You're probably thinking of gperf, not flex and bison.

Oh, I remember I did a plain and simple C port of an old gperf, cgperf https://www.rocketgit.com/user/sylware/cgperf

Ofc, I did add my own bugs.

I meant flex, for generating a switch table for that type of lexer. gperf is for hashing which is different. But, there may be better methods by now since the field has changed a lot.