Parse the Cache-Control HTTP header into an array
private function parseCacheControlDirective() {
$this->cacheControl = array();
$tokenized = $this
->getTokenizedHeader('Cache-Control', ',') ?: array();
foreach ($tokenized as $key => $value) {
if (is_numeric($key)) {
$this->cacheControl[$value] = true;
}
else {
$this->cacheControl[$key] = $value;
}
}
}