REOPENED 55650
Give Position's upstream and downstream more descriptive names 
https://bugs.webkit.org/show_bug.cgi?id=55650
Summary Give Position's upstream and downstream more descriptive names
Ryosuke Niwa
Reported 2011-03-02 22:46:51 PST
While I was working on the bug 55098, I realized that VisiblePosition can be upstream even if its affinity claims to be downstream. This bug is due to the following lines in http://trac.webkit.org/browser/trunk/Source/WebCore/editing/VisiblePosition.cpp. 456 Position candidate = position.upstream(); 457 if (candidate.isCandidate()) 458 return candidate; 459 candidate = position.downstream(); 460 if (candidate.isCandidate()) 461 return candidate; It returns an upstream position but it doesn't modify its affinity so we end up with a VisiblePosition that stores an upstream position but claims to be a downstream position.
Attachments
work in progress (56.80 KB, patch)
2011-03-08 01:21 PST, Ryosuke Niwa 		no flags
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
Levi Weintraub
Comment 1 2011-03-03 11:00:33 PST
I believe you're mixing your concepts here. Position's upstream/downstream concepts are not the same as VisiblePosition's; Upstream and downstream Positions are meant to be visually equivalent while upstream and downstream VisiblePositions explicitly are not. In other words, in the following scenario: <div>foo<br/> <span>bar</span> </div> A Position at the beginning of the second line would upstream to [span, 0] and downstream to ["bar", 0], but a VisiblePosition would jump from a downstream of [span, 0] to [br, 0].
Ryosuke Niwa
Comment 2 2011-03-03 14:56:23 PST
(In reply to comment #1) > I believe you're mixing your concepts here. Position's upstream/downstream concepts are not the same as VisiblePosition's; Upstream and downstream Positions are meant to be visually equivalent while upstream and downstream VisiblePositions explicitly are not. :( I wasn't aware of this. Thanks for the clarification.
Levi Weintraub
Comment 3 2011-03-03 14:57:47 PST
No problem. The naming is confusing, I know :(
Justin Garcia
Comment 4 2011-03-03 18:18:05 PST
(In reply to comment #3) > No problem. The naming is confusing, I know :( Maybe someone should do some renaming. Names that are descriptive for upstream()/ downstream() would be really verbose though I think.
Levi Weintraub
Comment 5 2011-03-03 22:52:22 PST
(In reply to comment #4) > Maybe someone should do some renaming. Names that are descriptive for upstream()/ downstream() would be really verbose though I think. I think renaming the Position methods would be do-able. Something like next/previousVisuallyEquivalentPosition?
Ryosuke Niwa
Comment 6 2011-03-07 22:49:34 PST
Okay, let's rename these two member functions.
Ryosuke Niwa
Comment 7 2011-03-08 01:21:56 PST
Created attachment 85034 [details] work in progress
Levi Weintraub
Comment 8 2011-03-08 14:06:51 PST
(In reply to comment #7) > Created an attachment (id=85034) [details] > work in progress I'm glad you went with renaming the Position, and not VisiblePosition methods. This is a good change except I'm slightly concerned with the names containing "next" and "previous" (despite that being my own proposal!). They aren't strictly next/previous, as calling the function again won't yield a further position that is also visually equivalent. They're really more like higher and lower visually equivalent boundary positions.
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