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 */
017package org.apache.commons.collections4.functors;
018
019import java.io.Serializable;
020
021import org.apache.commons.collections4.Transformer;
022
023/**
024 * Transformer implementation that returns a clone of the input object.
025 * <p>
026 * Clone is performed using <code>PrototypeFactory.prototypeFactory(input).create()</code>.
027 *
028 * @since 3.0
029 * @version $Id: CloneTransformer.html 887892 2013-11-24 13:43:45Z tn $
030 */
031public class CloneTransformer<T> implements Transformer<T, T>, Serializable {
032
033    /** Serial version UID */
034    private static final long serialVersionUID = -8188742709499652567L;
035
036    /** Singleton predicate instance */
037    @SuppressWarnings("rawtypes") // the singleton instance works for all types
038    public static final Transformer INSTANCE = new CloneTransformer<Object>();
039
040    /**
041     * Factory returning the singleton instance.
042     *
043     * @param <T>  the type of the objects to be cloned
044     * @return the singleton instance
045     * @since 3.1
046     */
047    @SuppressWarnings("unchecked") // the singleton instance works for all types
048    public static <T> Transformer<T, T> cloneTransformer() {
049        return (Transformer<T, T>) INSTANCE;
050    }
051
052    /**
053     * Constructor.
054     */
055    private CloneTransformer() {
056        super();
057    }
058
059    /**
060     * Transforms the input to result by cloning it.
061     *
062     * @param input  the input object to transform
063     * @return the transformed result
064     */
065    public T transform(final T input) {
066        if (input == null) {
067            return null;
068        }
069        return PrototypeFactory.prototypeFactory(input).create();
070    }
071
072    private Object readResolve() {
073        return INSTANCE;
074    }
075
076}