/**
  * Helper method for filtering out blacklisted categories from provided list of categories
  *
  * @author macbre
  */
 public static function filterOutBlacklistedCategories($categories)
 {
     wfProfileIn(__METHOD__);
     $service = new self();
     foreach ($categories as &$category) {
         if ($service->isCategoryBlacklisted($category)) {
             $category = false;
         }
     }
     // remove "false" entries and recalculate numeric keys
     $categories = array_values(array_filter($categories));
     wfProfileOut(__METHOD__);
     return $categories;
 }