Yours is far more complicated than what I did here. This is a translation of Cox's C program for a Thompson NFA simulation. Look at the source. It's only a few hundred lines. And the README should reveal that these are certainly not production ready programs. :-)

Oh yeah. I started with Rus's (amazingly demystifying) blog posts and then got a bit carried away and ended up atleast covering a good chunk of the js regex test suite. The wonders of not having to work on someone else's schedule!

By the way I loved what you did and all your work around making the regex engine exposed as a "configurable" API (I was going by one of your previous posts)!! My only regret is not doing this in Rust as I got a bit scared of the learning curve!