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.Procedure;
23
24 /**
25 * Adapts a {@link Function Function}
26 * to the {@link Procedure Procedure}
27 * interface by ignoring the value returned
28 * by the function.
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 function is. Attempts to serialize
34 * an instance whose delegate is not
35 * <code>Serializable</code> will result in an exception.
36 *
37 * @version $Revision: 1156778 $ $Date: 2011-08-11 21:50:51 +0200 (Thu, 11 Aug 2011) $
38 * @author Rodney Waldhoff
39 */
40 public final class FunctionProcedure implements Procedure, Serializable {
41 /**
42 * serialVersionUID declaration.
43 */
44 private static final long serialVersionUID = -7300031015086684901L;
45 /** The {@link Function Function} I'm wrapping. */
46 private final Function<?> function;
47
48 /**
49 * Create an {@link Procedure Procedure} wrapping
50 * the given {@link Function Function}.
51 * @param function the {@link Function Function} to wrap
52 */
53 public FunctionProcedure(Function<?> function) {
54 if (function == null) {
55 throw new IllegalArgumentException("Function argument was null");
56 }
57 this.function = function;
58 }
59
60 /**
61 * {@inheritDoc}
62 * {@link Function#evaluate Evaluate} my function,
63 * but ignore its returned value.
64 */
65 public void run() {
66 function.evaluate();
67 }
68
69 /**
70 * {@inheritDoc}
71 */
72 public boolean equals(Object that) {
73 return that == this || (that instanceof FunctionProcedure && equals((FunctionProcedure) that));
74 }
75
76 /**
77 * Learn whether another FunctionProcedure is equal to this.
78 * @param that FunctionProcedure to test
79 * @return boolean
80 */
81 public boolean equals(FunctionProcedure that) {
82 return null != that && (null == function ? null == that.function : function.equals(that.function));
83 }
84
85 /**
86 * {@inheritDoc}
87 */
88 public int hashCode() {
89 int hash = "FunctionProcedure".hashCode();
90 if (null != function) {
91 hash ^= function.hashCode();
92 }
93 return hash;
94 }
95
96 /**
97 * {@inheritDoc}
98 */
99 public String toString() {
100 return "FunctionProcedure<" + function + ">";
101 }
102
103 /**
104 * Adapt the given, possibly-<code>null</code>,
105 * {@link Function Function} to the
106 * {@link Procedure Procedure} interface.
107 * When the given <code>Function</code> is <code>null</code>,
108 * returns <code>null</code>.
109 *
110 * @param function the possibly-<code>null</code>
111 * {@link Function Function} to adapt
112 * @return a {@link Procedure Procedure} wrapping the given
113 * {@link Function Function}, or <code>null</code>
114 * if the given <code>Function</code> is <code>null</code>
115 */
116 public static FunctionProcedure adapt(Function<?> function) {
117 return null == function ? null : new FunctionProcedure(function);
118 }
119
120 }