Re: [Boost-users] [WAVE] position of tokens

From: Andreas Sæbjørnsen (andreas.saebjoernsen_at_[hidden])
Date: 2006-11-09 01:16:46

> >     * the position of a token in the original source code is
> > gone(default in standard Wave)
>
> What do you mean by that?

What I need is both the original position and the position from the
real_positions example available on a token.  This makes it possible
to locate a token using the real_positions (which is equivalent to
positions on output from a preprocessor) and then get the original
source code position from that token. Do you see any other way of
achieving this?

> >     * the line positioning is incorrect/non-standard (see
> > below for an example).
>
> This does not depend on the Wave library itself, but it's a matter of the
> real_positions example. Do you mind to submit a fix for that (I now changed
> the sample to output the detailed token information, which makes it easier
> to track the output)?

Yes. It was very easy to work with your code so that should be no
problem. Are the real_positions set before or after the tokens are
send to the preprocessing hooks?

Thanks
Andrea

> > On 11/7/06, Hartmut Kaiser <hartmut.kaiser_at_[hidden]> wrote:
> > >
> > > Andreas,
> > >
> > > > I need some advice regarding Wave. What I want to do is
> > to operate
> > > > with Wave on a token stream and extract the token stream
> > > > representing macro calls after expansion. The twist is
> > that I want
> > > > the token stream after expansion to have the positions
> > that another
> > > > preprocessor would see on the already expanded output from Wave.
> > > > E.g:
> > > > #define MACRO_CALL int x;
> > > > int main(){
> > > >      MACRO
> > > > };
> > > >
> > > > Exands into
> > > > #line 2
> > > > int main(){
> > > >      int x;
> > > > };
> > > >
> > > > Where 'int x' should have a position of line 3 instead of line 1
> > > > after expansion. I also want the column number to
> > represent what we
> > > > see on line 3 instead of what we see on line 1. Is this possible ?
> > >
> > > Ok, I've added a new pp hook (what else? :-P) to Wave:
> > >
> > >
> > //////////////////////////////////////////////////////////////////////
> > > /////
> > > //
> > > //  The function 'generated_token' will be called by the library
> > > whenever a //  token is about to be returned from the library.
> > > //
> > > //  The parameter 'ctx' is a reference to the context
> > object used for
> > > //  instantiating the preprocessing iterators by the user.
> > > //
> > > //  The parameter 't' is the token about to be returned
> > from the library.
> > > //  This function may alter the token, but in this case it
> > must be //
> > > implemented with a corresponding signature:
> > > //
> > > //      Token const&
> > > //      generated_token(Context const& ctx, Token& t);
> > > //
> > > //  which makes it possible to modify the token in place.
> > > //
> > > //  The default behavior is to return the token passed as the
> > > parameter //  without modification.
> > > //
> > >
> > //////////////////////////////////////////////////////////////
> > /////////////
> > >     template <typename Context, typename Token>
> > >     Token const&
> > >     generated_token(Context const& ctx, Token const& t)
> > >     { return t; }
> > >
> > > This should help solving your problem.
> > >
> > > To show how this hook function may help you I added a new sample
> > > 'real_positions' to Wave demonstrating its use. Everything
> > is in the
> > > Boost CVS::HEAD.
> > >
> > > HTH
> > > Regards Hartmut
> > >
> > > _______________________________________________
> > > Boost-users mailing list
> > > Boost-users_at_[hidden]
> > > http://lists.boost.org/mailman/listinfo.cgi/boost-users
> > >
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