/// <summary>
/// Returns all nodes in the schedule whose target appears prior to the node.
/// </summary>
/// <param name="g"></param>
/// <param name="schedule"></param>
/// <returns></returns>
internal static Set <NodeIndex> CollectUses(IndexedGraph g, IEnumerable <NodeIndex> schedule)
{
Set <NodeIndex> uses = new Set <NodeIndex>();
Set <NodeIndex> available = new Set <NodeIndex>();
foreach (NodeIndex node in schedule)
{
foreach (NodeIndex source in g.SourcesOf(node))
{
if (!available.Contains(source))
{
uses.Add(source);
}
}
available.Add(node);
}
return(uses);
}