Function isEnv

third-party/lua-5.4.6/src/ldebug.c:558–569

** Check whether table being indexed by instruction 'i' is the ** environment '_ENV'. If the table is an upvalue, get its name; ** otherwise, find some "name" for the table and check whether ** that name is the name of a local variable (and not, for instance, ** a string). Then check that, if there is a name, it is '_ENV'. */

** a string). Then check that, if there is a name, it is '_ENV'.
*/
static const char *isEnv (const Proto *p, int pc, Instruction i, int isup) {
  int t = GETARG_B(i);  /* table index */
  const char *name;  /* name of indexed variable */
  if (isup)  /* is 't' an upvalue? */
    name = upvalname(p, t);
  else {  /* 't' is a register */
    const char *what = basicgetobjname(p, &pc, t, &name);
    if (what != strlocal && what != strupval)
      name = NULL;  /* cannot be the variable _ENV */
  }
  return (name && strcmp(name, LUA_ENV) == 0) ? "global" : "field";
}


/*