Oh Jeeze I didn't even think about those kinds of cases...

For what I need I believe that as it checks each expression for validity (i'm interpreting lisp-like expressions) before it runs should rule that out. E.G. )+ <item1> <item2>)(( won't work because (in theory) )+ doesn't match up.

Because you posted that, however I'm definitely posting up links to a repo/cpan module I make of this so those interested can stress-test what I make.