class AuthenticationCollector

class AuthenticationCollector implements AuthenticationCollectorInterface {
    
    /**
     * Array of all registered authentication providers, keyed by ID.
     *
     * @var \Drupal\Core\Authentication\AuthenticationProviderInterface[]
     */
    protected $providers;
    
    /**
     * Array of all providers and their priority.
     *
     * @var array
     */
    protected $providerOrders = [];
    
    /**
     * Sorted list of registered providers.
     *
     * @var \Drupal\Core\Authentication\AuthenticationProviderInterface[]
     */
    protected $sortedProviders;
    
    /**
     * List of providers which are allowed on routes with no _auth option.
     *
     * @var string[]
     */
    protected $globalProviders;
    
    /**
     * {@inheritdoc}
     */
    public function addProvider(AuthenticationProviderInterface $provider, $provider_id, $priority = 0, $global = FALSE) {
        $this->providers[$provider_id] = $provider;
        $this->providerOrders[$priority][$provider_id] = $provider;
        // Force the providers to be re-sorted.
        $this->sortedProviders = NULL;
        if ($global) {
            $this->globalProviders[$provider_id] = TRUE;
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function isGlobal($provider_id) {
        return isset($this->globalProviders[$provider_id]);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getProvider($provider_id) {
        return $this->providers[$provider_id] ?? NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getSortedProviders() {
        if (!isset($this->sortedProviders)) {
            // Sort the providers according to priority.
            krsort($this->providerOrders);
            // Merge nested providers from $this->providers into $this->sortedProviders.
            $this->sortedProviders = array_merge(...$this->providerOrders);
        }
        return $this->sortedProviders;
    }

}