— For example, using the results of captures inside of your match or using lookahead
— All context free langs can be understood by automata
— I wrote a compiler compiler in C++ that does it :P
— You can't do infinite recursion with a DFA
— You need a stack, so it's a pushdown thing or whatever it's called
— Pushdown automaton - Wikipedia
https://en.m.wikipedia.org/wiki/Pushdown_automaton