Function luaK_infix

3rd/lua-5.4.3/src/lcode.c:1574–1615

** Process 1st operand 'v' of binary operation 'op' before reading ** 2nd operand. */

** 2nd operand.
*/
void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) {
  luaK_dischargevars(fs, v);
  switch (op) {
    case OPR_AND: {
      luaK_goiftrue(fs, v);  /* go ahead only if 'v' is true */
      break;
    }
    case OPR_OR: {
      luaK_goiffalse(fs, v);  /* go ahead only if 'v' is false */
      break;
    }
    case OPR_CONCAT: {
      luaK_exp2nextreg(fs, v);  /* operand must be on the stack */
      break;
    }
    case OPR_ADD: case OPR_SUB:
    case OPR_MUL: case OPR_DIV: case OPR_IDIV:
    case OPR_MOD: case OPR_POW:
    case OPR_BAND: case OPR_BOR: case OPR_BXOR:
    case OPR_SHL: case OPR_SHR: {
      if (!tonumeral(v, NULL))
        luaK_exp2anyreg(fs, v);
      /* else keep numeral, which may be folded with 2nd operand */
      break;
    }
    case OPR_EQ: case OPR_NE: {
      if (!tonumeral(v, NULL))
        luaK_exp2RK(fs, v);
      /* else keep numeral, which may be an immediate operand */
      break;
    }
    case OPR_LT: case OPR_LE:
    case OPR_GT: case OPR_GE: {
      int dummy, dummy2;
      if (!isSCnumber(v, &dummy, &dummy2))
        luaK_exp2anyreg(fs, v);
      /* else keep numeral, which may be an immediate operand */
      break;
    }
    default: lua_assert(0);
  }
}

/*
** Create code for '(e1 .. e2)'.