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Add sequenced decorator 

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/collections/trunk@131061 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Stephen Colebourne 2003-05-10 15:10:22 +00:00
parent 4ca59779e7
commit 4eb9212972
1 changed files with 205 additions and 0 deletions
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src/java/org/apache/commons/collections/decorators/SequencedSet.java Normal file
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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 $
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 2003 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "The Jakarta Project", "Commons", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache"
* nor may "Apache" appear in their names without prior written
* permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package org.apache.commons.collections.decorators;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
/**
* <code>SequencedSet</code> decorates another <code>Set</code>
* to ensure that the order of addition is retained and used by the iterator.
* <p>
* If an object is added to the Set for a second time, it will remain in the
* original position in the iteration.
* <p>
* The order can be observed via the iterator or toArray methods.
*
* @since Commons Collections 3.0
* @version $Revision: 1.1 $ $Date: 2003/05/10 15:10:22 $
*
* @author Stephen Colebourne
* @author Henning P. Schmiedehausen
*/
public class SequencedSet extends AbstractSetDecorator implements Set {
/** Internal list to hold the sequence of objects */
protected final List setOrder = new ArrayList();
/**
* Factory method to create an unmodifiable set.
*
* @param set the set to decorate, must not be null
* @throws IllegalArgumentException if set is null
*/
public static Set decorate(Set set) {
return new SequencedSet(set);
}
/**
* Constructor that wraps (not copies).
*
* @param set the set to decorate, must not be null
* @throws IllegalArgumentException if set is null
*/
protected SequencedSet(Set set) {
super(set);
setOrder.addAll(set);
}
//-----------------------------------------------------------------------
public void clear() {
collection.clear();
setOrder.clear();
}
public Iterator iterator() {
return new SequencedSetIterator(setOrder.iterator(), collection);
}
public boolean add(Object object) {
if (collection.contains(object)) {
// re-adding doesn't change order
return collection.add(object);
} else {
// first add, so add to both set and list
boolean result = collection.add(object);
setOrder.add(object);
return result;
}
}
public boolean addAll(Collection coll) {
boolean result = false;
for (Iterator it = coll.iterator(); it.hasNext();) {
Object object = it.next();
result = result | add(object);
}
return result;
}
public boolean remove(Object object) {
boolean result = collection.remove(object);
setOrder.remove(object);
return result;
}
public boolean removeAll(Collection coll) {
boolean result = false;
for (Iterator it = coll.iterator(); it.hasNext();) {
Object object = it.next();
result = result | remove(object);
}
return result;
}
public boolean retainAll(Collection coll) {
boolean result = collection.retainAll(coll);
if (result == false) {
return false;
} else if (collection.size() == 0) {
setOrder.clear();
} else {
for (Iterator it = setOrder.iterator(); it.hasNext();) {
Object object = (Object) it.next();
if (collection.contains(object) == false) {
it.remove();
}
}
}
return result;
}
public Object[] toArray() {
return setOrder.toArray();
}
public Object[] toArray(Object a[]) {
return setOrder.toArray(a);
}
/**
* Internal iterator handle remove.
*/
protected static class SequencedSetIterator extends AbstractIteratorDecorator {
/** Object we iterate on */
protected final Collection set;
/** Last object retrieved */
protected Object last;
private SequencedSetIterator(Iterator iterator, Collection set) {
super(iterator);
this.set = set;
}
public Object next() {
last = iterator.next();
return last;
}
public void remove() {
set.remove(last);
iterator.remove();
last = null;
}
}
}