On Wed, Jun 11, 2025 at 5:21 AM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
>
> What do you think about a more recursive representation for presets?
> E.g. as follows:
>
> struct rvalue {
> long long i; /* use find_enum_value() at parse time to avoid union */
> };
>
> struct lvalue {
> enum { VAR, FIELD, ARRAY } type;
> union {
> struct {
> char *name;
> } var;
> struct {
> struct lvalue *base;
> char *name;
> } field;
> struct {
> struct lvalue *base;
> struct rvalue index;
> } array;
> };
> };
>
> struct preset {
> struct lvalue *lv;
> struct rvalue rv;
> };
>
> It can handle matrices ("a[2][3]") and offset/type computation would
> be a simple recursive function.
>
Why do we need recursion, though? All we should need is an array specs
of one of the following types:
a) field access by name
a.1) we might want to distinguish array field vs non-array field
to better catch unintended user errors
b) indexing by immediate integer
c) indexing by symbolic enum name (or we can combine b and c,
whatever works better).
And that's all. And it will support multi-dimensional arrays.
We then process this array one at a time. Each *step* itself might be
recursive: finding a field by name in C struct is necessarily
recursive due to anonymous embedded struct/union fields. But other
than that, it's a simple sequential operation.
So unless I'm missing something, let's not add data recursion if it's
not needed.
