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.BinaryFunction;
22 import org.apache.commons.functor.BinaryProcedure;
23 import org.apache.commons.lang3.Validate;
24
25 /**
26 * Adapts a
27 * {@link BinaryProcedure BinaryProcedure}
28 * to the
29 * {@link BinaryFunction BinaryFunction} interface
30 * by always returning <code>null</code>.
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 procedure is. Attempts to serialize
36 * an instance whose delegate is not
37 * <code>Serializable</code> will result in an exception.
38 *
39 * @param <L> the left argument type.
40 * @param <R> the right argument type.
41 * @param <T> the returned value type.
42 * @version $Revision: 1365377 $ $Date: 2012-07-24 21:59:23 -0300 (Tue, 24 Jul 2012) $
43 */
44 public final class BinaryProcedureBinaryFunction<L, R, T> implements BinaryFunction<L, R, T>, Serializable {
45 /**
46 * serialVersionUID declaration.
47 */
48 private static final long serialVersionUID = 2099210273403668624L;
49 /** The {@link BinaryProcedure BinaryProcedure} I'm wrapping. */
50 private final BinaryProcedure<? super L, ? super R> procedure;
51
52 /**
53 * Create a new BinaryProcedureBinaryFunction.
54 * @param procedure to adapt as a BinaryFunction
55 */
56 public BinaryProcedureBinaryFunction(BinaryProcedure<? super L, ? super R> procedure) {
57 this.procedure = Validate.notNull(procedure, "BinaryProcedure argument was null");
58 }
59
60 /**
61 * {@inheritDoc}
62 */
63 public T evaluate(L left, R right) {
64 procedure.run(left, right);
65 return null;
66 }
67
68 /**
69 * {@inheritDoc}
70 */
71 @Override
72 public boolean equals(Object that) {
73 return that == this || (that instanceof BinaryProcedureBinaryFunction<?, ?, ?>
74 && equals((BinaryProcedureBinaryFunction<?, ?, ?>) that));
75 }
76
77 /**
78 * Learn whether another BinaryProcedureBinaryFunction is equal to this.
79 * @param that the BinaryProcedureBinaryFunction to test
80 * @return boolean
81 */
82 public boolean equals(BinaryProcedureBinaryFunction<?, ?, ?> that) {
83 return null != that && procedure.equals(that.procedure);
84 }
85
86 /**
87 * {@inheritDoc}
88 */
89 @Override
90 public int hashCode() {
91 int hash = "BinaryProcedureBinaryFunction".hashCode();
92 hash ^= procedure.hashCode();
93 return hash;
94 }
95
96 /**
97 * {@inheritDoc}
98 */
99 @Override
100 public String toString() {
101 return "BinaryProcedureBinaryFunction<" + procedure + ">";
102 }
103
104 /**
105 * Adapt the given, possibly-<code>null</code>,
106 * {@link BinaryProcedure BinaryProcedure} to the
107 * {@link BinaryFunction BinaryFunction} interface.
108 * When the given <code>BinaryProcedure</code> is <code>null</code>,
109 * returns <code>null</code>.
110 *
111 * @param <L> the left argument type.
112 * @param <R> the right argument type.
113 * @param <T> the returned value type.
114 * @param procedure the possibly-<code>null</code>
115 * {@link BinaryFunction BinaryFunction} to adapt
116 * @return a <code>BinaryProcedureBinaryFunction</code> wrapping the given
117 * {@link BinaryFunction BinaryFunction}, or <code>null</code>
118 * if the given <code>BinaryFunction</code> is <code>null</code>
119 */
120 public static <L, R, T> BinaryProcedureBinaryFunction<L, R, T> adapt(
121 BinaryProcedure<? super L, ? super R> procedure) {
122 return null == procedure ? null : new BinaryProcedureBinaryFunction<L, R, T>(procedure);
123 }
124
125 }