TranslateTool.PoReader.ReadLine C# (CSharp) Method

        internal PoLine ReadLine()
        {
            string s = reader.ReadLine();
            if (s == null)
                return null;

            lineNumber += 1;

            s = s.Trim();
            if (s == "") {
                return new PoLine() {kind = PoLineKind.Blank};
            }
            else if (s.StartsWith("#:")) {
                s = s.Substring(2).Trim();           // Remove command part.
                string[] a = s.Split(new char[] { ' ', '\t', ',' }, 2, StringSplitOptions.RemoveEmptyEntries);
                return new PoLine() { kind = PoLineKind.LocationComment, str1 = a[0], str2 = a[1] };
            }
            else if (s.StartsWith("#")) {
                return new PoLine() { kind = PoLineKind.Comment };
            }
            else if (s.StartsWith("\"")) {
                if (!s.EndsWith("\"") || s.Length < 2)
                    PoSyntaxError();
                s = s.Substring(1, s.Length - 2);
                return new PoLine() { kind = PoLineKind.String, str1 = ConvertQuotedString(s) };
            }
            else {
                int i = 0;
                while (i < s.Length && s[i] != ' ' && s[i] != '\t')
                    ++i;
                if (i >= s.Length || i == 0)
                    PoSyntaxError();

                string keyword = s.Substring(0, i);
                s = s.Substring(i).Trim();
                if (!(s.StartsWith("\"") && s.EndsWith("\"") && s.Length > 1))
                    PoSyntaxError();
                s = s.Substring(1, s.Length - 2);
                return new PoLine() { kind = PoLineKind.KeywordString, str1 = keyword, str2 = ConvertQuotedString(s) };
            }
        }

        string DumpLines(PoReader reader)
        {
            StringWriter writer = new StringWriter();
            PoReader.PoLine line;

            while ((line = reader.ReadLine()) != null) {
                writer.Write("{0}: ", reader.lineNumber);
                switch (line.kind) {
                case PoReader.PoLineKind.Blank:
                    writer.WriteLine("blank");  break;
                case PoReader.PoLineKind.Comment:
                    writer.WriteLine("comment"); break;
                case PoReader.PoLineKind.LocationComment:
                    writer.WriteLine("location: {0},{1}", line.str1, line.str2);  break;
                case PoReader.PoLineKind.KeywordString:
                    writer.WriteLine("kw({0}): '{1}'", line.str1, line.str2); break;
                case PoReader.PoLineKind.String:
                    writer.WriteLine("str: '{0}'", line.str1); break;
                default:
                    writer.WriteLine("unknown"); break;
                }
            }

            writer.WriteLine("EOF");

            return writer.ToString();
        }