/**
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright
 *    statements and notices.  Redistributions must also contain a
 *    copy of this document.
 *
 * 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 name "Exolab" must not be used to endorse or promote
 *    products derived from this Software without prior written
 *    permission of Exoffice Technologies.  For written permission,
 *    please contact info@exolab.org.
 *
 * 4. Products derived from this Software may not be called "Exolab"
 *    nor may "Exolab" appear in their names without prior written
 *    permission of Exoffice Technologies. Exolab is a registered
 *    trademark of Exoffice Technologies.
 *
 * 5. Due credit should be given to the Exolab Project
 *    (http://www.exolab.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
 * ``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
 * EXOFFICE TECHNOLOGIES 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.
 *
 * Copyright 1999 (C) Exoffice Technologies Inc. All Rights Reserved.
 *
 * $Id: ArrayStack.java,v 1.2 2002/02/25 20:31:01 dblevins Exp $
 */
package org.openejb.util;


import java.util.ArrayList;
import java.util.EmptyStackException;

/**
 * Unsynchronized Stack.
 */
public final class ArrayStack extends ArrayList implements Stack{


    /**
     * Sets the size of the stack and prunes entries from the top
     * of the stack that exceed the stack's new size.
     */
	public void setSize(int newSize) {
	    if (newSize == 0) clear();
	    else {
	        for (int i = size() - 1; i >= newSize; i--) remove(i);
	    }
	}

    /**
     * Adds the object to the top of the stack.
     */
	public Object push(Object item) {
	    add(item);
	    return item;
	}

	/**
	 * Removes the object at the top of this stack and returns that
	 * object as the value of this function.
	 *
	 * @return     The object at the top of this stack.
	 * @exception  EmptyStackException  if this stack is empty.
	 */
	public Object pop() {
	    Object	obj;
	    obj = peek();

	    int	len = size();
        remove(len - 1);

	    return obj;
	}

	/**
	 * Looks at the object at the top of this stack without removing it
	 * from the stack.
	 *
	 * @return     the object at the top of this stack.
	 * @exception  EmptyStackException  if this stack is empty.
	 */
	public Object peek() {
	    int	len = size();

	    if (len == 0) throw new EmptyStackException();

	    return get(len - 1);
	}
}
