The "circular references", or, as they're more commonly known, "recursive definitions", are precisely what differentiates a grammar from a flat, regular pattern, and the thing Perl's regex-engine can't properly handle, making a parser like Parse::RecDescent useful.

In reply to Re^3: Parse RecDescent Nesting (Followup) by bart
in thread Parse RecDescent Nesting (Followup) by tphyahoo

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