package exercise.run;
import exercise.algebra.number.NormRational;
import java.util.Stack;
public class RPN{
public static void main(String[] args){
if ( args.length == 0 ){
    System.out.println("Bitte einen Ausdruck in umgekehrter polnischer Notation angeben!");
    System.out.println("Usage: java RPN EXPR");
    return;
}

Stack s = new Stack();
int len = args.length;
long l;
for(int i=0;i<len;i++){

switch (args[i]){
    case "+":
        NormRational a = s.pop();
        NormRational b = s.pop();
        b.add(a);
        s.push(b);
        break;
    case "-":
        NormRational a = s.pop();
        NormRational b = s.pop();
        b.sub(a);
        s.push(b);
        break;
    case "*":
        NormRational a = s.pop();
        NormRational b = s.pop();
        b.mult(a);
        s.push(b);
        break;
    case "/":
        NormRational a = s.pop();
        NormRational b = s.pop();
        b.div(a);
        s.push(b);
        break;
    default:
        try{
            l = Long.parseLong(args[i]);
            if(l<0)
                throw new NumberFormatException();
            NormRational r = new NormRational(l);
            s.push(r);
        }
        catch(Exception e){
            System.err.println("Falsches Eingabeformat");
            System.err.println("Erlaubte Eingabe: 0..9 + - */");
        }
        break;
}
}
}
}