OverviewTerms::submitForm

public OverviewTerms::submitForm(array &$form, FormStateInterface $form_state)

public function submitForm(array &$form, FormStateInterface $form_state) {
  // Sort term order based on weight.
  uasort($form_state->getValue('terms'), array('Drupal\Component\Utility\SortArray', 'sortByWeightElement'));

  $vocabulary = $form_state->get(['taxonomy', 'vocabulary']);
  // Update the current hierarchy type as we go.
  $hierarchy = VocabularyInterface::HIERARCHY_DISABLED;

  $changed_terms = array();
  $tree = $this->storageController->loadTree($vocabulary->id(), 0, NULL, TRUE);

  if (empty($tree)) {
    return;
  }

  // Build a list of all terms that need to be updated on previous pages.
  $weight = 0;
  $term = $tree[0];
  while ($term->id() != $form['#first_tid']) {
    if ($term->parents[0] == 0 && $term->getWeight() != $weight) {
      $term->setWeight($weight);
      $changed_terms[$term->id()] = $term;
    }
    $weight++;
    $hierarchy = $term->parents[0] != 0 ? VocabularyInterface::HIERARCHY_SINGLE : $hierarchy;
    $term = $tree[$weight];
  }

  // Renumber the current page weights and assign any new parents.
  $level_weights = array();
  foreach ($form_state->getValue('terms') as $tid => $values) {
    if (isset($form['terms'][$tid]['#term'])) {
      $term = $form['terms'][$tid]['#term'];
      // Give terms at the root level a weight in sequence with terms on previous pages.
      if ($values['term']['parent'] == 0 && $term->getWeight() != $weight) {
        $term->setWeight($weight);
        $changed_terms[$term->id()] = $term;
      }
      // Terms not at the root level can safely start from 0 because they're all on this page.
      elseif ($values['term']['parent'] > 0) {
        $level_weights[$values['term']['parent']] = isset($level_weights[$values['term']['parent']]) ? $level_weights[$values['term']['parent']] + 1 : 0;
        if ($level_weights[$values['term']['parent']] != $term->getWeight()) {
          $term->setWeight($level_weights[$values['term']['parent']]);
          $changed_terms[$term->id()] = $term;
        }
      }
      // Update any changed parents.
      if ($values['term']['parent'] != $term->parents[0]) {
        $term->parent->target_id = $values['term']['parent'];
        $changed_terms[$term->id()] = $term;
      }
      $hierarchy = $term->parents[0] != 0 ? VocabularyInterface::HIERARCHY_SINGLE : $hierarchy;
      $weight++;
    }
  }

  // Build a list of all terms that need to be updated on following pages.
  for ($weight; $weight < count($tree); $weight++) {
    $term = $tree[$weight];
    if ($term->parents[0] == 0 && $term->getWeight() != $weight) {
      $term->parent->target_id = $term->parents[0];
      $term->setWeight($weight);
      $changed_terms[$term->id()] = $term;
    }
    $hierarchy = $term->parents[0] != 0 ? VocabularyInterface::HIERARCHY_SINGLE : $hierarchy;
  }

  // Save all updated terms.
  foreach ($changed_terms as $term) {
    $term->save();
  }

  // Update the vocabulary hierarchy to flat or single hierarchy.
  if ($vocabulary->getHierarchy() != $hierarchy) {
    $vocabulary->setHierarchy($hierarchy);
    $vocabulary->save();
  }
  drupal_set_message($this->t('The configuration options have been saved.'));
}