public void Visit(AdditionalExpression obj)
{
sb.Append("(");
obj.Left.Accept(this);
sb.Append("+");
obj.Right.Accept(this);
sb.Append(")");
}
static void Main(string[] args)
{
var e = new AdditionalExpression(
left: new DoubleExpression(3),
right: new AdditionalExpression(
left: new DoubleExpression(4),
right: new DoubleExpression(8)));
var ep = new ExpressionPrinter();
ep.Visit(e);
Console.WriteLine(ep);
Console.ReadKey();
}