/**
* How to use Relation::deleteLink() to delete link (a1,b1) from r:
* r :: A * B
* deleteLink(a1[A], b1[B], false);
* deleteLink(b1[B], a1[A], true);
*
* @param Atom $leftAtom
* @param Atom $rightAtom
* @param boolean $isFlipped
* @param string $source specifies who calls this function (e.g. 'User' or 'ExecEngine')
* @return void
*/
public function deleteLink($leftAtom, $rightAtom, $isFlipped = false, $source = 'User')
{
$this->logger->debug("Delete link ({$leftAtom->__toString()},{$rightAtom->__toString()}) from relation '{$this->__toString()}{({$isFlipped} ? '~' : '')}'");
// Determine src and tgt atom based on $isFlipped
$srcAtom = $isFlipped ? $rightAtom : $leftAtom;
$tgtAtom = $isFlipped ? $leftAtom : $rightAtom;
// Checks
if (!in_array($srcAtom->concept, $this->srcConcept->getSpecializationsIncl())) {
throw new Exception("Cannot delete link ({$srcAtom->__toString()},{$tgtAtom->__toString()}) from relation '{$this->__toString()}', because source concept does not match relation source or its specializations", 500);
}
if (!in_array($tgtAtom->concept, $this->tgtConcept->getSpecializationsIncl())) {
throw new Exception("Cannot delete link ({$srcAtom->__toString()},{$tgtAtom->__toString()}) from relation '{$this->__toString()}', because target concept does not match relation target or its specializations", 500);
}
// Delete link from relation table
$this->db->deleteLink($this, $srcAtom, $tgtAtom);
// Flag session var as affected when src or tgt concept of this relation is SESSION
if ($srcAtom->concept->isSession() || $tgtAtom->concept->isSession()) {
Session::singleton()->setSessionVarAffected();
}
}