[stupok]

Here's my attempt. (Attached as ini rather than txt to get past the filesize limit.)

My regex:

Function:
^(?:stock Handle:|	XS_LIBFUNC_ATTRIB bool:|	XS_LIBFUNC_ATTRIB Float:|	XS_LIBFUNC_ATTRIB |	stock Float:|	stock bool:|	stock |stock Float:|stock bool:|forward |native bool:|native Float:|native |public |stock |Float:|bool:)?([\w_\-\d]+)[\s]?(\(.*?\))

Constant:
^(?:#define|new const)\s+([^_][A-Z\d_]+)

Macro:
^(?:#define|new const)\s+([^_][\w\d_]+\(.*?\))

enum: (Once I've collected all the enums sloppily, I use this to refine the collection.)
^\s([\w\d_-]{2,64})

EDIT: Added some enums