001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.collections.functors;
018
019 import java.io.Serializable;
020 import java.util.Collection;
021
022 import org.apache.commons.collections.Predicate;
023
024 /**
025 * Predicate implementation that returns true if only one of the
026 * predicates return true.
027 * If the array of predicates is empty, then this predicate returns false.
028 * <p>
029 * NOTE: In versions prior to 3.2 an array size of zero or one
030 * threw an exception.
031 *
032 * @since Commons Collections 3.0
033 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
034 *
035 * @author Stephen Colebourne
036 * @author Matt Benson
037 */
038 public final class OnePredicate implements Predicate, PredicateDecorator, Serializable {
039
040 /** Serial version UID */
041 private static final long serialVersionUID = -8125389089924745785L;
042
043 /** The array of predicates to call */
044 private final Predicate[] iPredicates;
045
046 /**
047 * Factory to create the predicate.
048 * <p>
049 * If the array is size zero, the predicate always returns false.
050 * If the array is size one, then that predicate is returned.
051 *
052 * @param predicates the predicates to check, cloned, not null
053 * @return the <code>any</code> predicate
054 * @throws IllegalArgumentException if the predicates array is null
055 * @throws IllegalArgumentException if any predicate in the array is null
056 */
057 public static Predicate getInstance(Predicate[] predicates) {
058 FunctorUtils.validate(predicates);
059 if (predicates.length == 0) {
060 return FalsePredicate.INSTANCE;
061 }
062 if (predicates.length == 1) {
063 return predicates[0];
064 }
065 predicates = FunctorUtils.copy(predicates);
066 return new OnePredicate(predicates);
067 }
068
069 /**
070 * Factory to create the predicate.
071 *
072 * @param predicates the predicates to check, cloned, not null
073 * @return the <code>one</code> predicate
074 * @throws IllegalArgumentException if the predicates array is null
075 * @throws IllegalArgumentException if any predicate in the array is null
076 */
077 public static Predicate getInstance(Collection predicates) {
078 Predicate[] preds = FunctorUtils.validate(predicates);
079 return new OnePredicate(preds);
080 }
081
082 /**
083 * Constructor that performs no validation.
084 * Use <code>getInstance</code> if you want that.
085 *
086 * @param predicates the predicates to check, not cloned, not null
087 */
088 public OnePredicate(Predicate[] predicates) {
089 super();
090 iPredicates = predicates;
091 }
092
093 /**
094 * Evaluates the predicate returning true if only one decorated predicate
095 * returns true.
096 *
097 * @param object the input object
098 * @return true if only one decorated predicate returns true
099 */
100 public boolean evaluate(Object object) {
101 boolean match = false;
102 for (int i = 0; i < iPredicates.length; i++) {
103 if (iPredicates[i].evaluate(object)) {
104 if (match) {
105 return false;
106 }
107 match = true;
108 }
109 }
110 return match;
111 }
112
113 /**
114 * Gets the predicates, do not modify the array.
115 *
116 * @return the predicates
117 * @since Commons Collections 3.1
118 */
119 public Predicate[] getPredicates() {
120 return iPredicates;
121 }
122
123 }