From: Nick Dokos <ndokos@gmail.com>
To: emacs-orgmode@gnu.org
Subject: Re: Long lines prevent Org mode!
Date: Wed, 08 Jan 2014 01:05:51 -0500 [thread overview]
Message-ID: <87wqibypmo.fsf@gmail.com> (raw)
In-Reply-To: 87ha9fvyjm.fsf@iro.umontreal.ca
François Pinard <pinard@iro.umontreal.ca> writes:
> Nick Dokos <ndokos@gmail.com> writes:
>
>> you can leave org out of the picture altogether: create an empty
>> buffer, insert 33333 x's by hand, go to the beginning and evaluate
>
>> (looking-at ".*foo")
>
>> As Stefan says in the thread you pointed out, it's a limitation of the
>> emacs regexp engine.
>
> Yes, I got this from his article. However, it seems that "[^\nf]*foo"
> would succeed, avoiding the stack explosion. So, it is possible to
> rework the regexpes around the limitation.
>
> Surely not a fun job to do for Org regexpes, I know. Maybe not worth
> doing as very long lines are unusual, yet maybe worth doing nevertheless
> for Org files because long lines are still possible. The fact is that I
> was hit by this problem in the Org buffers generated by org-grep.
>
It would be better to reimplement the regexp engine using e.g. an NDFA.
IIRC, it requires constant stack but it limits the regexps allowed. See
e.g.
http://swtch.com/~rsc/regexp/regexp1.html
It might make sense to pair the NDFA with a backtracker. The pattern
compiler could then choose which one to use based on the regexp.
--
Nick
next prev parent reply other threads:[~2014-01-08 6:06 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-08 1:24 Long lines prevent Org mode! François Pinard
2014-01-08 4:41 ` Nick Dokos
2014-01-08 5:21 ` François Pinard
2014-01-08 6:05 ` Nick Dokos [this message]
2014-01-08 9:18 ` Sebastien Vauban
2014-01-08 12:10 ` Nick Dokos
2014-01-08 12:29 ` François Pinard
2014-01-09 8:57 ` Sebastien Vauban
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