private double CalculatePostfixQueue(Queue <CalcObject> postfixQueue)
{
Stack <double> resultStack = new Stack <double>();
int queueCount = postfixQueue.Count;
for (int i = 0; i < queueCount; ++i)
{
CalcObject currentObject = postfixQueue.Dequeue();
if (currentObject.ObjectType == CalcObject.Type.NUM)
{
resultStack.Push(currentObject.Number);
}
else
{
// encountered an operator.
if (resultStack.Count < 2)
{
throw new Exception("Calculating Postfix Queue: Encountered operator before two numbers.");
}
double right = resultStack.Pop();
double left = resultStack.Pop();
double result;
switch (currentObject.ObjectType)
{
case CalcObject.Type.OP_PLUS:
result = left + right;
break;
case CalcObject.Type.OP_MINUS:
result = left - right;
break;
case CalcObject.Type.OP_MULTIPLY:
result = left * right;
break;
case CalcObject.Type.OP_DIVIDE:
result = left / right;
break;
default:
throw new Exception("Calculating Postfix Queue: There must be an operator.");
}
resultStack.Push(result);
}
}
if (resultStack.Count != 1)
{
throw new Exception("Calculating Postfix Queue: Expected next operator.");
}
return(resultStack.Pop());
}
private Queue <CalcObject> ToPostFix(Queue <CalcObject> userInputQueue)
{
Queue <CalcObject> postFixQueue = new Queue <CalcObject>();
Stack <CalcObject> operatorStack = new Stack <CalcObject>();
// iterate user input queue and iterate
while (userInputQueue.Count > 0)
{
CalcObject userCalcObject = this.UserInputQueue.Dequeue();
if (userCalcObject.ObjectType == CalcObject.Type.NUM)
{
// if the object is a number
postFixQueue.Enqueue(userCalcObject);
}
else
{
if (postFixQueue.Count == 0)
{
throw new Exception("Converting Infix Queue to Postfix Queue: Encountered operator before first number.");
}
// if the object is an operator
int existingOperatorWeight = operatorStack.Count != 0 ? (int)operatorStack.Peek().ObjectType : 0;
if (existingOperatorWeight > 0 && (existingOperatorWeight >> 4) >= ((int)userCalcObject.ObjectType >> 4))
{
// if bigger or same weighted operator is in operator stack, pop it and enqueue in PostFix
postFixQueue.Enqueue(operatorStack.Pop());
}
// add operator to operator stack
operatorStack.Push(userCalcObject);
}
}
// now move from operator stack to postfix queue
int operatorStackCount = operatorStack.Count; // temp
for (int i = 0; i < operatorStackCount; i++)
{
postFixQueue.Enqueue(operatorStack.Pop());
}
return(postFixQueue);
}
public void AddCalcObject(CalcObject ob)
{
this.UserInputQueue.Enqueue(ob);
}