Make LayoutState always be RAII

Source/core/rendering/RenderView.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 208 matching lines @@
             || (renderer.isRenderBlock() && toRenderBlock(renderer).shapeInsideInfo())
             || (m_layoutState->shapeInsideInfo() && renderer.isRenderBlock() && !toRenderBlock(renderer).allowsShapeInsideInfoSharing(&m_layoutState->shapeInsideInfo()->owner()))
             ) {
             pushLayoutStateForCurrentFlowThread(renderer);
             m_layoutState = new LayoutState(m_layoutState, renderer, offset, pageHeight, pageHeightChanged, colInfo);
             return true;
         }
         return false;
     }
 
-    void layoutContent(const LayoutState&);
+    void layoutContent();
 #ifndef NDEBUG
-    void checkLayoutState(const LayoutState&);
+    void checkLayoutState();
 #endif
 
     void positionDialog(RenderBox*);
     void positionDialogs();
 
     void pushLayoutStateForCurrentFlowThread(const RenderObject&);
     void popLayoutStateForCurrentFlowThread();
 
     friend class LayoutStateMaintainer;
     friend class LayoutStateDisabler;
+    friend class RootLayoutStateScope;
 
     bool shouldUsePrintingLayout() const;
 
     FrameView* m_frameView;
 
     RenderObject* m_selectionStart;
     RenderObject* m_selectionEnd;
 
     int m_selectionStartPos;
     int m_selectionEndPos;
 
     LayoutUnit m_pageLogicalHeight;
     bool m_pageLogicalHeightChanged;
     LayoutState* m_layoutState;
     unsigned m_layoutStateDisableCount;
     OwnPtr<RenderLayerCompositor> m_compositor;
     OwnPtr<FlowThreadController> m_flowThreadController;
     RefPtr<IntervalArena> m_intervalArena;
 
     RenderQuote* m_renderQuoteHead;
     unsigned m_renderCounterCount;
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderView, isRenderView());
 
+class RootLayoutStateScope {
+public:
+    explicit RootLayoutStateScope(RenderView& view)
+        : m_view(view)
+    {
+        ASSERT(!m_view.m_layoutState);
+        initializeLayoutState();
+        m_view.m_layoutState = &m_rootLayoutState;
+    }
+
+    ~RootLayoutStateScope()
+    {
+        ASSERT(m_view.m_layoutState == &m_rootLayoutState);
+        m_view.m_layoutState = 0;
+    }
+private:
+    void initializeLayoutState();
+    RenderView& m_view;
+    LayoutState m_rootLayoutState;
+};
+
 // Stack-based class to assist with LayoutState push/pop
 class LayoutStateMaintainer {
     WTF_MAKE_NONCOPYABLE(LayoutStateMaintainer);
 public:
     // ctor to push now
     explicit LayoutStateMaintainer(RenderBox& root, const LayoutSize& offset, LayoutUnit pageHeight = 0, bool pageHeightChanged = false, ColumnInfo* colInfo = 0)
         : m_view(*root.view())
         , m_disabled(root.shouldDisableLayoutState())
         , m_didStart(false)
         , m_didEnd(false)
         , m_didCreateLayoutState(false)
     {
         push(root, offset, pageHeight, pageHeightChanged, colInfo);
     }
 
     // ctor to maybe push later
     explicit LayoutStateMaintainer(RenderBox& root)
         : m_view(*root.view())
         , m_disabled(false)
         , m_didStart(false)
         , m_didEnd(false)
         , m_didCreateLayoutState(false)
     {
     }
 
     ~LayoutStateMaintainer()
     {
+        if (m_didStart)
+            pop();
         ASSERT(m_didStart == m_didEnd);   // if this fires, it means that someone did a push(), but forgot to pop().
     }
 
     void push(RenderBox& root, const LayoutSize& offset, LayoutUnit pageHeight = 0, bool pageHeightChanged = false, ColumnInfo* colInfo = 0)
     {
         ASSERT(!m_didStart);
         // We push state even if disabled, because we still need to store layoutDelta
         m_didCreateLayoutState = m_view.pushLayoutState(root, offset, pageHeight, pageHeightChanged, colInfo);
         if (m_disabled && m_didCreateLayoutState)
             m_view.disableLayoutState();
         m_didStart = true;
     }
 
-    void pop()
-    {
-        if (m_didStart) {
-            ASSERT(!m_didEnd);
-            if (m_didCreateLayoutState) {
-                m_view.popLayoutState();
-                if (m_disabled)
-                    m_view.enableLayoutState();
-            }
-
-            m_didEnd = true;
-        }
-    }
-
     bool didPush() const { return m_didStart; }
 
 private:
+    void pop()
+    {
+        ASSERT(m_didStart && !m_didEnd);
+        if (m_didCreateLayoutState) {
+            m_view.popLayoutState();
+            if (m_disabled)
+                m_view.enableLayoutState();
+        }
+
+        m_didEnd = true;
+    }
+
     RenderView& m_view;
     bool m_disabled : 1;        // true if the offset and clip part of layoutState is disabled
     bool m_didStart : 1;        // true if we did a push or disable
     bool m_didEnd : 1;          // true if we popped or re-enabled
     bool m_didCreateLayoutState : 1; // true if we actually made a layout state.
 };
 
 class LayoutStateDisabler {
     WTF_MAKE_NONCOPYABLE(LayoutStateDisabler);
 public:
     LayoutStateDisabler(const RenderBox& root)
         : m_view(*root.view())
     {
         m_view.disableLayoutState();
     }
 
     ~LayoutStateDisabler()
     {
         m_view.enableLayoutState();
     }
 private:
     RenderView& m_view;
 };
 
 } // namespace WebCore
 
 #endif // RenderView_h