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.Predicate;
23 import org.apache.commons.lang3.Validate;
24
25 /**
26 * Adapts a
27 * {@link BinaryPredicate BinaryPredicate}
28 * to the
29 * {@link org.apache.commons.functor.UnaryPredicate UnaryPredicate} interface
30 * using a constant left-side 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 objects are. Attempts to serialize
36 * an instance whose delegates are not
37 * <code>Serializable</code> will result in an exception.
38 *
39 * @version $Revision: 1365377 $ $Date: 2012-07-24 21:59:23 -0300 (Tue, 24 Jul 2012) $
40 */
41 public final class FullyBoundPredicate implements Predicate, Serializable {
42
43 /**
44 * serialVersionUID declaration.
45 */
46 private static final long serialVersionUID = 7676235030688391839L;
47 /** The {@link BinaryPredicate BinaryPredicate} I'm wrapping. */
48 private final BinaryPredicate<Object, Object> predicate;
49 /** The left parameter to pass to {@code predicate}. */
50 private final Object left;
51 /** The right parameter to pass to {@code predicate}. */
52 private final Object right;
53
54 /**
55 * Create a new FullyBoundPredicate instance.
56 * @param <L> left type
57 * @param <R> right type
58 * @param predicate the predicate to adapt
59 * @param left the left argument to use
60 * @param right the right argument to use
61 */
62 @SuppressWarnings("unchecked")
63 public <L, R> FullyBoundPredicate(BinaryPredicate<? super L, ? super R> predicate, L left, R right) {
64 this.predicate =
65 (BinaryPredicate<Object, Object>) Validate.notNull(predicate,
66 "BinaryPredicate argument was null");
67 this.left = left;
68 this.right = right;
69 }
70
71 /**
72 * {@inheritDoc}
73 */
74 public boolean test() {
75 return predicate.test(left, right);
76 }
77
78 /**
79 * {@inheritDoc}
80 */
81 @Override
82 public boolean equals(Object that) {
83 return that == this || (that instanceof FullyBoundPredicate && equals((FullyBoundPredicate) that));
84 }
85
86 /**
87 * Learn whether another FullyBoundPredicate is equal to this.
88 * @param that FullyBoundPredicate to test
89 * @return boolean
90 */
91 public boolean equals(FullyBoundPredicate that) {
92 return null != that && predicate.equals(that.predicate)
93 && (null == left ? null == that.left : left.equals(that.left))
94 && (null == right ? null == that.right : right.equals(that.right));
95 }
96
97 /**
98 * {@inheritDoc}
99 */
100 @Override
101 public int hashCode() {
102 int hash = "FullyBoundPredicate".hashCode();
103 hash <<= 2;
104 hash ^= predicate.hashCode();
105 hash <<= 2;
106 if (null != left) {
107 hash ^= left.hashCode();
108 }
109 hash <<= 2;
110 if (null != right) {
111 hash ^= right.hashCode();
112 }
113 return hash;
114 }
115
116 /**
117 * {@inheritDoc}
118 */
119 @Override
120 public String toString() {
121 return "FullyBoundPredicate<" + predicate + "(" + left + ", " + right + ")>";
122 }
123
124 /**
125 * Adapt a BinaryPredicate to the Predicate interface.
126 * @param predicate to adapt
127 * @param <L> left type
128 * @param <R> right type
129 * @param left L argument to always send as the left operand to the wrapped function
130 * @param right R argument to always send as the right operand to the wrapped function
131 * @return FullyBoundPredicate
132 */
133 public static <L, R> FullyBoundPredicate bind(
134 BinaryPredicate<? super L, ? super R> predicate, L left, R right) {
135 return null == predicate ? null : new FullyBoundPredicate(predicate, left, right);
136 }
137 }