[fpc-devel] Alternative parsers

[Juha Manninen (gmail)]

On Wednesday 20 October 2010 13:52:58 Marco van de Voort wrote:
> In our previous episode, Juha Manninen (gmail) said:
> > Still, C would be doable, for porting SOME existing code to co-operarate
> > directly with pascal code. If the C code uses lots of library calls it
> > can't be used directly. But, there is code for math and compression etc.
> > which don't call libraries much.
> 
> The implementation is much easier I guess yes. But the interoperability
> remains the same. You still won't be able to access C headers directly from
> Pascal.
> 
> Moreover I think the goals of such project can be much easier accomplished
> by having a C compiler that outputs (FPC) pascal source.

True. DoDi must have some idea to solve it with the frontend.
Automatic header conversion as part of the frontend maybe?

> > Languages like ADA, Modula (and Fortran ? and Basic ? ) would be
> > realistic.
> 
> Modula2 is a special case since very related to Pascal. It needs some work
> in the module handling (but that work can be recycled for other pascal
> dialects that were inspired by that, like ISO Pascal too), but the main
> problem is the lexer/parser, because M2 is case sensitive and has a
> different block structure (which goes beyond merely being a pascal
> dialect).

So that requires changes also to compiler internals and not only to frontend?
Ok then.

> The only other problem I can think of is that is primarily has unsigned
> arithmetic, which might require enhancements/debugging on the semantic
> parts.
> 
> 
> I think the same goes for Ada as for C++. The language is so huge, that it
> is probably better to fork, throw away the pascal part, and then later when
> the ada support is ok, backport the pascal part back into the Ada compiler.
> (that will probably be somewhere near 2022)
> 
> I don't know fortran enough to comment, and Basic is so balkanized dialect
> mess that nothing can be said about that without specification of what
> dialect you mean.  I can only image VB here, but VB is very complex
> internally, and the existing codebases are horribly windows specific).
> Moreover when it finally would be production ready, VB6 would probably be
> near extinction.

I have to agree. A frontend can't solve those.
Fortran would be the most realistic I guess but only few people would need it.

Juha