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.Predicate;
22 import org.apache.commons.collections4.Transformer;
23
24 /**
25 * Transformer implementation that calls a Predicate using the input object
26 * and then returns the result.
27 *
28 * @since 3.0
29 */
30 public class PredicateTransformer<T> implements Transformer<T, Boolean>, Serializable {
31
32 /** Serial version UID */
33 private static final long serialVersionUID = 5278818408044349346L;
34
35 /**
36 * Factory method that performs validation.
37 *
38 * @param <T> the input type
39 * @param predicate the predicate to call, not null
40 * @return the {@code predicate} transformer
41 * @throws IllegalArgumentException if the predicate is null
42 */
43 public static <T> Transformer<T, Boolean> predicateTransformer(final Predicate<? super T> predicate) {
44 if (predicate == null) {
45 throw new IllegalArgumentException("Predicate must not be null");
46 }
47 return new PredicateTransformer<>(predicate);
48 }
49
50 /** The closure to wrap */
51 private final Predicate<? super T> iPredicate;
52
53 /**
54 * Constructor that performs no validation.
55 * Use {@code predicateTransformer} if you want that.
56 *
57 * @param predicate the predicate to call, not null
58 */
59 public PredicateTransformer(final Predicate<? super T> predicate) {
60 iPredicate = predicate;
61 }
62
63 /**
64 * Gets the predicate.
65 *
66 * @return the predicate
67 * @since 3.1
68 */
69 public Predicate<? super T> getPredicate() {
70 return iPredicate;
71 }
72
73 /**
74 * Transforms the input to result by calling a predicate.
75 *
76 * @param input the input object to transform
77 * @return the transformed result
78 */
79 @Override
80 public Boolean transform(final T input) {
81 return Boolean.valueOf(iPredicate.evaluate(input));
82 }
83
84 }