#!/usr/bin/perl
#
use strict;
use warnings;

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

our $rxNest;
$rxNest = qr
   {(?x)
       \(
       (?:
           (?>[^()]+)
       |
           (??{$rxNest})
       )*
       \)
   };

testString($_) for @toTest;

sub testString
{
    my $string = shift;
    print "\n$string\n";
    print "     Match ", $string =~ /$rxNest/ ?
       "succeeded\n" :
       "failed\n";
}

##</code><code>##

Cont(ains balanced( nested Br(ack)ets )in t)he text
     Match succeeded

Con(tains i(mbalan(ced Br(ack)ets, )one c)lose missing
     Match succeeded

Contains i(mbalan(ced Br(ack)ets, )one op)en m)missing
     Match succeeded

No brackets in this string
     Match failed

Won)ky br(ackets in) this s(tring
     Match succeeded

More wonky br(ackets in) th)is s(tring
     Match succeeded

Just the one( leading bracket
     Match failed

And just th)e one trailing bracket
     Match failed

So(me m(ultip)le n(est(s in) thi)s o)ne
     Match succeeded

Ther(e is( mo(re) de(e)p )nes(ti(n(g i)n (mul)ti)p(l)es) he)re
     Match succeeded

Some d((oub)le b)rackets
     Match succeeded

ab(())cde
     Match succeeded

ab(c(d)e
     Match succeeded

ab(c)d)e
     Match succeeded

##</code><code>##

...
our $rxNest;
$rxNest = qr
   {(?x)
       (
       \(
       (?:
           (?>[^()]+)
       |
           (??{$rxNest})
       )*
       \)
       )
   };
...

##</code><code>##

...
    if($string =~ /$rxNest/)
    {
        no strict 'refs';
        print "     Match succeeded\n";
        my $memNo = 1;
        while(defined ${$memNo})
        {
            print "     \$$memNo - ${$memNo}\n";
            $memNo ++;
        }
    }
    else
    {
        print "     Match failed\n";
    }
...

##</code><code>##

...
our @memoList;
our $rxNest;
$rxNest = qr
   {(?x)
       (
       \(
       (?:
           (?>[^()]+)
       |
           (??{$rxNest})
       )*
       \)
       )
       (?{push @memoList, $+})
...
    if($string =~ /$rxNest/)
    {
        print "     Match succeeded\n";
        print "     $_\n" for @memoList;
    }
    else
    {
        print "     Match failed\n";
    }
...

##</code><code>##

Cont(ains balanced( nested Br(ack)ets )in t)he text
     Match succeeded
     (ack)
     ( nested Br(ack)ets )
     (ains balanced( nested Br(ack)ets )in t)

##</code><code>##

Con(tains i(mbalan(ced Br(ack)ets, )one c)lose missing
     Match succeeded
     (ack)
     (ced Br(ack)ets, )
     (mbalan(ced Br(ack)ets, )one c)
     (ack)
     (ced Br(ack)ets, )
     (mbalan(ced Br(ack)ets, )one c)

##</code><code>##

#!/usr/bin/perl
#
use strict;
use warnings;

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

our @memoList;

our ($rxBefore, $rxNest, $rxAfter, $rxWhole);
$rxBefore = $rxAfter = qr{([^()]*)};
$rxNest = qr
   {(?x)
       (
       \(
       (?:
	   (?>[^()]+)
       |
	   (??{$rxNest})
       )*
       \)
       )
       (?{push @memoList, $+})
   };
$rxWhole = qr{^$rxBefore$rxNest$rxAfter$};

testString($_) for @toTest;

sub testString
{
    my $string = shift;
    @memoList = ();
    print "\nString: $string\n";
    if($string =~ /$rxWhole/)
    {
        print "     Match succeeded\n";
        print "     ---------------\n";
        print "     Before brackets:-\n";
        print "          $1\n";
        print "     Bracket pairs:-\n";
        print "          $_\n" for @memoList;
        print "     After brackets:-\n";
        print "          $3\n";
    }
    else
    {
        print "     Match failed\n";
    }
}

##</code><code>##

String: Cont(ains balanced( nested Br(ack)ets )in t)he text
     Match succeeded
     ---------------
     Before brackets:-
          Cont
     Bracket pairs:-
          (ack)
          ( nested Br(ack)ets )
          (ains balanced( nested Br(ack)ets )in t)
     After brackets:-
          he text

String: Con(tains i(mbalan(ced Br(ack)ets, )one c)lose missing
     Match failed

String: Contains i(mbalan(ced Br(ack)ets, )one op)en m)missing
     Match failed

String: No brackets in this string
     Match failed

String: Won)ky br(ackets in) this s(tring
     Match failed

String: More wonky br(ackets in) th)is s(tring
     Match failed

String: Just the one( leading bracket
     Match failed

String: And just th)e one trailing bracket
     Match failed

String: So(me m(ultip)le n(est(s in) thi)s o)ne
     Match succeeded
     ---------------
     Before brackets:-
          So
     Bracket pairs:-
          (ultip)
          (s in)
          (est(s in) thi)
          (me m(ultip)le n(est(s in) thi)s o)
     After brackets:-
          ne

String: Ther(e is( mo(re) de(e)p )nes(ti(n(g i)n (mul)ti)p(l)es) he)re
     Match succeeded
     ---------------
     Before brackets:-
          Ther
     Bracket pairs:-
          (re)
          (e)
          ( mo(re) de(e)p )
          (g i)
          (mul)

          (n(g i)n (mul)ti)
          (l)
          (ti(n(g i)n (mul)ti)p(l)es)
          (e is( mo(re) de(e)p )nes(ti(n(g i)n (mul)ti)p(l)es) he)
     After brackets:-
          re

String: Some d((oub)le b)rackets
     Match succeeded
     ---------------
     Before brackets:-
          Some d
     Bracket pairs:-
          (oub)
          ((oub)le b)
     After brackets:-
          rackets

String: ab(())cde
     Match succeeded
     ---------------
     Before brackets:-
          ab
     Bracket pairs:-
          ()
          (())
     After brackets:-
          cde

String: ab(c(d)e
     Match failed

String: ab(c)d)e
     Match failed

##</code><code>##

#!/usr/bin/perl
#
use strict;
use warnings;

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

our @memoList;

our $rxNest;
$rxNest = qr
   {(?x)
       ^
       ([^()]*)
       (
       \(
       (?:
           (?>[^()]+)
       |
           (??{$rxNest})
       )*
       \)
       )
       (?{push @memoList, $+})
       ([^()]*)
       $
   };

testString($_) for @toTest;

sub testString
{
    my $string = shift;
    @memoList = ();
    print "\nString: $string\n";
    if($string =~ /$rxNest/)
    {
        print "     Match succeeded\n";
        print "     ---------------\n";
        print "     Before brackets:-\n";
        print "          $1\n";
        print "     Bracket pairs:-\n";
        print "          $_\n" for @memoList;
        print "     After brackets:-\n";
        print "          $3\n";
    }
    else
    {
        print "     Match failed\n";
    }
}

##</code><code>##

String: Cont(ains balanced( nested Br(ack)ets )in t)he text
     Match failed

String: Con(tains i(mbalan(ced Br(ack)ets, )one c)lose missing
     Match failed

String: Contains i(mbalan(ced Br(ack)ets, )one op)en m)missing
     Match failed

String: No brackets in this string
     Match failed

String: Won)ky br(ackets in) this s(tring
     Match failed

String: More wonky br(ackets in) th)is s(tring
     Match failed

String: Just the one( leading bracket
     Match failed

String: And just th)e one trailing bracket
     Match failed

String: So(me m(ultip)le n(est(s in) thi)s o)ne
     Match failed

String: Ther(e is( mo(re) de(e)p )nes(ti(n(g i)n (mul)ti)p(l)es) he)re
     Match failed

String: Some d((oub)le b)rackets
     Match failed

String: ab(())cde
     Match failed

String: ab(c(d)e
     Match failed

String: ab(c)d)e
     Match failed