$regex = '^(.*)(?(?{my$x=substr$1,9,-4;$1ne"^(.*)(?(?{$x}))\\z"}))\z';

##</code><code>##

$test  = '^(.*)(?(?{my$japhy;my$x=substr$1,9,-4;$1ne"^(.*)(??{$x}))\\z"}))\z';