class FilterUrl

class FilterUrl extends FilterBase {
  
  /**
   * {@inheritdoc}
   */
  public function settingsForm(array $form, FormStateInterface $form_state) {
    $form['filter_url_length'] = [
      '#type' => 'number',
      '#title' => $this->t('Maximum link text length'),
      '#default_value' => $this->settings['filter_url_length'],
      '#min' => 1,
      '#field_suffix' => $this->t('characters'),
      '#description' => $this->t('URLs longer than this number of characters will be truncated to prevent long strings that break formatting. The link itself will be retained; just the text portion of the link will be truncated.'),
    ];
    return $form;
  }
  
  /**
   * {@inheritdoc}
   */
  public function process($text, $langcode) {
    return new FilterProcessResult(_filter_url($text, $this));
  }
  
  /**
   * {@inheritdoc}
   */
  public function tips($long = FALSE) {
    return $this->t('Web page addresses and email addresses turn into links automatically.');
  }

}