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.Predicate;
22 import org.apache.commons.functor.UnaryPredicate;
23 import org.apache.commons.lang3.Validate;
24
25 /**
26 * Adapts a
27 * {@link Predicate Predicate}
28 * to the
29 * {@link UnaryPredicate UnaryPredicate} interface
30 * by ignoring the given argument.
31 * <p/>
32 * Note that although this class implements
33 * {@link Serializable}, a given instance will
34 * only be truly <code>Serializable</code> if the
35 * underlying functor is. Attempts to serialize
36 * an instance whose delegate is not
37 * <code>Serializable</code> will result in an exception.
38 *
39 * @param <A> the argument type.
40 * @version $Revision: 1365377 $ $Date: 2012-07-24 21:59:23 -0300 (Tue, 24 Jul 2012) $
41 */
42 public final class PredicateUnaryPredicate<A> implements UnaryPredicate<A>, Serializable {
43 /**
44 * serialVersionUID declaration.
45 */
46 private static final long serialVersionUID = -5168896606842881702L;
47 /** The {@link Predicate Predicate} I'm wrapping. */
48 private final Predicate predicate;
49
50 /**
51 * Create a new PredicateUnaryPredicate.
52 * @param predicate to adapt
53 */
54 public PredicateUnaryPredicate(Predicate predicate) {
55 this.predicate = Validate.notNull(predicate, "Predicate argument was null");
56 }
57
58 /**
59 * {@inheritDoc}
60 */
61 public boolean test(Object obj) {
62 return predicate.test();
63 }
64
65 /**
66 * {@inheritDoc}
67 */
68 @Override
69 public boolean equals(Object that) {
70 return that == this || (that instanceof PredicateUnaryPredicate<?>
71 && equals((PredicateUnaryPredicate<?>) that));
72 }
73
74 /**
75 * Learn whether a given PredicateUnaryPredicate is equal to this.
76 * @param that PredicateUnaryPredicate to test
77 * @return boolean
78 */
79 public boolean equals(PredicateUnaryPredicate<?> that) {
80 return null != that && predicate.equals(that.predicate);
81 }
82
83 /**
84 * {@inheritDoc}
85 */
86 @Override
87 public int hashCode() {
88 int hash = "PredicateUnaryPredicate".hashCode();
89 hash ^= predicate.hashCode();
90 return hash;
91 }
92
93 /**
94 * {@inheritDoc}
95 */
96 @Override
97 public String toString() {
98 return "PredicateUnaryPredicate<" + predicate + ">";
99 }
100
101 /**
102 * Adapt a Predicate to the UnaryPredicate interface.
103 * @param <A> the argument type.
104 * @param predicate to adapt
105 * @return PredicateUnaryPredicate<A>
106 */
107 public static <A> PredicateUnaryPredicate<A> adapt(Predicate predicate) {
108 return null == predicate ? null : new PredicateUnaryPredicate<A>(predicate);
109 }
110
111 }