public void Visit(AddExpression expr)
{
if (expr.Left.Value.HasValue && expr.Right.Value.HasValue)
{
expr.Value = expr.Left.Value.Value + expr.Right.Value.Value;
}
}
public static void Main(string[] args)
{
var expr = new AddExpression
{
Left = new ValueExpression {
Value = 3
},
Right = new MultiplyExpression
{
Left = new ValueExpression {
Value = 2
},
Right = new ValueExpression {
Value = 7
}
}
};
var printer = new Printer();
expr.Accept(printer);
Console.WriteLine();
var evaluator = new Evaluator();
expr.Accept(evaluator);
Console.WriteLine(expr.Value.Value);
}
public void Visit(AddExpression expr)
{
Console.Write(" + ");
}
