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.functor.core.composite;
18
19 import java.io.Serializable;
20
21 import org.apache.commons.functor.UnaryPredicate;
22 import org.apache.commons.lang3.Validate;
23
24 /**
25 * A {@link UnaryPredicate UnaryPredicate}
26 * similiar to Java's "ternary"
27 * or "conditional" operator (<code>? :</code>).
28 * Given three {@link UnaryPredicate predicate}
29 * <i>p</i>, <i>q</i>, <i>r</i>,
30 * {@link #test tests}
31 * to
32 * <code>p.test(x) ? q.test(x) : r.test(x)</code>.
33 * <p>
34 * Note that although this class implements
35 * {@link Serializable}, a given instance will
36 * only be truly <code>Serializable</code> if all the
37 * underlying functors are. Attempts to serialize
38 * an instance whose delegates are not all
39 * <code>Serializable</code> will result in an exception.
40 * </p>
41 * @param <A> the predicate argument type.
42 * @version $Revision: 1365329 $ $Date: 2012-07-24 19:34:23 -0300 (Tue, 24 Jul 2012) $
43 */
44 public final class ConditionalUnaryPredicate<A> implements UnaryPredicate<A>, Serializable {
45 /**
46 * serialVersionUID declaration.
47 */
48 private static final long serialVersionUID = 1214714029872180155L;
49
50 /** Base hash integer used to shift hash. */
51 private static final int HASH_SHIFT = 4;
52 // attributes
53 // ------------------------------------------------------------------------
54 /**
55 * the condition to be evaluated.
56 */
57 private final UnaryPredicate<? super A> ifPred;
58 /**
59 * the predicate executed if the condition is satisfied.
60 */
61 private final UnaryPredicate<? super A> thenPred;
62 /**
63 * the predicate executed if the condition is not satisfied.
64 */
65 private final UnaryPredicate<? super A> elsePred;
66
67 // constructor
68 // ------------------------------------------------------------------------
69 /**
70 * Create a new ConditionalUnaryPredicate.
71 * @param ifPred if
72 * @param thenPred then
73 * @param elsePred else
74 */
75 public ConditionalUnaryPredicate(UnaryPredicate<? super A> ifPred, UnaryPredicate<? super A> thenPred,
76 UnaryPredicate<? super A> elsePred) {
77 this.ifPred = Validate.notNull(ifPred, "'if' UnaryPredicate argument was null");
78 this.thenPred = Validate.notNull(thenPred, "'then' UnaryPredicate argument was null");
79 this.elsePred = Validate.notNull(elsePred, "'else' UnaryPredicate argument was null");
80 }
81
82 // predicate interface
83 // ------------------------------------------------------------------------
84 /**
85 * {@inheritDoc}
86 */
87 public boolean test(A obj) {
88 return ifPred.test(obj) ? thenPred.test(obj) : elsePred.test(obj);
89 }
90
91 /**
92 * {@inheritDoc}
93 */
94 @Override
95 public boolean equals(Object that) {
96 return that == this || (that instanceof ConditionalUnaryPredicate<?>
97 && equals((ConditionalUnaryPredicate<?>) that));
98 }
99
100 /**
101 * Learn whether another ConditionalUnaryPredicate is equal to this.
102 * @param that ConditionalUnaryPredicate to test
103 * @return boolean
104 */
105 public boolean equals(ConditionalUnaryPredicate<?> that) {
106 return null != that
107 && ifPred.equals(that.ifPred)
108 && thenPred.equals(that.thenPred)
109 && elsePred.equals(that.elsePred);
110 }
111
112 /**
113 * {@inheritDoc}
114 */
115 @Override
116 public int hashCode() {
117 int hash = "ConditionalUnaryPredicate".hashCode();
118 hash <<= HASH_SHIFT;
119 hash ^= ifPred.hashCode();
120 hash <<= HASH_SHIFT;
121 hash ^= thenPred.hashCode();
122 hash <<= HASH_SHIFT;
123 hash ^= elsePred.hashCode();
124 return hash;
125 }
126
127 /**
128 * {@inheritDoc}
129 */
130 @Override
131 public String toString() {
132 return "ConditionalUnaryPredicate<" + ifPred + "?" + thenPred + ":" + elsePred + ">";
133 }
134
135 }