/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.collections15.functors;

import java.io.Serializable;

import org.apache.commons.collections15.Transformer;
import org.apache.commons.collections15.util.GWTCloneable;

/**
 * Transformer implementation that returns a clone of the input object.
 * <p>
 * Clone is performed using
 * <code>PrototypeFactory.getInstance(input).create()</code>.
 *
 * @since Commons Collections 3.0
 * @version $Revision$ $Date$
 *
 * @author Stephen Colebourne
 */
public class CloneTransformer<T> implements Transformer<T, T>, Serializable {

	/** Serial version UID */
	private static final long serialVersionUID = -8188742709499652567L;

	/** Singleton predicate instance */
	public static final Transformer<Object, Object> INSTANCE = new CloneTransformer<Object>();

	/**
	 * Factory returning the singleton instance.
	 * 
	 * @return the singleton instance
	 * @since Commons Collections 3.1
	 */
	@SuppressWarnings("unchecked")
	public static <T> Transformer<T, T> getInstance() {
		return (Transformer<T, T>) INSTANCE;
	}

	/**
	 * Constructor
	 */
	private CloneTransformer() {
		super();
	}

	/**
	 * Transforms the input to result by cloning it.
	 * 
	 * @param input
	 *            the input object to transform
	 * @return the transformed result
	 */
	@Override
	public T transform(T input) {
		if (input == null) {
			return null;
		}
		if (input instanceof GWTCloneable) {
			return (T) ((GWTCloneable) input).duplicate();
		}
		throw new RuntimeException("Cloning is not supported for:" + input);
	}


}