Regex literals optimization (or how to cheat on benchmarks)

How does it eg googles re2?<p>I remember a neat feature of re2 was you could give it a bunch of regex, and get it to check for all of them at the same time. Made all the difference in an early spam filter I built.

How does nim-regex implement capture groups and zero-width assertions (like \b)? Both of those are tricky with DFAs.