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.functor.UnaryProcedure;
23 import org.apache.commons.functor.core.NoOp;
24 import org.apache.commons.lang3.Validate;
25
26 /**
27 * A {@link UnaryProcedure UnaryProcedure}
28 * similiar to Java's "ternary"
29 * or "conditional" operator (<code>? :</code>).
30 * Given a {@link UnaryPredicate predicate}
31 * <i>p</i> and {@link UnaryProcedure procedures}
32 * <i>q</i> and <i>r</i>, {@link #run runs}
33 * <code>if (p.test(x)) { q.run(x); } else { r.run(x); }</code>.
34 * <p>
35 * Note that although this class implements
36 * {@link Serializable}, a given instance will
37 * only be truly <code>Serializable</code> if all the
38 * underlying functors are. Attempts to serialize
39 * an instance whose delegates are not all
40 * <code>Serializable</code> will result in an exception.
41 * </p>
42 * @param <A> the argument type.
43 * @version $Revision: 1365329 $ $Date: 2012-07-24 19:34:23 -0300 (Tue, 24 Jul 2012) $
44 */
45 public final class ConditionalUnaryProcedure<A> implements UnaryProcedure<A>, Serializable {
46 /**
47 * serialVersionUID declaration.
48 */
49 private static final long serialVersionUID = -895833369740247391L;
50
51 /** Base hash integer used to shift hash. */
52 private static final int HASH_SHIFT = 4;
53 // attributes
54 // ------------------------------------------------------------------------
55 /**
56 * the condition to be evaluated.
57 */
58 private final UnaryPredicate<? super A> ifPred;
59 /**
60 * the procedure executed if the condition is satisfied.
61 */
62 private final UnaryProcedure<? super A> thenProc;
63 /**
64 * the procedure executed if the condition is not satisfied.
65 */
66 private final UnaryProcedure<? super A> elseProc;
67
68 // constructor
69 // ------------------------------------------------------------------------
70 /**
71 * Create a new ConditionalUnaryProcedure.
72 * @param ifPred if
73 * @param thenProc then
74 */
75 public ConditionalUnaryProcedure(UnaryPredicate<? super A> ifPred, UnaryProcedure<? super A> thenProc) {
76 this(ifPred, thenProc, NoOp.instance());
77 }
78
79 /**
80 * Create a new ConditionalUnaryProcedure.
81 * @param ifPred if
82 * @param thenProc then
83 * @param elseProc else
84 */
85 public ConditionalUnaryProcedure(UnaryPredicate<? super A> ifPred,
86 UnaryProcedure<? super A> thenProc,
87 UnaryProcedure<? super A> elseProc) {
88 this.ifPred = Validate.notNull(ifPred, "UnaryPredicate argument was null");
89 this.thenProc = Validate.notNull(thenProc, "'then' UnaryProcedure argument was null");
90 this.elseProc = Validate.notNull(elseProc, "'else' UnaryProcedure argument was null");
91 }
92
93 // predicate interface
94 // ------------------------------------------------------------------------
95 /**
96 * {@inheritDoc}
97 */
98 public void run(A obj) {
99 if (ifPred.test(obj)) {
100 thenProc.run(obj);
101 } else {
102 elseProc.run(obj);
103 }
104 }
105
106 /**
107 * {@inheritDoc}
108 */
109 @Override
110 public boolean equals(Object that) {
111 return that == this || (that instanceof ConditionalUnaryProcedure<?>
112 && equals((ConditionalUnaryProcedure<?>) that));
113 }
114
115 /**
116 * Learn whether another ConditionalUnaryProcedure is equal to this.
117 * @param that ConditionalUnaryProcedure to test
118 * @return boolean
119 */
120 public boolean equals(ConditionalUnaryProcedure<?> that) {
121 return null != that
122 && ifPred.equals(that.ifPred)
123 && thenProc.equals(that.thenProc)
124 && elseProc.equals(that.elseProc);
125 }
126
127 /**
128 * {@inheritDoc}
129 */
130 @Override
131 public int hashCode() {
132 int hash = "ConditionalUnaryProcedure".hashCode();
133 hash <<= HASH_SHIFT;
134 hash ^= ifPred.hashCode();
135 hash <<= HASH_SHIFT;
136 hash ^= thenProc.hashCode();
137 hash <<= HASH_SHIFT;
138 hash ^= elseProc.hashCode();
139 return hash;
140 }
141
142 /**
143 * {@inheritDoc}
144 */
145 @Override
146 public String toString() {
147 return "ConditionalUnaryProcedure<" + ifPred + "?" + thenProc + ":" + elseProc + ">";
148 }
149
150 }