class MachineName

class MachineName extends ProcessPluginBase implements ContainerFactoryPluginInterface {
    
    /**
     * The transliteration service.
     *
     * @var \Drupal\Component\Transliteration\TransliterationInterface
     */
    protected $transliteration;
    
    /**
     * Constructs a MachineName plugin.
     *
     * @param array $configuration
     *   The plugin configuration.
     * @param string $plugin_id
     *   The plugin ID.
     * @param mixed $plugin_definition
     *   The plugin definition.
     * @param \Drupal\Component\Transliteration\TransliterationInterface $transliteration
     *   The transliteration service.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, TransliterationInterface $transliteration) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->transliteration = $transliteration;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('transliteration'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
        $new_value = $this->transliteration
            ->transliterate($value, LanguageInterface::LANGCODE_DEFAULT, '_');
        $new_value = strtolower($new_value);
        $new_value = preg_replace('/[^a-z0-9_]+/', '_', $new_value);
        return preg_replace('/_+/', '_', $new_value);
    }

}