Re: [boost] Spirit Rule<>s

From: joel de guzman (isis-tech_at_[hidden])
Date: 2001-05-31 20:06:33

----- Original Message ----- 
From: "Larry Evans" <jcampbell3_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Friday, June 01, 2001 7:06 AM
Subject: Re: [boost] Spirit Rule<>s

> joel de guzman wrote:
> 
> >
> 
> [snip]
> 
> >
> > I was trying to avoid virtual function at all costs. If only there
> > was a way in C++ to get the type of the rhs and pass it into
> > the lhs, I wouldn't have needed rules. In fact you can do away
> > with rules if you want to do more typing. Example:
> >
> > Alternative<ChLit<>, Sequence<ChLit<>, ChLit<> > > rule = a | b >> c;
> >
> 
> How would you do this with the following BNF rule?
> 
>   A ::= 'a' A | 'b'
> 
> 

Right. We still need rules. :-) I stand corrected. A will
still need to be a rule. You can't use a nonterminal in the rhs if
it is not declared.

Only rules that does not reference itself can benefit from the
auto type declaration.

Cheers,
Joel de Guzman