Boost.Spirit https://www.boost.org/library/latest/spirit/ Boost.Parser https://www.boost.org/library/latest/parser/ (which I think succeeds Boost.Spirit Boost.Metaparse: https://www.boost.org/doc/libs/latest/doc/html/metaparse.htm...
All of these allow you to build a parser using C++ syntax and then add semantic or composed actions.