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luaur_vm/functions/
lua_userdatatag.rs

1use core::ffi::c_int;
2
3use crate::functions::index_2_addr::index2addr;
4use crate::macros::ttisuserdata::ttisuserdata;
5use crate::macros::uvalue::uvalue;
6use crate::type_aliases::lua_state::lua_State;
7use crate::type_aliases::stk_id::StkId;
8
9#[allow(non_snake_case)]
10pub unsafe fn lua_userdatatag(L: *mut lua_State, idx: c_int) -> c_int {
11    let o: StkId = index2addr(L, idx);
12
13    if ttisuserdata!(o) {
14        // uvalue(o) returns a reference to the Udata struct.
15        // The tag field is a uint8_t.
16        (*uvalue!(o)).tag as c_int
17    } else {
18        -1
19    }
20}