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.BinaryPredicate;
022 import org.apache.commons.functor.UnaryFunction;
023
024 /**
025 * A {@link BinaryPredicate BinaryPredicate} composed of
026 * one binary predicate, <i>p</i>, and two unary
027 * functions, <i>f</i> and <i>g</i>,
028 * evaluating the ordered parameters <i>x</i>, <i>y</i>
029 * to <code><i>p</i>(<i>f</i>(<i>x</i>),<i>g</i>(<i>y</i>))</code>.
030 * <p>
031 * Note that although this class implements
032 * {@link Serializable}, a given instance will
033 * only be truly <code>Serializable</code> if all the
034 * underlying functors are. Attempts to serialize
035 * an instance whose delegates are not all
036 * <code>Serializable</code> will result in an exception.
037 * </p>
038 * @version $Revision: 1156337 $ $Date: 2011-08-10 21:44:54 +0200 (Wed, 10 Aug 2011) $
039 * @author Rodney Waldhoff
040 */
041 public class UnaryCompositeBinaryPredicate<L, R> implements BinaryPredicate<L, R>, Serializable {
042 /**
043 * serialVersionUID declaration.
044 */
045 private static final long serialVersionUID = 3841123079006929493L;
046
047 private static class Helper<G, H, L, R> implements BinaryPredicate<L, R>, Serializable {
048 /**
049 * serialVersionUID declaration.
050 */
051 private static final long serialVersionUID = -3463108273324567825L;
052 private BinaryPredicate<? super G, ? super H> f;
053 private UnaryFunction<? super L, ? extends G> g;
054 private UnaryFunction<? super R, ? extends H> h;
055
056 /**
057 * Create a new Helper.
058 * @param f BinaryPredicate to test <i>output(</i><code>f</code><i>), output(</i><code>g</code><i>)</i>
059 * @param g left UnaryFunction
060 * @param h right UnaryFunction
061 */
062 public Helper(BinaryPredicate<? super G, ? super H> f, UnaryFunction<? super L, ? extends G> g,
063 UnaryFunction<? super R, ? extends H> h) {
064 this.f = f;
065 this.g = g;
066 this.h = h;
067 }
068
069 /**
070 * {@inheritDoc}
071 */
072 public boolean test(L left, R right) {
073 return f.test(g.evaluate(left), h.evaluate(right));
074 }
075 }
076
077 // attributes
078 // ------------------------------------------------------------------------
079 private final Helper<?, ?, L, R> helper;
080
081 // constructor
082 // ------------------------------------------------------------------------
083 /**
084 * Create a new UnaryCompositeBinaryPredicate.
085 * @param f BinaryPredicate to test <i>output(</i><code>f</code><i>), output(</i><code>g</code><i>)</i>
086 * @param g left UnaryFunction
087 * @param h right UnaryFunction
088 */
089 public <G, H> UnaryCompositeBinaryPredicate(final BinaryPredicate<? super G, ? super H> f,
090 final UnaryFunction<? super L, ? extends G> g, final UnaryFunction<? super R, ? extends H> h) {
091 if (f == null) {
092 throw new IllegalArgumentException("BinaryPredicate must not be null");
093 }
094 if (g == null || h == null) {
095 throw new IllegalArgumentException("Left and right UnaryFunctions may not be null");
096 }
097 helper = new Helper<G, H, L, R>(f, g, h);
098 }
099
100 // function interface
101 // ------------------------------------------------------------------------
102 /**
103 * {@inheritDoc}
104 */
105 public boolean test(L left, R right) {
106 return helper.test(left, right);
107 }
108
109 /**
110 * {@inheritDoc}
111 */
112 public boolean equals(Object that) {
113 return that == this || (that instanceof UnaryCompositeBinaryPredicate<?, ?>
114 && equals((UnaryCompositeBinaryPredicate<?, ?>) that));
115 }
116
117 /**
118 * Learn whether another UnaryCompositeBinaryPredicate is equal to this.
119 * @param that UnaryCompositeBinaryPredicate to test
120 * @return boolean
121 */
122 public boolean equals(UnaryCompositeBinaryPredicate<?, ?> that) {
123 return null != that && helper.f.equals(that.helper.f) && helper.g.equals(that.helper.g)
124 && helper.h.equals(that.helper.h);
125 }
126
127 /**
128 * {@inheritDoc}
129 */
130 public int hashCode() {
131 int hash = "UnaryCompositeBinaryPredicate".hashCode();
132 hash <<= 4;
133 hash ^= helper.f.hashCode();
134 hash <<= 4;
135 hash ^= helper.g.hashCode();
136 hash <<= 4;
137 hash ^= helper.h.hashCode();
138 return hash;
139 }
140
141 /**
142 * {@inheritDoc}
143 */
144 public String toString() {
145 return "UnaryCompositeBinaryPredicate<" + helper.f + ";" + helper.g + ";" + helper.h + ">";
146 }
147
148 }