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.Factory;
022    import org.apache.commons.collections.Transformer;
023    
024    /**
025     * Transformer implementation that calls a Factory and returns the result.
026     * 
027     * @since Commons Collections 3.0
028     * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
029     *
030     * @author Stephen Colebourne
031     */
032    public class FactoryTransformer implements Transformer, Serializable {
033    
034        /** Serial version UID */
035        private static final long serialVersionUID = -6817674502475353160L;
036    
037        /** The factory to wrap */
038        private final Factory iFactory;
039    
040        /**
041         * Factory method that performs validation.
042         * 
043         * @param factory  the factory to call, not null
044         * @return the <code>factory</code> transformer
045         * @throws IllegalArgumentException if the factory is null
046         */
047        public static Transformer getInstance(Factory factory) {
048            if (factory == null) {
049                throw new IllegalArgumentException("Factory must not be null");
050            }
051            return new FactoryTransformer(factory);
052        }
053    
054        /**
055         * Constructor that performs no validation.
056         * Use <code>getInstance</code> if you want that.
057         * 
058         * @param factory  the factory to call, not null
059         */
060        public FactoryTransformer(Factory factory) {
061            super();
062            iFactory = factory;
063        }
064    
065        /**
066         * Transforms the input by ignoring the input and returning the result of
067         * calling the decorated factory.
068         * 
069         * @param input  the input object to transform
070         * @return the transformed result
071         */
072        public Object transform(Object input) {
073            return iFactory.create();
074        }
075    
076        /**
077         * Gets the factory.
078         * 
079         * @return the factory
080         * @since Commons Collections 3.1
081         */
082        public Factory getFactory() {
083            return iFactory;
084        }
085    
086    }