private void HandleOperator(char op)
{
_display.Print(_display.ParseDisplay());
if (UnaryOperatorProvider.IsUnaryOperator(op))
{
var fun = UnaryOperatorProvider.GetOperator(op);
_display.Print(fun(_display.ParseDisplay()));
_lastPressed = ButtonCategory.UnaryOperator;
}
else if (BinaryOperatorProvider.IsBinaryOperator(op))
{
if (double.IsNaN(_lastResult))
{
_lastResult = _display.ParseDisplay();
}
if (_operator != EMPTY_OPERATOR && _lastPressed != ButtonCategory.BinaryOperator)
{
double number = _display.ParseDisplay();
var fun = BinaryOperatorProvider.GetOperator(_operator);
_lastResult = fun(_lastResult, number);
_display.Print(_lastResult);
}
_operator = op;
_lastPressed = ButtonCategory.BinaryOperator;
}
else
{
throw new ArgumentException($"Unknown operator '{op}'");
}
}
private void EqualsSign()
{
if (_operator != EMPTY_OPERATOR)
{
double operand = _lastResult;
if (!string.IsNullOrEmpty(_display.CurrentState))
{
operand = _display.ParseDisplay();
}
if (double.IsNaN(_lastResult))
{
_lastResult = _display.ParseDisplay();
}
var op = BinaryOperatorProvider.GetOperator(_operator);
_display.Print(op(_lastResult, operand));
_operator = EMPTY_OPERATOR;
_lastResult = double.NaN;
}
else
{
_display.Print(_display.ParseDisplay());
}
}