class TaxonomyIndexTidDepth

class TaxonomyIndexTidDepth extends TaxonomyIndexTid {
  function operator_options($which = 'title') {
    return array(
      'or' => t('Is one of'),
    );
  }
  protected function defineOptions() {
    $options = parent::defineOptions();
    $options['depth'] = array(
      'default' => 0,
    );
    return $options;
  }
  public function buildExtraOptionsForm(&$form, &$form_state) {
    parent::buildExtraOptionsForm($form, $form_state);
    $form['depth'] = array(
      '#type' => 'weight',
      '#title' => t('Depth'),
      '#default_value' => $this->options['depth'],
      '#description' => t('The depth will match nodes tagged with terms in the hierarchy. For example, if you have the term "fruit" and a child term "apple", with a depth of 1 (or higher) then filtering for the term "fruit" will get nodes that are tagged with "apple" as well as "fruit". If negative, the reverse is true; searching for "apple" will also pick up nodes tagged with "fruit" if depth is -1 (or lower).'),
    );
  }
  public function query() {

    // If no filter values are present, then do nothing.
    if (count($this->value) == 0) {
      return;
    }
    elseif (count($this->value) == 1) {

      // Somethis $this->value is an array with a single element so convert it.
      if (is_array($this->value)) {
        $this->value = current($this->value);
      }
      $operator = '=';
    }
    else {
      $operator = 'IN';

      # " IN (" . implode(', ', array_fill(0, sizeof($this->value), '%d')) . ")";
    }

    // The normal use of ensureMyTable() here breaks Views.
    // So instead we trick the filter into using the alias of the base table.
    // See http://drupal.org/node/271833
    // If a relationship is set, we must use the alias it provides.
    if (!empty($this->relationship)) {
      $this->tableAlias = $this->relationship;
    }
    elseif (isset($this->query->table_queue[$this->view->storage
      ->get('base_table')]['alias'])) {
      $this->tableAlias = $this->query->table_queue[$this->view->storage
        ->get('base_table')]['alias'];
    }
    else {
      return;
    }

    // Now build the subqueries.
    $subquery = db_select('taxonomy_index', 'tn');
    $subquery
      ->addField('tn', 'nid');
    $where = db_or()
      ->condition('tn.tid', $this->value, $operator);
    $last = "tn";
    if ($this->options['depth'] > 0) {
      $subquery
        ->leftJoin('taxonomy_term_hierarchy', 'th', "th.tid = tn.tid");
      $last = "th";
      foreach (range(1, abs($this->options['depth'])) as $count) {
        $subquery
          ->leftJoin('taxonomy_term_hierarchy', "th{$count}", "{$last}.parent = th{$count}.tid");
        $where
          ->condition("th{$count}.tid", $this->value, $operator);
        $last = "th{$count}";
      }
    }
    elseif ($this->options['depth'] < 0) {
      foreach (range(1, abs($this->options['depth'])) as $count) {
        $subquery
          ->leftJoin('taxonomy_term_hierarchy', "th{$count}", "{$last}.tid = th{$count}.parent");
        $where
          ->condition("th{$count}.tid", $this->value, $operator);
        $last = "th{$count}";
      }
    }
    $subquery
      ->condition($where);
    $this->query
      ->add_where($this->options['group'], "{$this->tableAlias}.{$this->realField}", $subquery, 'IN');
  }

}