System.Net.Http.Headers.WarningHeaderValue.TryReadDate C# (CSharp) Метод

        private static bool TryReadDate(string input, ref int current, out DateTimeOffset? date)
        {
            date = null;

            // Make sure we have at least one whitespace between <text> and <date> (if we have <date>)
            int whitespaceLength = HttpRuleParser.GetWhitespaceLength(input, current);
            current = current + whitespaceLength;

            // Read <date> in '<code> <agent> <text> ["<date>"]'
            if ((current < input.Length) && (input[current] == '"'))
            {
                if (whitespaceLength == 0)
                {
                    return false; // we have characters after <text> but they were not separated by a whitespace
                }

                current++; // skip opening '"'

                // Find the closing '"'
                int dateStartIndex = current;
                while (current < input.Length)
                {
                    if (input[current] == '"')
                    {
                        break;
                    }
                    current++;
                }

                if ((current == input.Length) || (current == dateStartIndex))
                {
                    return false; // we couldn't find the closing '"' or we have an empty quoted string.
                }

                DateTimeOffset temp;
                if (!HttpRuleParser.TryStringToDate(input.Substring(dateStartIndex, current - dateStartIndex), out temp))
                {
                    return false;
                }

                date = temp;

                current++; // skip closing '"'
                current = current + HttpRuleParser.GetWhitespaceLength(input, current);
            }

            return true;
        }