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 org.apache.commons.functor.BinaryPredicate;
20 import org.apache.commons.functor.BinaryProcedure;
21 import org.apache.commons.functor.core.NoOp;
22 import org.apache.commons.lang3.Validate;
23
24 /**
25 * A {@link BinaryProcedure BinaryProcedure}
26 * similiar to Java's "ternary"
27 * or "conditional" operator (<code>? :</code>).
28 * Given a {@link BinaryPredicate predicate}
29 * <i>p</i> and {@link BinaryProcedure procedures}
30 * <i>q</i> and <i>r</i>, {@link #run runs}
31 * <code>if (p.test(x,y)) { q.run(x,y); } else { r.run(x,y); }</code>.
32 * @param <L> the left argument type.
33 * @param <R> the right argument type.
34 * @version $Revision: 1537602 $ $Date: 2013-10-31 20:53:09 +0100 (Do, 31 Okt 2013) $
35 */
36 public final class ConditionalBinaryProcedure<L, R> implements BinaryProcedure<L, R> {
37
38 /** Base hash integer used to shift hash. */
39 private static final int HASH_SHIFT = 4;
40 // attributes
41 // ------------------------------------------------------------------------
42 /**
43 * the condition to be evaluated.
44 */
45 private final BinaryPredicate<? super L, ? super R> ifPred;
46 /**
47 * the predicate executed if the condition is satisfied.
48 */
49 private final BinaryProcedure<? super L, ? super R> thenProc;
50 /**
51 * the predicate executed if the condition is not satisfied.
52 */
53 private final BinaryProcedure<? super L, ? super R> elseProc;
54
55 // constructor
56 // ------------------------------------------------------------------------
57
58 /**
59 * Create a new ConditionalBinaryProcedure.
60 * @param ifPred to evaluate
61 * @param thenProc if <code>ifPred</code> yields <code>true</code>
62 */
63 public ConditionalBinaryProcedure(BinaryPredicate<? super L, ? super R> ifPred,
64 BinaryProcedure<? super L, ? super R> thenProc) {
65 this(ifPred, thenProc, NoOp.instance());
66 }
67
68 /**
69 * Create a new ConditionalBinaryProcedure.
70 * @param ifPred to evaluate
71 * @param thenProc if <code>ifPred</code> yields <code>true</code>
72 * @param elseProc if <code>ifPred</code> yields <code>false</code>
73 */
74 public ConditionalBinaryProcedure(BinaryPredicate<? super L, ? super R> ifPred,
75 BinaryProcedure<? super L, ? super R> thenProc, BinaryProcedure<? super L, ? super R> elseProc) {
76 this.ifPred = Validate.notNull(ifPred, "BinaryPredicate argument was null");
77 this.thenProc = Validate.notNull(thenProc, "'then' BinaryProcedure argument was null");
78 this.elseProc = Validate.notNull(elseProc, "'else' BinaryProcedure argument was null");
79 }
80
81 // predicate interface
82 // ------------------------------------------------------------------------
83
84 /**
85 * {@inheritDoc}
86 */
87 public void run(L left, R right) {
88 if (ifPred.test(left, right)) {
89 thenProc.run(left, right);
90 } else {
91 elseProc.run(left, right);
92 }
93 }
94
95 /**
96 * {@inheritDoc}
97 */
98 @Override
99 public boolean equals(Object obj) {
100 if (obj == this) {
101 return true;
102 }
103 if (!(obj instanceof ConditionalBinaryProcedure<?, ?>)) {
104 return false;
105 }
106 ConditionalBinaryProcedure<?, ?> that = (ConditionalBinaryProcedure<?, ?>) obj;
107 return this.ifPred.equals(that.ifPred)
108 && this.thenProc.equals(that.thenProc)
109 && this.elseProc.equals(that.elseProc);
110 }
111
112 /**
113 * {@inheritDoc}
114 */
115 @Override
116 public int hashCode() {
117 int hash = "ConditionalBinaryProcedure".hashCode();
118 hash <<= HASH_SHIFT;
119 hash ^= ifPred.hashCode();
120 hash <<= HASH_SHIFT;
121 hash ^= thenProc.hashCode();
122 hash <<= HASH_SHIFT;
123 hash ^= elseProc.hashCode();
124 return hash;
125 }
126
127 /**
128 * {@inheritDoc}
129 */
130 @Override
131 public String toString() {
132 return "ConditionalBinaryProcedure<" + ifPred + "?" + thenProc + ":" + elseProc + ">";
133 }
134 }