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;
021
022import org.apache.commons.collections4.Closure;
023
024/**
025 * Closure implementation that chains the specified closures together.
026 *
027 * @since 3.0
028 */
029public class ChainedClosure<E> implements Closure<E>, Serializable {
030
031    /** Serial version UID */
032    private static final long serialVersionUID = -3520677225766901240L;
033
034    /** The closures to call in turn */
035    private final Closure<? super E>[] iClosures;
036
037    /**
038     * Factory method that performs validation and copies the parameter array.
039     *
040     * @param <E> the type that the closure acts on
041     * @param closures  the closures to chain, copied, no nulls
042     * @return the <code>chained</code> closure
043     * @throws NullPointerException if the closures array is null
044     * @throws NullPointerException if any closure in the array is null
045     */
046    public static <E> Closure<E> chainedClosure(final Closure<? super E>... closures) {
047        FunctorUtils.validate(closures);
048        if (closures.length == 0) {
049            return NOPClosure.<E>nopClosure();
050        }
051        return new ChainedClosure<>(closures);
052    }
053
054    /**
055     * Create a new Closure that calls each closure in turn, passing the
056     * result into the next closure. The ordering is that of the iterator()
057     * method on the collection.
058     *
059     * @param <E> the type that the closure acts on
060     * @param closures  a collection of closures to chain
061     * @return the <code>chained</code> closure
062     * @throws NullPointerException if the closures collection is null
063     * @throws NullPointerException if any closure in the collection is null
064     */
065    @SuppressWarnings("unchecked")
066    public static <E> Closure<E> chainedClosure(final Collection<? extends Closure<? super E>> closures) {
067        if (closures == null) {
068            throw new NullPointerException("Closure collection must not be null");
069        }
070        if (closures.size() == 0) {
071            return NOPClosure.<E>nopClosure();
072        }
073        // convert to array like this to guarantee iterator() ordering
074        final Closure<? super E>[] cmds = new Closure[closures.size()];
075        int i = 0;
076        for (final Closure<? super E> closure : closures) {
077            cmds[i++] = closure;
078        }
079        FunctorUtils.validate(cmds);
080        return new ChainedClosure<>(false, cmds);
081    }
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 E>... closures) {
090        super();
091        iClosures = clone ? FunctorUtils.copy(closures) : closures;
092    }
093
094    /**
095     * Constructor that performs no validation.
096     * Use <code>chainedClosure</code> if you want that.
097     *
098     * @param closures  the closures to chain, copied, no nulls
099     */
100    public ChainedClosure(final Closure<? super E>... closures) {
101        this(true, closures);
102    }
103
104    /**
105     * Execute a list of closures.
106     *
107     * @param input  the input object passed to each closure
108     */
109    @Override
110    public void execute(final E input) {
111        for (final Closure<? super E> iClosure : iClosures) {
112            iClosure.execute(input);
113        }
114    }
115
116    /**
117     * Gets the closures.
118     *
119     * @return a copy of the closures
120     * @since 3.1
121     */
122    public Closure<? super E>[] getClosures() {
123        return FunctorUtils.<E>copy(iClosures);
124    }
125
126}