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 first 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: 1157611 $ $Date: 2011-08-14 21:45:14 +0200 (Sun, 14 Aug 2011) $
41 * @author Rodney Waldhoff
42 */
43 public final class IgnoreLeftPredicate<L, R> implements BinaryPredicate<L, R>, Serializable {
44 /**
45 * serialVersionUID declaration.
46 */
47 private static final long serialVersionUID = -3200352647509255939L;
48 /** The {@link UnaryPredicate UnaryPredicate} I'm wrapping. */
49 private final UnaryPredicate<? super R> predicate;
50
51 /**
52 * Create a new IgnoreLeftPredicate.
53 * @param predicate the right predicate
54 */
55 public IgnoreLeftPredicate(UnaryPredicate<? super R> 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(right);
67 }
68
69 /**
70 * {@inheritDoc}
71 */
72 public boolean equals(Object that) {
73 return that == this || (that instanceof IgnoreLeftPredicate<?, ?> && equals((IgnoreLeftPredicate<?, ?>) that));
74 }
75
76 /**
77 * Learn whether another IgnoreLeftPredicate is equal to this.
78 * @param that the IgnoreLeftPredicate to test
79 * @return boolean
80 */
81 public boolean equals(IgnoreLeftPredicate<?, ?> that) {
82 return null != that && (null == predicate ? null == that.predicate : predicate.equals(that.predicate));
83 }
84
85 /**
86 * {@inheritDoc}
87 */
88 public int hashCode() {
89 int hash = "IgnoreLeftPredicate".hashCode();
90 if (null != predicate) {
91 hash ^= predicate.hashCode();
92 }
93 return hash;
94 }
95
96 /**
97 * {@inheritDoc}
98 */
99 public String toString() {
100 return "IgnoreLeftPredicate<" + predicate + ">";
101 }
102
103 /**
104 * Adapt a UnaryPredicate to an IgnoreLeftPredicate.
105 * @param <L> left type
106 * @param <R> right type
107 * @param predicate to adapt
108 * @return IgnoreLeftPredicate<L, R>
109 */
110 public static <L, R> IgnoreLeftPredicate<L, R> adapt(UnaryPredicate<? super R> predicate) {
111 return null == predicate ? null : new IgnoreLeftPredicate<L, R>(predicate);
112 }
113
114 }