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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
> * 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.

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

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