/**
* Gives the database a hint about the query
*
* @param mixed $index - Index to use for the query. If a string is
* passed, it should correspond to an index name. If an array or object
* is passed, it should correspond to the specification used to create
* the index (i.e. the first argument to
* MongoCollection::ensureIndex()).
*
* @return MongoCursor - Returns this cursor.
*/
public function hint($index)
{
if (is_object($index)) {
$index = get_object_vars($index);
}
if (is_array($index)) {
$index = MongoCollection::_toIndexString($index);
}
$this->query['$hint'] = $index;
return $this;
}