/**
* Unmarshall a MathOperator object into a QTI mathOperator element.
*
* @param QtiComponent The MathOperator object to marshall.
* @param array An array of child DOMEelement objects.
* @return DOMElement The marshalled QTI mathOperator element.
*/
protected function marshallChildrenKnown(QtiComponent $component, array $elements)
{
$element = self::getDOMCradle()->createElement($component->getQtiClassName());
self::setDOMElementAttribute($element, 'name', MathFunctions::getNameByConstant($component->getName()));
foreach ($elements as $elt) {
$element->appendChild($elt);
}
return $element;
}
public function createFakeExpression($constant)
{
return $this->createComponentFromXml('
<mathOperator name="' . MathFunctions::getNameByConstant($constant) . '">
<baseValue baseType="float">1.5708</baseValue>
</mathOperator>
');
}
/**
* Process the MathOperator operator.
*
* @return float|integer|null The result of the MathOperator call or NULL if any of the sub-expressions is NULL. See the class documentation for special cases.
*/
public function process()
{
$operands = $this->getOperands();
if ($operands->containsNull() === true) {
return null;
}
if ($operands->exclusivelySingle() === false) {
$msg = "The MathOperator operator only accepts operands with a single cardinality.";
throw new OperatorProcessingException($msg, $this, OperatorProcessingException::WRONG_CARDINALITY);
}
if ($operands->exclusivelyNumeric() === false) {
$msg = "The MathOperator operator only accepts operands with an integer or float baseType.";
throw new OperatorProcessingException($msg, $this, OperatorProcessingException::WRONG_BASETYPE);
}
$qtiFuncName = MathFunctions::getNameByConstant($this->getExpression()->getName());
$methodName = 'process' . ucfirst($qtiFuncName);
$result = call_user_func_array(array($this, $methodName), array());
if ($result instanceof Float && is_nan($result->getValue()) === true) {
// outside the domain of the function.
return null;
} else {
return $result;
}
}