Re: [boost] [xpressive]: nested regular expressions for dynamic xpressive and basic_regex assignment

From: Andreas Pokorny (andreas.pokorny_at_[hidden])
Date: 2007-08-27 13:22:23

Hi Eric,

Eric Niebler wrote:
> (Sorry for the delay, I just got back from a week-long vacation.)
>
> Andreas Pokorny wrote:
> > Do you see a nicer solution?
>
> Hi Andreas. I *also* recently made nested regexes work for dynamic
> regexes, and I made an announcement about it on this list not too long
> ago. See here: http://lists.boost.org/Archives/boost/2007/06/122641.php.

Oh dear, I switched from my old gmx email account to the gmail based for
boost, there are still 7k unread boost messages.

> In particular, see "Dynamic Regex Grammars with Named Regexes", which
> has the following example:
>
>     sregex_compiler comp;
>     sregex rx = comp.compile("^bar(?$RE)baz$");
>     comp.compile("(?$RE=)\\d+ \\d+");
>
> The regex_compiler holds a map from names to regex objects. The first
> call to compile() creates a forward reference to a regex object named
> "RE" and the second call binds a regex to the name "RE".
>
> Is this the sort of thing you had in mind? (This is only available in
> the repository -- no public release has this feature yet.)

(?$ looks like an assertion. I wanted to use that feature to implement
configureable/extensible syntax highlighting withing quickbook. What
happens if you add RE regex line
e.g. comp.compile("(?$RE=)\\w+ ");

Did you consider a different syntax for specifiying named regular
expressions, or is (?$=) and (?$) something that exists in other regex engine?

Regards
Andreas Pokorny