my $extractor;    # Must be a seperate statement.
$extractor = qr/
   \[\[
   (?:
      (?:  (?! \[\[ | \]\] ) .  )+
   |
      (??{ $extractor })
   )+
   \]\]
/x;

my @links = $text =~ /$extractor/g;

##</code><code>##

my $extractor;    # Must be a seperate statement.
$extractor = qr/
   \[\[
   (?> (?:
      (?:
         (?> [^\[\]]+ )
      |
         \[ (?! \[ )
      |
         \] (?! \] )
      )
   |
      (??{ $extractor })
   )+ )
   \]\]
/x;

my @links = $text =~ /$extractor/g;