public static CalcItem Parse(string s)
{
var item = new CalcItem();
if (double.TryParse(s, out item.value))
{
item.op = Operator.Push;
}
else
{
if (s.Length > 1)
{
throw new ArgumentException("If not a number, string must be a single character");
}
item.op = s switch
{
"+" => Operator.Add,
"-" => Operator.Subtract,
"*" => Operator.Multiply,
"/" => Operator.Divide,
_ => throw new ArgumentException("Unrecognized operator")
};
}
return(item);
}
public void PerformSingle(CalcItem item)
{
if (item.op == Operator.Push)
{
_stack.Push(item);
}
else
{
if (_stack.Count < 2)
{
throw new Exception("Not enough values to operate on");
}
var val2 = _stack.Pop().value;
var val1 = _stack.Pop().value;
PerformSingle(CalcItem.Value(item.op switch
{
Operator.Add => val1 + val2,
Operator.Subtract => val1 - val2,
Operator.Multiply => val1 * val2,
Operator.Divide => val1 / val2
}));