public override SiteMapNode FindSiteMapNode(string url)
        {
            SiteMapNode node = null;

            if (directoryFactory.TryCreateNodeFromUrl(url, ref node) && filter.ShowDirectory(node.Key))
            {
                return(node);
            }

            if (fileFactory.TryCreateNodeFromUrl(url, ref node) && filter.ShowFile(node.Key))
            {
                return(node);
            }

            return(null);
        }