/*
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is Rhino code, released
 * May 6, 1999.
 *
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1997-1999 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s):
 * Norris Boyd
 * Roger Lawrence
 *
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU Public License (the "GPL"), in which case the
 * provisions of the GPL are applicable instead of those above.
 * If you wish to allow use of your version of this file only
 * under the terms of the GPL and not to allow others to use your
 * version of this file under the NPL, indicate your decision by
 * deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL.  If you do not delete
 * the provisions above, a recipient may use your version of this
 * file under either the NPL or the GPL.
 */




package org.mozilla.javascript.optimizer;

import org.mozilla.javascript.*;

import java.util.Stack;

public class StmtNodeIterator {

    public StmtNodeIterator(Node start)
    {
        itsStart = start;
    }

    private Node findFirstInterestingNode(Node theNode)
    {
        if (theNode == null) return null;

        if ((theNode.getType() == TokenStream.BLOCK)
                || (theNode.getType() == TokenStream.LOOP)
                || (theNode.getType() == TokenStream.FUNCTION)) {
            if (theNode.getFirst() == null) {
                return findFirstInterestingNode(theNode.getNext());
            }
            else {
                itsStack.push(theNode);
                return findFirstInterestingNode(theNode.getFirst());
            }
        }
        else
            return theNode;
    }

    public Node nextNode()
    {
        if (itsCurrentNode == null)
            return itsCurrentNode = findFirstInterestingNode(itsStart);

        itsCurrentNode = itsCurrentNode.getNext();
        if (itsCurrentNode == null) {
            while ( ! itsStack.isEmpty()) {
                Node n = (Node)(itsStack.pop());
                if (n.getNext() != null) {
                    return itsCurrentNode = findFirstInterestingNode(n.getNext());
                }
            }
            return null;
        }
        else
            return itsCurrentNode = findFirstInterestingNode(itsCurrentNode);
    }

    private Stack itsStack = new Stack();
    private Node itsStart;
    private Node itsCurrentNode;

}
