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.UnaryFunction;
22 import org.apache.commons.functor.UnaryProcedure;
23
24 /**
25 * Adapts a
26 * {@link UnaryProcedure UnaryProcedure}
27 * to the
28 * {@link UnaryFunction UnaryFunction} interface
29 * by always returning <code>null</code>.
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 procedure is. Attempts to serialize
35 * an instance whose delegate is not
36 * <code>Serializable</code> will result in an exception.
37 *
38 * @param <A> the argument type.
39 * @param <T> the returned value type.
40 * @version $Revision: 1157657 $ $Date: 2011-08-14 22:28:19 +0200 (Sun, 14 Aug 2011) $
41 * @author Rodney Waldhoff
42 */
43 public final class UnaryProcedureUnaryFunction<A, T> implements UnaryFunction<A, T>, Serializable {
44 /**
45 * serialVersionUID declaration.
46 */
47 private static final long serialVersionUID = 6153848695167906659L;
48 /** The {@link UnaryProcedure UnaryProcedure} I'm wrapping. */
49 private final UnaryProcedure<? super A> procedure;
50
51 /**
52 * Create a new UnaryProcedureUnaryFunction.
53 * @param procedure to adapt
54 */
55 public UnaryProcedureUnaryFunction(UnaryProcedure<? super A> procedure) {
56 if (procedure == null) {
57 throw new IllegalArgumentException("UnaryProcedure argument was null");
58 }
59 this.procedure = procedure;
60 }
61
62 /**
63 * {@inheritDoc}
64 */
65 public T evaluate(A obj) {
66 procedure.run(obj);
67 return null;
68 }
69
70 /**
71 * {@inheritDoc}
72 */
73 public boolean equals(Object that) {
74 return that == this || (that instanceof UnaryProcedureUnaryFunction<?, ?>
75 && equals((UnaryProcedureUnaryFunction<?, ?>) that));
76 }
77
78 /**
79 * Learn whether a given UnaryProcedureUnaryFunction is equal to this.
80 * @param that UnaryProcedureUnaryFunction to test
81 * @return boolean
82 */
83 public boolean equals(UnaryProcedureUnaryFunction<?, ?> that) {
84 return null != that && (null == procedure ? null == that.procedure : procedure.equals(that.procedure));
85 }
86
87 /**
88 * {@inheritDoc}
89 */
90 public int hashCode() {
91 int hash = "UnaryProcedureUnaryFunction".hashCode();
92 if (null != procedure) {
93 hash ^= procedure.hashCode();
94 }
95 return hash;
96 }
97
98 /**
99 * {@inheritDoc}
100 */
101 public String toString() {
102 return "UnaryProcedureUnaryFunction<" + procedure + ">";
103 }
104
105 /**
106 * Adapt a UnaryProcedure to the UnaryFunction interface.
107 * @param <A> the argument type.
108 * @param <T> the returned value type.
109 * @param procedure to adapt
110 * @return UnaryProcedureUnaryFunction
111 */
112 public static <A, T> UnaryProcedureUnaryFunction<A, T> adapt(UnaryProcedure<? super A> procedure) {
113 return null == procedure ? null : new UnaryProcedureUnaryFunction<A, T>(procedure);
114 }
115
116 }