// add element to head of queue
public void WriteFirst(T data)
{
var node = new DoubleNode <T>(data);
if (last == null)
{
last = node;
}
else
{
first.Previous = node;
node.Next = first;
}
first = node;
++count;
}
// add element to end of queue
public void WriteLast(T data)
{
var node = new DoubleNode <T>(data);
if (first == null)
{
first = node;
}
else
{
last.Next = node;
node.Previous = last;
}
last = node;
++count;
}
// get element from head of queue
public T ReadFirst()
{
if (count == 0)
{
first = last = null;
throw (new InvalidOperationException(EmptyMsg));
}
var node = first;
first = first.Next;
node.Next = node.Previous = null;
--count;
return(node.Data);
}
