class OptionsAllowedValues

class OptionsAllowedValues implements OptionsAllowedValuesInterface {
  
  /**
   * Cache tag set on all cached allowed values.
   */
  const CACHE_TAG = 'options_allowed_values';
  public function __construct(#[Autowire(service: 'cache.memory')] protected CacheBackendInterface $cache) {
  }
  
  /**
   * {@inheritdoc}
   */
  public function getAllowedValues(FieldStorageDefinitionInterface $definition, ?FieldableEntityInterface $entity = NULL) : array {
    $cid = $this->getCid([
      $definition->getTargetEntityTypeId(),
      $definition->getName(),
      $entity ? 'entity' : 'any',
    ]);
    if ($cache = $this->cache
      ->get($cid)) {
      return $cache->data;
    }
    $callback = $definition->getSetting('allowed_values_function');
    // If $cacheable is FALSE, then the allowed values are not cached.
    // \Drupal\options_test\OptionsAllowedValues::dynamicValues() offers an
    // example of generating dynamic and uncached values.
    // @see \Drupal\options_test\OptionsAllowedValues::dynamicValues()
    $cacheable = TRUE;
    if (!empty($callback) && is_callable($callback)) {
      $allowedValues = $callback($definition, $entity, $cacheable);
    }
    else {
      $allowedValues = $definition->getSetting('allowed_values') ?? [];
    }
    if ($cacheable) {
      $tags = Cache::mergeTags($definition->getCacheTags(), [
        static::CACHE_TAG,
      ]);
      $this->cache
        ->set($cid, $allowedValues, CacheBackendInterface::CACHE_PERMANENT, $tags);
    }
    return $allowedValues;
  }
  
  /**
   * Returns the CID used to cache the options allowed values.
   *
   * @param array $path
   *   The parts identifying the allowed values: the target entity type ID,
   *   the field name and whether an entity is available.
   *
   * @return string
   *   The cache ID.
   */
  protected function getCid(array $path) : string {
    return 'options.allowed_values:' . implode(':', $path);
  }

}