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.Transformer;
023
024 /**
025 * Transformer implementation that calls a Closure using the input object
026 * and then returns the input.
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 ClosureTransformer implements Transformer, Serializable {
034
035 /** Serial version UID */
036 private static final long serialVersionUID = 478466901448617286L;
037
038 /** The closure to wrap */
039 private final Closure iClosure;
040
041 /**
042 * Factory method that performs validation.
043 *
044 * @param closure the closure to call, not null
045 * @return the <code>closure</code> transformer
046 * @throws IllegalArgumentException if the closure is null
047 */
048 public static Transformer getInstance(Closure closure) {
049 if (closure == null) {
050 throw new IllegalArgumentException("Closure must not be null");
051 }
052 return new ClosureTransformer(closure);
053 }
054
055 /**
056 * Constructor that performs no validation.
057 * Use <code>getInstance</code> if you want that.
058 *
059 * @param closure the closure to call, not null
060 */
061 public ClosureTransformer(Closure closure) {
062 super();
063 iClosure = closure;
064 }
065
066 /**
067 * Transforms the input to result by executing a closure.
068 *
069 * @param input the input object to transform
070 * @return the transformed result
071 */
072 public Object transform(Object input) {
073 iClosure.execute(input);
074 return input;
075 }
076
077 /**
078 * Gets the closure.
079 *
080 * @return the closure
081 * @since Commons Collections 3.1
082 */
083 public Closure getClosure() {
084 return iClosure;
085 }
086
087 }