public function parse($content, StylesheetConstraint $stylesheetConstraint = null)
    {
        if($stylesheetConstraint !== null)
        {
            $this->setStylesheetConstraint($stylesheetConstraint);
        }

        $pageCollection = parent::parse($content);
        
        $this->fireOnEndParsing($pageCollection);

        $this->initialize();

        return $pageCollection;
    }