private function determineWhichAdapterToUse($filename = null)
    {
        if (null === $filename || !is_string($filename)) {
            return;
        }

        $pieces = explode('.', $filename);
        if (1 > count($pieces)) {
            return;
        }

        $ext = '.'.$pieces[count($pieces) - 1];
        $adaptersForExt = $this->manageableExt->get($ext);
        if (!is_array($adaptersForExt) || 0 === count($adaptersForExt)) {
            return;
        }

        $adapter = $this->getRightAdapter($adaptersForExt);

        return $this->rendererAdapters->get($adapter);
    }