| 1 | /* |
| 2 | * Copyright 2001-2005 Stephen Colebourne |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | package org.joda.time.field; |
| 17 | |
| 18 | import org.joda.time.DateTimeFieldType; |
| 19 | import org.joda.time.DurationField; |
| 20 | import org.joda.time.DurationFieldType; |
| 21 | |
| 22 | /** |
| 23 | * Abstract datetime field class that defines its own DurationField, which |
| 24 | * delegates back into this ImpreciseDateTimeField. |
| 25 | * <p> |
| 26 | * This DateTimeField is useful for defining DateTimeFields that are composed |
| 27 | * of imprecise durations. If both duration fields are precise, then a |
| 28 | * {@link PreciseDateTimeField} should be used instead. |
| 29 | * <p> |
| 30 | * When defining imprecise DateTimeFields where a matching DurationField is |
| 31 | * already available, just extend BaseDateTimeField directly so as not to |
| 32 | * create redundant DurationField instances. |
| 33 | * <p> |
| 34 | * ImpreciseDateTimeField is thread-safe and immutable, and its subclasses must |
| 35 | * be as well. |
| 36 | * |
| 37 | * @author Brian S O'Neill |
| 38 | * @see PreciseDateTimeField |
| 39 | * @since 1.0 |
| 40 | */ |
| 41 | public abstract class ImpreciseDateTimeField extends BaseDateTimeField { |
| 42 | |
| 43 | private static final long serialVersionUID = 7190739608550251860L; |
| 44 | |
| 45 | final long iUnitMillis; |
| 46 | private final DurationField iDurationField; |
| 47 | |
| 48 | /** |
| 49 | * Constructor. |
| 50 | * |
| 51 | * @param type the field type |
| 52 | * @param unitMillis the average duration unit milliseconds |
| 53 | */ |
| 54 | public ImpreciseDateTimeField(DateTimeFieldType type, long unitMillis) { |
| 55 | super(type); |
| 56 | iUnitMillis = unitMillis; |
| 57 | iDurationField = new LinkedDurationField(type.getDurationType()); |
| 58 | } |
| 59 | |
| 60 | public abstract int get(long instant); |
| 61 | |
| 62 | public abstract long set(long instant, int value); |
| 63 | |
| 64 | public abstract long add(long instant, int value); |
| 65 | |
| 66 | public abstract long add(long instant, long value); |
| 67 | |
| 68 | /** |
| 69 | * Computes the difference between two instants, as measured in the units |
| 70 | * of this field. Any fractional units are dropped from the result. Calling |
| 71 | * getDifference reverses the effect of calling add. In the following code: |
| 72 | * |
| 73 | * <pre> |
| 74 | * long instant = ... |
| 75 | * int v = ... |
| 76 | * int age = getDifference(add(instant, v), instant); |
| 77 | * </pre> |
| 78 | * |
| 79 | * The value 'age' is the same as the value 'v'. |
| 80 | * <p> |
| 81 | * The default implementation call getDifferenceAsLong and converts the |
| 82 | * return value to an int. |
| 83 | * |
| 84 | * @param minuendInstant the milliseconds from 1970-01-01T00:00:00Z to |
| 85 | * subtract from |
| 86 | * @param subtrahendInstant the milliseconds from 1970-01-01T00:00:00Z to |
| 87 | * subtract off the minuend |
| 88 | * @return the difference in the units of this field |
| 89 | */ |
| 90 | public int getDifference(long minuendInstant, long subtrahendInstant) { |
| 91 | return FieldUtils.safeToInt(getDifferenceAsLong(minuendInstant, subtrahendInstant)); |
| 92 | } |
| 93 | |
| 94 | /** |
| 95 | * Computes the difference between two instants, as measured in the units |
| 96 | * of this field. Any fractional units are dropped from the result. Calling |
| 97 | * getDifference reverses the effect of calling add. In the following code: |
| 98 | * |
| 99 | * <pre> |
| 100 | * long instant = ... |
| 101 | * long v = ... |
| 102 | * long age = getDifferenceAsLong(add(instant, v), instant); |
| 103 | * </pre> |
| 104 | * |
| 105 | * The value 'age' is the same as the value 'v'. |
| 106 | * <p> |
| 107 | * The default implementation performs a guess-and-check algorithm using |
| 108 | * getDurationField().getUnitMillis() and the add() method. Subclasses are |
| 109 | * encouraged to provide a more efficient implementation. |
| 110 | * |
| 111 | * @param minuendInstant the milliseconds from 1970-01-01T00:00:00Z to |
| 112 | * subtract from |
| 113 | * @param subtrahendInstant the milliseconds from 1970-01-01T00:00:00Z to |
| 114 | * subtract off the minuend |
| 115 | * @return the difference in the units of this field |
| 116 | */ |
| 117 | public long getDifferenceAsLong(long minuendInstant, long subtrahendInstant) { |
| 118 | if (minuendInstant < subtrahendInstant) { |
| 119 | return -getDifferenceAsLong(subtrahendInstant, minuendInstant); |
| 120 | } |
| 121 | |
| 122 | long difference = (minuendInstant - subtrahendInstant) / iUnitMillis; |
| 123 | if (add(subtrahendInstant, difference) < minuendInstant) { |
| 124 | do { |
| 125 | difference++; |
| 126 | } while (add(subtrahendInstant, difference) <= minuendInstant); |
| 127 | difference--; |
| 128 | } else if (add(subtrahendInstant, difference) > minuendInstant) { |
| 129 | do { |
| 130 | difference--; |
| 131 | } while (add(subtrahendInstant, difference) > minuendInstant); |
| 132 | } |
| 133 | return difference; |
| 134 | } |
| 135 | |
| 136 | public final DurationField getDurationField() { |
| 137 | return iDurationField; |
| 138 | } |
| 139 | |
| 140 | public abstract DurationField getRangeDurationField(); |
| 141 | |
| 142 | public abstract long roundFloor(long instant); |
| 143 | |
| 144 | protected final long getDurationUnitMillis() { |
| 145 | return iUnitMillis; |
| 146 | } |
| 147 | |
| 148 | private final class LinkedDurationField extends BaseDurationField { |
| 149 | private static final long serialVersionUID = -203813474600094134L; |
| 150 | |
| 151 | LinkedDurationField(DurationFieldType type) { |
| 152 | super(type); |
| 153 | } |
| 154 | |
| 155 | public boolean isPrecise() { |
| 156 | return false; |
| 157 | } |
| 158 | |
| 159 | public long getUnitMillis() { |
| 160 | return iUnitMillis; |
| 161 | } |
| 162 | |
| 163 | public int getValue(long duration, long instant) { |
| 164 | return ImpreciseDateTimeField.this |
| 165 | .getDifference(instant + duration, instant); |
| 166 | } |
| 167 | |
| 168 | public long getValueAsLong(long duration, long instant) { |
| 169 | return ImpreciseDateTimeField.this |
| 170 | .getDifferenceAsLong(instant + duration, instant); |
| 171 | } |
| 172 | |
| 173 | public long getMillis(int value, long instant) { |
| 174 | return ImpreciseDateTimeField.this.add(instant, value) - instant; |
| 175 | } |
| 176 | |
| 177 | public long getMillis(long value, long instant) { |
| 178 | return ImpreciseDateTimeField.this.add(instant, value) - instant; |
| 179 | } |
| 180 | |
| 181 | public long add(long instant, int value) { |
| 182 | return ImpreciseDateTimeField.this.add(instant, value); |
| 183 | } |
| 184 | |
| 185 | public long add(long instant, long value) { |
| 186 | return ImpreciseDateTimeField.this.add(instant, value); |
| 187 | } |
| 188 | |
| 189 | public int getDifference(long minuendInstant, long subtrahendInstant) { |
| 190 | return ImpreciseDateTimeField.this |
| 191 | .getDifference(minuendInstant, subtrahendInstant); |
| 192 | } |
| 193 | |
| 194 | public long getDifferenceAsLong(long minuendInstant, long subtrahendInstant) { |
| 195 | return ImpreciseDateTimeField.this |
| 196 | .getDifferenceAsLong(minuendInstant, subtrahendInstant); |
| 197 | } |
| 198 | } |
| 199 | |
| 200 | } |