Add sequenced decorator
git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/collections/trunk@131061 13f79535-47bb-0310-9956-ffa450edef68
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Stephen Colebourne
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/*
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* $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//collections/src/java/org/apache/commons/collections/decorators/Attic/SequencedSet.java,v 1.1 2003/05/10 15:10:22 scolebourne Exp $
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* ====================================================================
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*
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* The Apache Software License, Version 1.1
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*
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* Copyright (c) 2003 The Apache Software Foundation. All rights
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* reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. The end-user documentation included with the redistribution, if
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* any, must include the following acknowledgment:
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* "This product includes software developed by the
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* Apache Software Foundation (http://www.apache.org/)."
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* Alternately, this acknowledgment may appear in the software itself,
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* if and wherever such third-party acknowledgments normally appear.
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*
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* 4. The names "The Jakarta Project", "Commons", and "Apache Software
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* Foundation" must not be used to endorse or promote products derived
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* from this software without prior written permission. For written
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* permission, please contact apache@apache.org.
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*
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* 5. Products derived from this software may not be called "Apache"
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* nor may "Apache" appear in their names without prior written
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* permission of the Apache Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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* ====================================================================
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*
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* This software consists of voluntary contributions made by many
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* individuals on behalf of the Apache Software Foundation. For more
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* information on the Apache Software Foundation, please see
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* <http://www.apache.org/>.
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*
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*/
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package org.apache.commons.collections.decorators;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.List;
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import java.util.Set;
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/**
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* <code>SequencedSet</code> decorates another <code>Set</code>
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* to ensure that the order of addition is retained and used by the iterator.
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* <p>
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* If an object is added to the Set for a second time, it will remain in the
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* original position in the iteration.
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* <p>
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* The order can be observed via the iterator or toArray methods.
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*
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* @since Commons Collections 3.0
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* @version $Revision: 1.1 $ $Date: 2003/05/10 15:10:22 $
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*
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* @author Stephen Colebourne
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* @author Henning P. Schmiedehausen
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*/
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public class SequencedSet extends AbstractSetDecorator implements Set {
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/** Internal list to hold the sequence of objects */
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protected final List setOrder = new ArrayList();
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/**
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* Factory method to create an unmodifiable set.
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*
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* @param set the set to decorate, must not be null
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* @throws IllegalArgumentException if set is null
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*/
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public static Set decorate(Set set) {
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return new SequencedSet(set);
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}
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/**
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* Constructor that wraps (not copies).
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*
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* @param set the set to decorate, must not be null
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* @throws IllegalArgumentException if set is null
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*/
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protected SequencedSet(Set set) {
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super(set);
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setOrder.addAll(set);
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}
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//-----------------------------------------------------------------------
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public void clear() {
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collection.clear();
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setOrder.clear();
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}
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public Iterator iterator() {
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return new SequencedSetIterator(setOrder.iterator(), collection);
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}
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public boolean add(Object object) {
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if (collection.contains(object)) {
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// re-adding doesn't change order
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return collection.add(object);
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} else {
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// first add, so add to both set and list
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boolean result = collection.add(object);
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setOrder.add(object);
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return result;
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}
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}
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public boolean addAll(Collection coll) {
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boolean result = false;
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for (Iterator it = coll.iterator(); it.hasNext();) {
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Object object = it.next();
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result = result | add(object);
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}
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return result;
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}
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public boolean remove(Object object) {
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boolean result = collection.remove(object);
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setOrder.remove(object);
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return result;
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}
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public boolean removeAll(Collection coll) {
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boolean result = false;
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for (Iterator it = coll.iterator(); it.hasNext();) {
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Object object = it.next();
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result = result | remove(object);
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}
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return result;
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}
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public boolean retainAll(Collection coll) {
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boolean result = collection.retainAll(coll);
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if (result == false) {
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return false;
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} else if (collection.size() == 0) {
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setOrder.clear();
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} else {
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for (Iterator it = setOrder.iterator(); it.hasNext();) {
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Object object = (Object) it.next();
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if (collection.contains(object) == false) {
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it.remove();
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}
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}
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}
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return result;
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}
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public Object[] toArray() {
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return setOrder.toArray();
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}
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public Object[] toArray(Object a[]) {
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return setOrder.toArray(a);
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}
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/**
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* Internal iterator handle remove.
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*/
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protected static class SequencedSetIterator extends AbstractIteratorDecorator {
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/** Object we iterate on */
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protected final Collection set;
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/** Last object retrieved */
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protected Object last;
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private SequencedSetIterator(Iterator iterator, Collection set) {
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super(iterator);
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this.set = set;
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}
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public Object next() {
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last = iterator.next();
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return last;
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}
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public void remove() {
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set.remove(last);
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iterator.remove();
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last = null;
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}
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}
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}
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