Piwik\Segment::isEmpty PHP Method

    public function isEmpty()
    {
        return $this->segmentExpression->isEmpty();
    }

 public static function shouldProcessReportsAllPlugins(array $idSites, Segment $segment, $periodLabel)
 {
     if ($segment->isEmpty() && $periodLabel != 'range') {
         return true;
     }
     return self::isSegmentPreProcessed($idSites, $segment);
 }