package examples.stack2;

import examples.stack2.Stack;
import resources.Element;

/**
 * Author: W. M. Farmer <BR>
 * Revised: February 21, 2007 <BR>
 * <BR>
 * Description: A definitional extension of the Stack class.
 *
 * @author W. M. Farmer
 */
public class StackPlus extends Stack {

    public StackPlus() {
	super();
    }

    /**
     * Mutator that changes the top element of the stack.
     * 
     * @param e the new top Element
     */
    public void setTop(Element e) throws EmptyStackException {
	pop();
	push(e);
    }

    /**
     * Mutator that empties the stack.
     */
    public void reset() {
	try {
	    while (height() != 0) {
		pop();
	    }
	}
	catch (EmptyStackException x) {
	    // EmptyStackException should not occur.
	    System.out.println(x.toString());
	}	
    }

    /**
     * Predicate that checks if the stack is empty.
     *
     * @return true iff the stack is empty
     */
    public boolean isEmpty() {
	return height() == 0;
    }


}