sub analyze {
  my $htree = shift;
  my $rul   = shift;
  my $hist  = (split /\n/, $htree->data)[0];
  my $str   = (split /\|/, $hist)[0];
  my ($k, $v);

  $hist = "|$hist";

  while(($k,$v) = each %$rul) {
    my @out = @{&proccode($str,$v)};

    for my $h (@out) {
      if($hist !~ /\|$h\|/) {
	my $new = $htree->append("$h$hist\n$k");
	&analyze($new,$rul);
	# PROBLEM: the @out loop is iterated again
	# even a 'next' does not force it to increment/end
      }
    }
  }
}

##</code><code>##

...
  my @rules = keys %$rul;

  for my $k (@rules) {
    my @out = @{&proccode($str,$$rul{$k})};
...