class NodeAccessGrantsCacheContext

class NodeAccessGrantsCacheContext extends UserCacheContextBase implements CalculatedCacheContextInterface {
    
    /**
     * {@inheritdoc}
     */
    public static function getLabel() {
        return t("Content access view grants");
    }
    
    /**
     * {@inheritdoc}
     */
    public function getContext($operation = NULL) {
        // If the current user either can bypass node access then we don't need to
        // determine the exact node grants for the current user.
        if ($this->user
            ->hasPermission('bypass node access')) {
            return 'all';
        }
        // When no specific operation is specified, check the grants for all three
        // possible operations.
        if ($operation === NULL) {
            $result = [];
            foreach ([
                'view',
                'update',
                'delete',
            ] as $op) {
                $result[] = $this->checkNodeGrants($op);
            }
            return implode('-', $result);
        }
        else {
            return $this->checkNodeGrants($operation);
        }
    }
    
    /**
     * Checks the node grants for the given operation.
     *
     * @param string $operation
     *   The operation to check the node grants for.
     *
     * @return string
     *   The string representation of the cache context.
     */
    protected function checkNodeGrants($operation) {
        // When checking the grants for the 'view' operation and the current user
        // has a global view grant (i.e. a view grant for node ID 0) — note that
        // this is automatically the case if no node access modules exist (no
        // hook_node_grants() implementations) then we don't need to determine the
        // exact node view grants for the current user.
        if ($operation === 'view' && node_access_view_all_nodes($this->user)) {
            return 'view.all';
        }
        $grants = node_access_grants($operation, $this->user);
        $grants_context_parts = [];
        foreach ($grants as $realm => $gids) {
            $grants_context_parts[] = $realm . ':' . implode(',', $gids);
        }
        return $operation . '.' . implode(';', $grants_context_parts);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheableMetadata($operation = NULL) {
        $cacheable_metadata = new CacheableMetadata();
        if (!\Drupal::moduleHandler()->hasImplementations('node_grants')) {
            return $cacheable_metadata;
        }
        // The node grants may change if the user is updated. (The max-age is set to
        // zero below, but sites may override this cache context, and change it to a
        // non-zero value. In such cases, this cache tag is needed for correctness.)
        $cacheable_metadata->setCacheTags([
            'user:' . $this->user
                ->id(),
        ]);
        // If the site is using node grants, this cache context can not be
        // optimized.
        return $cacheable_metadata->setCacheMaxAge(0);
    }

}