001: /*
002: * Copyright 2001-2004,2006 The Apache Software Foundation
003: *
004: * Licensed under the Apache License, Version 2.0 (the "License");
005: * you may not use this file except in compliance with the License.
006: * You may obtain a copy of the License at
007: *
008: * http://www.apache.org/licenses/LICENSE-2.0
009: *
010: * Unless required by applicable law or agreed to in writing, software
011: * distributed under the License is distributed on an "AS IS" BASIS,
012: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013: * See the License for the specific language governing permissions and
014: * limitations under the License.
015: */
016: package org.apache.commons.collections.functors;
017:
018: import java.io.Serializable;
019: import java.util.Collection;
020:
021: import org.apache.commons.collections.Predicate;
022:
023: /**
024: * Predicate implementation that returns true if only one of the
025: * predicates return true.
026: * If the array of predicates is empty, then this predicate returns false.
027: * <p>
028: * NOTE: In versions prior to 3.2 an array size of zero or one
029: * threw an exception.
030: *
031: * @since Commons Collections 3.0
032: * @version $Revision: 406071 $ $Date: 2006-05-13 11:44:37 +0100 (Sat, 13 May 2006) $
033: *
034: * @author Stephen Colebourne
035: * @author Matt Benson
036: */
037: public final class OnePredicate implements Predicate,
038: 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: }
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