bug#9470: 24.0.50; Possible bidi-related slowness

[Eli Zaretskii]

> From: Lars Magne Ingebrigtsen <larsi@gnus.org>
> Cc: 9470@debbugs.gnu.org
> Date: Sat, 10 Sep 2011 22:11:08 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Then I don't see how can I fix this specific case.  The bidi display
> > must know the paragraph direction in order to DTRT.  Ideas are
> > welcome.  Doing something simple, like force left-to-right paragraph
> > direction if paragraph start isn't found in N lines, doesn't sound
> > right, as this will cause different display depending on how far we
> > are from the text beginning.  Hmmm...
> 
> If the algorithm has looked at N lines (where N is a reasonably big
> number, like 10K), and found nothing exciting, then it would be
> reasonable to bail out, won't it?

The question is, what is "exciting", and what should we do when we
"bail out"?

If by "exciting" you mean the paragraph beginning, then the question
of the paragraph direction is still there.

> "Paragraphs" like the one presented, with 200K lines, are a pretty
> terminal case, and no "real" text ever looks like that.  I think.

Right, but I can easily concoct an example of equally un-exciting
long paragraph that is full of R2L text, and should be displayed
starting at the right margin of the window.