Improve how DocumentMarkerController updates markers in response to text edits

third_party/WebKit/Source/core/editing/markers/DocumentMarker.h

 /*
  * This file is part of the DOM implementation for WebCore.
  *
  * 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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef DocumentMarker_h
 #define DocumentMarker_h
 
 #include "core/CoreExport.h"
 #include "platform/graphics/Color.h"
 #include "platform/heap/Handle.h"
+#include "wtf/Optional.h"
 #include "wtf/VectorTraits.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class DocumentMarkerDetails;
 
 // A range of a node within a document that is "marked", such as the range of a
 // misspelled word. It optionally includes a description that could be displayed
 // in the user interface. It also optionally includes a flag specifying whether
@@ skipping 118 matching lines @@
   const String& Description() const;
   bool IsActiveMatch() const;
   Color UnderlineColor() const;
   bool Thick() const;
   Color BackgroundColor() const;
   DocumentMarkerDetails* Details() const;
 
   void SetIsActiveMatch(bool);
   void ClearDetails() { details_.Clear(); }
 
+  struct MarkerOffsets {
+    unsigned start_offset;
+    unsigned end_offset;
+  };
+
+  Optional<MarkerOffsets> ComputeOffsetsAfterShift(unsigned offset,
+                                                   unsigned old_length,
+                                                   unsigned new_length) const;
+
   // Offset modifications are done by DocumentMarkerController.
   // Other classes should not call following setters.
   void SetStartOffset(unsigned offset) { start_offset_ = offset; }
   void SetEndOffset(unsigned offset) { end_offset_ = offset; }
   void ShiftOffsets(int delta);
 
   bool operator==(const DocumentMarker& o) const {
     return GetType() == o.GetType() && StartOffset() == o.StartOffset() &&
            EndOffset() == o.EndOffset();
   }
@@ skipping 23 matching lines @@
   virtual bool IsDescription() const { return false; }
   virtual bool IsTextMatch() const { return false; }
   virtual bool IsComposition() const { return false; }
 
   DEFINE_INLINE_VIRTUAL_TRACE() {}
 };
 
 }  // namespace blink
 
 #endif  // DocumentMarker_h