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}