ometa CalcParser {

  sign = ('+'|'-')? ,
  exponent = ('e'|'E') sign digit+ ,
  float = <sign digit+ '.' digit* exponent?>:f -> parseFloat(f)
        | <sign '.' digit+ exponent?>:f -> parseFloat(f)
        | <sign digit+ exponent>:f -> parseFloat(f) ,

  hexdigit = digit:c | char:c ?((c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')) ,
  int = <sign ('0x'|'0X') hexdigit+>:i -> parseInt(i, 16)
      | <sign digit+>:i -> parseInt(i) ,

  number = float | int ,

  addexp = addexp:l "+" mulexp:r -> ['add', l, r]
         | addexp:l "-" mulexp:r -> ['sub', l, r]
         | mulexp ,
  mulexp = mulexp:l "*" powexp:r -> ['mul', l, r]
         | mulexp:l "/" powexp:r -> ['div', l, r]
         | mulexp:l "%" powexp:r -> ['mod', l, r]
         | powexp ,
  powexp = parexp:l "^" powexp:r -> ['pow', l, r]
         | parexp ,
  parexp = "(" exp:e ")" -> e
         | number ,

  exp = addexp
}

CalcParser.matchAll('1+2^3^4-5*6', 'exp')