[svn.haxx.se] · SVN Dev · SVN Users · SVN Org · TSVN Dev · TSVN Users · Subclipse Dev · Subclipse Users · this month's index

RE: Regular expressions in Subversion

From: Bert Huijben <bert_at_qqmail.nl>
Date: Wed, 17 Oct 2012 18:41:20 +0200

> -----Original Message-----
> From: Hyrum K Wright [mailto:hyrum_at_hyrumwright.org]
> Sent: woensdag 17 oktober 2012 18:20
> To: Subversion Development
> Subject: Regular expressions in Subversion
>
> There are several places where regular expressions would be useful in
> Subversion. Off hand, the new log --search feature and svn:ignore
> properties feel like they'd be use candidates for regexs, and they
> could probably also apply to authz rules eventually. I'm sure there
> are more.
>
> Historically, the argument against using regexes in Subversion was
> that they would be a potential DoS target, or could lead to unexpected
> performance problems. However, I recently ran across a new regex
> engine, RE2, which claims to have linear time complexity in the size
> of the input with the ability to also limit memory consumption[1].
> These come at the expenses of a couple of less-used regex features,
> and it feels like it'd be a good fit for Subversion.
>
> There are a few downsides:
> * RE2 is written in C++; we'd need a C wrapper to use it within
Subversion.
> * RE2 packages don't exist for a number of platforms, though we might
> be able to embedded it in Subversion.
> * RE2 doesn't claim to compile on Windows. :)

Just checking the RE2 site, it appears that RE2 should work with Visual
Studio 2008 and later.

If/when APR and HTTPD switch to these 'recent' versions there should be no
problem in getting this supported on both server and client side.

Last time I checked the Httpd 2.2.X binaries were still delivered using the
1998 / 6.0 version of the compiler and the project explicitly says they are
incompatible with that old versions of C++.

I would guess that CollabNet, Wandisco and VisualSVN use modern compilers
for the entire product chain by now, so maybe we can stop caring about the
default binaries.

        Bert
Received on 2012-10-17 18:42:04 CEST

This is an archived mail posted to the Subversion Dev mailing list.