Function lua_topointer

3rd/lua-5.4.3/src/lapi.c:469–482

** Returns a pointer to the internal representation of an object. ** Note that ANSI C does not allow the conversion of a pointer to ** function to a 'void*', so the conversion here goes through ** a 'size_t'. (As the returned pointer is only informative, this ** conversion should not be a problem.) */

** conversion should not be a problem.)
*/
LUA_API const void *lua_topointer (lua_State *L, int idx) {
  const TValue *o = index2value(L, idx);
  switch (ttypetag(o)) {
    case LUA_VLCF: return cast_voidp(cast_sizet(fvalue(o)));
    case LUA_VUSERDATA: case LUA_VLIGHTUSERDATA:
      return touserdata(o);
    default: {
      if (iscollectable(o))
        return gcvalue(o);
      else
        return NULL;
    }
  }
}