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()}.
025 * </p>
026 * <p>
027 * <strong>WARNING:</strong> from v4.1 onwards this class will <strong>not</strong> be serializable anymore
028 * in order to prevent potential remote code execution exploits. Please refer to
029 * <a href="https://issues.apache.org/jira/browse/COLLECTIONS-580">COLLECTIONS-580</a>
030 * for more details.
031 * </p>
032 *
033 * @param <T> the type of the input and result to the function.
034 * @since 3.0
035 */
036public class CloneTransformer<T> implements Transformer<T, T> {
037
038    /** Singleton predicate instance */
039    @SuppressWarnings("rawtypes") // the singleton instance works for all types
040    public static final Transformer INSTANCE = new CloneTransformer<>();
041
042    /**
043     * Factory returning the singleton instance.
044     *
045     * @param <T>  the type of the objects to be cloned
046     * @return the singleton instance
047     * @since 3.1
048     */
049    public static <T> Transformer<T, T> cloneTransformer() {
050        return INSTANCE;
051    }
052
053    /**
054     * Constructs a new instance.
055     */
056    private CloneTransformer() {
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    @Override
066    public T transform(final T input) {
067        if (input == null) {
068            return null;
069        }
070        return PrototypeFactory.prototypeFactory(input).get();
071    }
072
073}