diff -r 000000000000 -r 6474c204b198 layout/mathml/nsMathMLmfencedFrame.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/mathml/nsMathMLmfencedFrame.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,112 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMathMLmfencedFrame_h
+#define nsMathMLmfencedFrame_h
+
+#include "mozilla/Attributes.h"
+#include "nsMathMLContainerFrame.h"
+
+//
+// <mfenced> -- surround content with a pair of fences
+//
+
+class nsMathMLmfencedFrame : public nsMathMLContainerFrame {
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  friend nsIFrame* NS_NewMathMLmfencedFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
+
+  virtual void
+  SetAdditionalStyleContext(int32_t          aIndex, 
+                            nsStyleContext*  aStyleContext) MOZ_OVERRIDE;
+  virtual nsStyleContext*
+  GetAdditionalStyleContext(int32_t aIndex) const MOZ_OVERRIDE;
+
+  NS_IMETHOD
+  InheritAutomaticData(nsIFrame* aParent) MOZ_OVERRIDE;
+
+  virtual nsresult
+  SetInitialChildList(ChildListID     aListID,
+                      nsFrameList&    aChildList) MOZ_OVERRIDE;
+
+  virtual nsresult
+  Reflow(nsPresContext*          aPresContext,
+         nsHTMLReflowMetrics&     aDesiredSize,
+         const nsHTMLReflowState& aReflowState,
+         nsReflowStatus&          aStatus) MOZ_OVERRIDE;
+
+  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists) MOZ_OVERRIDE;
+
+  virtual void
+  GetIntrinsicWidthMetrics(nsRenderingContext* aRenderingContext,
+                           nsHTMLReflowMetrics& aDesiredSize) MOZ_OVERRIDE;
+
+  virtual nsresult
+  AttributeChanged(int32_t         aNameSpaceID,
+                   nsIAtom*        aAttribute,
+                   int32_t         aModType) MOZ_OVERRIDE;
+
+  // override the base method because we must keep separators in sync
+  virtual nsresult
+  ChildListChanged(int32_t aModType) MOZ_OVERRIDE;
+
+  // override the base method so that we can deal with fences and separators
+  virtual nscoord
+  FixInterFrameSpacing(nsHTMLReflowMetrics& aDesiredSize) MOZ_OVERRIDE;
+
+  // helper routines to format the MathMLChars involved here
+  static nsresult
+  ReflowChar(nsPresContext*      aPresContext,
+             nsRenderingContext& aRenderingContext,
+             nsMathMLChar*        aMathMLChar,
+             nsOperatorFlags      aForm,
+             int32_t              aScriptLevel,
+             nscoord              axisHeight,
+             nscoord              leading,
+             nscoord              em,
+             nsBoundingMetrics&   aContainerSize,
+             nscoord&             aAscent,
+             nscoord&             aDescent,
+             bool                 aRTL);
+
+  static void
+  PlaceChar(nsMathMLChar*      aMathMLChar,
+            nscoord            aDesiredSize,
+            nsBoundingMetrics& bm,
+            nscoord&           dx);
+
+  virtual bool
+  IsMrowLike() MOZ_OVERRIDE
+  {
+    // Always treated as an mrow with > 1 child as
+    // <mfenced> <mo>%</mo> </mfenced>
+    // renders equivalently to
+    // <mrow> <mo> ( </mo> <mo>%</mo> <mo> ) </mo> </mrow>
+    // This also holds with multiple children.  (MathML3 3.3.8.1)
+    return true;
+  }
+
+protected:
+  nsMathMLmfencedFrame(nsStyleContext* aContext) : nsMathMLContainerFrame(aContext) {}
+  virtual ~nsMathMLmfencedFrame();
+  
+  nsMathMLChar* mOpenChar;
+  nsMathMLChar* mCloseChar;
+  nsMathMLChar* mSeparatorsChar;
+  int32_t       mSeparatorsCount;
+
+  // clean up
+  void
+  RemoveFencesAndSeparators();
+
+  // add fences and separators when all child frames are known
+  void
+  CreateFencesAndSeparators(nsPresContext* aPresContext);
+};
+
+#endif /* nsMathMLmfencedFrame_h */