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.functor.core.composite;
018
019import java.io.Serializable;
020import java.util.ArrayList;
021import java.util.Iterator;
022import java.util.List;
023
024import org.apache.commons.functor.Procedure;
025
026/**
027 * A {@link Procedure Procedure}
028 * that {@link Procedure#run runs} an ordered
029 * sequence of {@link Procedure Procedures}.
030 * When the sequence is empty, this procedure is does
031 * nothing.
032 * <p>
033 * Note that although this class implements
034 * {@link Serializable}, a given instance will
035 * only be truly <code>Serializable</code> if all the
036 * underlying functors are.  Attempts to serialize
037 * an instance whose delegates are not all
038 * <code>Serializable</code> will result in an exception.
039 * </p>
040 * @version $Revision: 1365329 $ $Date: 2012-07-24 18:34:23 -0400 (Tue, 24 Jul 2012) $
041 */
042public class Sequence implements Procedure, Serializable {
043
044    /**
045     * serialVersionUID declaration.
046     */
047    private static final long serialVersionUID = 8041703589149547883L;
048    // attributes
049    // ------------------------------------------------------------------------
050    /**
051     * The data structure where storing procedures sequence.
052     */
053    private List<Procedure> list = new ArrayList<Procedure>();
054
055    // constructor
056    // ------------------------------------------------------------------------
057    /**
058     * Create a new Sequence.
059     */
060    public Sequence() {
061        super();
062    }
063
064    /**
065     * Create a new Sequence instance.
066     *
067     * @param procedures to run sequentially
068     */
069    public Sequence(Procedure... procedures) {
070        this();
071        if (procedures != null) {
072            for (Procedure p : procedures) {
073                then(p);
074            }
075        }
076    }
077
078    /**
079     * Create a new Sequence instance.
080     *
081     * @param procedures to run sequentially
082     */
083    public Sequence(Iterable<Procedure> procedures) {
084        this();
085        if (procedures != null) {
086            for (Procedure p : procedures) {
087                then(p);
088            }
089        }
090    }
091
092    // modifiers
093    // ------------------------------------------------------------------------
094    /**
095     * Fluently add a Procedure.
096     * @param p Procedure to add
097     * @return this
098     */
099    public final Sequence then(Procedure p) {
100        if (p != null) {
101            list.add(p);
102        }
103        return this;
104    }
105
106    // predicate interface
107    // ------------------------------------------------------------------------
108    /**
109     * {@inheritDoc}
110     */
111    public final void run() {
112        for (Iterator<Procedure> iter = list.iterator(); iter.hasNext();) {
113            iter.next().run();
114        }
115    }
116
117    /**
118     * {@inheritDoc}
119     */
120    @Override
121    public final boolean equals(Object that) {
122        return that == this || (that instanceof Sequence && equals((Sequence) that));
123    }
124
125    /**
126     * Learn whether a given Sequence is equal to this.
127     * @param that Sequence to test
128     * @return boolean
129     */
130    public boolean equals(Sequence that) {
131        // by construction, list is never null
132        return null != that && list.equals(that.list);
133    }
134
135    /**
136     * {@inheritDoc}
137     */
138    @Override
139    public int hashCode() {
140        // by construction, list is never null
141        return "Sequence".hashCode() ^ list.hashCode();
142    }
143
144    /**
145     * {@inheritDoc}
146     */
147    @Override
148    public String toString() {
149        return "Sequence<" + list + ">";
150    }
151
152}