They don't need to. You just have to tell the regex engine exactly what you want. The regex he used has no anchors - why? There's also a bunch of useless capturing parens, and in fact one paren pair that's completely superfluous. All of that is not what we wanted. I've got no Perl here, so I'll have to test this later, but I'm pretty positive that the following works as specified, and very certain that it'll perform tons better. 
/\A
    (?>  (?> [^(]* \( ) {$lvl}  )
    ( .+ )
    \) {$lvl}
\z/x;

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Makeshifts last the longest.

In reply to Re^3: Peeling the Peelings by Aristotle
in thread Peeling the Peelings by PetaMem

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