public Queue <string> Parse(string mathematicalExpression)
{
var operatorStack = new Stack <OperatorMetadata>();
var outputQueue = new Queue <string>();
string accumulatingNumber = string.Empty;
foreach (char character in mathematicalExpression)
{
if (OperatorManifest.IsOperator(character))
{
outputQueue.Enqueue(accumulatingNumber);
accumulatingNumber = string.Empty;
OperatorMetadata operatorMetadata = OperatorManifest.Parse(character);
while (operatorStack.Count > 0 && operatorStack.Peek().Priority >= operatorMetadata.Priority)
{
OperatorMetadata poppedOperator = operatorStack.Pop();
outputQueue.Enqueue(poppedOperator.Symbol);
}
operatorStack.Push(operatorMetadata);
}
else
{
accumulatingNumber += character;
}
}
if (!string.IsNullOrEmpty(accumulatingNumber))
{
outputQueue.Enqueue(accumulatingNumber);
}
while (operatorStack.Count > 0)
{
outputQueue.Enqueue(operatorStack.Pop().Symbol);
}
return(outputQueue);
}
public string Compute(string mathematicalExpression)
{
Console.WriteLine($"Executing computation for {mathematicalExpression}");
// Convert from infix to postfix format
Queue <string> postfixQueue = _parser.Parse(mathematicalExpression);
Console.WriteLine($"Postfix string: {string.Join(":", postfixQueue)}");
Stack <double> operands = new Stack <double>();
try
{
foreach (string token in postfixQueue)
{
if (OperatorManifest.IsOperator(token))
{
ICalculation calculation = _calculationFactory.CreateCalculation(token);
double secondOperand = operands.Pop();
double firstOperand = operands.Pop();
double result = calculation.Compute(firstOperand, secondOperand);
operands.Push(result);
}
else
{
operands.Push(string.IsNullOrEmpty(token) ? 0 : double.Parse(token));
}
}
double finalResult = operands.Count > 0 ? operands.Pop() : 0;
return(finalResult.ToString());
}
catch (OverflowException)
{
throw new CalculatorException(ErrorCode.Overflow);
}
}