public void Print()
{
int frontData = -1;
int backData = -1;
PCQueueNode p = m_front;
Console.WriteLine("queue");
//get first item in queue
while (!(p is PCQueueNodeNull))
{
frontData = p.Data;
p = p.Next;
break;
}
p = m_front;
//get last item in queue
while (!(p is PCQueueNodeNull))
{
backData = p.Data;
p = p.Next;
}
//print last and first item of queue
Console.WriteLine(backData);
Console.WriteLine(frontData);
}
public bool Enqueue(int dataValue)
{
PCQueueNode newNode = new PCQueueNodeData(dataValue, m_dummy as PCQueueNodeNull);
//insert into empty list // if back is empty, front is empty
if (Object.ReferenceEquals(m_back, m_dummy))
{
//dequeue can't be happening at this point because there is no
//no case where front is not empty and back is empty
m_back = newNode;
m_front = newNode; //at this point dequeuing can resume
return(true);
}
//case handles potential enqueue onto invalid node
else if (Object.ReferenceEquals(m_front, m_dummy) && Object.ReferenceEquals(m_front, m_back.Next))
{
//at this point dequeue will only enter and immediately return false
m_back.Next = newNode;
m_back = m_back.Next;
m_front = m_back; //after this line we can dequeue again
return(true);
}
else
{
//"normal" enqueue
//here we just worry about the back
//in the event that the front advances past of the back, we handle that with the case above
m_back.Next = newNode;
m_back = m_back.Next;
return(true);
}
}
public PCQueue()
{
//we have our dummy node which will take the place of null
m_dummy = new PCQueueNodeNull();
m_front = m_dummy;
m_back = m_dummy;
}
public bool Dequeue(ref int out_value)
{
//in the case the the front is null (points to dummy), our queue is empty, return false
if (Object.ReferenceEquals(m_front, m_dummy)) //or m_front is PCQueueNodeNull
{
return(false);
}
//otherwise, get front value and advance the pointer
//the back pointer may change at anytime from here
out_value = m_front.Data;
//to here
m_front = m_front.Next;
//to here
//neither of these places concern us because we are only touching the front
//front will not change in those places
return(true);
}