use strict;
use warnings;

my @toTest =
(
   q{Cont(ains balanced( nested Br(ack)ets )in t)he text},
   q{Con(tains i(mbalan(ced Br(ack)ets, )one c)lose missing},
   q{Contains i(mbalan(ced Br(ack)ets, )one op)en m)missing},
   q{No brackets in this string},
   q{Won)ky br(ackets in) this s(tring},
   q{More wonky br(ackets in) th)is s(tring},
   q{Just the one( leading bracket},
   q{And just th)e one trailing bracket},
   q{So(me m(ultip)le n(est(s in) thi)s o)ne},
   q{Ther(e is( mo(re) de(e)p )nes(ti(n(g i)n (mul)ti)p(l)es) he)re},
   q{Th(er(e is( mo(re) de(e)p )nes(ti(n(g i)n (mul)ti)p(l)es) he)re},
   q{Ther(e is( mo(re) de(e)p )nes(ti(n(g i)n (mul)ti)p(l)es) he)r)e},
   q{Ther(e is( mo(re) de(e)p )n(es(ti(n(g i)n (mul)ti)p(l)es) he)re},
   q{Some d((oub)le b)rackets},
   q{(Some d((oub)le b)rackets)},
   q{ab(())cde},
   q{ab(c(d)e},
   q{ab(c)d)e},
   q{ab(c)de},
);

my @memoList;
my $rxNest;
$rxNest = qr
{(?x)
   (
      \(
      [^()]*
      (?:
         (??{$rxNest})
         [^()]*
      )*
      \)
   )
   (?{ [ @{$^R}, $^N ] })
};

my $rxOnlyNested;
{
    use re q(eval);
    $rxOnlyNested = qr
    {(?x)
       (?{ [] })
       ^
       [^()]*
       (?:
          $rxNest
          [^()]*
       )+
       \z
       (?{ @memoList = @{$^R} })
    };
}

testString($_) for @toTest;

sub testString
{
    my $string = shift;
    @memoList = ();
    print qq{\nString: $string\n};
    if($string =~ /$rxOnlyNested/)
    {
        print qq{     Match succeeded\n};
        print qq{     ---------------\n};
        print qq{     Before brackets:-\n};
        print qq{       -->@{[substr $string, 0, $-[1]]}<--\n};
        print qq{     Bracket pairs:-\n};
        print qq{          $_\n} for @memoList;
        print qq{     After brackets:-\n};
        print qq{       -->@{[substr $string, $+[1]]}<--\n};
    }
    else
    {
        print qq{     Match failed\n};
    }
}