001 /*
002 * Copyright (C) 2010 The Guava Authors
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 */
016
017 package com.google.common.collect;
018
019 import com.google.common.annotations.Beta;
020 import com.google.common.annotations.GwtCompatible;
021
022 import java.io.Serializable;
023 import java.math.BigInteger;
024
025 /**
026 * Factories for common {@link DiscreteDomain} instances.
027 *
028 * <p>See the Guava User Guide section on <a href=
029 * "http://code.google.com/p/guava-libraries/wiki/RangesExplained#Discrete_Domains">
030 * {@code DiscreteDomain}</a>.
031 *
032 * @author Gregory Kick
033 * @since 10.0
034 */
035 @GwtCompatible
036 @Beta
037 public final class DiscreteDomains {
038 private DiscreteDomains() {}
039
040 /**
041 * Returns the discrete domain for values of type {@code Integer}.
042 */
043 public static DiscreteDomain<Integer> integers() {
044 return IntegerDomain.INSTANCE;
045 }
046
047 private static final class IntegerDomain extends DiscreteDomain<Integer>
048 implements Serializable {
049 private static final IntegerDomain INSTANCE = new IntegerDomain();
050
051 @Override public Integer next(Integer value) {
052 int i = value;
053 return (i == Integer.MAX_VALUE) ? null : i + 1;
054 }
055
056 @Override public Integer previous(Integer value) {
057 int i = value;
058 return (i == Integer.MIN_VALUE) ? null : i - 1;
059 }
060
061 @Override public long distance(Integer start, Integer end) {
062 return (long) end - start;
063 }
064
065 @Override public Integer minValue() {
066 return Integer.MIN_VALUE;
067 }
068
069 @Override public Integer maxValue() {
070 return Integer.MAX_VALUE;
071 }
072
073 private Object readResolve() {
074 return INSTANCE;
075 }
076
077 private static final long serialVersionUID = 0;
078 }
079
080 /**
081 * Returns the discrete domain for values of type {@code Long}.
082 */
083 public static DiscreteDomain<Long> longs() {
084 return LongDomain.INSTANCE;
085 }
086
087 private static final class LongDomain extends DiscreteDomain<Long>
088 implements Serializable {
089 private static final LongDomain INSTANCE = new LongDomain();
090
091 @Override public Long next(Long value) {
092 long l = value;
093 return (l == Long.MAX_VALUE) ? null : l + 1;
094 }
095
096 @Override public Long previous(Long value) {
097 long l = value;
098 return (l == Long.MIN_VALUE) ? null : l - 1;
099 }
100
101 @Override public long distance(Long start, Long end) {
102 long result = end - start;
103 if (end > start && result < 0) { // overflow
104 return Long.MAX_VALUE;
105 }
106 if (end < start && result > 0) { // underflow
107 return Long.MIN_VALUE;
108 }
109 return result;
110 }
111
112 @Override public Long minValue() {
113 return Long.MIN_VALUE;
114 }
115
116 @Override public Long maxValue() {
117 return Long.MAX_VALUE;
118 }
119
120 private Object readResolve() {
121 return INSTANCE;
122 }
123
124 private static final long serialVersionUID = 0;
125 }
126
127 /**
128 * Returns the discrete domain for values of type {@code BigInteger}.
129 */
130 // TODO(kevinb): make sure it's tested, and make it public
131 static DiscreteDomain<BigInteger> bigIntegers() {
132 return BigIntegerDomain.INSTANCE;
133 }
134
135 private static final class BigIntegerDomain extends DiscreteDomain<BigInteger>
136 implements Serializable {
137 private static final BigIntegerDomain INSTANCE = new BigIntegerDomain();
138
139 private static final BigInteger MIN_LONG =
140 BigInteger.valueOf(Long.MIN_VALUE);
141 private static final BigInteger MAX_LONG =
142 BigInteger.valueOf(Long.MAX_VALUE);
143
144 @Override public BigInteger next(BigInteger value) {
145 return value.add(BigInteger.ONE);
146 }
147
148 @Override public BigInteger previous(BigInteger value) {
149 return value.subtract(BigInteger.ONE);
150 }
151
152 @Override public long distance(BigInteger start, BigInteger end) {
153 return start.subtract(end).max(MIN_LONG).min(MAX_LONG).longValue();
154 }
155
156 private Object readResolve() {
157 return INSTANCE;
158 }
159
160 private static final long serialVersionUID = 0;
161 }
162 }