/**
* Deletes all contacts from a specific address book.
*
* @param string $sourceName The source to remove all contacts from.
*
* @return array An array of UIDs
* @throws Turba_Exception
*/
protected function _deleteAll($sourceName = null)
{
if (is_null($sourceName)) {
$sourceName = $this->getContactOwner();
}
return $this->_driver->_deleteAll($sourceName);
}