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     * Closure implementation that calls a Transformer using the input object
026     * and ignore the result.
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 TransformerClosure implements Closure, Serializable {
034    
035        /** Serial version UID */
036        private static final long serialVersionUID = -5194992589193388969L;
037    
038        /** The transformer to wrap */
039        private final Transformer iTransformer;
040    
041        /**
042         * Factory method that performs validation.
043         * <p>
044         * A null transformer will return the <code>NOPClosure</code>.
045         * 
046         * @param transformer  the transformer to call, null means nop
047         * @return the <code>transformer</code> closure
048         */
049        public static Closure getInstance(Transformer transformer) {
050            if (transformer == null) {
051                return NOPClosure.INSTANCE;
052            }
053            return new TransformerClosure(transformer);
054        }
055    
056        /**
057         * Constructor that performs no validation.
058         * Use <code>getInstance</code> if you want that.
059         * 
060         * @param transformer  the transformer to call, not null
061         */
062        public TransformerClosure(Transformer transformer) {
063            super();
064            iTransformer = transformer;
065        }
066    
067        /**
068         * Executes the closure by calling the decorated transformer.
069         * 
070         * @param input  the input object
071         */
072        public void execute(Object input) {
073            iTransformer.transform(input);
074        }
075    
076        /**
077         * Gets the transformer.
078         * 
079         * @return the transformer
080         * @since Commons Collections 3.1
081         */
082        public Transformer getTransformer() {
083            return iTransformer;
084        }
085    
086    }