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