[MacRuby-devel] StringScanner Performance

[Sylvester Keil]

you're absolutely right, this issue is related. So we would require a Regular Expression method that matches only at the beginning of the string and does not populate Regexp.last_match.


On Apr 19, 2012, at 3:58 PM, Watson wrote:

> Hi,
> 
> I think your report is relating with http://www.macruby.org/trac/ticket/1341
> 
> 
> Thanks
> 
> 2012/4/19 Sylvester Keil <sylvester.keil at gmail.com>:
>> Dear all,
>> 
>> while debugging performance issues for a gem (bibtex-ruby) I noticed that MacRuby's StringScanner implementation creates new Regular Expression objects every time #scan is called; as I am dealing with a lexical analyzer based on StringScanner the #scan method is quite crucial and the current implementation performs so slowly that it is basically unusable on MacRuby.
>> 
>> This is the problematic method in MacRuby:
>> 
>> https://github.com/MacRuby/MacRuby/blob/master/lib/strscan.rb#L638
>> 
>> Both MRI and Rubinius work around this by using a feature of Oniguruma patterns to match the pattern at the beginning of a string only. Here are the corresponding sections:
>> 
>> https://github.com/ruby/ruby/blob/trunk/ext/strscan/strscan.c#L437
>> https://github.com/rubinius/rubinius/blob/master/lib/strscan.rb#L264
>> 
>> Do regular expressions in MacRuby expose similar functionality to either Ruby or C extensions? I'd be happy to help resolving this issue, but have no experience with MacRuby so any pointers on how to best approach this are much appreciated.
>> 
>> Thanks,
>> 
>> Sylvester
>> 
>> 
>> 
>> 
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