The true power of regular expressions (2012)

[kogens]

https://www.npopov.com/2012/06/15/The-true-power-of-regular-expressions.html

[precompute]

This is a great article.

I recently tried converting Org-mode files to html with sed and hit a block pretty soon -- sed's extended regex doesn't account for newline characters. That led to me abandoning the project, because even though I had it down 90%, I couldn't make code blocks free from being interpreted as regular org syntax. With PCRE it would have been much easier.

[invpix]

Great article! Ah someone else also read it through...

"Matching of regular expressions is NP-complete. As such you can solve any other NP problem using regular expressions."

Would love to see that be the mechanism of that proof.

[ktpsns]

This is a really nice article.

tl,dr: Regexp with backrefs can "solve" NP-hard problems and thus theoretically can parse HTML, but in practice they are not the right tool to do so.