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.Procedure;
22 import org.apache.commons.functor.UnaryProcedure;
23 import org.apache.commons.lang3.Validate;
24
25 /**
26 * Adapts a
27 * {@link UnaryProcedure UnaryProcedure}
28 * to the
29 * {@link Procedure Procedure} interface
30 * using a constant unary 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 BoundProcedure implements Procedure, Serializable {
42 /**
43 * serialVersionUID declaration.
44 */
45 private static final long serialVersionUID = -6010802933400471747L;
46 /** The {@link UnaryProcedure UnaryProcedure} I'm wrapping. */
47 private final UnaryProcedure<Object> procedure;
48 /** The parameter to pass to {@code procedure}. */
49 private final Object param;
50
51 /**
52 * Create a new BoundProcedure instance.
53 * @param <A> arg type
54 * @param procedure the procedure to adapt
55 * @param arg the constant argument to use
56 */
57 @SuppressWarnings("unchecked")
58 public <A> BoundProcedure(UnaryProcedure<? super A> procedure, A arg) {
59 this.procedure =
60 (UnaryProcedure<Object>) Validate.notNull(procedure,
61 "UnaryProcedure argument was null");
62 this.param = arg;
63 }
64
65 /**
66 * {@inheritDoc}
67 */
68 public void run() {
69 procedure.run(param);
70 }
71
72 /**
73 * {@inheritDoc}
74 */
75 @Override
76 public boolean equals(Object that) {
77 return that == this || (that instanceof BoundProcedure && equals((BoundProcedure) that));
78 }
79
80 /**
81 * Learn whether a given BoundProcedure is equal to this.
82 * @param that the BoundProcedure to test
83 * @return boolean
84 */
85 public boolean equals(BoundProcedure that) {
86 return null != that
87 && procedure.equals(that.procedure)
88 && (null == param ? null == that.param : param.equals(that.param));
89 }
90
91 /**
92 * {@inheritDoc}
93 */
94 @Override
95 public int hashCode() {
96 int hash = "BoundProcedure".hashCode();
97 hash <<= 2;
98 hash ^= procedure.hashCode();
99 if (null != param) {
100 hash <<= 2;
101 hash ^= param.hashCode();
102 }
103 return hash;
104 }
105
106 /**
107 * {@inheritDoc}
108 */
109 @Override
110 public String toString() {
111 return "BoundProcedure<" + procedure + "(" + param + ")>";
112 }
113
114 /**
115 * Adapt the given, possibly-<code>null</code>,
116 * {@link UnaryProcedure UnaryProcedure} to the
117 * {@link Procedure Procedure} interface by binding
118 * the specified <code>Object</code> as a constant
119 * argument.
120 * When the given <code>UnaryProcedure</code> is <code>null</code>,
121 * returns <code>null</code>.
122 *
123 * @param <A> arg type
124 * @param procedure the possibly-<code>null</code>
125 * {@link UnaryProcedure UnaryProcedure} to adapt
126 * @param arg the object to bind as a constant argument
127 * @return a <code>BoundProcedure</code> wrapping the given
128 * {@link UnaryProcedure UnaryProcedure}, or <code>null</code>
129 * if the given <code>UnaryProcedure</code> is <code>null</code>
130 */
131 public static <A> BoundProcedure bind(UnaryProcedure<? super A> procedure, A arg) {
132 return null == procedure ? null : new BoundProcedure(procedure, arg);
133 }
134
135 }