private function guardGlobPattern()
    {
        $invalidGlobPattern = false;

        if (substr($this->globPattern, 0) !== '{'
            && (substr($this->globPattern, -1) !== '}' && substr($this->globPattern, -2) !== '}*')) {
            $invalidGlobPattern = true;
        }

        $bracesContent = trim(substr($this->globPattern, 1, -1));

        if (empty($bracesContent)) {
            $invalidGlobPattern = true;
        }

        $globPatterns = explode(',', $bracesContent);

        if (count($globPatterns) == 1) {
            $invalidGlobPattern = true;
        }

        if ($invalidGlobPattern === true) {
            throw new InvalidGlobPattern;
        }
    }