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