https://github.com/warewolf/Tree-ReverseDomain test.pl

testpl.txt

www.richardharman.com 3
digg.com 2
www.digg.com 1
$tree = bless( {
                 'root' => {
                             '.' => {},
                             'com' => {
                                        'digg' => {
                                                    'www' => {
                                                               '.' => {
                                                                        'count' => 1
                                                                      }
                                                             },
                                                    '.' => {
                                                             'count' => 2
                                                           }
                                                  },
                                        'richardharman' => {
                                                             'www' => {
                                                                        '.' => {
                                                                                 'count' => 3
                                                                               }
                                                                      }
                                                           }
                                      }
                           }
               }, 'Tree::ReverseDomain' );