;p;one
;greybox_start;
;h2;two
;greybox_end;
;p;three

##</code><code>##

$VAR1 = [
  ['div',{'id' => 'article'},
    ['p','one'],
    ['div',{'class' => 'greybox'},
      ['h2','two'],
    ],
    ['p','three']
  ]
];

##</code><code>##

$VAR1 = [
  ['div',{'id' => 'article'},
    ['p','one'],
    ['div',{'class' => 'greybox'}],
    ['h2','two'],
    ['p','three']
  ]
];

##</code><code>##

#!/usr/local/bin/perl

use strict;
use warnings;

use Data::Dumper;
$Data::Dumper::Indent = 1;

my @lines = <DATA>;
chomp @lines;

my @list = ([q{div}, {id => q{article}}]);
my (@current_list);
my $depth = 0;

for my $line (@lines){
  my ($tag, $txt) = $line =~ /^;([^;]+);(.*)/;
  
  if ($tag eq q{greybox_start}){
    push @{$list[$depth]}, @current_list;
    push @{$list[$depth]}, [q{div}, {class => q{greybox}}];
    $depth++;
    @current_list = ();
    next;
  }
  elsif ($tag eq q{greybox_end}){
    $depth--;
    push @{$list[$depth]}, @current_list;
    @current_list = ();
    next;
  }
  
  push @current_list, [$tag, $txt];
  
}
push @{$list[$depth]}, @current_list;

print Dumper(\@list),

__DATA__
;p;one
;greybox_start;
;h2;two
;greybox_end;
;p;three