FieldUiTable::tablePreRender

public static FieldUiTable::tablePreRender($elements)

public static function tablePreRender($elements) {
  $js_settings = array();

  // For each region, build the tree structure from the weight and parenting
  // data contained in the flat form structure, to determine row order and
  // indentation.
  $regions = $elements['#regions'];
  $tree = ['' => ['name' => '', 'children' => []]];
  $trees = array_fill_keys(array_keys($regions), $tree);

  $parents = [];
  $children = Element::children($elements);
  $list = array_combine($children, $children);

  // Iterate on rows until we can build a known tree path for all of them.
  while ($list) {
    foreach ($list as $name) {
      $row = &$elements[$name];
      $parent = $row['parent_wrapper']['parent']['#value'];
      // Proceed if parent is known.
      if (empty($parent) || isset($parents[$parent])) {
        // Grab parent, and remove the row from the next iteration.
        $parents[$name] = $parent ? array_merge($parents[$parent], [$parent]) : [];
        unset($list[$name]);

        // Determine the region for the row.
        $region_name = call_user_func($row['#region_callback'], $row);

        // Add the element in the tree.
        $target = &$trees[$region_name][''];
        foreach ($parents[$name] as $key) {
          $target = &$target['children'][$key];
        }
        $target['children'][$name] = ['name' => $name, 'weight' => $row['weight']['#value']];

        // Add tabledrag indentation to the first row cell.
        if ($depth = count($parents[$name])) {
          $children = Element::children($row);
          $cell = current($children);
          $indentation = [
            '#theme' => 'indentation',
            '#size' => $depth,
            '#suffix' => isset($row[$cell]['#prefix']) ? $row[$cell]['#prefix'] : '',
          ];
          $row[$cell]['#prefix'] = \Drupal::service('renderer')->render($indentation);
        }

        // Add row id and associate JS settings.
        $id = Html::getClass($name);
        $row['#attributes']['id'] = $id;
        if (isset($row['#js_settings'])) {
          $row['#js_settings'] += [
            'rowHandler' => $row['#row_type'],
            'name' => $name,
            'region' => $region_name,
          ];
          $js_settings[$id] = $row['#js_settings'];
        }
      }
    }
  }

  // Determine rendering order from the tree structure.
  foreach ($regions as $region_name => $region) {
    $elements['#regions'][$region_name]['rows_order'] = array_reduce($trees[$region_name], [static::class, 'reduceOrder']);
  }

  $elements['#attached']['drupalSettings']['fieldUIRowsData'] = $js_settings;

  // If the custom #tabledrag is set and there is a HTML ID, add the table's
  // HTML ID to the options and attach the behavior.
  // @see \Drupal\Core\Render\Element\Table::preRenderTable()
  if (!empty($elements['#tabledrag']) && isset($elements['#attributes']['id'])) {
    foreach ($elements['#tabledrag'] as $options) {
      $options['table_id'] = $elements['#attributes']['id'];
      drupal_attach_tabledrag($elements, $options);
    }
  }

  return $elements;
}