Backrefs are nonregular. I believe lookaround by itself is not a problem -- it's essentially intersection, which is regular (though often omitted from regex eng

Backrefs are nonregular. I believe lookaround by itself is not a problem -- it's essentially intersection, which is regular (though often omitted from regex engines). Yeah, here's a reference: https://cs.stackexchange.com/questions/2557/how-to-simulate-backreferences-lookaheads-and-lookbehinds-in-finite-state-auto https://cs.stackexchange.com/questions/2557/how-to-simulate-...