The string type is useful for passing around strings (the only thing
that they can do, currently), particularly as arguments to functions.
The voidptr type is (currently) never generated by the core cexpr
system, but is useful for storing pointers via cexpr (probably a bit of
a hack, but it seems to work well in my current use).
The inconsistencies in clang's handling of casts was bad enough, and its
silliness with certain extensions, but discovering that it doesn't
support raw strings was just too much. Yes, it gives a 3s boost to qfvis
on gmsp3v2.bsp, but it's not worth the hassle.
The prefix gives more context to the error messages, making the system a
lot easier to use (it was especially helpful when getting my cvar revamp
into shape).
Based on the flags type used in vkparse (difference is the lack of
support for plists). Having this will make supporting named flags in
cvars much easier (though setting up the enum type is a bit of a chore).
This allows for easy (and safe) printing of cexpr values where the type
supports it. Types that don't support printing would be due to being too
complex or possibly write-only (eg, password strings, when strings are
supported directly).
For now, just dot product, trig, and min/max/bound, but it works well as
a proof of concept. The main goal was actually min. Only the list of
symbols is provided, it is the user's responsibility to set up the
symbol table and context.
cexpr's symbol tables currently aren't readily extended, and dynamic
scoping is usually a good thing anyway. The chain of contexts is walked
when a symbol is not found in the current context's symtab, but minor
efforts are made to avoid checking the same symtab twice (usually cased
by cloning a context but not updating the symtab).
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 way I wound up using the field meant that exprctx should not "own"
the hashlinks chain, but rather just point to it. This fixes the nasty
access errors I had.
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.
