/**
* Process the Repeat operator.
*
* Note: NULL values are simply ignored. If all sub-expressions are NULL, NULL is
* returned.
*
* @return \qtism\runtime\common\OrderedContainer An ordered container filled sequentially by evaluating each sub-expressions, repeated a 'numberRepeats' of times. NULL is returned if all sub-expressions are NULL or numberRepeats < 1.
* @throws \qtism\runtime\expressions\operators\OperatorProcessingException
*/
public function process()
{
$operands = $this->getOperands();
// get the value of numberRepeats
$expression = $this->getExpression();
$numberRepeats = $expression->getNumberRepeats();
if (gettype($numberRepeats) === 'string') {
// Variable reference found.
$state = $this->getState();
$varName = Utils::sanitizeVariableRef($numberRepeats);
$varValue = $state[$varName];
if (is_null($varValue) === true) {
$msg = "The variable with name '{$varName}' could not be resolved.";
throw new OperatorProcessingException($msg, $this);
} elseif ($varValue instanceof Integer) {
$msg = "The variable with name '{$varName}' is not an integer value.";
throw new OperatorProcessingException($msg, $this);
}
$numberRepeats = $varValue->getValue();
}
if ($numberRepeats < 1) {
return null;
}
$result = null;
for ($i = 0; $i < $numberRepeats; $i++) {
$refType = null;
foreach ($operands as $operand) {
// If null, ignore
if (is_null($operand) || $operand instanceof Container && $operand->isNull()) {
continue;
}
// Check cardinality.
if ($operand->getCardinality() !== Cardinality::SINGLE && $operand->getCardinality() !== Cardinality::ORDERED) {
$msg = "The Repeat operator only accepts operands with a single or ordered cardinality.";
throw new OperatorProcessingException($msg, $this, OperatorProcessingException::WRONG_CARDINALITY);
}
// Check baseType.
$currentType = RuntimeUtils::inferBaseType($operand);
if ($refType !== null && $currentType !== $refType) {
$msg = "The Repeat operator only accepts operands with the same baseType.";
throw new OperatorProcessingException($msg, $this, OperatorProcessingException::WRONG_BASETYPE);
} elseif (is_null($result)) {
$refType = $currentType;
$result = new OrderedContainer($refType);
}
// Okay we are good...
$operandCardinality = RuntimeUtils::inferCardinality($operand);
if ($operandCardinality !== Cardinality::ORDERED) {
$operand = new OrderedContainer($currentType, array($operand));
}
foreach ($operand as $o) {
$result[] = $o instanceof QtiDatatype ? clone $o : $o;
}
}
}
if (isset($result) && $result->isNull() !== true) {
return $result;
} else {
return null;
}
}
