I'm taking the liberty to shamelessly mention my recent project here, as this seems the appropriate thread to do so: NPeg is a PEG-style parser generator which allows free mixing of grammar and Nim code, which should be suitable for the task of lexing and parsing.
It can collect simple string captures, complex captures as a JSON tree, or run arbitrary Nim code at match time. NPeg is available in nimble, the manual and project page are at [https://github.com/zevv/npeg](https://github.com/zevv/npeg)
