/**
* compare 2 collections
* @return bool
*/
public function compare(abs_collection $subj)
{
$subj->rewind();
while ($item = $subj->next()) {
if (!(($tmp = $this->get_element_by_id($item->id)) && $tmp->get_data() == $item->get_data())) {
return false;
}
}
if ($subj->count() != $this->count()) {
return false;
}
// passed
return true;
}