/**
  * Handles access restriction capability modifications from bulk-editing.
  * This is called once for each post that is included in bulk-editing.
  * The fields that are handled here are rendered through the
  * bulk_edit_custom_box() method in this class.
  * 
  * @param int $post_id
  */
 public static function save_post($post_id)
 {
     if (isset($_REQUEST['capabilities-action'])) {
         if (wp_verify_nonce($_REQUEST['bulk-post-capability-nonce'], 'post-capability')) {
             $field = Groups_Post_Access::POSTMETA_PREFIX . 'bulk-' . Groups_Post_Access::READ_POST_CAPABILITY;
             if (!empty($_REQUEST[$field]) && is_array($_REQUEST[$field])) {
                 if (Groups_Access_Meta_Boxes::user_can_restrict()) {
                     $valid_read_caps = Groups_Access_Meta_Boxes::get_valid_read_caps_for_user();
                     foreach ($_REQUEST[$field] as $capability_name) {
                         if ($capability = Groups_Capability::read_by_capability($capability_name)) {
                             if (in_array($capability->capability, $valid_read_caps)) {
                                 switch ($_REQUEST['capabilities-action']) {
                                     case 'add-capability':
                                         Groups_Post_Access::create(array('post_id' => $post_id, 'capability' => $capability->capability));
                                         break;
                                     case 'remove-capability':
                                         Groups_Post_Access::delete($post_id, $capability->capability);
                                         break;
                                 }
                             }
                         }
                     }
                 }
             }
         }
     }
 }