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.Predicate;
22 import org.apache.commons.collections.Transformer;
23
24 /**
25 * Predicate implementation that transforms the given object before invoking
26 * another <code>Predicate</code>.
27 *
28 * @since 3.1
29 * @version $Id: TransformedPredicate.java 1435965 2013-01-20 21:13:18Z tn $
30 */
31 public final class TransformedPredicate<T> implements Predicate<T>, PredicateDecorator<T>, Serializable {
32
33 /** Serial version UID */
34 private static final long serialVersionUID = -5596090919668315834L;
35
36 /** The transformer to call */
37 private final Transformer<? super T, ? extends T> iTransformer;
38
39 /** The predicate to call */
40 private final Predicate<? super T> iPredicate;
41
42 /**
43 * Factory to create the predicate.
44 *
45 * @param <T> the type that the predicate queries
46 * @param transformer the transformer to call
47 * @param predicate the predicate to call with the result of the transform
48 * @return the predicate
49 * @throws IllegalArgumentException if the transformer or the predicate is null
50 */
51 public static <T> Predicate<T> transformedPredicate(final Transformer<? super T, ? extends T> transformer,
52 final Predicate<? super T> predicate) {
53 if (transformer == null) {
54 throw new IllegalArgumentException("The transformer to call must not be null");
55 }
56 if (predicate == null) {
57 throw new IllegalArgumentException("The predicate to call must not be null");
58 }
59 return new TransformedPredicate<T>(transformer, predicate);
60 }
61
62 /**
63 * Constructor that performs no validation.
64 * Use <code>getInstance</code> if you want that.
65 *
66 * @param transformer the transformer to use
67 * @param predicate the predicate to decorate
68 */
69 public TransformedPredicate(final Transformer<? super T, ? extends T> transformer,
70 final Predicate<? super T> predicate) {
71 iTransformer = transformer;
72 iPredicate = predicate;
73 }
74
75 /**
76 * Evaluates the predicate returning the result of the decorated predicate
77 * once the input has been transformed
78 *
79 * @param object the input object which will be transformed
80 * @return true if decorated predicate returns true
81 */
82 public boolean evaluate(final T object) {
83 final T result = iTransformer.transform(object);
84 return iPredicate.evaluate(result);
85 }
86
87 /**
88 * Gets the predicate being decorated.
89 *
90 * @return the predicate as the only element in an array
91 * @since 3.1
92 */
93 @SuppressWarnings("unchecked")
94 public Predicate<? super T>[] getPredicates() {
95 return new Predicate[] {iPredicate};
96 }
97
98 /**
99 * Gets the transformer in use.
100 *
101 * @return the transformer
102 */
103 public Transformer<? super T, ? extends T> getTransformer() {
104 return iTransformer;
105 }
106
107 }