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