/**
* @access private
*/
function _sort(&$graph)
{
// Mark every node as not visited
$nodes =& $graph->getNodes();
$nodeKeys = array_keys($nodes);
$refGenerator = array();
foreach ($nodeKeys as $key) {
$refGenerator[] = false;
$nodes[$key]->setMetadata('topological-sort-visited', $refGenerator[sizeof($refGenerator) - 1]);
}
// Iteratively peel off leaf nodes
$topologicalLevel = 0;
do {
// Find out which nodes are leafs (excluding visited nodes)
$leafNodes = array();
foreach ($nodeKeys as $key) {
if (!$nodes[$key]->getMetadata('topological-sort-visited') && Structures_Graph_Manipulator_TopologicalSorter::_nonVisitedInDegree($nodes[$key]) == 0) {
$leafNodes[] =& $nodes[$key];
}
}
// Mark leafs as visited
$refGenerator[] = $topologicalLevel;
for ($i = sizeof($leafNodes) - 1; $i >= 0; $i--) {
$visited =& $leafNodes[$i]->getMetadata('topological-sort-visited');
$visited = true;
$leafNodes[$i]->setMetadata('topological-sort-visited', $visited);
$leafNodes[$i]->setMetadata('topological-sort-level', $refGenerator[sizeof($refGenerator) - 1]);
}
$topologicalLevel++;
} while (sizeof($leafNodes) > 0);
// Cleanup visited marks
foreach ($nodeKeys as $key) {
$nodes[$key]->unsetMetadata('topological-sort-visited');
}
}
