/**
*
* sort returns the graph's nodes, sorted by topological order.
*
* The result is an array with
* as many entries as topological levels. Each entry in this array is an array of nodes within
* the given topological level.
*
* @return array The graph's nodes, sorted by topological order.
* @access public
*/
function sort(&$graph)
{
// We only sort graphs
if (!is_a($graph, 'Structures_Graph')) {
return Pear::raiseError('Structures_Graph_Manipulator_TopologicalSorter::sort received an object that is not a Structures_Graph', STRUCTURES_GRAPH_ERROR_GENERIC);
}
if (!Structures_Graph_Manipulator_AcyclicTest::isAcyclic($graph)) {
return Pear::raiseError('Structures_Graph_Manipulator_TopologicalSorter::sort received an graph that has cycles', STRUCTURES_GRAPH_ERROR_GENERIC);
}
Structures_Graph_Manipulator_TopologicalSorter::_sort($graph);
$result = array();
// Fill out result array
$nodes =& $graph->getNodes();
$nodeKeys = array_keys($nodes);
foreach ($nodeKeys as $key) {
if (!array_key_exists($nodes[$key]->getMetadata('topological-sort-level'), $result)) {
$result[$nodes[$key]->getMetadata('topological-sort-level')] = array();
}
$result[$nodes[$key]->getMetadata('topological-sort-level')][] =& $nodes[$key];
$nodes[$key]->unsetMetadata('topological-sort-level');
}
return $result;
}
