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.Predicate;
23 import org.apache.commons.collections4.Transformer;
24
25 /**
26 * Predicate implementation that transforms the given object before invoking
27 * another {@code Predicate}.
28 *
29 * @since 3.1
30 */
31 public final class TransformedPredicate<T> implements PredicateDecorator<T>, Serializable {
32
33 /** Serial version UID */
34 private static final long serialVersionUID = -5596090919668315834L;
35
36 /**
37 * Factory to create the predicate.
38 *
39 * @param <T> the type that the predicate queries
40 * @param transformer the transformer to call
41 * @param predicate the predicate to call with the result of the transform
42 * @return the predicate
43 * @throws NullPointerException if the transformer or the predicate is null
44 */
45 public static <T> Predicate<T> transformedPredicate(final Transformer<? super T, ? extends T> transformer,
46 final Predicate<? super T> predicate) {
47 return new TransformedPredicate<>(Objects.requireNonNull(transformer, "transformer"),
48 Objects.requireNonNull(predicate, "predicate"));
49 }
50
51 /** The transformer to call */
52 private final Transformer<? super T, ? extends T> iTransformer;
53
54 /** The predicate to call */
55 private final Predicate<? super T> iPredicate;
56
57 /**
58 * Constructor that performs no validation.
59 * Use {@code transformedPredicate} if you want that.
60 *
61 * @param transformer the transformer to use
62 * @param predicate the predicate to decorate
63 */
64 public TransformedPredicate(final Transformer<? super T, ? extends T> transformer,
65 final Predicate<? super T> predicate) {
66 iTransformer = transformer;
67 iPredicate = predicate;
68 }
69
70 /**
71 * Evaluates the predicate returning the result of the decorated predicate
72 * once the input has been transformed
73 *
74 * @param object the input object which will be transformed
75 * @return true if decorated predicate returns true
76 */
77 @Override
78 public boolean evaluate(final T object) {
79 final T result = iTransformer.transform(object);
80 return iPredicate.evaluate(result);
81 }
82
83 /**
84 * Gets the predicate being decorated.
85 *
86 * @return the predicate as the only element in an array
87 * @since 3.1
88 */
89 @Override
90 @SuppressWarnings("unchecked")
91 public Predicate<? super T>[] getPredicates() {
92 return new Predicate[] {iPredicate};
93 }
94
95 /**
96 * Gets the transformer in use.
97 *
98 * @return the transformer
99 */
100 public Transformer<? super T, ? extends T> getTransformer() {
101 return iTransformer;
102 }
103
104 }