Function diff_l

other_src/lua/src/lpeg.cpp:1354–1381

static int diff_l (lua_State *L) {
  int l1, l2;
  Instruction *p1 = getpatt(L, 1, &l1);
  Instruction *p2 = getpatt(L, 2, &l2);
  CharsetTag st1, st2;
  if (tocharset(p1, &st1) == ISCHARSET && tocharset(p2, &st2) == ISCHARSET) {
    Instruction *p = newcharset(L);
    loopset(i, p[1].buff[i] = st1.cs[i] & ~st2.cs[i]);
  }
  else if (isheadfail(p2)) {
    Instruction *p = newpatt(L, l2 + 1 + l1);
    p += addpatt(L, p, 2);
    check2test(p - l2, l2 + 1);
    setinst(p++, IFail, 0);
    addpatt(L, p, 1);
  }
  else {  /* !e2 . e1 */
    /* !e -> choice L1; e; failtwice; L1: ... */
    Instruction *p = newpatt(L, 1 + l2 + 1 + l1);
    Instruction *pi = p;
    setinst(p++, IChoice, 1 + l2 + 1);
    p += addpatt(L, p, 2);
    setinst(p++, IFailTwice, 0);
    addpatt(L, p, 1);
    optimizechoice(pi);
  }
  return 1;
}


static int unm_l (lua_State *L) {