/**
* Subtract a duration to this one. If $duration is greather than or equal to
* the current duration, a duration of 0 seconds is returned.
*
* For instance P2S - P1S = P1S
*/
public function sub(QtiDuration $duration)
{
if ($duration->longerThanOrEquals($this) === true) {
$this->setInterval(new DateInterval('PT0S'));
} else {
$refStrDate = '@0';
$tz = new DateTimeZone(self::TIMEZONE);
$d1 = new DateTime($refStrDate, $tz);
$d2 = new DateTime($refStrDate, $tz);
$d1->add(new DateInterval($this->__toString()));
$d2->add(new DateInterval($duration->__toString()));
$interval = $d1->diff($d2);
$this->setInterval($interval);
}
}
public function testSub()
{
$d1 = new QtiDuration('PT2S');
$d2 = new QtiDuration('PT1S');
$d1->sub($d2);
$this->assertEquals('PT1S', $d1->__toString());
$d1 = new QtiDuration('PT2S');
$d2 = new QtiDuration('PT4S');
$d1->sub($d2);
$this->assertEquals('PT0S', $d1->__toString());
$d1 = new QtiDuration('P1DT2H25M30S');
$d2 = new QtiDuration('P1DT2H');
$d1->sub($d2);
$this->assertEquals('PT25M30S', $d1->__toString());
$d1 = new QtiDuration('PT20S');
$d2 = new QtiDuration('PT20S');
$d1->sub($d2);
$this->assertEquals('PT0S', $d1->__toString());
$d1 = new QtiDuration('PT20S');
$d2 = new QtiDuration('PT21S');
$d1->sub($d2);
$this->assertTrue($d1->isNegative());
}
/**
* Marshall a QTI duration datatype into its PCI JSON Representation.
*
* @param \qtism\common\datatypes\Duration $duration
* @return array
*/
protected function marshallDuration(QtiDuration $duration)
{
return array('base' => array('duration' => $duration->__toString()));
}
/**
* Write a Duration in the current binary stream.
*
* @param \qtism\common\datatypes\Duration $duration A Duration object.
* @throws \qtism\runtime\storage\binary\QtiBinaryStreamAccessException
*/
public function writeDuration(QtiDuration $duration)
{
try {
$this->writeString($duration->__toString());
} catch (BinaryStreamAccessException $e) {
$msg = "An error occured while writing a duration.";
throw new QtiBinaryStreamAccessException($msg, $this, QtiBinaryStreamAccessException::DURATION, $e);
}
}
