Wow, I have no idea what regexps mean? I can write a book about regexps, and if you really want to learn what regexps are, let me know, we can scedule a session

Wow, I have no idea what regexps mean? I can write a book about regexps, and if you really want to learn what regexps are, let me know, we can scedule a session. Anyway, real REGUALR expressions belong to the regular languages class, thus equivalent to DFAs. Given a regexp, you can construct a DFA in O(2^n), where n is the number of operators in the regexp. Now this DFA will have a Linear time complexity match. If you extend regular expressions with backreferences, you can't build DFAs anymore, and you also lose the fundamental property of regularity: the pumping lemma for regular languages. Furthermore, the languages you can build with this extension go even outside the context-free class. Not only that: you are also dealing with an NP-complete matching. Again, why do you still call them regular?