Function luaL_ref

Source/Misc/lua/src/lua.c:10693–10713

LUALIB_API int luaL_ref (lua_State *L, int t) {
int ref;
t = abs_index(L, t);
if (lua_isnil(L, -1)) {
lua_pop(L, 1);  /* remove from stack */
return LUA_REFNIL;  /* `nil' has a unique fixed reference */
}
lua_rawgeti(L, t, FREELIST_REF);  /* get first free element */
ref = (int)lua_tointeger(L, -1);  /* ref = t[FREELIST_REF] */
lua_pop(L, 1);  /* remove it from stack */
if (ref != 0) {  /* any free element? */
lua_rawgeti(L, t, ref);  /* remove it from list */
lua_rawseti(L, t, FREELIST_REF);  /* (t[FREELIST_REF] = t[ref]) */
}
else {  /* no free elements */
ref = (int)lua_objlen(L, t);
ref++;  /* create new reference */
}
lua_rawseti(L, t, ref);
return ref;
}


LUALIB_API void luaL_unref (lua_State *L, int t, int ref) {