[senkora]

Regular expressions can only parse regular languages. More powerful parser techniques can parse context-free languages or even recursively enumerable languages. These are fundamentally distinct levels of complexity.

It is fundamentally impossible to correctly parse e.g. HTML with regular expressions. See: https://stackoverflow.com/a/1732454

[rob74]

Ah yes, the classic StackOverflow answer. If that doesn't teach you not to parse HTML with regex, nothing will...