CircularList

class CircularList<T> : IEnumerable<T>
    {
        private class Node
        {
            public T item;
            public Node next;
            public Node previous;
        }

        Node current;
        int count;

        public int Count
        {
            get { return count; }
            set {  }
        }

        public CircularList()
        {

        }

        public void Add(T item)
        {
            if (count == 0)
            {
                current = new Node();
                current.item = item;
                current.next = current;
                current.previous = current;
                count++;
                return;
            }
            Node nodeNew = new Node();
            nodeNew.item = item;
            nodeNew.previous = current.previous;
            nodeNew.next = current;
            current.previous.next = nodeNew;
            current.previous = nodeNew;
            count++;
        }

        public T GetCurrent()
        {
            if (count < 1)
            {
                throw new IndexOutOfRangeException("List is empty.");
            }
            return current.item;
        }

        public void Next()
        {
            if (count < 1)
            {
                throw new IndexOutOfRangeException("List is empty.");
            }
            current = current.next;
        }

        public void Previous()
        {
            if (count < 1)
            {
                throw new IndexOutOfRangeException("List is empty.");
            }
            current = current.previous;
        }

        public void Remove()
        {
            if (count < 1)
            {
                throw new IndexOutOfRangeException("List is empty.");
            }
            current.previous.next = current.next;
            current.next.previous = current.previous;
            current = current.next;
            count--;
        }

        public IEnumerator<T> GetEnumerator()
        {
            Node start = this.current;

            do
            {
                yield return current.item;
                current = current.next;
            }
            while (current != start);
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
    }