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

java.lang.Object
  com.hp.hpl.jena.reasoner.rulesys.impl.Generator

All Implemented Interfaces:

LPAgendaEntry, LPInterpreterContext, LPInterpreterState

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public class Generator

extends java.lang.Object

implements LPAgendaEntry, LPInterpreterContext

A generator represents a set of memoized results for a single tabled subgoal. The generator may be complete (in which case it just contains the complete cached set of results for a goal), ready (not complete but likely to product more results if called) or blocked (not complete and awaiting results from a dependent generator).

Each generator may have multiple associated consumer choice points representing different choices in satisfying the generator's goal.

Version:

$Revision: 1.7 $ on $Date: 2005/04/12 17:01:41 $

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Nested Class Summary
private static class	Generator.LFlag           Inner class used to flag generator states during completeness check.

 

Field Summary
protected  boolean	checkReadyNeeded           set to true if at least one branch has block so an active readiness check is required
protected  Generator.LFlag	completionState           Flags whether the generator is live/dead/unknown during completion checking
protected  java.util.Set	consumingCPs           The list of active consumer choice points consuming results from this generator
protected  java.util.Set	generatingCPs           The set of choice points producing results for us to use
protected  com.hp.hpl.jena.reasoner.TriplePattern	goal           The goal the generator is satisfying - just used in debugging
protected  LPInterpreter	interpreter           The intepreter instance which generates the results for this goal, null if the generator is complete
protected  boolean	isReady           set to true if the dependent generator has new results ready for us
protected  boolean	isSingleton           True if this generator can produce at most one answer
protected  java.util.ArrayList	results           The ordered set of results available for the goal
protected  java.util.Set	resultSet           A indexed version of the result set, used while the generator is live to detect duplicate results

 

Constructor Summary

Generator(LPInterpreter interpreter, com.hp.hpl.jena.reasoner.TriplePattern goal)           Constructor.

 

Method Summary
void	addConsumer(ConsumerChoicePointFrame ccp)           Add a new client choince point to consume results from this generator.
void	checkForCompletions()           Check for deadlocked states where none of the generators we are (indirectly) dependent on can run.
static void	checkForCompletions(java.util.Collection completions)           Check for deadlocked states across a collection of generators which have been run.
Generator	getGenerator()           Return the generator associated with this entry (might be the entry itself)
boolean	isComplete()           Return true if the generator is complete.
boolean	isReady()           Return true if the generator is ready to be scheduled (i.e.
void	notifyBlockedOn(ConsumerChoicePointFrame ccp)           Notify that the interpreter has now blocked on the given choice point.
void	notifyFinished(ConsumerChoicePointFrame ccp)           Notify this context that the given choice point has terminated and can be remove from the wait list.
void	notifyResults()           Signal dependents that we have new results.
int	numResults()           Return the number of results available from this context.
protected static void	postCompletionCheckScan(java.util.Set visited)           Scan the result of a (set of) completion check(s) to detect which of the unknowns are actually live and set the remaining (deadlocked) states to complete.
protected  void	propagateLive(java.util.Set filter)           Propagate liveness state forward to consuming generators, but only those within the filter set.
void	pump()           Start this generator running for the first time.
void	pump(LPInterpreterState context)           Start this generator running from the given previous blocked generating choice point.
void	removeConsumer(ConsumerChoicePointFrame ccp)           Remove a terminated consuming choice point from the state set.
protected  Generator.LFlag	runCompletionCheck(java.util.Set visited)           Check whether this generator is live (indirectly dependent on a ready generator), dead (complete) or in a deadlock loop which might or might not be live (unknown).
void	setComplete()           Signal that this generator is complete, no more results can be created.
void	setReady(ConsumerChoicePointFrame ccp)           Directly set that this generator is ready (because the generator for one of its generatingCPs has produced new results).

 

Methods inherited from class java.lang.Object

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

 

Field Detail

interpreter

protected LPInterpreter interpreter

The intepreter instance which generates the results for this goal, null if the generator is complete

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results

protected java.util.ArrayList results

The ordered set of results available for the goal

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resultSet

protected java.util.Set resultSet

A indexed version of the result set, used while the generator is live to detect duplicate results

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isReady

protected boolean isReady

set to true if the dependent generator has new results ready for us

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checkReadyNeeded

protected boolean checkReadyNeeded

set to true if at least one branch has block so an active readiness check is required

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generatingCPs

protected java.util.Set generatingCPs

The set of choice points producing results for us to use

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consumingCPs

protected java.util.Set consumingCPs

The list of active consumer choice points consuming results from this generator

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completionState

protected Generator.LFlag completionState

Flags whether the generator is live/dead/unknown during completion checking

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goal

protected com.hp.hpl.jena.reasoner.TriplePattern goal

The goal the generator is satisfying - just used in debugging

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isSingleton

protected boolean isSingleton

True if this generator can produce at most one answer

Constructor Detail

Generator

public Generator(LPInterpreter interpreter,
                 com.hp.hpl.jena.reasoner.TriplePattern goal)

Constructor.

Method Detail

numResults

public int numResults()

Return the number of results available from this context.

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isReady

public boolean isReady()

Return true if the generator is ready to be scheduled (i.e. it is not known to be complete and not known to be waiting for a dependent generator).

Specified by:

isReady in interface LPAgendaEntry

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setReady

public void setReady(ConsumerChoicePointFrame ccp)

Directly set that this generator is ready (because the generator for one of its generatingCPs has produced new results).

Specified by:

setReady in interface LPInterpreterContext

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isComplete

public boolean isComplete()

Return true if the generator is complete.

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setComplete

public void setComplete()

Signal that this generator is complete, no more results can be created.

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addConsumer

public void addConsumer(ConsumerChoicePointFrame ccp)

Add a new client choince point to consume results from this generator.

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removeConsumer

public void removeConsumer(ConsumerChoicePointFrame ccp)

Remove a terminated consuming choice point from the state set.

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notifyResults

public void notifyResults()

Signal dependents that we have new results.

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notifyBlockedOn

public void notifyBlockedOn(ConsumerChoicePointFrame ccp)

Notify that the interpreter has now blocked on the given choice point.

Specified by:

notifyBlockedOn in interface LPInterpreterContext

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notifyFinished

public void notifyFinished(ConsumerChoicePointFrame ccp)

Notify this context that the given choice point has terminated and can be remove from the wait list.

Specified by:

notifyFinished in interface LPInterpreterContext

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pump

public void pump()

Start this generator running for the first time. Should be called from within an appropriately synchronized block.

Specified by:

pump in interface LPAgendaEntry

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pump

public void pump(LPInterpreterState context)

Start this generator running from the given previous blocked generating choice point. Should be called from within an appropriately synchronized block.

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getGenerator

public Generator getGenerator()

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

Specified by:

getGenerator in interface LPAgendaEntry

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checkForCompletions

public void checkForCompletions()

Check for deadlocked states where none of the generators we are (indirectly) dependent on can run.

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checkForCompletions

public static void checkForCompletions(java.util.Collection completions)

Check for deadlocked states across a collection of generators which have been run.

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runCompletionCheck

protected Generator.LFlag runCompletionCheck(java.util.Set visited)

Check whether this generator is live (indirectly dependent on a ready generator), dead (complete) or in a deadlock loop which might or might not be live (unknown).

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postCompletionCheckScan

protected static void postCompletionCheckScan(java.util.Set visited)

Scan the result of a (set of) completion check(s) to detect which of the unknowns are actually live and set the remaining (deadlocked) states to complete.

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propagateLive

protected void propagateLive(java.util.Set filter)

Propagate liveness state forward to consuming generators, but only those within the filter set.

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Overview  Package   Class  Use  Deprecated  Index
Home >> All >> com >> hp >> hpl >> jena >> reasoner >> rulesys >> [ impl overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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