class Editor

class Editor extends PluginBase implements InPlaceEditorInterface {
  
  /**
   * {@inheritdoc}
   */
  public function isCompatible(FieldItemListInterface $items) {
    $field_definition = $items->getFieldDefinition();
    // This editor is incompatible with multivalued fields.
    if ($field_definition->getFieldStorageDefinition()
      ->getCardinality() != 1) {
      return FALSE;
    }
    elseif ($editor = editor_load($items[0]->format)) {
      $definition = \Drupal::service('plugin.manager.editor')->getDefinition($editor->getEditor());
      if ($definition['supports_inline_editing'] === TRUE) {
        return TRUE;
      }
    }
    return FALSE;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getMetadata(FieldItemListInterface $items) {
    $format_id = $items[0]->format;
    $metadata['format'] = $format_id;
    $metadata['formatHasTransformations'] = $this->textFormatHasTransformationFilters($format_id);
    return $metadata;
  }
  
  /**
   * Returns whether the text format has transformation filters.
   *
   * @param int $format_id
   *   A text format ID.
   *
   * @return bool
   */
  protected function textFormatHasTransformationFilters($format_id) {
    $format = FilterFormat::load($format_id);
    return (bool) count(array_intersect([
      FilterInterface::TYPE_TRANSFORM_REVERSIBLE,
      FilterInterface::TYPE_TRANSFORM_IRREVERSIBLE,
    ], $format->getFiltertypes()));
  }
  
  /**
   * {@inheritdoc}
   */
  public function getAttachments() {
    $user = \Drupal::currentUser();
    $user_format_ids = array_keys(filter_formats($user));
    $manager = \Drupal::service('plugin.manager.editor');
    $definitions = $manager->getDefinitions();
    // Filter the current user's formats to those that support inline editing.
    $formats = [];
    foreach ($user_format_ids as $format_id) {
      if ($editor = editor_load($format_id)) {
        $editor_id = $editor->getEditor();
        if (isset($definitions[$editor_id]['supports_inline_editing']) && $definitions[$editor_id]['supports_inline_editing'] === TRUE) {
          $formats[] = $format_id;
        }
      }
    }
    // Get the attachments for all text editors that the user might use.
    $attachments = $manager->getAttachments($formats);
    // Also include quickedit.module's formatted text editor.
    $attachments['library'][] = 'quickedit/quickedit.inPlaceEditor.formattedText';
    return $attachments;
  }

}