/**
* Set the statistics operator to use.
*
* @param integer $name A value from the Statistics enumeration.
* @throws InvalidArgumentException If $name is not a value from the Statistics enumeration.
*/
public function setName($name)
{
if (in_array($name, Statistics::asArray())) {
$this->name = $name;
} else {
$msg = "The name argument must be a value from the Statistics enumeration, '" . $name . "' given.";
throw new InvalidArgumentException($msg);
}
}
/**
* Unmarshall a QTI statsOperator operator element into a StatsOperator object.
*
* @param \DOMElement The statsOperator element to unmarshall.
* @param \qtism\data\QtiComponentCollection A collection containing the child Expression objects composing the Operator.
* @return \qtism\data\QtiComponent A StatsOperator object.
* @throws \qtism\data\storage\xml\marshalling\UnmarshallingException
*/
protected function unmarshallChildrenKnown(DOMElement $element, QtiComponentCollection $children)
{
if (($name = static::getDOMElementAttributeAs($element, 'name')) !== null) {
$object = new StatsOperator($children, Statistics::getConstantByName($name));
return $object;
} else {
$msg = "The mandatory attribute 'name' is missing from element '" . $element->localName . "'.";
throw new UnmarshallingException($msg, $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>
');
}