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 org.apache.commons.functor.NullaryFunction;
20 import org.apache.commons.functor.NullaryProcedure;
21 import org.apache.commons.lang3.Validate;
22
23 /**
24 * Adapts a
25 * {@link NullaryProcedure NullaryProcedure}
26 * to the
27 * {@link NullaryFunction NullaryFunction} interface
28 * by always returning <code>null</code>.
29 *
30 * @param <T> the returned value type.
31 * @version $Revision: 1365377 $ $Date: 2012-07-24 21:59:23 -0300 (Tue, 24 Jul 2012) $
32 */
33 public final class NullaryProcedureNullaryFunction<T> implements NullaryFunction<T> {
34 /** The {@link NullaryProcedure NullaryProcedure} I'm wrapping. */
35 private final NullaryProcedure procedure;
36
37 /**
38 * Create a new NullaryProcedureNullaryFunction.
39 * @param procedure to adapt
40 */
41 public NullaryProcedureNullaryFunction(NullaryProcedure procedure) {
42 this.procedure = Validate.notNull(procedure, "NullaryProcedure argument was null");
43 }
44
45 /**
46 * {@inheritDoc}
47 */
48 public T evaluate() {
49 procedure.run();
50 return null;
51 }
52
53 /**
54 * {@inheritDoc}
55 */
56 @Override
57 public boolean equals(Object obj) {
58 if (obj == this) {
59 return true;
60 }
61 if (!(obj instanceof NullaryProcedureNullaryFunction<?>)) {
62 return false;
63 }
64 NullaryProcedureNullaryFunction<?> that = (NullaryProcedureNullaryFunction<?>) obj;
65 return this.procedure.equals(that.procedure);
66 }
67
68 /**
69 * {@inheritDoc}
70 */
71 @Override
72 public int hashCode() {
73 int hash = "NullaryProcedureNullaryFunction".hashCode();
74 hash ^= procedure.hashCode();
75 return hash;
76 }
77
78 /**
79 * {@inheritDoc}
80 */
81 @Override
82 public String toString() {
83 return "NullaryProcedureNullaryFunction<" + procedure + ">";
84 }
85
86 /**
87 * Adapt a NullaryProcedure as a NullaryFunction.
88 * @param <T> the returned value type.
89 * @param procedure to adapt
90 * @return NullaryProcedureNullaryFunction<T>
91 */
92 public static <T> NullaryProcedureNullaryFunction<T> adapt(NullaryProcedure procedure) {
93 return null == procedure ? null : new NullaryProcedureNullaryFunction<T>(procedure);
94 }
95
96 }