Class DepthFirstWalker

  extended by org.apache.pig.newplan.PlanWalker
      extended by org.apache.pig.newplan.DepthFirstWalker

public class DepthFirstWalker
extends PlanWalker

Do a depth first traversal of the graph.

Field Summary
Fields inherited from class org.apache.pig.newplan.PlanWalker
Constructor Summary
DepthFirstWalker(OperatorPlan plan)
Method Summary
 PlanWalker spawnChildWalker(OperatorPlan plan)
          Return a new instance of this same type of walker for a subplan.
 void walk(PlanVisitor visitor)
          Begin traversing the graph.
Methods inherited from class org.apache.pig.newplan.PlanWalker
getPlan, setPlan
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public DepthFirstWalker(OperatorPlan plan)
Method Detail


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
plan - Plan for the new walker.
Instance of the same type of walker with plan set to plan.


public void walk(PlanVisitor visitor)
          throws FrontendException
Begin traversing the graph.

Specified by:
walk in class PlanWalker
visitor - Visitor this walker is being used by.
FrontendException - if an error is encountered while walking.

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