function _node_types($op = '', $node = NULL, $reset = FALSE) {
  static $node_types = array(), $node_labels = array();

  $field_exists = module_exist('field');

  if ($reset || empty($node_types)) {
    if ($field_exists && ($cached = cache_get('node_types'))) {
      $node_types = unserialize($cached->data);
      $cached = cache_get('node_labels');
      $node_labels = unserialize($cached->data);
    }
    else {
      $node_types = array();
      $type_result = db_query('SELECT * FROM {node_type} nt ORDER BY nt.name ASC');
      while ($type_object = db_fetch_object($type_result)) {
        $type_object->fields = module_invoke('field', 'load_type', $type_object->name);
        $node_types[$type->name] = $type_object;
        $node_labels[$type->name] = $type_object->label;
      }

      if ($field_exists) {
        cache_set('node_types', serialize($node_types), CACHE_PERMANENT);
        cache_set('node_labels', serialize($node_labels), CACHE_PERMANENT);
      }
    }
  }

  if ($node) {
    if (is_array($node)) {
      $type = $node['type'];
    }
    elseif (is_object($node)) {
      $type = $node->type;
    }
    elseif (is_string($node)) {
      $type = $node;
    }
    if (!isset($node_types[$type])) {
      return FALSE;
    }
  }
  switch ($op) {
    case 'types':
      return $node_types;
    case 'type':
      return $node_types[$node];
    case 'base':
      return $node_types[$type]->base;
    case 'list':
      return $node_labels;
    case 'label':
      return $node_labels[$type];
  }
}