Unless you're using a pre-specified configuration file format (e.g. TOML), then parsing configuration files requires a general parsing library. This is a non-trivial task requiring a real parser operating over a well-specified grammar. A tokenization pipeline just won't cut it.

I worked on a project a few years ago that read its custom-format config file in line by line, chopped everything off each line following the first '#' character (to support comments), and then trimmed the whitespace. This sounds like a reasonable and elegant approach until you consider that now none of your user controlled fields (via a GUI in our case) can contain the '#' character. This effected customers, but nobody ever fixed it.

With the tools and languages out there now, there's just no excuse for this crap.