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;
020
021import org.apache.commons.collections4.Closure;
022import org.apache.commons.collections4.Transformer;
023
024/**
025 * Transformer implementation that calls a Closure using the input object
026 * and then returns the input.
027 *
028 * @since 3.0
029 */
030public class ClosureTransformer<T> implements Transformer<T, T>, Serializable {
031
032    /** Serial version UID */
033    private static final long serialVersionUID = 478466901448617286L;
034
035    /** The closure to wrap */
036    private final Closure<? super T> iClosure;
037
038    /**
039     * Factory method that performs validation.
040     *
041     * @param <T>  the type of the object to transform
042     * @param closure  the closure to call, not null
043     * @return the <code>closure</code> transformer
044     * @throws NullPointerException if the closure is null
045     */
046    public static <T> Transformer<T, T> closureTransformer(final Closure<? super T> closure) {
047        if (closure == null) {
048            throw new NullPointerException("Closure must not be null");
049        }
050        return new ClosureTransformer<>(closure);
051    }
052
053    /**
054     * Constructor that performs no validation.
055     * Use <code>closureTransformer</code> if you want that.
056     *
057     * @param closure  the closure to call, not null
058     */
059    public ClosureTransformer(final Closure<? super T> closure) {
060        super();
061        iClosure = closure;
062    }
063
064    /**
065     * Transforms the input to result by executing a closure.
066     *
067     * @param input  the input object to transform
068     * @return the transformed result
069     */
070    @Override
071    public T transform(final T input) {
072        iClosure.execute(input);
073        return input;
074    }
075
076    /**
077     * Gets the closure.
078     *
079     * @return the closure
080     * @since 3.1
081     */
082    public Closure<? super T> getClosure() {
083        return iClosure;
084    }
085
086}