From: "Peter Neilson" <neilson@windstream.net>
To: emacs-orgmode@gnu.org
Subject: Re: Stackoverflow in regexp matcher
Date: Wed, 03 Feb 2016 06:44:17 -0500 [thread overview]
Message-ID: <op.yb89j3icrns8nc@odin> (raw)
In-Reply-To: <87si1a9h2o.fsf@nicolasgoaziou.fr>
On Wed, 03 Feb 2016 06:19:43 -0500, Nicolas Goaziou
<mail@nicolasgoaziou.fr> wrote:
> "Loris Bennett" <loris.bennett@fu-berlin.de> writes:
>
>> re-search-forward("^[^%]*\\\\usepackage.*{biblatex}" nil t)
>
> This is a pathological regexp. [^%] is anything but a percent sign, so
> it can contain newline characters. Basically [^%]* can match an entire
> buffer if it doesn't contain any %.
>
> I think the regexp used in `reftex-using-biblatex-p' should be
>
> "^[^%\n]*\\\\usepackage.*{biblatex}"
Here's a link about the extreme difficulty of detecting pathological
regular expressions:
https://mail.python.org/pipermail/python-dev/2003-May/035916.html
The author analyses the exponential not-found situation for (x+x+)+y and
then suggests that for larger expressions, "... no more than 1 programmer
in 1000 has even a vague idea how to start looking for such problems."
prev parent reply other threads:[~2016-02-03 11:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-02 13:56 Stackoverflow in regexp matcher Loris Bennett
2016-02-02 15:47 ` Nick Dokos
2016-02-03 7:36 ` Loris Bennett
2016-02-03 11:19 ` Nicolas Goaziou
2016-02-03 11:34 ` Loris Bennett
2016-02-03 17:50 ` Alan Schmitt
2016-02-04 7:30 ` Loris Bennett
2016-02-03 11:44 ` Peter Neilson [this message]
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