Function isEnv

third-party/lua-5.5.0/src/ldebug.c:550–563

** Check whether table being indexed by instruction 'i' is the ** environment '_ENV' */

** environment '_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);
    /* 'name' must be the name of a local variable (at the current
       level or an upvalue) */
    if (what != strlocal && what != strupval)
      name = NULL;  /* cannot be the variable _ENV */
  }
  return (name && strcmp(name, LUA_ENV) == 0) ? "global" : "field";
}


/*