Re: [boost] [wave] ifndef/ifdef callbacks

From: Felipe Magno de Almeida (felipe.m.almeida_at_[hidden])
Date: 2006-05-11 19:59:09

On 5/11/06, Hartmut Kaiser <hartmut.kaiser_at_[hidden]> wrote:
>
> Felipe Magno de Almeida wrote:
>
> > I see that there are some hooks for appending callbacks for
> > certain situations in the preprocessing. I think this is
> > great. But, I would like to know if it is possible for the
> > user to know when the preprocessor is evaluating an
> > preprocessor conditional, and to know what the condition is.
>
> There is the evaluated_conditional_expression() preprocessing hook getting
> called whenever a #if/#elif/#ifdef/#ifndef directive was encountered. This
> hook gets 2 parameters: the (non-expanded) evaluated expression and the
> outcome of this evaluation (true/false).

Yes, exactly what I need. Have I missed it from the documentation?

>
> Is that what you need?
>
> > And to fork the preprocessing to when the condition is met
> > and when not.
>
> Could you please elaborate on this? I'm not sure what you've meant here.

I would like to continue preprocessing the file but with two different
contexts, one with the evaluation being false and another being true.

>
> Regards Hartmut

Thank you,
-- 
Felipe Magno de Almeida