Yet more proof that anyone who uses regular expressions to attempt to parse a context-free grammar is in a state of sin. Balanced parentheses form a context-fr

Yet more proof that anyone who uses regular expressions to attempt to parse a context-free grammar is in a state of sin. Balanced parentheses form a context-free grammar, and thus cannot be parsed by regular expressions. There are extensions to regexps which make them irregular — and hence capable of parsing CFGs — but they often lead to poor performance, as here.