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Subject: Re: [boost] [xpressive] Performance Tuning?
From: Eric Niebler (eric_at_[hidden])
Date: 2009-07-01 15:23:02

Stewart, Robert wrote:
> Dave Jenkins wrote:
>>>> Each call to parse() is constructing the sregex variables.
>>>> If you make them static or move them out of the loop, it
>>>> should help a lot.
>>> Thanks, but see my reply to Eric's. While that would help
>>> with the benchmark performance, the nature of the function
>>> I'm testing means I can't do that otherwise.
>> How about making them static const? That should be thread safe.
> I'm sorry, I read your original suggestion as being the same as Eric's: reuse the match_results. Unfortunately, the semantic actions reference local variables, so I don't think I can make the sregex's static (please correct me if I'm wrong, but I can't see how multiple parallel invocations of the function could reference separate stack variables from static sregex's). I did make the sregex's const; that appears to have improved performance a bit.

You can still make the regex objects static const and use placeholders
in the semantic actions. See the following section:

Eric Niebler
BoostPro Computing

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