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From: Eric Niebler (eric_at_[hidden])
Date: 2007-04-26 12:29:36

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
- The backreference number is less than or equal to the number of
capturing groups seen so far.

I believe that's perl's rule.

Eric Niebler
Boost Consulting

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