1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.functor.core.comparator;
18
19 import java.io.Serializable;
20 import java.util.Comparator;
21
22 import org.apache.commons.functor.BinaryPredicate;
23 import org.apache.commons.functor.UnaryPredicate;
24 import org.apache.commons.functor.adapter.RightBoundPredicate;
25
26 /**
27 * A {@link BinaryPredicate BinaryPredicate} that {@link #test tests}
28 * <code>true</code> iff the left argument is greater than or equal
29 * to the right argument under the specified {@link Comparator}.
30 * When no (or a <code>null</code> <code>Comparator</code> is specified,
31 * a {@link Comparable Comparable} <code>Comparator</code> is used.
32 *
33 * @version $Revision: 1166343 $ $Date: 2011-09-07 21:45:53 +0200 (Wed, 07 Sep 2011) $
34 * @author Rodney Waldhoff
35 */
36 public final class IsGreaterThanOrEqual<T> implements BinaryPredicate<T, T>, Serializable {
37
38 /**
39 * Basic IsGreaterThanOrEqual instance.
40 */
41 public static final IsGreaterThanOrEqual<Comparable<?>> INSTANCE = IsGreaterThanOrEqual
42 .<Comparable<?>> instance();
43
44 /**
45 * serialVersionUID declaration.
46 */
47 private static final long serialVersionUID = 5262405026444050167L;
48
49 private final Comparator<? super T> comparator;
50
51 /**
52 * Construct a <code>IsGreaterThanOrEqual</code> {@link BinaryPredicate predicate}
53 * for {@link Comparable Comparable}s.
54 */
55 @SuppressWarnings("unchecked")
56 public IsGreaterThanOrEqual() {
57 this(ComparableComparator.INSTANCE);
58 }
59
60 /**
61 * Construct a <code>IsGreaterThanOrEqual</code> {@link BinaryPredicate predicate}
62 * for the given {@link Comparator Comparator}.
63 *
64 * @param comparator the {@link Comparator Comparator}, when <code>null</code>,
65 * a <code>Comparator</code> for {@link Comparable Comparable}s will
66 * be used.
67 */
68 public IsGreaterThanOrEqual(Comparator<? super T> comparator) {
69 if (comparator == null) {
70 throw new IllegalArgumentException("Comparator argument must not be null");
71 }
72 this.comparator = comparator;
73 }
74
75 /**
76 * Return <code>true</code> iff the <i>left</i> parameter is
77 * greater than or equal to the <i>right</i> parameter under my current
78 * {@link Comparator Comparator}.
79 * {@inheritDoc}
80 */
81 public boolean test(T left, T right) {
82 return comparator.compare(left, right) >= 0;
83 }
84
85 /**
86 * {@inheritDoc}
87 */
88 public boolean equals(Object that) {
89 return that == this || (that instanceof IsGreaterThanOrEqual<?> && equals((IsGreaterThanOrEqual<?>) that));
90 }
91
92 /**
93 * Learn whether another IsGreaterThanOrEqual is equal to this.
94 * @param that IsGreaterThanOrEqual to test
95 * @return boolean
96 */
97 public boolean equals(IsGreaterThanOrEqual<?> that) {
98 if (null != that) {
99 if (null == comparator) {
100 return null == that.comparator;
101 }
102 return comparator.equals(that.comparator);
103 }
104 return false;
105 }
106
107 /**
108 * {@inheritDoc}
109 */
110 public int hashCode() {
111 int hash = "IsGreaterThanOrEqual".hashCode();
112 // by construction, comparator is never null
113 hash ^= comparator.hashCode();
114 return hash;
115 }
116
117 /**
118 * {@inheritDoc}
119 */
120 public String toString() {
121 return "IsGreaterThanOrEqual<" + comparator + ">";
122 }
123
124 /**
125 * Get a typed IsGreaterThanOrEqual instance.
126 * @param <T>
127 * @return IsGreaterThanOrEqual<T>
128 */
129 public static <T extends Comparable<?>> IsGreaterThanOrEqual<T> instance() {
130 return new IsGreaterThanOrEqual<T>();
131 }
132
133 /**
134 * Get an IsGreaterThanOrEqual UnaryPredicate.
135 * @param right the right side object of the IsGreaterThanOrEqual comparison
136 * @return UnaryPredicate
137 */
138 public static <T extends Comparable<?>> UnaryPredicate<T> instance(T right) {
139 return RightBoundPredicate.bind(new IsGreaterThanOrEqual<T>(), right);
140 }
141
142 }