/**
* Convert a FormalDate to a string
* @return string
*/
public function __toString()
{
$result = array();
if ($this->isRecurring) {
$result[] = "R";
if ($this->numRepetitions !== null) {
$result[] = $this->numRepetitions;
}
$result[] = "/";
} elseif ($this->isApproximate) {
$result[] = "A";
}
if ($this->start !== null) {
$result[] = $this->start->__toString();
}
if ($this->isRange) {
$result[] = "/";
}
if ($this->end !== null) {
$result[] = $this->end->__toString();
} elseif ($this->duration !== null) {
$result[] = $this->duration->__toString();
}
return implode("", $result);
}