package step7;
import step7.expr.yyLex;
import step7.expr.yyTree.*;
/** evaluate {@link expr} tree with integer arithmetic.
    This implementation demonstrates local state.
  */
public class stack implements jag.Visitor {
  /** result of current {@link #visit}.
    */
  protected int result;
%%

Add: Object Object {{ $2; int right = result; $1; result += right; }};
Sub: Object Object {{ $2; int right = result; $1; result -= right; }};
Mul: Object Object {{ $2; int right = result; $1; result *= right; }};
Div: Object Object {{ $2; int right = result; $1; result /= right; }};
Mod: Object Object {{ $2; int right = result; $1; result %= right; }};
Minus: Object { $1; result = - result; };

Number: { result = $0.intValue(); };

%%
  /** read an expression from standard input and output it's value.
    */
  public static void main (String[] args) throws Exception {
    stack s = new stack();
    s.visit(new expr().yyparse(new yyLex(System.in)));
    System.out.println("\t"+s.result);
  }
}