    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 *      https://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}