public double Calculate(IEnumerable <Token> tokens)
{
var stack = new Stack <double>(16);
foreach (var token in tokens)
{
switch (token)
{
case NumberToken n:
stack.Push(n.Value);
break;
case VariableToken v:
stack.Push(Context.GetVariableValue(v.Text));
break;
case OperatorToken op:
stack.Push(OperatorMap[op.Text].Eval(null, stack));
break;
case FunctionToken func:
var count = Context.GetFunctionArgumentCount(func.Text);
var args = new List <double>(count);
for (int i = 0; i < count; i++)
{
args.Add(stack.Pop());
}
stack.Push(Context.EvalFunction(func.Text, args.ToArray()));
break;
default:
throw new InvalidOperationException();
}
}
return(stack.Peek());
}