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();
printer.Visit(expr);
Console.WriteLine();
var evaluator = new Evaluator();
evaluator.Visit(expr);
Console.WriteLine(evaluator.Result);
}
protected override void Visit(AddExpression expr)
{
Console.Write("(");
Visit(expr.Left);
Console.Write(" + ");
Visit(expr.Right);
Console.Write(")");
}
protected override void Visit(AddExpression expr)
{
Visit(expr.Left);
Visit(expr.Right);
var right = Stack.Pop();
var left = Stack.Pop();
Stack.Push(left + right);
}
protected abstract void Visit(AddExpression expr);