use Tree::DAG_Node;
use Data::Dumper;
local $Data::Dumper::Indent=1;

use strict;
use warnings;

my $t = tits( \*DATA );
#print Dumper( $t ),$/;
print Dumper( $t->tree_to_lol ), $/;
print map { "$_\n" } @{$t->draw_ascii_tree};


sub tits {
    my( $fh, $d ) = @_;

    $d ||= 2;
    
    my @t = Tree::DAG_Node->new();
    my $depth = 0;
    my @pdepth = 0;

    while(defined( $_ = readline $fh )){
        chomp;
        if(/\A((?:\s{$d})+)(.*)\z/){

            $depth = length $1;

            if( $depth > $pdepth[-1] ){
                my $newd = $t[-1]->new_daughter({ name => $2 });
                push @t, $newd;
                push @pdepth, $depth;
            }
            elsif( $depth == $pdepth[-1] ){
                $t[-1]->new_daughter({ name => $2 });
            }
            else {
                pop @t;
                pop @pdepth;
            }
        } else { # should only happen at root (depth/pdepth both 0)
            $t[0]->name($_);
        }
        $depth = $pdepth[-1];
    }
    return $t[0];
}

__DATA__
Building
  House
    Window
      Glas
        Silicium
    Door
    Roof
      Wood
  Hut
    Pizza
  Garage
    Door
[download]

$VAR1 = [
  [
    [
      [
        [
          'Silicium'
        ],
        'Glas'
      ],
      [
        'Wood'
      ],
      [
        'Pizza'
      ],
      'Window'
    ],
    [
      'Door'
    ],
    'House'
  ],
  'Building'
];

               |                
           <Building>           
               |                
            <House>             
            /---------------\   
            |               |   
        <Window>          <Door>
    /--------+-------\          
    |        |       |          
  <Glas>   <Wood> <Pizza>       
    |                           
<Silicium>
[download]

update3: seeing how i got ++ed besides this code being broken, here it is, fixed up (i also added readmore tags, made clear which update was which):

use Tree::DAG_Node;
use Data::Dumper;
local $Data::Dumper::Indent=1;

use strict;
use warnings;

my $t = tits( \*DATA );
#print Dumper( $t ),$/;
print Dumper( $t->tree_to_lol ), $/;
print map { "$_\n" } @{$t->draw_ascii_tree};


sub tits {
    my( $fh, $d ) = @_;

    $d ||= 2;
    
    my @t = Tree::DAG_Node->new();
    my $depth = 0;
    my $pdepth = 0;

    while(defined( $_ = readline $fh )){
        chomp;
        if(/\A((?:\s{$d})+)(.*)\z/){

            $depth = length($1)/$d;

            if( $depth > $pdepth ){
                push @t, $t[-1]->new_daughter({ name => $2 });
            }
            elsif( $depth == $pdepth ){
                $t[-1] = $t[-1]->mother->new_daughter({ name => $2 });
            }
            else {
                pop @t until @t == $depth;
                push @t, $t[-1]->new_daughter({ name => $2 });
            }
        } else { # should only happen at root (depth/pdepth both 0)
            $t[0]->name($_);
        }
        $pdepth = $depth;
    }
    return $t[0];
}

__DATA__
Building
  House
    Window
      Glas
        Silicium
    Door
    Roof
      Wood
  Hut
    Pizza
  Garage
    Door
[download]

$VAR1 = [
  [
    [
      [
        [
          'Silicium'
        ],
        'Glas'
      ],
      'Window'
    ],
    [
      'Door'
    ],
    [
      [
        'Wood'
      ],
      'Roof'
    ],
    'House'
  ],
  [
    [
      'Pizza'
    ],
    'Hut'
  ],
  [
    [
      'Door'
    ],
    'Garage'
  ],
  'Building'
];

                    |                    
               <Building>                
           /----------------+-------\    
           |                |       |    
        <House>           <Hut>  <Garage>
    /--------+------\       |       |    
    |        |      |    <Pizza>  <Door> 
 <Window>  <Door> <Roof>                 
    |               |                    
  <Glas>          <Wood>                 
    |                                    
<Silicium>