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 java.io.Serializable;
020import java.util.Objects;
021
022import org.apache.commons.collections4.Factory;
023import org.apache.commons.collections4.Transformer;
024
025/**
026 * Transformer implementation that calls a Factory and returns the result.
027 *
028 * @since 3.0
029 */
030public class FactoryTransformer<I, O> implements Transformer<I, O>, Serializable {
031
032    /** Serial version UID */
033    private static final long serialVersionUID = -6817674502475353160L;
034
035    /**
036     * Factory method that performs validation.
037     *
038     * @param <I>  the input type
039     * @param <O>  the output type
040     * @param factory  the factory to call, not null
041     * @return the {@code factory} transformer
042     * @throws NullPointerException if the factory is null
043     */
044    public static <I, O> Transformer<I, O> factoryTransformer(final Factory<? extends O> factory) {
045        return new FactoryTransformer<>(Objects.requireNonNull(factory, "factory"));
046    }
047
048    /** The factory to wrap */
049    private final Factory<? extends O> iFactory;
050
051    /**
052     * Constructor that performs no validation.
053     * Use {@code factoryTransformer} if you want that.
054     *
055     * @param factory  the factory to call, not null
056     */
057    public FactoryTransformer(final Factory<? extends O> factory) {
058        iFactory = factory;
059    }
060
061    /**
062     * Gets the factory.
063     *
064     * @return the factory
065     * @since 3.1
066     */
067    public Factory<? extends O> getFactory() {
068        return iFactory;
069    }
070
071    /**
072     * Transforms the input by ignoring the input and returning the result of
073     * calling the decorated factory.
074     *
075     * @param input  the input object to transform
076     * @return the transformed result
077     */
078    @Override
079    public O transform(final I input) {
080        return iFactory.create();
081    }
082
083}