System.Uri.CreateHelper C# (CSharp) Method

        internal static Uri CreateHelper(string uriString, bool dontEscape, UriKind uriKind, ref UriFormatException e)
        {
            // if (!Enum.IsDefined(typeof(UriKind), uriKind)) -- We currently believe that Enum.IsDefined() is too slow 
            // to be used here.
            if ((int)uriKind < (int)UriKind.RelativeOrAbsolute || (int)uriKind > (int)UriKind.Relative)
            {
                throw new ArgumentException(SR.Format(SR.net_uri_InvalidUriKind, uriKind));
            }

            UriParser syntax = null;
            Flags flags = Flags.Zero;
            ParsingError err = ParseScheme(uriString, ref flags, ref syntax);

            if (dontEscape)
                flags |= Flags.UserEscaped;

            // We won't use User factory for these errors
            if (err != ParsingError.None)
            {
                // If it looks as a relative Uri, custom factory is ignored
                if (uriKind != UriKind.Absolute && err <= ParsingError.LastRelativeUriOkErrIndex)
                    return new Uri((flags & Flags.UserEscaped), null, uriString);

                return null;
            }

            // Cannot be relative Uri if came here
            Uri result = new Uri(flags, syntax, uriString);

            // Validate instance using ether built in or a user Parser
            try
            {
                result.InitializeUri(err, uriKind, out e);

                if (e == null)
                    return result;

                return null;
            }
            catch (UriFormatException ee)
            {
                Debug.Assert(!syntax.IsSimple, "A UriPraser threw on InitializeAndValidate.");
                e = ee;
                // A precaution since custom Parser should never throw in this case.
                return null;
            }
        }