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.collections4.functors;
18
19 import java.io.Serializable;
20
21 import org.apache.commons.collections4.Closure;
22 import org.apache.commons.collections4.Transformer;
23
24 /**
25 * Transformer implementation that calls a Closure using the input object
26 * and then returns the input.
27 *
28 * @since 3.0
29 */
30 public class ClosureTransformer<T> implements Transformer<T, T>, Serializable {
31
32 /** Serial version UID */
33 private static final long serialVersionUID = 478466901448617286L;
34
35 /** The closure to wrap */
36 private final Closure<? super T> iClosure;
37
38 /**
39 * Factory method that performs validation.
40 *
41 * @param <T> the type of the object to transform
42 * @param closure the closure to call, not null
43 * @return the <code>closure</code> transformer
44 * @throws NullPointerException if the closure is null
45 */
46 public static <T> Transformer<T, T> closureTransformer(final Closure<? super T> closure) {
47 if (closure == null) {
48 throw new NullPointerException("Closure must not be null");
49 }
50 return new ClosureTransformer<>(closure);
51 }
52
53 /**
54 * Constructor that performs no validation.
55 * Use <code>closureTransformer</code> if you want that.
56 *
57 * @param closure the closure to call, not null
58 */
59 public ClosureTransformer(final Closure<? super T> closure) {
60 super();
61 iClosure = closure;
62 }
63
64 /**
65 * Transforms the input to result by executing a closure.
66 *
67 * @param input the input object to transform
68 * @return the transformed result
69 */
70 @Override
71 public T transform(final T input) {
72 iClosure.execute(input);
73 return input;
74 }
75
76 /**
77 * Gets the closure.
78 *
79 * @return the closure
80 * @since 3.1
81 */
82 public Closure<? super T> getClosure() {
83 return iClosure;
84 }
85
86 }