Re: scanner interface limitations

From: David Abrahams (dave_at_[hidden])
Date: 2004-12-01 07:45:52

Vladimir Prus wrote:

> I think the problem is that
> 
> 1. We can't mark a specific group in regexp as "unimportant". In Perl/Python, 
> regexp can have "non-capturing paranthesis", 
> 
> >>> r = re.compile("(?:foo|bar)(.*)")
> >>> m = r.match("foo10")
> >>> m.group(1)
> '10'
> >>>
> 
> but I don't think bjam's regexps support that
> 
> 2. Bjam passes only the first matched parenthesised group to the scanner. 
> 
> Looks like your hack is the simplest solution. 

I'm not sure it will work, though :(. Are you?

The most proper solution would be to provide an additional (outer) 
virtual function in the scanner class that can be used to get more 
control over exactly what gets examined when scanning. It might be 
neccessary to change the bjam core to do that, though. And maintaining 
scanning speed is important there.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com