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 org.apache.commons.collections4.Transformer;
020
021/**
022 * Transformer implementation that returns a clone of the input object.
023 * <p>
024 * Clone is performed using <code>PrototypeFactory.prototypeFactory(input).create()</code>.
025 * <p>
026 * <b>WARNING:</b> from v4.1 onwards this class will <b>not</b> be serializable anymore
027 * in order to prevent potential remote code execution exploits. Please refer to
028 * <a href="https://issues.apache.org/jira/browse/COLLECTIONS-580">COLLECTIONS-580</a>
029 * for more details.
030 *
031 * @since 3.0
032 */
033public class CloneTransformer<T> implements Transformer<T, T> {
034
035    /** Singleton predicate instance */
036    @SuppressWarnings("rawtypes") // the singleton instance works for all types
037    public static final Transformer INSTANCE = new CloneTransformer<>();
038
039    /**
040     * Factory returning the singleton instance.
041     *
042     * @param <T>  the type of the objects to be cloned
043     * @return the singleton instance
044     * @since 3.1
045     */
046    @SuppressWarnings("unchecked") // the singleton instance works for all types
047    public static <T> Transformer<T, T> cloneTransformer() {
048        return INSTANCE;
049    }
050
051    /**
052     * Constructor.
053     */
054    private CloneTransformer() {
055        super();
056    }
057
058    /**
059     * Transforms the input to result by cloning it.
060     *
061     * @param input  the input object to transform
062     * @return the transformed result
063     */
064    @Override
065    public T transform(final T input) {
066        if (input == null) {
067            return null;
068        }
069        return PrototypeFactory.prototypeFactory(input).create();
070    }
071
072}