public function addState(__IFlowState &$state)
{
$this->_states[$state->getId()] =& $state;
if ($state instanceof __StartFlowState) {
if ($this->_start_state == null) {
$this->_start_state =& $state;
} else {
throw __ExceptionFactory::getInstance()->createException('Multiple start states in flow ' . $this->_id);
}
}
}
