    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.Collection;
    021import java.util.Objects;
    022
    023import org.apache.commons.collections4.Closure;
    024
    025/**
    026 * Closure implementation that chains the specified closures together.
    027 *
    028 * @param <T> the type of the input to the operation.
    029 * @since 3.0
    030 */
    031public class ChainedClosure<T> implements Closure<T>, Serializable {
    032
    033    /** Serial version UID */
    034    private static final long serialVersionUID = -3520677225766901240L;
    035
    036    /**
    037     * Factory method that performs validation and copies the parameter array.
    038     *
    039     * @param <E> the type that the closure acts on
    040     * @param closures  the closures to chain, copied, no nulls
    041     * @return the {@code chained} closure
    042     * @throws NullPointerException if the closures array is null
    043     * @throws NullPointerException if any closure in the array is null
    044     */
    045    public static <E> Closure<E> chainedClosure(final Closure<? super E>... closures) {
    046        FunctorUtils.validate(closures);
    047        if (closures.length == 0) {
    048            return NOPClosure.<E>nopClosure();
    049        }
    050        return new ChainedClosure<>(closures);
    051    }
    052
    053    /**
    054     * Create a new Closure that calls each closure in turn, passing the
    055     * result into the next closure. The ordering is that of the iterator()
    056     * method on the collection.
    057     *
    058     * @param <E> the type that the closure acts on
    059     * @param closures  a collection of closures to chain
    060     * @return the {@code chained} closure
    061     * @throws NullPointerException if the closures collection is null
    062     * @throws NullPointerException if any closure in the collection is null
    063     */
    064    @SuppressWarnings("unchecked")
    065    public static <E> Closure<E> chainedClosure(final Collection<? extends Closure<? super E>> closures) {
    066        Objects.requireNonNull(closures, "closures");
    067        if (closures.isEmpty()) {
    068            return NOPClosure.<E>nopClosure();
    069        }
    070        // convert to array like this to guarantee iterator() ordering
    071        final Closure<? super E>[] cmds = new Closure[closures.size()];
    072        int i = 0;
    073        for (final Closure<? super E> closure : closures) {
    074            cmds[i++] = closure;
    075        }
    076        FunctorUtils.validate(cmds);
    077        return new ChainedClosure<>(false, cmds);
    078    }
    079
    080    /** The closures to call in turn */
    081    private final Closure<? super T>[] iClosures;
    082
    083    /**
    084     * Hidden constructor for the use by the static factory methods.
    085     *
    086     * @param clone  if {@code true} the input argument will be cloned
    087     * @param closures  the closures to chain, no nulls
    088     */
    089    private ChainedClosure(final boolean clone, final Closure<? super T>... closures) {
    090        iClosures = clone ? FunctorUtils.copy(closures) : closures;
    091    }
    092
    093    /**
    094     * Constructor that performs no validation.
    095     * Use {@code chainedClosure} if you want that.
    096     *
    097     * @param closures  the closures to chain, copied, no nulls
    098     */
    099    public ChainedClosure(final Closure<? super T>... closures) {
    100        this(true, closures);
    101    }
    102
    103    /**
    104     * Execute a list of closures.
    105     *
    106     * @param input  the input object passed to each closure
    107     */
    108    @Override
    109    public void execute(final T input) {
    110        for (final Closure<? super T> iClosure : iClosures) {
    111            iClosure.accept(input);
    112        }
    113    }
    114
    115    /**
    116     * Gets the closures.
    117     *
    118     * @return a copy of the closures
    119     * @since 3.1
    120     */
    121    public Closure<? super T>[] getClosures() {
    122        return FunctorUtils.copy(iClosures);
    123    }
    124
    125}