On Sat, Oct 26, 2019 at 3:17 PM Dejan Milosavljevic via Std-Proposals <std-proposals@lists.isocpp.org> wrote:

1. Point of proposal is Lex it self. This is one of possible implementation.
2. Open question: is there regex_search complexity guarantee?
3. Next step should be something like `yacc`. Covering Type-2 or
Type-3 grammars will be very helpful.

And as usual allow small inconsistency and incompleteness.

Document: https://github.com/dmilos/cpp_proposal/blob/master/lex.md

Received. I assume nobody's responding because it's not a very widely interesting proposal, and doesn't have any motivation.
It sounds like you're describing a library that you could implement yourself and put on GitHub, where anyone could use it regardless of standardization. Have you tried implementing it? Is the implementation useful to you? Is the implementation useful to others?