protected function parseListOfIcons()
    {
        $cache = $this->cacheManager->getCache('Default');
        $cacheId = 'FontIconDataSource_parseListOfIcons';

        if (!($icons = $cache->get($cacheId))) {
            $icons = [];
            foreach (file(self::$iconsListFilePath) as $content) {
                if (preg_match('#fa-var-([-_a-z0-9]+):#i', $content, $match)) {
                    $icons[] = $match[1];
                }
            }

            $cache->set($cacheId, $icons, [], 0);
        }

        return $icons;
    }