class views_handler_field_machine_name extends views_handler_field {
  /**
   * @var array Stores the available options.
   */
  var $value_options;

  function get_value_options() {
    if (isset($this->value_options)) {
      return;
    }

    if (isset($this->definition['options callback']) && is_callable($this->definition['options callback'])) {
      if (isset($this->definition['options arguments']) && is_array($this->definition['options arguments'])) {
        $this->value_options = call_user_func_array($this->definition['options callback'], $this->definition['options arguments']);
      }
      else {
        $this->value_options = call_user_func($this->definition['options callback']);
      }
    }
    else {
      $this->value_options = array();
    }
  }

  function option_definition() {
    $options = parent::option_definition();
    $options['machine_name'] = array('default' => FALSE, 'bool' => TRUE);

    return $options;
  }

  function options_form(&$form, &$form_state) {
    parent::options_form($form, $form_state);

    $form['machine_name'] = array(
      '#title' => t('Output machine name'),
      '#description' => t('Display field as machine name.'),
      '#type' => 'checkbox',
      '#default_value' => !empty($this->options['machine_name']),
    );
  }

  function pre_render(&$values) {
    $this->get_value_options();
  }

  function render($values) {
    $value = $values->{$this->field_alias};
    if (!empty($this->options['machine_name']) || !isset($this->value_options[$value])) {
      $result = check_plain($value);
    }
    else {
      $result = $this->value_options[$value];
    }

    return $result;
  }
}