While the cexpr parser itself doesn't support void functions, they have
their uses when used with the system, and mixing them into the list of
function overloads shouldn't break non-void functions.
At least with a push-parser, by the time the parser has figured out it
has an identifier, the lexer has forgotten the token, thus the annoying
and uninformative "undefined identifier " error messages. Since
identifiers should always have a value (and functions need a function
type), setting up a dummy symbol with just the identifier name
duplicated seems to do the trick. It is a bit wasteful of memory if
there are a lot of such errors between cmem resets, though.
If the result object type pointer is null, then the parsed result type
and value pointers are written directly to the result object rather than
testing the parsed result type against the object type and copying the
parsed result value data to the location of the object value. It is then
up to the caller to check the type and copy the value data.
While there may be better solutions, I needed a varargs function for
building Vulkan specialization data. Like progs functions, negative
parameter counts indicate ellipsis with the number of fixed parameters
being equal to -param_count - 1.
Setting the result type cexpr_exprval tells cexpr to simply return whoe
exprval object rather than the referenced value, thus allowing the
caller to check the type when the expression is context sensitive.
This allows plist objects to be accessed directly from cexpr expressions
using struct.field syntax for dictionary objects and array[index] syntax
for array objects.
The problem is that I needed to support dynamic types on operators (for
bit-field enums), had things working, but a bad edit messed things up
and I had to rebuild that bit of code. Missed one bit :P
It is capable of parsing single expressions with fairly simple
operations. It current supports ints, enums, cvars and (external) data
structs. It is also thread-safe (in theory, needs proper testing) and
the memory it uses can be mass-freed.
