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From: noitalmost <noitalmost@cox.net>
Newsgroups: comp.compilers
Subject: Re: Having trouble converting composite variables to intermediate form
Date: Mon, 10 Mar 2014 15:18:43 -0400
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On Friday, February 28, 2014 11:27:00 AM Momchil Velikov wrote:
> On Saturday, February 22, 2014 7:32:01 PM UTC+2, noitalmost wrote:
> > x := r.a[2] + 5;
> >
> >
> > After parsing, the Wirl AST fragment looks like:
> >
> > Assign
> >
> >   Ident x
> >   Op +
> >
> >     RecAccess
> >
> >       Ident r
> >       ArrAccess
> >
> >         Ident a
> >         Num 2
>
> You have currently
>
> RecAccess(r, ArrAccess(Ident(a), Num(2)))
>
> Note, however, that the array is not `a`, it's `r.a`. The subtree
> `ArrAccess(Ident(a), Num(2)) `is incorrect, because you don't have in fact
> a variable named `a` of an array type.
>
> Here the record access should take precedence over array access, i.e.
> the AST should look like:
>
> ArrAccess(RecAccess(r, Ident(a)), Num(2))

Thanks. I eventually figured it out independently by working backward from the
C code I wanted to generate. The compiler can now handle arbitrary
combinations of records, arrays, and pointers. I spent a week jumping up and
down and dancing. Wirl has now graduated from toy to fun toy :)