/**
* Process the Gcd operator.
*
* @return integer The integer value equal in value to the greatest common divisor of the sub-expressions. If any of the sub-expressions is NULL, the result is NULL.
* @throws \qtism\runtime\expressions\operators\OperatorProcessingException
*/
public function process()
{
$operands = $this->getOperands();
if ($operands->containsNull() === true) {
return null;
}
if ($operands->anythingButRecord() === false) {
$msg = "The Gcd operator only accepts operands with a cardinality of single, multiple or ordered.";
throw new OperatorProcessingException($msg, $this, OperatorProcessingException::WRONG_CARDINALITY);
}
if ($operands->exclusivelyInteger() === false) {
$msg = "The Gcd operator only accepts operands with an integer baseType.";
throw new OperatorProcessingException($msg, $this, OperatorProcessingException::WRONG_BASETYPE);
}
// Make a flat collection first.
$flatCollection = new OperandsCollection();
$zeroCount = 0;
$valueCount = 0;
foreach ($operands as $operand) {
if ($operand instanceof QtiScalar) {
$valueCount++;
if ($operand->getValue() !== 0) {
$flatCollection[] = $operand;
} else {
$zeroCount++;
}
} elseif ($operand->contains(null)) {
// Container with at least one null value inside.
// -> If any of the sub-expressions is null or not numeric, returns null.
return null;
} else {
// Container with no null values.
foreach ($operand as $o) {
$valueCount++;
if ($o->getValue() !== 0) {
$flatCollection[] = $o;
} else {
$zeroCount++;
}
}
}
}
if ($zeroCount === $valueCount) {
// All arguments of gcd() are 0.
return new QtiInteger(0);
} else {
$g = $flatCollection[0];
$loopLimit = count($flatCollection) - 1;
$i = 0;
while ($i < $loopLimit) {
$g = new QtiInteger(Utils::gcd($g->getValue(), $flatCollection[$i + 1]->getValue()));
$i++;
}
return $g;
}
}
/**
* @dataProvider gcdProvider
*
* @param integer $a
* @param integer $b
* @param integer $expected
*/
public function testGcd($a, $b, $expected)
{
$result = OperatorsUtils::gcd($a, $b);
$this->assertInternalType('integer', $result);
$this->assertSame($expected, $result);
}
