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.collections.functors;
18
19 import java.io.Serializable;
20
21 import org.apache.commons.collections.Transformer;
22
23 /**
24 * Transformer implementation that returns a clone of the input object.
25 * <p>
26 * Clone is performed using <code>PrototypeFactory.getInstance(input).create()</code>.
27 *
28 * @since 3.0
29 * @version $Id: CloneTransformer.java 1435965 2013-01-20 21:13:18Z tn $
30 */
31 public class CloneTransformer<T> implements Transformer<T, T>, Serializable {
32
33 /** Serial version UID */
34 private static final long serialVersionUID = -8188742709499652567L;
35
36 /** Singleton predicate instance */
37 public static final Transformer<Object, Object> INSTANCE = new CloneTransformer<Object>();
38
39 /**
40 * Factory returning the singleton instance.
41 *
42 * @param <T> the type of the objects to be cloned
43 * @return the singleton instance
44 * @since 3.1
45 */
46 @SuppressWarnings("unchecked")
47 public static <T> Transformer<T, T> cloneTransformer() {
48 return (Transformer<T, T>) INSTANCE;
49 }
50
51 /**
52 * Constructor
53 */
54 private CloneTransformer() {
55 super();
56 }
57
58 /**
59 * Transforms the input to result by cloning it.
60 *
61 * @param input the input object to transform
62 * @return the transformed result
63 */
64 public T transform(final T input) {
65 if (input == null) {
66 return null;
67 }
68 return PrototypeFactory.prototypeFactory(input).create();
69 }
70
71 private Object readResolve() {
72 return INSTANCE;
73 }
74
75 }