class ProcessField

class ProcessField extends ProcessPluginBase implements ContainerFactoryPluginInterface {
    
    /**
     * The field plugin manager.
     *
     * @var \Drupal\migrate_drupal\Plugin\MigrateFieldPluginManagerInterface
     */
    protected $fieldPluginManager;
    
    /**
     * The migration being run.
     *
     * @var \Drupal\migrate\Plugin\MigrationInterface
     */
    protected $migration;
    
    /**
     * Constructs a ProcessField plugin.
     *
     * @param array $configuration
     *   The plugin configuration.
     * @param string $plugin_id
     *   The plugin ID.
     * @param mixed $plugin_definition
     *   The plugin definition.
     * @param \Drupal\migrate_drupal\Plugin\MigrateFieldPluginManagerInterface $field_plugin_manager
     *   The field plugin manager.
     * @param \Drupal\migrate\Plugin\MigrationInterface $migration
     *   The migration being run.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrateFieldPluginManagerInterface $field_plugin_manager, MigrationInterface $migration = NULL) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->fieldPluginManager = $field_plugin_manager;
        $this->migration = $migration;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('plugin.manager.migrate.field'), $migration);
    }
    
    /**
     * {@inheritdoc}
     */
    public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
        if (!is_string($value)) {
            throw new MigrateException('The input value must be a string.');
        }
        if (empty($this->configuration['method'])) {
            throw new MigrateException('You need to specify the name of a method to be called on the Field plugin.');
        }
        $method = $this->configuration['method'];
        try {
            return $this->callMethodOnFieldPlugin($this->fieldPluginManager, $value, $method, $row);
        } catch (PluginNotFoundException $e) {
            return NULL;
        }
    }
    
    /**
     * Instantiate a field plugin and call a method on it.
     *
     * @param \Drupal\migrate_drupal\Plugin\MigrateFieldPluginManagerInterface $field_plugin_manager
     *   The field plugin manager.
     * @param string $field_type
     *   The field type for which to get the field plugin.
     * @param string $method
     *   The method to call on the field plugin.
     * @param \Drupal\migrate\Row $row
     *   The row from the source to process.
     *
     * @return mixed
     *   The return value from the method called on the field plugin.
     */
    protected function callMethodOnFieldPlugin(MigrateFieldPluginManagerInterface $field_plugin_manager, $field_type, $method, Row $row) {
        $plugin_id = $field_plugin_manager->getPluginIdFromFieldType($field_type, [], $this->migration);
        $plugin_instance = $field_plugin_manager->createInstance($plugin_id, [], $this->migration);
        if (!is_callable([
            $plugin_instance,
            $method,
        ])) {
            throw new MigrateException('The specified method does not exist or is not callable.');
        }
        return call_user_func_array([
            $plugin_instance,
            $method,
        ], [
            $row,
        ]);
    }

}