org.apache.pig.experimental.plan
Class ReverseDependencyOrderWalker
java.lang.Object
org.apache.pig.experimental.plan.PlanWalker
org.apache.pig.experimental.plan.ReverseDependencyOrderWalker
public class ReverseDependencyOrderWalker
- extends PlanWalker
Visit a plan in the reverse of the dependency order. That is, every node
after every node that depends on it is visited. Thus this is equivalent to
doing a reverse topilogical sort on the graph and then visiting it in order.
Fields inherited from class org.apache.pig.experimental.plan.PlanWalker |
plan |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
ReverseDependencyOrderWalker
public ReverseDependencyOrderWalker(OperatorPlan plan)
spawnChildWalker
public PlanWalker spawnChildWalker(OperatorPlan plan)
- Description copied from class:
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.
- Specified by:
spawnChildWalker
in class PlanWalker
- Parameters:
plan
- Plan for the new walker.
- Returns:
- Instance of the same type of walker with plan set to plan.
walk
public void walk(PlanVisitor visitor)
throws IOException
- Begin traversing the graph.
- Specified by:
walk
in class PlanWalker
- Parameters:
visitor
- Visitor this walker is being used by.
- Throws:
VisitorException
- if an error is encountered while walking.
IOException
doAllSuccessors
protected void doAllSuccessors(Operator node,
Set<Operator> seen,
Collection<Operator> fifo)
throws IOException
- Throws:
IOException
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