ConsumerChoicePointFrame

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com.hp.hpl.jena.reasoner.rulesys.impl
Class ConsumerChoicePointFrame

java.lang.Object
  com.hp.hpl.jena.reasoner.rulesys.impl.FrameObject
      com.hp.hpl.jena.reasoner.rulesys.impl.GenericChoiceFrame
          com.hp.hpl.jena.reasoner.rulesys.impl.GenericTripleMatchFrame
              com.hp.hpl.jena.reasoner.rulesys.impl.ConsumerChoicePointFrame

All Implemented Interfaces:: LPAgendaEntry, LPInterpreterState

public class ConsumerChoicePointFrame
extends GenericTripleMatchFrame
implements LPAgendaEntry, LPInterpreterState

Frame in the LPInterpreter's control stack used to represent matching to the results of a tabled predicate. Conventionally the system state which finds and tables the goal results is called the generator and states which require those results are called consumers.

This is used in the inner loop of the interpreter and so is a pure data structure not an abstract data type and assumes privileged access to the interpreter state.

Version:: $Revision: 1.9 $ on $Date: 2005/04/12 17:01:41 $

Field Summary

protected LPInterpreterContext context
          The generator or top iterator we are producting results for

protected Generator generator
          The generator whose tabled results we are selecting over

protected com.hp.hpl.jena.graph.Node[] pVars
          The preserved permanent registers for the pickled interpreter

protected int resultIndex
          The index in the generator's result set that we have reached so far.

protected int trailLength
          The length of the preserved trail

protected com.hp.hpl.jena.graph.Node[] trailValues
          The preserved trail bound values for the picked interpreter

protected com.hp.hpl.jena.reasoner.rulesys.Node_RuleVariable[] trailVars
          The preserved trail variables for the picked interpreter

Fields inherited from class com.hp.hpl.jena.reasoner.rulesys.impl.GenericTripleMatchFrame

goal, objectFunctor, objectVar, predicateVar, subjectVar

Fields inherited from class com.hp.hpl.jena.reasoner.rulesys.impl.GenericChoiceFrame

cac, cpc, envFrame, trailIndex

Fields inherited from class com.hp.hpl.jena.reasoner.rulesys.impl.FrameObject

link

Constructor Summary

ConsumerChoicePointFrame(LPInterpreter interpreter)
          Constructor.

Method Summary

LPInterpreterContext getConsumingContext()
          Return the interpeter context which is reading the results of this consumer.

Generator getGenerator()
          Return the generator associated with this entry (might be the entry itself)

void init(LPInterpreter interpreter)
          Initialize the choice point state.

boolean isReady()
          Return true if this choice point could usefully be restarted.

StateFlag nextMatch(LPInterpreter interpreter)
          Find the next result triple and bind the result vars appropriately.

void preserveState(java.util.List trail)
          Preserve the state of an interpreter into this frame.

void pump()
          Reactivate this choice point to return new results.

void restoreState(LPInterpreter interp)
          Restore the state of an interpreter from this frame

void setFinished()
          Notify that this consumer choice point has finished consuming all the results of a closed generator.

void setReady()
          Called by generator when there are more results available.

Methods inherited from class com.hp.hpl.jena.reasoner.rulesys.impl.GenericTripleMatchFrame

bindResult, functorMatch

Methods inherited from class com.hp.hpl.jena.reasoner.rulesys.impl.GenericChoiceFrame

setContinuation

Methods inherited from class com.hp.hpl.jena.reasoner.rulesys.impl.FrameObject

close, fastLinkTo, getLink, linkTo

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

generator

protected Generator generator

The generator whose tabled results we are selecting over

resultIndex

protected int resultIndex

The index in the generator's result set that we have reached so far.

pVars

protected com.hp.hpl.jena.graph.Node[] pVars

The preserved permanent registers for the pickled interpreter

trailVars

protected com.hp.hpl.jena.reasoner.rulesys.Node_RuleVariable[] trailVars

The preserved trail variables for the picked interpreter

trailValues

protected com.hp.hpl.jena.graph.Node[] trailValues

The preserved trail bound values for the picked interpreter

trailLength

protected int trailLength

The length of the preserved trail

context

protected LPInterpreterContext context

The generator or top iterator we are producting results for

Constructor Detail