/// <summary>
/// Removes and returns the object at the beginning of the <see cref="LinkedListQueue{T}"/>.
/// </summary>
/// <returns>The object that is removed from the beginning of the <see cref="LinkedListQueue{T}"/>.</returns>
/// <exception cref="InvalidOperationException">
/// Thrown when the <see cref="LinkedListQueue{T}"/> is empty.
/// </exception>
public T Dequeue()
{
if (_count == 0 || _first == null)
{
throw new InvalidOperationException("Trying to dequeue from an empty queue.");
}
T removed = _first.Value;
// This is the last item in the queue.
if (_first == _last)
{
_first.Invalidate();
_first = _last = null;
}
else
{
QueueNode <T> temp = _first;
_first = _first.Next;
_first.Previous = null;
temp.Invalidate();
temp = null;
}
_count--;
_version++;
return(removed);
}
/// <summary>
/// Tries to remove and return the object at the beginning of the <see cref="LinkedListQueue{T}"/>.
/// </summary>
/// <param name="result">The object that is removed from the beginning of the <see cref="LinkedListQueue{T}"/>.</param>
/// <returns>True if the object was removed from the queue, false otherwise.</returns>
public bool TryDequeue(out T result)
{
if (_first == null || _count == 0)
{
result = default(T);
return(false);
}
else
{
result = _first.Value;
// This is the last item in the queue.
if (_first == _last)
{
_first.Invalidate();
_first = _last = null;
}
else
{
QueueNode <T> temp = _first;
_first = _first.Next;
_first.Previous = null;
temp.Invalidate();
temp = null;
}
_count--;
_version++;
return(true);
}
}
/// <summary>
/// Removes all items from the queue and resets the count.
/// </summary>
public void Clear()
{
QueueNode <T> current = _first;
while (current != null)
{
QueueNode <T> temp = current;
current = current.Next;
temp.Invalidate();
}
_first = _last = null;
_count = 0;
_version++;
}
