/*

 * 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.collections4.functors;

import java.io.Serializable;

import org.apache.commons.collections4.Factory;

import org.apache.commons.collections4.Transformer;

/**

 * Transformer implementation that calls a Factory and returns the result.

 *

 * @since 3.0

 */

public class FactoryTransformer<I, O> implements Transformer<I, O>, Serializable {

    /** Serial version UID */

    private static final long serialVersionUID = -6817674502475353160L;

    /** The factory to wrap */

    private final Factory<? extends O> iFactory;

    /**

     * Factory method that performs validation.

     *

     * @param <I>  the input type

     * @param <O>  the output type

     * @param factory  the factory to call, not null

     * @return the <code>factory</code> transformer

     * @throws NullPointerException if the factory is null

     */

    public static <I, O> Transformer<I, O> factoryTransformer(final Factory<? extends O> factory) {

        if (factory == null) {

            throw new NullPointerException("Factory must not be null");

        }

        return new FactoryTransformer<>(factory);

    }

    /**

     * Constructor that performs no validation.

     * Use <code>factoryTransformer</code> if you want that.

     *

     * @param factory  the factory to call, not null

     */

    public FactoryTransformer(final Factory<? extends O> factory) {

        super();

        iFactory = factory;

    }

    /**

     * Transforms the input by ignoring the input and returning the result of

     * calling the decorated factory.

     *

     * @param input  the input object to transform

     * @return the transformed result

     */

    @Override

    public O transform(final I input) {

        return iFactory.create();

    }

    /**

     * Gets the factory.

     *

     * @return the factory

     * @since 3.1

     */

    public Factory<? extends O> getFactory() {

        return iFactory;

    }

}