package org.apache.commons.collections;

/**
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999-2001 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 acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements 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 Group.
 *
 * 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/>.
 *
 */

import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;

/**
 * An implementation of {@link Set} that is backed by an {@link
 * ArrayList}. Insertion order is maintained - thus
 * First-In-First-Out.
 *
 * @author Lance Lavandowska
 **/
public class FIFOSet extends AbstractSet
{
	private ArrayList _list;
	
	public FIFOSet()
	{
		super();
		_list = new ArrayList();
	}
	
	public FIFOSet(Collection c)
	{
		super();
		_list = new ArrayList(c.size());
		Iterator i = c.iterator();
		while (i.hasNext())
		{
			this.add(i.next());
		}
		_list.trimToSize();
	}
	
	public boolean add(Object o)
	{
		int objectIndex = _list.indexOf(o);
		if (objectIndex == -1)
		{
			_list.add(o);
			return true;
		}
		
		return false;
	}
	
	public boolean addAll(Collection c)
	{
		int listSize = _list.size();
		_list.ensureCapacity(listSize + c.size());
		Iterator i = c.iterator();
		while (i.hasNext())
		{
			this.add(i.next());
		}
		_list.trimToSize();
		
		if (listSize == _list.size())
		{
			return false;
		}
		
		return true;
	}
	
	public void clear()
	{
		_list.clear();
	}
	
	public boolean contains(Object o)
	{
		return _list.contains(o);
	}
	
	public boolean containsAll(Collection c)
	{
		return _list.containsAll(c);
	}
	
	public boolean isEmpty()
	{
		return _list.isEmpty();
	}
	
	public Iterator iterator()
	{
		return _list.iterator();
	}
	
	public boolean remove(Object o)
	{
		int objectIndex = _list.indexOf(o);
		if (objectIndex > -1)
		{
			_list.remove(objectIndex);
			return true;
		}
		
		return false;
	}
	
	public boolean removeAll(Collection c)
	{
		int listSize = _list.size();
		Iterator i = c.iterator();
		while (i.hasNext())
		{
			this.remove(i.next());
		}
		_list.trimToSize();		
		
		if (listSize == _list.size())
		{
			return false;
		}
		
		return true;
	}
	
	public int size()
	{
		return _list.size();
	}
	
	public Object[] toArray()
	{
		return _list.toArray();
	}
	
	public Object[] toArray(Object[] a)
	{
		return _list.toArray(a);
	}
}