Refactor DocumentMarkerController

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

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 148 matching lines @@
       m_details(TextCompositionMarkerDetails::create(underlineColor,
                                                      thick,
                                                      backgroundColor)) {}
 
 DocumentMarker::DocumentMarker(const DocumentMarker& marker)
     : m_type(marker.type()),
       m_startOffset(marker.startOffset()),
       m_endOffset(marker.endOffset()),
       m_details(marker.details()) {}
 
+DocumentMarker::ShiftMarkerResult DocumentMarker::getShiftedMarkerPosition(
+    unsigned offset,
+    unsigned oldLength,
+    unsigned newLength) const {
+  ShiftMarkerResult result;
+  result.newStartOffset = startOffset();
+  result.newEndOffset = endOffset();
+  result.shouldRemoveMarker = false;
+
+  // algorithm inspired by https://dom.spec.whatwg.org/#concept-cd-replace
+  // but with some changes
+  if (startOffset() > offset) {
+    // Deviation from the concept-cd-replace algorithm: < instead of <= in
+    // the next line
+    if (startOffset() < offset + oldLength) {
+      // Marker start was in the replaced text. Move to end of new text
+      // (Deviation from the concept-cd-replace algorithm: that algorithm
+      // would move to the beginning of the new text here)
+      result.newStartOffset = offset + newLength;
+    } else {
+      // Marker start was after the replaced text. Shift by length
+      // difference
+      result.newStartOffset = startOffset() + newLength - oldLength;
+    }
+  }
+
+  if (endOffset() > offset) {
+    // Deviation from the concept-cd-replace algorithm: < instead of <= in
+    // the next line
+    if (endOffset() < offset + oldLength) {
+      // Marker end was in the replaced text. Move to beginning of new text
+      result.newEndOffset = offset;
+    } else {
+      // Marker end was after the replaced text. Shift by length difference
+      result.newEndOffset = endOffset() + newLength - oldLength;
+    }
+  }
+
+  if (result.newStartOffset >= result.newEndOffset)
+    result.shouldRemoveMarker = true;
+
+  return result;
+}
+
 void DocumentMarker::shiftOffsets(int delta) {
   m_startOffset += delta;
   m_endOffset += delta;
 }
 
 void DocumentMarker::setActiveMatch(bool active) {
   m_details = DocumentMarkerTextMatch::create(active);
 }
 
 const String& DocumentMarker::description() const {
@@ skipping 29 matching lines @@
           toTextCompositionMarkerDetails(m_details.get()))
     return details->backgroundColor();
   return Color::transparent;
 }
 
 DEFINE_TRACE(DocumentMarker) {
   visitor->trace(m_details);
 }
 
 }  // namespace blink