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.functor.core.composite;
018
019 import java.io.Serializable;
020
021 import org.apache.commons.functor.UnaryPredicate;
022
023 /**
024 * A {@link UnaryPredicate UnaryPredicate}
025 * similiar to Java's "ternary"
026 * or "conditional" operator (<code>? :</code>).
027 * Given three {@link UnaryPredicate predicate}
028 * <i>p</i>, <i>q</i>, <i>r</i>,
029 * {@link #test tests}
030 * to
031 * <code>p.test(x) ? q.test(x) : r.test(x)</code>.
032 * <p>
033 * Note that although this class implements
034 * {@link Serializable}, a given instance will
035 * only be truly <code>Serializable</code> if all the
036 * underlying functors are. Attempts to serialize
037 * an instance whose delegates are not all
038 * <code>Serializable</code> will result in an exception.
039 * </p>
040 * @version $Revision: 1170779 $ $Date: 2011-09-14 21:16:47 +0200 (Wed, 14 Sep 2011) $
041 * @author Rodney Waldhoff
042 */
043 public final class ConditionalUnaryPredicate<A> implements UnaryPredicate<A>, Serializable {
044 /**
045 * serialVersionUID declaration.
046 */
047 private static final long serialVersionUID = 1214714029872180155L;
048
049 /** Base hash integer used to shift hash */
050 private static final int HASH_SHIFT = 4;
051 // attributes
052 // ------------------------------------------------------------------------
053 private final UnaryPredicate<? super A> ifPred;
054 private final UnaryPredicate<? super A> thenPred;
055 private final UnaryPredicate<? super A> elsePred;
056
057 // constructor
058 // ------------------------------------------------------------------------
059 /**
060 * Create a new ConditionalUnaryPredicate.
061 * @param ifPred if
062 * @param thenPred then
063 * @param elsePred else
064 */
065 public ConditionalUnaryPredicate(UnaryPredicate<? super A> ifPred, UnaryPredicate<? super A> thenPred,
066 UnaryPredicate<? super A> elsePred) {
067 if (ifPred == null || thenPred == null || elsePred == null) {
068 throw new IllegalArgumentException("One or more UnaryPredicate arguments was null");
069 }
070 this.ifPred = ifPred;
071 this.thenPred = thenPred;
072 this.elsePred = elsePred;
073 }
074
075 // predicate interface
076 // ------------------------------------------------------------------------
077 /**
078 * {@inheritDoc}
079 */
080 public boolean test(A obj) {
081 return ifPred.test(obj) ? thenPred.test(obj) : elsePred.test(obj);
082 }
083
084 /**
085 * {@inheritDoc}
086 */
087 public boolean equals(Object that) {
088 return that == this || (that instanceof ConditionalUnaryPredicate<?>
089 && equals((ConditionalUnaryPredicate<?>) that));
090 }
091
092 /**
093 * Learn whether another ConditionalUnaryPredicate is equal to this.
094 * @param that ConditionalUnaryPredicate to test
095 * @return boolean
096 */
097 public boolean equals(ConditionalUnaryPredicate<?> that) {
098 return null != that
099 && (null == ifPred ? null == that.ifPred : ifPred.equals(that.ifPred))
100 && (null == thenPred ? null == that.thenPred : thenPred.equals(that.thenPred))
101 && (null == elsePred ? null == that.elsePred : elsePred.equals(that.elsePred));
102 }
103
104 /**
105 * {@inheritDoc}
106 */
107 public int hashCode() {
108 int hash = "ConditionalUnaryPredicate".hashCode();
109 if (null != ifPred) {
110 hash <<= HASH_SHIFT;
111 hash ^= ifPred.hashCode();
112 }
113 if (null != thenPred) {
114 hash <<= HASH_SHIFT;
115 hash ^= thenPred.hashCode();
116 }
117 if (null != elsePred) {
118 hash <<= HASH_SHIFT;
119 hash ^= elsePred.hashCode();
120 }
121 return hash;
122 }
123
124 /**
125 * {@inheritDoc}
126 */
127 public String toString() {
128 return "ConditionalUnaryPredicate<" + ifPred + "?" + thenPred + ":" + elsePred + ">";
129 }
130
131 }