Not really a question, but if you ever get to the point of wondering what a good next challenging project would be, consider generalizing some of these techniques into a next generation Yacc / Bison replacement.

Something that can take generic grammer rules and turn it into a high performance parsing engine.

It wouldn't have to support every possible grammar or option. Json isn't that complex of a language, but even a limited set of grammar options in exchange for a performant parser could be of benefit for a very large set of problems.