/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla 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/MPL/
 *
 * 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 Mozilla Communicator client code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Original Author: David W. Hyatt (hyatt@netscape.com)
 *
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 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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/*
 * a class that walks the lexicographic tree of rule nodes as style
 * rules are matched
 */

#include "nsRuleNode.h"

class nsRuleWalker {
public:
  nsRuleNode* GetCurrentNode() { return mCurrent; }
  void SetCurrentNode(nsRuleNode* aNode) { mCurrent = aNode; }

  void Forward(nsIStyleRule* aRule) { 
    if (mCurrent) { // check for OOM from previous step
      mCurrent = mCurrent->Transition(aRule, mLevel, mImportance);
    }
  }

  void Reset() { mCurrent = mRoot; }

  PRBool AtRoot() { return mCurrent == mRoot; }

  void SetLevel(PRUint8 aLevel, PRBool aImportance) {
    mLevel = aLevel;
    mImportance = aImportance;
  }
  PRUint8 GetLevel() const { return mLevel; }
  PRBool GetImportance() const { return mImportance; }

private:
  nsRuleNode* mCurrent; // Our current position.
  nsRuleNode* mRoot; // The root of the tree we're walking.
  PRUint8 mLevel; // an nsStyleSet::sheetType
  PRPackedBool mImportance;

public:
  nsRuleWalker(nsRuleNode* aRoot) :mCurrent(aRoot), mRoot(aRoot) { MOZ_COUNT_CTOR(nsRuleWalker); }
  ~nsRuleWalker() { MOZ_COUNT_DTOR(nsRuleWalker); }
};
