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.BinaryPredicate;
22 import org.apache.commons.functor.UnaryFunction;
23 import org.apache.commons.lang3.Validate;
24
25 /**
26 * A {@link BinaryPredicate BinaryPredicate} composed of
27 * one binary predicate, <i>p</i>, and two unary
28 * functions, <i>f</i> and <i>g</i>,
29 * evaluating the ordered parameters <i>x</i>, <i>y</i>
30 * to <code><i>p</i>(<i>f</i>(<i>x</i>),<i>g</i>(<i>y</i>))</code>.
31 * <p>
32 * Note that although this class implements
33 * {@link Serializable}, a given instance will
34 * only be truly <code>Serializable</code> if all the
35 * underlying functors are. Attempts to serialize
36 * an instance whose delegates are not all
37 * <code>Serializable</code> will result in an exception.
38 * </p>
39 * @param <L> the left argument type.
40 * @param <R> the right argument type.
41 * @version $Revision: 1345136 $ $Date: 2012-06-01 09:47:06 -0300 (Fri, 01 Jun 2012) $
42 */
43 public class UnaryCompositeBinaryPredicate<L, R> implements BinaryPredicate<L, R>, Serializable {
44 /**
45 * serialVersionUID declaration.
46 */
47 private static final long serialVersionUID = 3841123079006929493L;
48
49 /** Base hash integer used to shift hash. */
50 private static final int HASH_SHIFT = 4;
51
52 /**
53 * Internal helper.
54 *
55 * @param <G> right function type.
56 * @param <H> right function type.
57 * @param <L> left function type.
58 * @param <R> left function type.
59 */
60 private static class Helper<G, H, L, R> implements BinaryPredicate<L, R>, Serializable {
61 /**
62 * serialVersionUID declaration.
63 */
64 private static final long serialVersionUID = -3463108273324567825L;
65 /**
66 * BinaryPredicate to test <i>output(</i><code>f</code><i>), output(</i><code>g</code><i>)</i>.
67 */
68 private BinaryPredicate<? super G, ? super H> f;
69 /**
70 * left UnaryFunction.
71 */
72 private UnaryFunction<? super L, ? extends G> g;
73 /**
74 * right UnaryFunction.
75 */
76 private UnaryFunction<? super R, ? extends H> h;
77
78 /**
79 * Create a new Helper.
80 * @param f BinaryPredicate to test <i>output(</i><code>f</code><i>), output(</i><code>g</code><i>)</i>
81 * @param g left UnaryFunction
82 * @param h right UnaryFunction
83 */
84 public Helper(BinaryPredicate<? super G, ? super H> f, UnaryFunction<? super L, ? extends G> g,
85 UnaryFunction<? super R, ? extends H> h) {
86 this.f = f;
87 this.g = g;
88 this.h = h;
89 }
90
91 /**
92 * {@inheritDoc}
93 */
94 public boolean test(L left, R right) {
95 return f.test(g.evaluate(left), h.evaluate(right));
96 }
97 }
98
99 // attributes
100 // ------------------------------------------------------------------------
101 /**
102 * The adapted helper.
103 */
104 private final Helper<?, ?, L, R> helper;
105
106 // constructor
107 // ------------------------------------------------------------------------
108 /**
109 * Create a new UnaryCompositeBinaryPredicate.
110 *
111 * @param <G> right function type.
112 * @param <H> right function type.
113 * @param f BinaryPredicate to test <i>output(</i><code>f</code><i>), output(</i><code>g</code><i>)</i>
114 * @param g left UnaryFunction
115 * @param h right UnaryFunction
116 */
117 public <G, H> UnaryCompositeBinaryPredicate(final BinaryPredicate<? super G, ? super H> f,
118 final UnaryFunction<? super L, ? extends G> g, final UnaryFunction<? super R, ? extends H> h) {
119 helper = new Helper<G, H, L, R>(
120 Validate.notNull(f, "BinaryPredicate must not be null"),
121 Validate.notNull(g, "left UnaryFunction must not be null"),
122 Validate.notNull(h, "right UnaryFunction must not be null")
123 );
124 }
125
126 // function interface
127 // ------------------------------------------------------------------------
128 /**
129 * {@inheritDoc}
130 */
131 public boolean test(L left, R right) {
132 return helper.test(left, right);
133 }
134
135 /**
136 * {@inheritDoc}
137 */
138 @Override
139 public boolean equals(Object that) {
140 return that == this || (that instanceof UnaryCompositeBinaryPredicate<?, ?>
141 && equals((UnaryCompositeBinaryPredicate<?, ?>) that));
142 }
143
144 /**
145 * Learn whether another UnaryCompositeBinaryPredicate is equal to this.
146 * @param that UnaryCompositeBinaryPredicate to test
147 * @return boolean
148 */
149 public boolean equals(UnaryCompositeBinaryPredicate<?, ?> that) {
150 return null != that && helper.f.equals(that.helper.f) && helper.g.equals(that.helper.g)
151 && helper.h.equals(that.helper.h);
152 }
153
154 /**
155 * {@inheritDoc}
156 */
157 @Override
158 public int hashCode() {
159 int hash = "UnaryCompositeBinaryPredicate".hashCode();
160 hash <<= HASH_SHIFT;
161 hash ^= helper.f.hashCode();
162 hash <<= HASH_SHIFT;
163 hash ^= helper.g.hashCode();
164 hash <<= HASH_SHIFT;
165 hash ^= helper.h.hashCode();
166 return hash;
167 }
168
169 /**
170 * {@inheritDoc}
171 */
172 @Override
173 public String toString() {
174 return "UnaryCompositeBinaryPredicate<" + helper.f + ";" + helper.g + ";" + helper.h + ">";
175 }
176
177 }