private function tryFindMatchResultFor($hash, $dataValue)
{
$descriptionFactory = $this->queryFactory->newDescriptionFactory();
$contextPage = $dataValue->getContextPage();
// Exclude the current page from the result match to check whether another
// page matches the condition and if so then the value can no longer be
// assigned and is not unique
$description = $descriptionFactory->newConjunction(array($descriptionFactory->newFromDataValue($dataValue), $descriptionFactory->newValueDescription($contextPage, null, SMW_CMP_NEQ)));
$query = $this->queryFactory->newQuery($description);
$query->setLimit(1);
$dataItems = $this->cachedPropertyValuesPrefetcher->queryPropertyValuesFor($query);
if (!is_array($dataItems) || $dataItems === array()) {
// No other assignments were found therefore it is assumed that at
// the time of the query request, the "contextPage" holds a unique
// value for the property
$page = $contextPage;
} else {
$page = end($dataItems);
}
// Create a linked list so that when the subject is altered or deleted
// the related uniqueness container can be removed as well
$blobStore = $this->cachedPropertyValuesPrefetcher->getBlobStore();
$container = $blobStore->read($this->cachedPropertyValuesPrefetcher->getRootHashFrom($page));
$container->addToLinkedList($hash);
$blobStore->save($container);
return $page;
}
