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.adapter;
018
019 import java.io.Serializable;
020
021 import org.apache.commons.functor.BinaryPredicate;
022 import org.apache.commons.functor.Predicate;
023
024 /**
025 * Adapts a
026 * {@link BinaryPredicate BinaryPredicate}
027 * to the
028 * {@link org.apache.commons.functor.UnaryPredicate UnaryPredicate} interface
029 * using a constant left-side argument.
030 * <p/>
031 * Note that although this class implements
032 * {@link Serializable}, a given instance will
033 * only be truly <code>Serializable</code> if the
034 * underlying objects are. Attempts to serialize
035 * an instance whose delegates are not
036 * <code>Serializable</code> will result in an exception.
037 *
038 * @version $Revision: 1156320 $ $Date: 2011-08-10 21:14:50 +0200 (Wed, 10 Aug 2011) $
039 * @author Matt Benson
040 */
041 public final class FullyBoundPredicate implements Predicate, Serializable {
042
043 /**
044 * serialVersionUID declaration.
045 */
046 private static final long serialVersionUID = 7676235030688391839L;
047 /** The {@link BinaryPredicate BinaryPredicate} I'm wrapping. */
048 private final BinaryPredicate<Object, Object> predicate;
049 /** The left parameter to pass to {@code predicate}. */
050 private final Object left;
051 /** The right parameter to pass to {@code predicate}. */
052 private final Object right;
053
054 /**
055 * Create a new FullyBoundPredicate instance.
056 * @param <L> left type
057 * @param <R> right type
058 * @param predicate the predicate to adapt
059 * @param left the left argument to use
060 * @param right the right argument to use
061 */
062 @SuppressWarnings("unchecked")
063 public <L, R> FullyBoundPredicate(BinaryPredicate<? super L, ? super R> predicate, L left, R right) {
064 if (predicate == null) {
065 throw new IllegalArgumentException("BinaryPredicate argument was null");
066 }
067 this.predicate = (BinaryPredicate<Object, Object>) predicate;
068 this.left = left;
069 this.right = right;
070 }
071
072 /**
073 * {@inheritDoc}
074 */
075 public boolean test() {
076 return predicate.test(left, right);
077 }
078
079 /**
080 * {@inheritDoc}
081 */
082 public boolean equals(Object that) {
083 return that == this || (that instanceof FullyBoundPredicate && equals((FullyBoundPredicate) that));
084 }
085
086 /**
087 * Learn whether another FullyBoundPredicate is equal to this.
088 * @param that FullyBoundPredicate to test
089 * @return boolean
090 */
091 public boolean equals(FullyBoundPredicate that) {
092 return null != that && (null == predicate ? null == that.predicate : predicate.equals(that.predicate))
093 && (null == left ? null == that.left : left.equals(that.left))
094 && (null == right ? null == that.right : right.equals(that.right));
095 }
096
097 /**
098 * {@inheritDoc}
099 */
100 public int hashCode() {
101 int hash = "FullyBoundPredicate".hashCode();
102 if (null != predicate) {
103 hash <<= 2;
104 hash ^= predicate.hashCode();
105 }
106 hash <<= 2;
107 if (null != left) {
108 hash ^= left.hashCode();
109 }
110 hash <<= 2;
111 if (null != right) {
112 hash ^= right.hashCode();
113 }
114 return hash;
115 }
116
117 /**
118 * {@inheritDoc}
119 */
120 public String toString() {
121 return "FullyBoundPredicate<" + predicate + "(" + left + ", " + right + ")>";
122 }
123
124 /**
125 * Adapt a BinaryPredicate to the Predicate interface.
126 * @param predicate to adapt
127 * @param <L> left type
128 * @param <R> right type
129 * @param left L argument to always send as the left operand to the wrapped function
130 * @param right R argument to always send as the right operand to the wrapped function
131 * @return FullyBoundPredicate
132 */
133 public static <L, R> FullyBoundPredicate bind(
134 BinaryPredicate<? super L, ? super R> predicate, L left, R right) {
135 return null == predicate ? null : new FullyBoundPredicate(predicate, left, right);
136 }
137 }