[Smart Text] Make SurroundingText work for input elements

third_party/WebKit/Source/core/editing/SurroundingText.cpp

 /*
  * Copyright (C) 2012 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 44 matching lines @@
   DCHECK_EQ(start_position.GetDocument(), end_position.GetDocument());
 
   const unsigned half_max_length = max_length / 2;
 
   Document* document = start_position.GetDocument();
   // The position will have no document if it is null (as in no position).
   if (!document || !document->documentElement())
     return;
   DCHECK(!document->NeedsLayoutTreeUpdate());
 
-  // The forward range starts at the selection end and ends at the document's
-  // end. It will then be updated to only contain the text in the text in the
-  // right range around the selection.
+  // The forward range starts at the selection end and ends at the end of the
+  // root container: either document's end or the end of shadow root for input
+  // elements. It will then be updated to only contain the text in the text in
+  // the right range around the selection.
+
+  Node* end_root_container = end_position.ComputeContainerNode();

[yosin_UTC9, 2017/06/05 04:59:32]

You can do this by 

Node* end_container = end_position.ComputeContianerNode();
Node* end_root_container = end_container->ContainingShadowRoot() ?
end_container->ContainingShadowRoot() : document;

For CharacterIterator, LastPositionInNode(document) and
LastPositonInNode(document->documentElement()) are equivalent.
We may have some anti-pattern, e.g. 
- document.documentElement.append('foo')
- document.replace(documentElement, 'foo') makes document->documentElement() ==
nullptr

[Tima Vaisburd, 2017/06/06 23:39:09]

I used RootEditableElementOf() eventually, I thought it is the preferred way.
Unfortunately many tests broke after I replaced document->documentElement() with
document (off-by-one error in the ranges).

+  while (end_root_container->parentNode())
+    end_root_container = end_root_container->parentNode();
+
+  Node* last_node = end_root_container->IsShadowRoot()

[yosin_UTC9, 2017/06/05 04:59:32]

The name |last_node| is confusion. Usually, document element isn't the last
node.
Sorry, I don't have an idea of another name.

Although, when we use Node::ContainingShadowRoot(), we don't need to use
|last_node|.

[Tima Vaisburd, 2017/06/06 23:39:09]

Not used anymore.

+                        ? end_root_container
+                        : document->documentElement();
+
   CharacterIterator forward_iterator(
       end_position,
-      Position::LastPositionInNode(document->documentElement())
-          .ParentAnchoredEquivalent(),
+      Position::LastPositionInNode(last_node).ParentAnchoredEquivalent(),
       TextIteratorBehavior::Builder().SetStopsOnFormControls(true).Build());
   // FIXME: why do we stop going trough the text if we were not able to select
   // something on the right?
   if (!forward_iterator.AtEnd())
     forward_iterator.Advance(max_length - half_max_length);
 
   EphemeralRange forward_range = forward_iterator.Range();
   if (forward_range.IsNull() ||
       !Range::Create(*document, end_position, forward_range.StartPosition())
            ->GetText()
            .length())
     return;
 
+  Node* start_root_container = start_position.ComputeContainerNode();
+  while (start_root_container->parentNode())
+    start_root_container = start_root_container->parentNode();
+
+  Node* first_node = start_root_container->IsShadowRoot()
+                         ? start_root_container
+                         : document->documentElement();
+
   // Same as with the forward range but with the backward range. The range
   // starts at the document's start and ends at the selection start and will
   // be updated.
   BackwardsCharacterIterator backwards_iterator(
-      Position::FirstPositionInNode(document->documentElement())
-          .ParentAnchoredEquivalent(),
+      Position::FirstPositionInNode(first_node).ParentAnchoredEquivalent(),
       start_position,
       TextIteratorBehavior::Builder().SetStopsOnFormControls(true).Build());
   if (!backwards_iterator.AtEnd())
     backwards_iterator.Advance(half_max_length);
 
   const TextIteratorBehavior behavior =
       TextIteratorBehavior::NoTrailingSpaceRangeLengthBehavior();
   start_offset_in_content_ = TextIterator::RangeLength(
       backwards_iterator.EndPosition(), start_position, behavior);
   end_offset_in_content_ = TextIterator::RangeLength(
@@ skipping 15 matching lines @@
 
 unsigned SurroundingText::StartOffsetInContent() const {
   return start_offset_in_content_;
 }
 
 unsigned SurroundingText::EndOffsetInContent() const {
   return end_offset_in_content_;
 }
 
 }  // namespace blink