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.Function;
22 import org.apache.commons.functor.Predicate;
23 import org.apache.commons.lang3.Validate;
24
25 /**
26 * Adapts a <code>Boolean</code>-valued
27 * {@link Function Function} to the
28 * {@link Predicate Predicate} interface.
29 * <p/>
30 * Note that although this class implements
31 * {@link Serializable}, a given instance will
32 * only be truly <code>Serializable</code> if the
33 * underlying functor is. Attempts to serialize
34 * an instance whose delegate is not
35 * <code>Serializable</code> will result in an exception.
36 *
37 * @version $Revision: 1365377 $ $Date: 2012-07-24 21:59:23 -0300 (Tue, 24 Jul 2012) $
38 */
39 public final class FunctionPredicate implements Predicate, Serializable {
40
41 /**
42 * serialVersionUID declaration.
43 */
44 private static final long serialVersionUID = 6564796937660102222L;
45 /** The {@link Function Function} I'm wrapping. */
46 private final Function<Boolean> function;
47
48 /**
49 * Create a new FunctionPredicate.
50 * @param function to adapt
51 */
52 public FunctionPredicate(Function<Boolean> function) {
53 this.function = Validate.notNull(function, "Function argument was null");
54 }
55
56 /**
57 * Returns the <code>boolean</code> value of the non-<code>null</code>
58 * <code>Boolean</code> returned by the {@link Function#evaluate evaluate}
59 * method of my underlying function.
60 * {@inheritDoc}
61 */
62 public boolean test() {
63 return function.evaluate().booleanValue();
64 }
65
66 /**
67 * {@inheritDoc}
68 */
69 @Override
70 public boolean equals(Object that) {
71 return that == this || (that instanceof FunctionPredicate && equals((FunctionPredicate) that));
72 }
73
74 /**
75 * Learn whether another FunctionPredicate is equal to this.
76 * @param that FunctionPredicate to test
77 * @return boolean
78 */
79 public boolean equals(FunctionPredicate that) {
80 return null != that && function.equals(that.function);
81 }
82
83 /**
84 * {@inheritDoc}
85 */
86 @Override
87 public int hashCode() {
88 int hash = "FunctionPredicate".hashCode();
89 hash ^= function.hashCode();
90 return hash;
91 }
92
93 /**
94 * {@inheritDoc}
95 */
96 @Override
97 public String toString() {
98 return "FunctionPredicate<" + function + ">";
99 }
100
101 /**
102 * Adapt a Function as a Predicate.
103 * @param function to adapt
104 * @return FunctionPredicate
105 */
106 public static FunctionPredicate adapt(Function<Boolean> function) {
107 return null == function ? null : new FunctionPredicate(function);
108 }
109 }