System.Net.Http.Headers.ViaHeaderValue.GetViaLength C# (CSharp) Метод

        internal static int GetViaLength(string input, int startIndex, out object parsedValue)
        {
            Debug.Assert(startIndex >= 0);

            parsedValue = null;

            if (string.IsNullOrEmpty(input) || (startIndex >= input.Length))
            {
                return 0;
            }

            // Read <protocolName> and <protocolVersion> in '[<protocolName>/]<protocolVersion> <receivedBy> [<comment>]'
            string protocolName = null;
            string protocolVersion = null;
            int current = GetProtocolEndIndex(input, startIndex, out protocolName, out protocolVersion);

            // If we reached the end of the string after reading protocolName/Version we return (we expect at least
            // <receivedBy> to follow). If reading protocolName/Version read 0 bytes, we return. 
            if ((current == startIndex) || (current == input.Length))
            {
                return 0;
            }
            Debug.Assert(protocolVersion != null);

            // Read <receivedBy> in '[<protocolName>/]<protocolVersion> <receivedBy> [<comment>]'
            string receivedBy = null;
            int receivedByLength = HttpRuleParser.GetHostLength(input, current, true, out receivedBy);

            if (receivedByLength == 0)
            {
                return 0;
            }

            current = current + receivedByLength;
            current = current + HttpRuleParser.GetWhitespaceLength(input, current);

            string comment = null;
            if ((current < input.Length) && (input[current] == '('))
            {
                // We have a <comment> in '[<protocolName>/]<protocolVersion> <receivedBy> [<comment>]'
                int commentLength = 0;
                if (HttpRuleParser.GetCommentLength(input, current, out commentLength) != HttpParseResult.Parsed)
                {
                    return 0; // We found a '(' character but it wasn't a valid comment. Abort.
                }

                comment = input.Substring(current, commentLength);

                current = current + commentLength;
                current = current + HttpRuleParser.GetWhitespaceLength(input, current);
            }

            ViaHeaderValue result = new ViaHeaderValue();
            result._protocolVersion = protocolVersion;
            result._protocolName = protocolName;
            result._receivedBy = receivedBy;
            result._comment = comment;

            parsedValue = result;
            return current - startIndex;
        }