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Re: Regular expressions in Subversion

From: Stefan Küng <tortoisesvn_at_gmail.com>
Date: Wed, 17 Oct 2012 19:53:57 +0200

On 17.10.2012 18:20, Hyrum K Wright wrote:
> 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. :)
> Anyway, I was just wondering what folks feelings were about this
> possibility, and whether it's finally time to start thinking about
> proper regex support within Subversion.

I'm wondering: if C++ is an option, why not use the regex that comes
with the C++ library itself?


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Received on 2012-10-17 19:54:39 CEST

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