/**
* Unmarshall a StatsOperator object into a QTI statsOperator element.
*
* @param \qtism\data\QtiComponent $component The StatsOperator object to marshall.
* @param array $elements An array of child DOMEelement objects.
* @return \DOMElement The marshalled QTI statsOperator element.
*/
protected function marshallChildrenKnown(QtiComponent $component, array $elements)
{
$element = self::getDOMCradle()->createElement($component->getQtiClassName());
self::setDOMElementAttribute($element, 'name', Statistics::getNameByConstant($component->getName()));
foreach ($elements as $elt) {
$element->appendChild($elt);
}
return $element;
}
/**
* Process the StatsOperator.
*
* @return float A single float or NULL if the sub-expression or any value contained therein is NULL.
* @throws \qtism\runtime\expressions\operators\OperatorProcessingException
*/
public function process()
{
$operands = $this->getOperands();
if ($operands->containsNull() === true) {
return null;
}
if ($operands->exclusivelyMultipleOrOrdered() === false) {
$msg = "The StatsOperator operator only accepts operands with a multiple or ordered cardinality.";
throw new OperatorProcessingException($msg, $this, OperatorProcessingException::WRONG_CARDINALITY);
}
if ($operands->exclusivelyNumeric() === false) {
$msg = "The StatsOperator operator only accepts operands with a multiple or ordered cardinality.";
throw new OperatorProcessingException($msg, $this, OperatorProcessingException::WRONG_BASETYPE);
}
$qtiFuncName = Statistics::getNameByConstant($this->getExpression()->getName());
$methodName = 'process' . ucfirst($qtiFuncName);
return call_user_func_array(array($this, $methodName), array());
}
public function createFakeExpression($name)
{
$name = Statistics::getNameByConstant($name);
return $this->createComponentFromXml('
<statsOperator name="' . $name . '">
<multiple>
<baseValue baseType="integer">10</baseValue>
<baseValue baseType="integer">20</baseValue>
<baseValue baseType="integer">30</baseValue>
</multiple>
</statsOperator>
');
}
