public class PrettyPrint implements ExpressionVisitor {

  public void visit(IntExp e) {

    System.out.print( e.getValue() );

  }

  public void visitBefore(AddExp e) {
    System.out.print(" ( ");
  }

  public void visit(AddExp e) {
    System.out.print(" + ");
  }

  public void visitAfter(AddExp e) {
    System.out.print(" ) ");
  }

}