compiladoresDeMerda

options
{
  JDK_VERSION = "1.5";
  STATIC = false;
}

PARSER_BEGIN(Calculator)

public class Calculator
{
    public static void main(String args[]) throws
    ParseException
{
    Calculator parser = new Calculator(System.in);
    while (true)
    {
    parser.parseLine();
    }
  }
}

PARSER_END(Calculator)

SKIP :
{
" "
| "\r"
| "\t"
}

TOKEN:
{
< NUMBER: (<DIGIT>)+ ( "."(<DIGIT>)+ )? >| < DIGIT: ["0"-"9"] >| < EOL: "\n" >
}

void parseLine():
{
  double a;
}
{
  a=expr() < EOL > {System.out.println(a); }
  |< EOL >
  |< EOF > {System.exit(-1); }
}

double expr():
{
  double a;
  double b;
}

{
  a=term()
  (
    "+" b=term() { a += b; }
   |"-" b=term() { a -= b; }

  )*
  { return a; }
}

double term():
{
  double a;
  double b;
}
{
  a=unary()
  (
    "*" b=term() { a *= b; }
   |"/" b=term() { a /= b; }

  )*
  { return a; }
}

double unary():
{
  double a;
}
{
  "-" a=element() { return -a; }
  |a=element() { return a; }
}

double element():
{
  Token t;
  double a;
}
{
  t = < NUMBER > { return Double.parseDouble(t.toString()); }
  | "(" a=expr() ")" { return a; }
}