System.Xml.XPath.XPathNavigator.IsDescendant C# (CSharp) Method

        public virtual bool IsDescendant(XPathNavigator nav)
        {
            if (nav != null)
            {
                nav = nav.Clone();
                while (nav.MoveToParent())
                    if (nav.IsSamePosition(this))
                        return true;
            }
            return false;
        }

		public virtual XmlNodeOrder ComparePosition (XPathNavigator nav)
		{
			if (IsSamePosition (nav))
				return XmlNodeOrder.Same;

			// quick check for direct descendant
			if (IsDescendant (nav))
				return XmlNodeOrder.Before;

			// quick check for direct ancestor
			if (nav.IsDescendant (this))
				return XmlNodeOrder.After;

			XPathNavigator nav1 = Clone ();
			XPathNavigator nav2 = nav.Clone ();

			// check if document instance is the same.
			nav1.MoveToRoot ();
			nav2.MoveToRoot ();
			if (!nav1.IsSamePosition (nav2))
				return XmlNodeOrder.Unknown;
			nav1.MoveTo (this);
			nav2.MoveTo (nav);

			int depth1 = 0;
			while (nav1.MoveToParent ())
				depth1++;
			nav1.MoveTo (this);
			int depth2 = 0;
			while (nav2.MoveToParent ())
				depth2++;
			nav2.MoveTo (nav);

			// find common parent depth
			int common = depth1;
			for (;common > depth2; common--)
				nav1.MoveToParent ();
			for (int i = depth2; i > common; i--)
				nav2.MoveToParent ();
			while (!nav1.IsSamePosition (nav2)) {
				nav1.MoveToParent ();
				nav2.MoveToParent ();
				common--;
			}

			// For each this and target, move to the node that is 
			// ancestor of the node and child of the common parent.
			nav1.MoveTo (this);
			for (int i = depth1; i > common + 1; i--)
				nav1.MoveToParent ();
			nav2.MoveTo (nav);
			for (int i = depth2; i > common + 1; i--)
				nav2.MoveToParent ();

			// Those children of common parent are comparable.
			// namespace nodes precede to attributes, and they
			// precede to other nodes.
			if (nav1.NodeType == XPathNodeType.Namespace) {
				if (nav2.NodeType != XPathNodeType.Namespace)
					return XmlNodeOrder.Before;
				while (nav1.MoveToNextNamespace ())
					if (nav1.IsSamePosition (nav2))
						return XmlNodeOrder.Before;
				return XmlNodeOrder.After;
			}
			if (nav2.NodeType == XPathNodeType.Namespace)
				return XmlNodeOrder.After;
			if (nav1.NodeType == XPathNodeType.Attribute) {
				if (nav2.NodeType != XPathNodeType.Attribute)
					return XmlNodeOrder.Before;
				while (nav1.MoveToNextAttribute ())
					if (nav1.IsSamePosition (nav2))
						return XmlNodeOrder.Before;
				return XmlNodeOrder.After;
			}
			while (nav1.MoveToNext ())
				if (nav1.IsSamePosition (nav2))
					return XmlNodeOrder.Before;
			return XmlNodeOrder.After;
		}