().hashCode();
145        return hash;
146    }
147
148}