public static IEnumerable <T> TopologicalSortReverse <T>(this ICollection <T> list, NodeLinksResolver <T> linkResolver)
{
TopologicalSortState <T> state = new TopologicalSortState <T>
{
Unmarked = new HashSet <T>(list),
GetLinks = linkResolver,
};
while (state.Unmarked.Count > 0)
{
Visit(state.Unmarked.First(), state);
}
return(state.SortedNodes);
}
internal static void Visit <T>(T node, TopologicalSortState <T> state)
{
if (state.TemporaryMarked.Contains(node))
{
throw new InvalidOperationException("Not a DAG");
}
if (!state.Unmarked.Contains(node))
{
return;
}
state.TemporaryMarked.Add(node);
foreach (T link in state.GetLinks(node))
{
Visit(link, state);
}
state.SortedNodes.Add(node);
state.TemporaryMarked.Remove(node);
state.Unmarked.Remove(node);
}