'''
class OysterIterator : IIterator<BSTNode>
	{
		enum NodeType
		{
			Left, Right, Self, None
		}
		private BSTNode Root { get; set; }
		private OysterIterator Iterator { get; set; }
		private NodeType NodeToGet { get; set; }
		private bool HasParent { get; set; }


		public OysterIterator(BSTNode root)
		{
			Root = root;
			Reset();
		}

		private OysterIterator(BSTNode root, bool hasParent): this(root)
		{
			HasParent = hasParent;
		}

		// Left branch -> Root -> Right branch -> Null/Reset
		public BSTNode Next()
		{
			if (NodeToGet == NodeType.None)
				if (!HasParent) // Only the top root should reset the iterator
				{
					Reset();
					if (NodeToGet == NodeType.None) // After reset it can still be empty (so the collection is empty)
						return null;
				}
				else
					return null;
			if (NodeToGet == NodeType.Self)
			{
				if (Root.Right == null)
					NodeToGet = NodeType.None;
				else
				{
					NodeToGet = NodeType.Right;
					Iterator = new OysterIterator(Root.Right, true);
				}
				return Root;
			}

			var node = Iterator.Next();
			if (node == null)
			{
				if (NodeToGet == NodeType.Left)
					NodeToGet = NodeType.Self;
				else // right node returned null
					NodeToGet = NodeType.None;
				node = Next();
			}
			return node;
		}

		public void Reset()
		{
			Iterator = null;
			NodeToGet = NodeType.None;
			if (Root == null) return;
			if (Root.Left != null)
			{
				Iterator = new OysterIterator(Root.Left, true);
				NodeToGet = NodeType.Left;
			}
			else
				NodeToGet = NodeType.Self;
		}
	}
'''