Propriety requires that someone point out that any "regular expression" permitting recursion is not, in fact, a regular expression in the formal sense. Luckily

Propriety requires that someone point out that any "regular expression" permitting recursion is not, in fact, a regular expression in the formal sense. Luckily for anybody wanting to do it anyway, parsing expression grammars can handle that sort of thing with theoretical aplomb: http://en.wikipedia.org/wiki/Parsing_expression_grammar http://en.wikipedia.org/wiki/Parsing_expression_grammar