Re: [boost] [regex] number of back references

From: Lorenzo Bettini (bettini_at_[hidden])
Date: 2007-04-27 12:08:34

Eric Niebler wrote:
> John Maddock wrote:
>> Lorenzo Bettini wrote:
>>> Hi
>>>
>>> is there any plan to support more than 9 back references in the regex
>>> library?
>> You can have as many marked sub-expressions as you want, and refer to them 
>> in the match_results structure once you have a match.  What you can't do at 
>> present is have a true back-reference say \12 in your expression.  This is 
>> basically a problem with the regex syntax, so if you know of a good syntax 
>> extension that's already in use then it would trivial to support this.
> 
> 
> You could use xpressive, which handles this case. Any \ddd where d is a 
> decimal digit is interpreted as a back-reference if
> 
> - The backreference number is less than 10
> -OR-
> - The backreference number is less than or equal to the number of 
> capturing groups seen so far.
> 
> I believe that's perl's rule.
> 

OK, thanks, I'll take a look at it...  is xpressive compatible with
boost::regex expressions?

Lorenzo

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