public class DependencyOrderWalker
A walker to walk graphs in dependency order. It is guaranteed that a node
will not be visited until all of its predecessors have been visited. This
is equivalent to doing a topilogical sort on the graph and then visiting
the nodes in order.
Fields inherited from class org.apache.pig.newplan.PlanWalker
Return a new instance of this same type of walker for a subplan.
When this method is called the same type of walker with the
provided plan set as the plan, must be returned. This can then be
used to walk subplans. This allows abstract visitors to clone
walkers without knowning the type of walker their subclasses used.