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 import java.util.Collection;
021 import java.util.Iterator;
022
023 import org.apache.commons.collections.Closure;
024
025 /**
026 * Closure implementation that chains the specified closures together.
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 */
033 public class ChainedClosure implements Closure, Serializable {
034
035 /** Serial version UID */
036 private static final long serialVersionUID = -3520677225766901240L;
037
038 /** The closures to call in turn */
039 private final Closure[] iClosures;
040
041 /**
042 * Factory method that performs validation and copies the parameter array.
043 *
044 * @param closures the closures to chain, copied, no nulls
045 * @return the <code>chained</code> closure
046 * @throws IllegalArgumentException if the closures array is null
047 * @throws IllegalArgumentException if any closure in the array is null
048 */
049 public static Closure getInstance(Closure[] closures) {
050 FunctorUtils.validate(closures);
051 if (closures.length == 0) {
052 return NOPClosure.INSTANCE;
053 }
054 closures = FunctorUtils.copy(closures);
055 return new ChainedClosure(closures);
056 }
057
058 /**
059 * Create a new Closure that calls each closure in turn, passing the
060 * result into the next closure. The ordering is that of the iterator()
061 * method on the collection.
062 *
063 * @param closures a collection of closures to chain
064 * @return the <code>chained</code> closure
065 * @throws IllegalArgumentException if the closures collection is null
066 * @throws IllegalArgumentException if any closure in the collection is null
067 */
068 public static Closure getInstance(Collection closures) {
069 if (closures == null) {
070 throw new IllegalArgumentException("Closure collection must not be null");
071 }
072 if (closures.size() == 0) {
073 return NOPClosure.INSTANCE;
074 }
075 // convert to array like this to guarantee iterator() ordering
076 Closure[] cmds = new Closure[closures.size()];
077 int i = 0;
078 for (Iterator it = closures.iterator(); it.hasNext();) {
079 cmds[i++] = (Closure) it.next();
080 }
081 FunctorUtils.validate(cmds);
082 return new ChainedClosure(cmds);
083 }
084
085 /**
086 * Factory method that performs validation.
087 *
088 * @param closure1 the first closure, not null
089 * @param closure2 the second closure, not null
090 * @return the <code>chained</code> closure
091 * @throws IllegalArgumentException if either closure is null
092 */
093 public static Closure getInstance(Closure closure1, Closure closure2) {
094 if (closure1 == null || closure2 == null) {
095 throw new IllegalArgumentException("Closures must not be null");
096 }
097 Closure[] closures = new Closure[] { closure1, closure2 };
098 return new ChainedClosure(closures);
099 }
100
101 /**
102 * Constructor that performs no validation.
103 * Use <code>getInstance</code> if you want that.
104 *
105 * @param closures the closures to chain, not copied, no nulls
106 */
107 public ChainedClosure(Closure[] closures) {
108 super();
109 iClosures = closures;
110 }
111
112 /**
113 * Execute a list of closures.
114 *
115 * @param input the input object passed to each closure
116 */
117 public void execute(Object input) {
118 for (int i = 0; i < iClosures.length; i++) {
119 iClosures[i].execute(input);
120 }
121 }
122
123 /**
124 * Gets the closures, do not modify the array.
125 * @return the closures
126 * @since Commons Collections 3.1
127 */
128 public Closure[] getClosures() {
129 return iClosures;
130 }
131
132 }