package SecondTerm.week7;

import SecondTerm.week2.EmptyCollectionException;

import java.util.Scanner;

public class PostfixTester {

    public static void main(String[] args) throws EmptyCollectionException {
        String expression, again;
        int result;

        Scanner in = new Scanner(System.in);

        do {
            PostfixEvaluator evaluator = new PostfixEvaluator();
            System.out.println("Enter a valid post-fix expression one token " + "at a time with a space between each token (e.g.5 4 + 3 2 1 - + *)");
            System.out.println("Each token must be an integer or an operator(+,-,*,/)");
            expression = in.nextLine();

            result = evaluator.evaluate(expression);
            System.out.println();
            System.out.println("That expression equals " + result);

            System.out.println("The Expression Tree for that expression is:");
            System.out.println(evaluator.getTree());

            System.out.println("Evaluate another expression [Y/N]?");
            again = in.nextLine();
            System.out.println();
        }
        while (again.equalsIgnoreCase("Y"));

    }

}