System.Web.WebPages.WebPageRoute.MatchRequest C# (CSharp) Method

        internal static WebPageMatch MatchRequest(string pathValue, string[] supportedExtensions, Func<string, bool> virtualPathExists, HttpContextBase context, DisplayModeProvider displayModes)
        {
            string currentLevel = String.Empty;
            string currentPathInfo = pathValue;

            // We can skip the file exists check and normal lookup for empty paths, but we still need to look for default pages
            if (!String.IsNullOrEmpty(pathValue))
            {
                // If the file exists and its not a supported extension, let the request go through
                if (FileExists(pathValue, virtualPathExists))
                {
                    // TODO: Look into switching to RawURL to eliminate the need for this issue
                    bool foundSupportedExtension = false;
                    for (int i = 0; i < supportedExtensions.Length; i++)
                    {
                        string supportedExtension = supportedExtensions[i];
                        if (PathHelpers.EndsWithExtension(pathValue, supportedExtension))
                        {
                            foundSupportedExtension = true;
                            break;
                        }
                    }

                    if (!foundSupportedExtension)
                    {
                        return null;
                    }
                }

                // For each trimmed part of the path try to add a known extension and
                // check if it matches a file in the application.
                currentLevel = pathValue;
                currentPathInfo = String.Empty;
                while (true)
                {
                    // Does the current route level patch any supported extension?
                    string routeLevelMatch = GetRouteLevelMatch(currentLevel, supportedExtensions, virtualPathExists, context, displayModes);
                    if (routeLevelMatch != null)
                    {
                        return new WebPageMatch(routeLevelMatch, currentPathInfo);
                    }

                    // Try to remove the last path segment (e.g. go from /foo/bar to /foo)
                    int indexOfLastSlash = currentLevel.LastIndexOf('/');
                    if (indexOfLastSlash == -1)
                    {
                        // If there are no more slashes, we're done
                        break;
                    }
                    else
                    {
                        // Chop off the last path segment to get to the next one
                        currentLevel = currentLevel.Substring(0, indexOfLastSlash);

                        // And save the path info in case there is a match
                        currentPathInfo = pathValue.Substring(indexOfLastSlash + 1);
                    }
                }
            }

            return MatchDefaultFiles(pathValue, supportedExtensions, virtualPathExists, context, displayModes, currentLevel);
        }