public string Clear()
{
_tokens.Clear();
_status = CalculatorStatus.Empty;
_decimalFound = false;
return(STR_0);
}
public bool Calculate(out decimal result)
{
result = 0.0m;
switch (_status)
{
case CalculatorStatus.Empty:
//Nothing to do
return false;
case CalculatorStatus.FirstNumber:
//The first number becomes a result
result = decimal.Parse(_tokens.Peek().Value, CultureInfo.InvariantCulture.NumberFormat);
_tokens.Push(new Token("=", TokenType.Operator));
_status = CalculatorStatus.Operator;
return false;
case CalculatorStatus.Operator:
//TODO ?
return false;
case CalculatorStatus.SecondNumber:
var secondNumber = decimal.Parse(_tokens.Pop().Value, CultureInfo.InvariantCulture.NumberFormat);
var @operator = _tokens.Pop().Value;
var firstNumber = decimal.Parse(_tokens.Pop().Value, CultureInfo.InvariantCulture.NumberFormat);
switch (@operator)
{
case "=":
//The operator "=" is used as a placeholder to prevent editing the result of an operation
//Nothing to do
break;
case "+":
result = firstNumber + secondNumber;
_tokens.Push(new Token(result.ToString(CultureInfo.InvariantCulture.NumberFormat), TokenType.Number));
_tokens.Push(new Token("=", TokenType.Operator));
_status = CalculatorStatus.Operator;
break;
case "-":
result = firstNumber - secondNumber;
_tokens.Push(new Token(result.ToString(CultureInfo.InvariantCulture.NumberFormat), TokenType.Number));
_tokens.Push(new Token("=", TokenType.Operator));
_status = CalculatorStatus.Operator;
break;
case "*":
result = firstNumber * secondNumber;
_tokens.Push(new Token(result.ToString(CultureInfo.InvariantCulture.NumberFormat), TokenType.Number));
_tokens.Push(new Token("=", TokenType.Operator));
_status = CalculatorStatus.Operator;
break;
case "/":
result = firstNumber / secondNumber;
_tokens.Push(new Token(result.ToString(CultureInfo.InvariantCulture.NumberFormat), TokenType.Number));
_tokens.Push(new Token("=", TokenType.Operator));
_status = CalculatorStatus.Operator;
break;
default:
//TODO add support for additional operators
break;
}
if (!ReferenceEquals(_resultCallback, null))
{
_resultCallback.Invoke(result);
}
return true;
default:
//TODO ?
return false;
}
}
public Calculator(Action<decimal> resultCallback)
{
_tokens = new Stack<Token>();
_status = CalculatorStatus.Empty;
_resultCallback = resultCallback;
}
private void AddToken(Token token)
{
switch (_status)
{
case CalculatorStatus.Empty:
switch (token.Type)
{
case TokenType.Number:
_tokens.Push(token);
_status = CalculatorStatus.FirstNumber;
_decimalFound = false;
break;
case TokenType.Operator:
_tokens.Push(new Token(STR_0, TokenType.Number));
_tokens.Push(token);
_status = CalculatorStatus.Operator;
break;
case TokenType.Special:
if (token.Value == STR_Dot)
{
_tokens.Push(new Token(STR_0 + STR_Dot, TokenType.Number));
_status = CalculatorStatus.FirstNumber;
_decimalFound = true;
}
//TODO (HOMEWORK) add support for parenthesis
break;
default:
//TODO
break;
}
break;
case CalculatorStatus.FirstNumber:
switch (token.Type)
{
case TokenType.Number:
_tokens.Push(new Token(_tokens.Pop().Value + token.Value, TokenType.Number));
break;
case TokenType.Operator:
_tokens.Push(token);
_status = CalculatorStatus.Operator;
break;
case TokenType.Special:
if (token.Value == STR_Dot)
{
if (!_decimalFound)
{
_tokens.Push(new Token(_tokens.Pop().Value + STR_Dot, TokenType.Number));
_status = CalculatorStatus.FirstNumber;
_decimalFound = true;
}
}
//TODO (HOMEWORK) add support for parenthesis
break;
default:
//TODO
break;
}
break;
case CalculatorStatus.Operator:
switch (token.Type)
{
case TokenType.Number:
//The operator "=" means that the input is being recieved after requesting a result
//If we find the operator "=" we discard all
if (_tokens.Peek().Value == "=")
{
//discard
Clear();
AddToken(token);
}
else
{
_tokens.Push(token);
_status = CalculatorStatus.SecondNumber;
_decimalFound = false;
}
break;
case TokenType.Operator:
//replace the operator
_tokens.Pop();
_tokens.Push(token);
break;
case TokenType.Special:
//The operator "=" means that the input is being recieved after requesting a result
//If we find the operator "=" we discard all
if (_tokens.Peek().Value == "=")
{
//discard
Clear();
AddToken(token);
}
else
{
if (token.Value == STR_Dot)
{
_tokens.Push(new Token(STR_0 + STR_Dot, TokenType.Number));
_decimalFound = true;
_status = CalculatorStatus.SecondNumber;
}
//TODO (HOMEWORK) add support for parenthesis
}
break;
default:
//TODO
break;
}
break;
case CalculatorStatus.SecondNumber:
switch (token.Type)
{
case TokenType.Number:
_tokens.Push(new Token(_tokens.Pop().Value + token.Value, TokenType.Number));
break;
case TokenType.Operator:
//It is like pressing equals and then taking the result as first number, afterwards add the operator
Calculate();
AddToken(token);
break;
case TokenType.Special:
if (token.Value == STR_Dot)
{
if (!_decimalFound)
{
_tokens.Push(new Token(_tokens.Pop().Value + STR_Dot, TokenType.Number));
_status = CalculatorStatus.FirstNumber;
_decimalFound = true;
}
}
//TODO (HOMEWORK) add support for parenthesis
break;
default:
//TODO
break;
}
break;
default:
//TODO ?
break;
}
}
public string Clear()
{
_tokens.Clear();
_status = CalculatorStatus.Empty;
_decimalFound = false;
return STR_0;
}
public bool Calculate(out decimal result)
{
result = 0.0m;
switch (_status)
{
case CalculatorStatus.Empty:
//Nothing to do
return(false);
case CalculatorStatus.FirstNumber:
//The first number becomes a result
result = decimal.Parse(_tokens.Peek().Value, CultureInfo.InvariantCulture.NumberFormat);
_tokens.Push(new Token("=", TokenType.Operator));
_status = CalculatorStatus.Operator;
return(false);
case CalculatorStatus.Operator:
//TODO ?
return(false);
case CalculatorStatus.SecondNumber:
var secondNumber = decimal.Parse(_tokens.Pop().Value, CultureInfo.InvariantCulture.NumberFormat);
var @operator = _tokens.Pop().Value;
var firstNumber = decimal.Parse(_tokens.Pop().Value, CultureInfo.InvariantCulture.NumberFormat);
switch (@operator)
{
case "=":
//The operator "=" is used as a placeholder to prevent editing the result of an operation
//Nothing to do
break;
case "+":
result = firstNumber + secondNumber;
_tokens.Push(new Token(result.ToString(CultureInfo.InvariantCulture.NumberFormat), TokenType.Number));
_tokens.Push(new Token("=", TokenType.Operator));
_status = CalculatorStatus.Operator;
break;
case "-":
result = firstNumber - secondNumber;
_tokens.Push(new Token(result.ToString(CultureInfo.InvariantCulture.NumberFormat), TokenType.Number));
_tokens.Push(new Token("=", TokenType.Operator));
_status = CalculatorStatus.Operator;
break;
case "*":
result = firstNumber * secondNumber;
_tokens.Push(new Token(result.ToString(CultureInfo.InvariantCulture.NumberFormat), TokenType.Number));
_tokens.Push(new Token("=", TokenType.Operator));
_status = CalculatorStatus.Operator;
break;
case "/":
result = firstNumber / secondNumber;
_tokens.Push(new Token(result.ToString(CultureInfo.InvariantCulture.NumberFormat), TokenType.Number));
_tokens.Push(new Token("=", TokenType.Operator));
_status = CalculatorStatus.Operator;
break;
default:
//TODO add support for additional operators
break;
}
if (!ReferenceEquals(_resultCallback, null))
{
_resultCallback.Invoke(result);
}
return(true);
default:
//TODO ?
return(false);
}
}
public Calculator(Action <decimal> resultCallback)
{
_tokens = new Stack <Token>();
_status = CalculatorStatus.Empty;
_resultCallback = resultCallback;
}
private void AddToken(Token token)
{
switch (_status)
{
case CalculatorStatus.Empty:
switch (token.Type)
{
case TokenType.Number:
_tokens.Push(token);
_status = CalculatorStatus.FirstNumber;
_decimalFound = false;
break;
case TokenType.Operator:
_tokens.Push(new Token(STR_0, TokenType.Number));
_tokens.Push(token);
_status = CalculatorStatus.Operator;
break;
case TokenType.Special:
if (token.Value == STR_Dot)
{
_tokens.Push(new Token(STR_0 + STR_Dot, TokenType.Number));
_status = CalculatorStatus.FirstNumber;
_decimalFound = true;
}
//TODO (HOMEWORK) add support for parenthesis
break;
default:
//TODO
break;
}
break;
case CalculatorStatus.FirstNumber:
switch (token.Type)
{
case TokenType.Number:
_tokens.Push(new Token(_tokens.Pop().Value + token.Value, TokenType.Number));
break;
case TokenType.Operator:
_tokens.Push(token);
_status = CalculatorStatus.Operator;
break;
case TokenType.Special:
if (token.Value == STR_Dot)
{
if (!_decimalFound)
{
_tokens.Push(new Token(_tokens.Pop().Value + STR_Dot, TokenType.Number));
_status = CalculatorStatus.FirstNumber;
_decimalFound = true;
}
}
//TODO (HOMEWORK) add support for parenthesis
break;
default:
//TODO
break;
}
break;
case CalculatorStatus.Operator:
switch (token.Type)
{
case TokenType.Number:
//The operator "=" means that the input is being recieved after requesting a result
//If we find the operator "=" we discard all
if (_tokens.Peek().Value == "=")
{
//discard
Clear();
AddToken(token);
}
else
{
_tokens.Push(token);
_status = CalculatorStatus.SecondNumber;
_decimalFound = false;
}
break;
case TokenType.Operator:
//replace the operator
_tokens.Pop();
_tokens.Push(token);
break;
case TokenType.Special:
//The operator "=" means that the input is being recieved after requesting a result
//If we find the operator "=" we discard all
if (_tokens.Peek().Value == "=")
{
//discard
Clear();
AddToken(token);
}
else
{
if (token.Value == STR_Dot)
{
_tokens.Push(new Token(STR_0 + STR_Dot, TokenType.Number));
_decimalFound = true;
_status = CalculatorStatus.SecondNumber;
}
//TODO (HOMEWORK) add support for parenthesis
}
break;
default:
//TODO
break;
}
break;
case CalculatorStatus.SecondNumber:
switch (token.Type)
{
case TokenType.Number:
_tokens.Push(new Token(_tokens.Pop().Value + token.Value, TokenType.Number));
break;
case TokenType.Operator:
//It is like pressing equals and then taking the result as first number, afterwards add the operator
Calculate();
AddToken(token);
break;
case TokenType.Special:
if (token.Value == STR_Dot)
{
if (!_decimalFound)
{
_tokens.Push(new Token(_tokens.Pop().Value + STR_Dot, TokenType.Number));
_status = CalculatorStatus.FirstNumber;
_decimalFound = true;
}
}
//TODO (HOMEWORK) add support for parenthesis
break;
default:
//TODO
break;
}
break;
default:
//TODO ?
break;
}
}
