/*
 * BSTEnumerator.java - Enumerate A BST
 *
 * Copyright (c) 1996 Chuck McManis, All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and without
 * fee is hereby granted provided that this copyright notice
 * appears in all copies.
 *
 * CHUCK MCMANIS MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE
 * SUITABILITY OF THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING
 * BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. CHUCK MCMANIS
 * SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT
 * OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 */

import java.util.Enumeration;
import java.util.NoSuchElementException;

/**
 * This class is used to enumerate a BST from the first to the last node.
 */

class BSTEnumerator extends BSTNode implements Enumeration {
    private BSTNode currentNode;
    private boolean keys;

    BSTEnumerator(BSTNode start, boolean doKeys) {
        super();
        currentNode = (start != null) ? start.min() : null;
        keys = doKeys;
    }

    public boolean hasMoreElements() {
        return (currentNode != null);
    }

    public Object nextElement() {
        if (currentNode == null)
            throw new NoSuchElementException();
        BSTNode n = currentNode;
        currentNode = n.successor();
        return (keys ? n.key : n.payload);
    }
}