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.collections.functors;
018
019 import java.io.Serializable;
020
021 import org.apache.commons.collections.Closure;
022 import org.apache.commons.collections.Predicate;
023
024 /**
025 * Closure implementation acts as an if statement calling one or other closure
026 * based on a predicate.
027 *
028 * @since Commons Collections 3.0
029 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
030 *
031 * @author Stephen Colebourne
032 * @author Matt Benson
033 */
034 public class IfClosure implements Closure, Serializable {
035
036 /** Serial version UID */
037 private static final long serialVersionUID = 3518477308466486130L;
038
039 /** The test */
040 private final Predicate iPredicate;
041 /** The closure to use if true */
042 private final Closure iTrueClosure;
043 /** The closure to use if false */
044 private final Closure iFalseClosure;
045
046 /**
047 * Factory method that performs validation.
048 * <p>
049 * This factory creates a closure that performs no action when
050 * the predicate is false.
051 *
052 * @param predicate predicate to switch on
053 * @param trueClosure closure used if true
054 * @return the <code>if</code> closure
055 * @throws IllegalArgumentException if either argument is null
056 * @since Commons Collections 3.2
057 */
058 public static Closure getInstance(Predicate predicate, Closure trueClosure) {
059 return getInstance(predicate, trueClosure, NOPClosure.INSTANCE);
060 }
061
062 /**
063 * Factory method that performs validation.
064 *
065 * @param predicate predicate to switch on
066 * @param trueClosure closure used if true
067 * @param falseClosure closure used if false
068 * @return the <code>if</code> closure
069 * @throws IllegalArgumentException if any argument is null
070 */
071 public static Closure getInstance(Predicate predicate, Closure trueClosure, Closure falseClosure) {
072 if (predicate == null) {
073 throw new IllegalArgumentException("Predicate must not be null");
074 }
075 if (trueClosure == null || falseClosure == null) {
076 throw new IllegalArgumentException("Closures must not be null");
077 }
078 return new IfClosure(predicate, trueClosure, falseClosure);
079 }
080
081 /**
082 * Constructor that performs no validation.
083 * Use <code>getInstance</code> if you want that.
084 * <p>
085 * This constructor creates a closure that performs no action when
086 * the predicate is false.
087 *
088 * @param predicate predicate to switch on, not null
089 * @param trueClosure closure used if true, not null
090 * @since Commons Collections 3.2
091 */
092 public IfClosure(Predicate predicate, Closure trueClosure) {
093 this(predicate, trueClosure, NOPClosure.INSTANCE);
094 }
095
096 /**
097 * Constructor that performs no validation.
098 * Use <code>getInstance</code> if you want that.
099 *
100 * @param predicate predicate to switch on, not null
101 * @param trueClosure closure used if true, not null
102 * @param falseClosure closure used if false, not null
103 */
104 public IfClosure(Predicate predicate, Closure trueClosure, Closure falseClosure) {
105 super();
106 iPredicate = predicate;
107 iTrueClosure = trueClosure;
108 iFalseClosure = falseClosure;
109 }
110
111 /**
112 * Executes the true or false closure accoring to the result of the predicate.
113 *
114 * @param input the input object
115 */
116 public void execute(Object input) {
117 if (iPredicate.evaluate(input) == true) {
118 iTrueClosure.execute(input);
119 } else {
120 iFalseClosure.execute(input);
121 }
122 }
123
124 /**
125 * Gets the predicate.
126 *
127 * @return the predicate
128 * @since Commons Collections 3.1
129 */
130 public Predicate getPredicate() {
131 return iPredicate;
132 }
133
134 /**
135 * Gets the closure called when true.
136 *
137 * @return the closure
138 * @since Commons Collections 3.1
139 */
140 public Closure getTrueClosure() {
141 return iTrueClosure;
142 }
143
144 /**
145 * Gets the closure called when false.
146 *
147 * @return the closure
148 * @since Commons Collections 3.1
149 */
150 public Closure getFalseClosure() {
151 return iFalseClosure;
152 }
153
154 }