Iterates over the nodes of a graph in
Depth First Topological Sort pattern. The following is an illustration of the iteration.
Initially all nodes of degree less than two are
active (ready to be visited). As nodes are visited, a node can become active when all but one of its related nodes have been visited ( degree = counter + 1). When a node becomes active it is placed into the
active node queue (queue of nodes to be visited). The Depth First Topological iterator places nodes into the queue in
Last In First Out order (a Stack).
To determine when a node is to become active the iterator uses the counter associated with each node. If these counters are modified by an entity other then the iterator, the iteration may be affected in undefined ways.
@author Justin Deoliveira, Refractions Research Inc, jdeolive@refractions.net
@source $URL$