private void parseLine(string line, ParsingContext context, IDocumentTemplate template)
        {
            bool anyTokenProcessed = false;

            // section token and option token should never be on the same line.
            // so at most one of following tokens can be encountered
            if (_tokenParser.TryParseSection(line, context.CurrentLineIndex, out SectionToken sectionToken))
            {
                context.AddSection(sectionToken);
                var lengthOfToken = sectionToken.StartIndex + sectionToken.Lenght;
                line = line.Substring(lengthOfToken);
                anyTokenProcessed = true;
            }

            else if (_tokenParser.TryParseOption(line, context.CurrentLineIndex, out OptionToken optionToken))
            {
                OptionParser.processOptionToken(context, template, optionToken);

                var lengthOfToken = optionToken.StartIndex + optionToken.Length;
                line = line.Substring(lengthOfToken);
                anyTokenProcessed = true;
            }

            // comment can be on the same line
            // since the parser is line oriented. This case must be handled separately
            if (_tokenParser.TryParseComment(line, context.CurrentLineIndex, out CommentToken commentToken))
            {
                context.AddComment(commentToken, anyTokenProcessed);
                line = "";
            }

            line = line.Trim();
            if (!string.IsNullOrEmpty(line))
            {
                throw new FormatException($"line #{context.CurrentLineIndex} contains " +
                                           $"text that could not be parsed \"{line}\" ");
            }
        }