Re: [RFA] Add language-dependent post-parser

[Daniel Jacobowitz <drow@false.org>]

On Wed, Mar 31, 2004 at 03:02:45AM -0500, Paul Hilfinger wrote:
> 
> Daniel,
> 
> > I don't see why you can't do it, for instance, here:
> > simple_exp :    simple_exp '(' arglist ')'
> >                        { 
> >                          write_exp_elt_opcode (OP_FUNCALL);
> >                          write_exp_elt_longcst ($3);
> >				/* check arguments */
> >                          write_exp_elt_opcode (OP_FUNCALL);
> >                        }
> >        ;
> 
> > You'd have to wiggle the expression machinery to give you back the
> > expression node for the function name, probably by making the
> > write_exp_* functions return a pointer.  But that's less intrusive and
> > more efficient than adding a second pass.
> 
> Yes, that's exactly how I'd LIKE to do it. And I would, but for one
> miserable little fact: the expression at this point is in POSTFIX
> form.  So, for example, I can't use evaluate_type or the evaluate_exp
> member of exp_descriptor, both of which work on PREFIX form.

How much work would it be to duplicate and prefixify them, then? 
prefixify_subexp has the right interface already; if you write out the
OP_FUNCALL, you could then call a function which returns a new struct
expression in prefix form containing just the call and its arguments.
It would just need to allocate enough memory (could be generous about
it and just use the size of the original expression), call
prefixify_subexp, and fiddle out->nelts.

OK, it's not so _efficient_, but... it could be made efficient if
someone overhauls the representation at some point.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer