options{
    //DEBUG_PARSER = true; DEBUG_TOKEN_MANAGER = true;
    STATIC=false;
}

PARSER_BEGIN(Calculator)
import java.util.Scanner;
import java.io.StringReader;

public class Calculator {

    private static double currentNumber;

    public static double fromString(String stringToParse) throws ParseException{
        currentNumber = 0.0;

        Calculator parser = new Calculator(new StringReader(stringToParse));
        parser.parse();
        return currentNumber;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (true){
            System.out.print("Type your expression: ");
            String expression = scanner.nextLine();
            try{
                System.out.println("Returned: " + fromString(expression));
            }catch (Throwable t){
                System.out.println(t);
            }
        }
    }
}
PARSER_END(Calculator)

/**
* For now only using the Hello World grammar
*/

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

TOKEN : {
	<PAL: "(">|
	<PAR: ")">|
	<ADD: "+">|
	<SUB: "-">|
	<MUL: "*">|
	<DIV: "/">|
	<EQU: "=">|
	<LET: "let">|
	<END: "exit">|
    <NUM: (["0"-"9"])+("."((["0"-"9"])+))?>|
	<ID: (["a"-"z"]|["A"-"Z"])+>
}



double factor() :
{
    Token t;
    double i;
}
{
    t = <NUM>
        {
            i = Double.parseDouble(t.image);
            currentNumber += i;
            return i;
        }
}

void parse() : {
}
{
	(factor())* <EOF>
}