Ensure valid input for CompositeEditCommand::moveParagraph[s]

third_party/WebKit/Source/core/editing/commands/ReplaceSelectionCommand.cpp

 /*
  * Copyright (C) 2005, 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009, 2010, 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 1507 matching lines @@
       lastPositionInOrAfterNode(insertedNodes.lastLeafInserted());
 
   // Determine whether or not we should merge the end of inserted content with
   // what's after it before we do the start merge so that the start merge
   // doesn't effect our decision.
   m_shouldMergeEnd = shouldMergeEnd(selectionEndWasEndOfParagraph);
 
   if (shouldMergeStart(selectionStartWasStartOfParagraph,
                        fragment.hasInterchangeNewlineAtStart(),
                        startIsInsideMailBlockquote)) {
-    // TODO(xiaochengh): Stop storing VisiblePositions through mutations.
     VisiblePosition startOfParagraphToMove = positionAtStartOfInsertedContent();
     VisiblePosition destination = previousPositionOf(startOfParagraphToMove);
+
+    // Helpers for making the VisiblePositions valid again after DOM changes.
+    PositionWithAffinity startOfParagraphToMovePosition =
+        startOfParagraphToMove.toPositionWithAffinity();
+    PositionWithAffinity destinationPosition =
+        destination.toPositionWithAffinity();
+
     // We need to handle the case where we need to merge the end
     // but our destination node is inside an inline that is the last in the
     // block.
     // We insert a placeholder before the newly inserted content to avoid being
     // merged into the inline.
     Node* destinationNode = destination.deepEquivalent().anchorNode();
     if (m_shouldMergeEnd &&
         destinationNode != enclosingInline(destinationNode) &&
         enclosingInline(destinationNode)->nextSibling()) {
       insertNodeBefore(HTMLBRElement::create(document()), refNode,
                        editingState);
       if (editingState->isAborted())
         return;
     }
 
     // Merging the the first paragraph of inserted content with the content that
     // came before the selection that was pasted into would also move content
     // after the selection that was pasted into if: only one paragraph was being
     // pasted, and it was not wrapped in a block, the selection that was pasted
     // into ended at the end of a block and the next paragraph didn't start at
     // the start of a block.
     // Insert a line break just after the inserted content to separate it from
     // what comes after and prevent that from happening.
     VisiblePosition endOfInsertedContent = positionAtEndOfInsertedContent();
     if (startOfParagraph(endOfInsertedContent).deepEquivalent() ==
-        startOfParagraphToMove.deepEquivalent()) {
+        startOfParagraphToMovePosition.position()) {
       insertNodeAt(HTMLBRElement::create(document()),
                    endOfInsertedContent.deepEquivalent(), editingState);
       if (editingState->isAborted())
         return;
       // Mutation events (bug 22634) triggered by inserting the <br> might have
       // removed the content we're about to move
-      if (!startOfParagraphToMove.deepEquivalent().isConnected())
+      if (!startOfParagraphToMovePosition.position().isConnected())
         return;
     }
 
     document().updateStyleAndLayoutIgnorePendingStylesheets();
 
+    // Making the two VisiblePositions valid again.
+    startOfParagraphToMove =
+        createVisiblePosition(startOfParagraphToMovePosition);
+    destination = createVisiblePosition(destinationPosition);
+
     // FIXME: Maintain positions for the start and end of inserted content
     // instead of keeping nodes.  The nodes are only ever used to create
     // positions where inserted content starts/ends.
     moveParagraph(startOfParagraphToMove,
-                  endOfParagraph(createVisiblePosition(
-                      startOfParagraphToMove.toPositionWithAffinity())),
-                  destination, editingState);
+                  endOfParagraph(startOfParagraphToMove), destination,
+                  editingState);
     if (editingState->isAborted())
       return;
 
     document().updateStyleAndLayoutIgnorePendingStylesheets();
     m_startOfInsertedContent = mostForwardCaretPosition(
         endingSelection().visibleStart().deepEquivalent());
     if (m_endOfInsertedContent.isOrphan()) {
       m_endOfInsertedContent = mostBackwardCaretPosition(
           endingSelection().visibleEnd().deepEquivalent());
     }
@@ skipping 479 matching lines @@
   visitor->trace(m_startOfInsertedContent);
   visitor->trace(m_endOfInsertedContent);
   visitor->trace(m_insertionStyle);
   visitor->trace(m_documentFragment);
   visitor->trace(m_startOfInsertedRange);
   visitor->trace(m_endOfInsertedRange);
   CompositeEditCommand::trace(visitor);
 }
 
 }  // namespace blink