*** FOR PROTOTYPE PURPOSES ONLY! NOT INTENDED FOR COMMIT! ***

Source/core/rendering/RenderObject.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 157 matching lines @@
     RenderObject* lastChild() const
     {
         if (const RenderObjectChildList* children = virtualChildren())
             return children->lastChild();
         return 0;
     }
 
     virtual RenderObjectChildList* virtualChildren() { return 0; }
     virtual const RenderObjectChildList* virtualChildren() const { return 0; }
 
+    // Introduce a non-recursive traversal algorithm for layout
+    enum Order { Pre, Post };
+    RenderObject* nextForLayout(Order& order, const RenderObject* stayWithin, bool skippingChildren) const;
+
     RenderObject* nextInPreOrder() const;
     RenderObject* nextInPreOrder(const RenderObject* stayWithin) const;
     RenderObject* nextInPreOrderAfterChildren() const;
     RenderObject* nextInPreOrderAfterChildren(const RenderObject* stayWithin) const;
     RenderObject* previousInPreOrder() const;
     RenderObject* previousInPreOrder(const RenderObject* stayWithin) const;
     RenderObject* childAt(unsigned) const;
 
     RenderObject* lastLeafChild() const;
 
@@ skipping 470 matching lines @@
 
     void updateFillImages(const FillLayer*, const FillLayer*);
     void updateImage(StyleImage*, StyleImage*);
     void updateShapeImage(const ShapeValue*, const ShapeValue*);
 
     virtual void paint(PaintInfo&, const LayoutPoint&);
 
     // Subclasses must reimplement this method to compute the size and position
     // of this object and all its descendants.
     virtual void layout() = 0;
+
+    // These are hooks into the non-recursive layout variation.  Each subclass
+    // would override these methods and implement non-recursive layout.
+    virtual bool isNonRecursiveLayout() const { return false; }
+    // We have pre/post layout methods in order to facilitate work to be done
+    // before children are visited and after.
+    virtual void preLayout() { ASSERT_NOT_REACHED(); }
+    virtual void postLayout() { ASSERT_NOT_REACHED(); }
+
     virtual bool updateImageLoadingPriorities() { return false; }
     void setHasPendingResourceUpdate(bool hasPendingResourceUpdate) { m_bitfields.setHasPendingResourceUpdate(hasPendingResourceUpdate); }
     bool hasPendingResourceUpdate() const { return m_bitfields.hasPendingResourceUpdate(); }
 
     /* This function performs a layout only if one is needed. */
     void layoutIfNeeded() { if (needsLayout()) layout(); }
 
     void forceLayout();
     void forceChildLayout();
 
@@ skipping 739 matching lines @@
 void showTree(const WebCore::RenderObject*);
 void showLineTree(const WebCore::RenderObject*);
 void showRenderTree(const WebCore::RenderObject* object1);
 // We don't make object2 an optional parameter so that showRenderTree
 // can be called from gdb easily.
 void showRenderTree(const WebCore::RenderObject* object1, const WebCore::RenderObject* object2);
 
 #endif
 
 #endif // RenderObject_h