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.UnaryPredicate;
022 import org.apache.commons.functor.UnaryProcedure;
023 import org.apache.commons.functor.core.NoOp;
024
025 /**
026 * A {@link UnaryProcedure UnaryProcedure}
027 * similiar to Java's "ternary"
028 * or "conditional" operator (<code>? :</code>).
029 * Given a {@link UnaryPredicate predicate}
030 * <i>p</i> and {@link UnaryProcedure procedures}
031 * <i>q</i> and <i>r</i>, {@link #run runs}
032 * <code>if (p.test(x)) { q.run(x); } else { r.run(x); }</code>.
033 * <p>
034 * Note that although this class implements
035 * {@link Serializable}, a given instance will
036 * only be truly <code>Serializable</code> if all the
037 * underlying functors are. Attempts to serialize
038 * an instance whose delegates are not all
039 * <code>Serializable</code> will result in an exception.
040 * </p>
041 * @version $Revision: 1170782 $ $Date: 2011-09-14 21:18:31 +0200 (Wed, 14 Sep 2011) $
042 * @author Rodney Waldhoff
043 */
044 public final class ConditionalUnaryProcedure<A> implements UnaryProcedure<A>, Serializable {
045 /**
046 * serialVersionUID declaration.
047 */
048 private static final long serialVersionUID = -895833369740247391L;
049
050 /** Base hash integer used to shift hash */
051 private static final int HASH_SHIFT = 4;
052 // attributes
053 // ------------------------------------------------------------------------
054 private final UnaryPredicate<? super A> ifPred;
055 private final UnaryProcedure<? super A> thenProc;
056 private final UnaryProcedure<? super A> elseProc;
057
058 // constructor
059 // ------------------------------------------------------------------------
060 /**
061 * Create a new ConditionalUnaryProcedure.
062 * @param ifPred if
063 * @param thenProc then
064 */
065 public ConditionalUnaryProcedure(UnaryPredicate<? super A> ifPred, UnaryProcedure<? super A> thenProc) {
066 this(ifPred, thenProc, NoOp.instance());
067 }
068
069 /**
070 * Create a new ConditionalUnaryProcedure.
071 * @param ifPred if
072 * @param thenProc then
073 * @param elseProc else
074 */
075 public ConditionalUnaryProcedure(UnaryPredicate<? super A> ifPred,
076 UnaryProcedure<? super A> thenProc,
077 UnaryProcedure<? super A> elseProc) {
078 if (ifPred == null) {
079 throw new IllegalArgumentException("UnaryPredicate argument was null");
080 }
081 this.ifPred = ifPred;
082 if (thenProc == null || elseProc == null) {
083 throw new IllegalArgumentException("One or more UnaryProcedure arguments was null");
084 }
085 this.thenProc = thenProc;
086 this.elseProc = elseProc;
087 }
088
089 // predicate interface
090 // ------------------------------------------------------------------------
091 /**
092 * {@inheritDoc}
093 */
094 public void run(A obj) {
095 if (ifPred.test(obj)) {
096 thenProc.run(obj);
097 } else {
098 elseProc.run(obj);
099 }
100 }
101
102 /**
103 * {@inheritDoc}
104 */
105 public boolean equals(Object that) {
106 return that == this || (that instanceof ConditionalUnaryProcedure<?>
107 && equals((ConditionalUnaryProcedure<?>) that));
108 }
109
110 /**
111 * Learn whether another ConditionalUnaryProcedure is equal to this.
112 * @param that ConditionalUnaryProcedure to test
113 * @return boolean
114 */
115 public boolean equals(ConditionalUnaryProcedure<?> that) {
116 return null != that
117 && (null == ifPred ? null == that.ifPred : ifPred.equals(that.ifPred))
118 && (null == thenProc ? null == that.thenProc : thenProc.equals(that.thenProc))
119 && (null == elseProc ? null == that.elseProc : elseProc.equals(that.elseProc));
120 }
121
122 /**
123 * {@inheritDoc}
124 */
125 public int hashCode() {
126 int hash = "ConditionalUnaryProcedure".hashCode();
127 if (null != ifPred) {
128 hash <<= HASH_SHIFT;
129 hash ^= ifPred.hashCode();
130 }
131 if (null != thenProc) {
132 hash <<= HASH_SHIFT;
133 hash ^= thenProc.hashCode();
134 }
135 if (null != elseProc) {
136 hash <<= HASH_SHIFT;
137 hash ^= elseProc.hashCode();
138 }
139 return hash;
140 }
141
142 /**
143 * {@inheritDoc}
144 */
145 public String toString() {
146 return "ConditionalUnaryProcedure<" + ifPred + "?" + thenProc + ":" + elseProc + ">";
147 }
148
149 }