Google.SafeBrowsing.API.ParseListData C# (CSharp) Method

        private ListData ParseListData(Stream stream)
        {
            var listData = new ListData();

            var redirects = new List<string>();
            Regex regex = new Regex(@"^(e|r|n|i|u|sd|ad)\:(.+)$");
            Match match = null;
            string line = null, type = null, value = null;
            int state = 0xA;
            bool error = false;
            var sr = new StreamReader(stream);

            //simple state machine
            while (!sr.EndOfStream)
            {
                line = sr.ReadLine();
                match = regex.Match(line);

                if (!match.Success)
                    continue;   //client must ignore lines it does not understand

                type = match.Groups[1].Value;
                value = match.Groups[2].Value;

                switch (type)
                {
                    case "n"://n: xxxx   delay in seconds before poling again
                        if (state != 0xA)
                        {
                            error = true;
                            break;
                        }
                        //delay gets ignored at the moment
                        state = 0xB;
                        break;
                    case "e":
                        if (state != 0xA)
                        {
                            error = true;
                            break;
                        }
                        //error gets ignored at the moment
                        break;
                    case "r":
                        if (state != 0xB)
                        {
                            error = true;
                            break;
                        }
                        //reset signal gets ignored at the moment
                        break;
                    case "i":   //i:xxxx   list name
                        //list name is ignored
                        state = 0xB;
                        break;
                    case "u":   //u:xxxx   redirect url
                        if (state != 0xB)
                        {
                            error = true;
                            break;
                        }
                        redirects.Add(value);
                        break;
                    case "sd":  //sd:x-y,z
                        if (state != 0xB)
                        {
                            error = true;
                            break;
                        }
                        listData.BlacklistDelete = ParseIntervals(value.Split(':').LastOrDefault());
                        break;
                    case "ad":  //ad:x-y,z
                        if (state != 0xB)
                        {
                            error = true;
                            break;
                        }
                        listData.WhitelistDelete = ParseIntervals(value.Split(':').LastOrDefault());
                        break;
                }

                if (error)
                    throw new Exception("Unable to parse data");
            }

            listData.Redirects = redirects;
            return listData;
        }