ViewsExposedForm::submitForm

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

public function submitForm(array &$form, FormStateInterface $form_state) {
  // Form input keys that will not be included in $view->exposed_raw_data.
  $exclude = array('submit', 'form_build_id', 'form_id', 'form_token', 'exposed_form_plugin', 'reset');
  $values = $form_state->getValues();
  foreach (array('field', 'filter') as $type) {
    /** @var \Drupal\views\Plugin\views\ViewsHandlerInterface[] $handlers */
    $handlers = &$form_state->get('view')->$type;
    foreach ($handlers as $key => $info) {
      if ($handlers[$key]->acceptExposedInput($values)) {
        $handlers[$key]->submitExposed($form, $form_state);
      }
      else {
        // The input from the form did not validate, exclude it from the
        // stored raw data.
        $exclude[] = $key;
      }
    }
  }

  $view = $form_state->get('view');
  $view->exposed_data = $values;
  $view->exposed_raw_input = [];

  $exclude = array('submit', 'form_build_id', 'form_id', 'form_token', 'exposed_form_plugin', 'reset');
  /** @var \Drupal\views\Plugin\views\exposed_form\ExposedFormPluginBase $exposed_form_plugin */
  $exposed_form_plugin = $view->display_handler->getPlugin('exposed_form');
  $exposed_form_plugin->exposedFormSubmit($form, $form_state, $exclude);
  foreach ($values as $key => $value) {
    if (!empty($key) && !in_array($key, $exclude)) {
      if (is_array($value)) {
        // Handle checkboxes, we only want to include the checked options.
        // @todo: revisit the need for this when
        //   https://www.drupal.org/node/342316 is resolved.
        $checked = Checkboxes::getCheckedCheckboxes($value);
        foreach ($checked as $option_id) {
          $view->exposed_raw_input[$option_id] = $value[$option_id];
        }
      }
      else {
        $view->exposed_raw_input[$key] = $value;
      }
    }
  }
}