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.adapter;
18
19 import java.io.Serializable;
20
21 import org.apache.commons.functor.BinaryPredicate;
22 import org.apache.commons.functor.UnaryPredicate;
23
24 /**
25 * Adapts a
26 * {@link UnaryPredicate UnaryPredicate}
27 * to the
28 * {@link BinaryPredicate BinaryPredicate} interface
29 * by ignoring the second binary argument.
30 * <p/>
31 * Note that although this class implements
32 * {@link Serializable}, a given instance will
33 * only be truly <code>Serializable</code> if the
34 * underlying functor is. Attempts to serialize
35 * an instance whose delegate is not
36 * <code>Serializable</code> will result in an exception.
37 *
38 * @param <L> the left argument type.
39 * @param <R> the right argument type.
40 * @version $Revision: 1157616 $ $Date: 2011-08-14 21:52:29 +0200 (Sun, 14 Aug 2011) $
41 * @author Rodney Waldhoff
42 */
43 public final class IgnoreRightPredicate<L, R> implements BinaryPredicate<L, R>, Serializable {
44 /**
45 * serialVersionUID declaration.
46 */
47 private static final long serialVersionUID = -4236624667788627722L;
48 /** The {@link UnaryPredicate UnaryPredicate} I'm wrapping. */
49 private final UnaryPredicate<? super L> predicate;
50
51 /**
52 * Create a new IgnoreRightPredicate.
53 * @param predicate left
54 */
55 public IgnoreRightPredicate(UnaryPredicate<? super L> predicate) {
56 if (predicate == null) {
57 throw new IllegalArgumentException("UnaryPredicate argument was null");
58 }
59 this.predicate = predicate;
60 }
61
62 /**
63 * {@inheritDoc}
64 */
65 public boolean test(L left, R right) {
66 return predicate.test(left);
67 }
68
69 /**
70 * {@inheritDoc}
71 */
72 public boolean equals(Object that) {
73 return that == this || (that instanceof IgnoreRightPredicate<?, ?>
74 && equals((IgnoreRightPredicate<?, ?>) that));
75 }
76
77 /**
78 * Learn whether a given IgnoreRightPredicate is equal to this.
79 * @param that IgnoreRightPredicate to test
80 * @return boolean
81 */
82 public boolean equals(IgnoreRightPredicate<?, ?> that) {
83 return null != that && (null == predicate ? null == that.predicate : predicate.equals(that.predicate));
84 }
85
86 /**
87 * {@inheritDoc}
88 */
89 public int hashCode() {
90 int hash = "IgnoreRightPredicate".hashCode();
91 if (null != predicate) {
92 hash ^= predicate.hashCode();
93 }
94 return hash;
95 }
96
97 /**
98 * {@inheritDoc}
99 */
100 public String toString() {
101 return "IgnoreRightPredicate<" + predicate + ">";
102 }
103
104 /**
105 * Adapt a UnaryPredicate as an IgnoreRightPredicate.
106 * @param <L> left type
107 * @param <R> right type
108 * @param predicate to adapt
109 * @return IgnoreRightPredicate<L, R>
110 */
111 public static <L, R> IgnoreRightPredicate<L, R> adapt(UnaryPredicate<? super L> predicate) {
112 return null == predicate ? null : new IgnoreRightPredicate<L, R>(predicate);
113 }
114
115 }