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