Package org.projog.core.predicate.udp

Class SingleRetryableRulePredicateFactory

java.lang.Object

org.projog.core.predicate.udp.SingleRetryableRulePredicateFactory

All Implemented Interfaces:

PredicateFactory, PreprocessablePredicateFactory

final class SingleRetryableRulePredicateFactory
extends java.lang.Object
implements PreprocessablePredicateFactory

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	SingleRetryableRulePredicateFactory.RetryableRulePredicate

Field Summary

Fields

Modifier and Type	Field	Description
private ClauseAction	clause
private SpyPoints.SpyPoint	spyPoint

Constructor Summary

Constructors

Constructor	Description
SingleRetryableRulePredicateFactory(ClauseAction clause, SpyPoints.SpyPoint spyPoint)

Method Summary

Modifier and Type	Method	Description
SingleRetryableRulePredicateFactory.RetryableRulePredicate	getPredicate(Term[] args)	Returns a Predicate to be used in the evaluation of a goal.
boolean	isRetryable()	Should instances of this implementation be re-evaluated when backtracking?
PredicateFactory	preprocess(Term arg)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.projog.core.predicate.PredicateFactory

isAlwaysCutOnBacktrack

Field Detail

clause

private final ClauseAction clause

spyPoint

private final SpyPoints.SpyPoint spyPoint

Constructor Detail

SingleRetryableRulePredicateFactory

public SingleRetryableRulePredicateFactory(ClauseAction clause,
                                           SpyPoints.SpyPoint spyPoint)

Method Detail

getPredicate

public SingleRetryableRulePredicateFactory.RetryableRulePredicate getPredicate(Term[] args)

Description copied from interface: PredicateFactory

Returns a Predicate to be used in the evaluation of a goal.

Specified by:

getPredicate in interface PredicateFactory

Parameters:

args - the arguments to use in the evaluation of the goal

Returns:

Predicate to be used in the evaluation of the goal

See Also:

Predicate.evaluate()

isRetryable

public boolean isRetryable()

Description copied from interface: PredicateFactory

Should instances of this implementation be re-evaluated when backtracking?

Some goals (e.g. X is 1) are only meant to be evaluated once (the statement is either true or false) while others (e.g. repeat(3)) are meant to be evaluated multiple times. For instances of Predicate that are designed to possibly have Predicate.evaluate() called on them multiple times for the same individual query this method should return true. For instances of Predicate that are designed to only be evaluated once per individual query this method should return false.

Specified by:

isRetryable in interface PredicateFactory

Returns:

true if an attempt should be made to re-evaluate instances of implementing classes when backtracking, false otherwise

preprocess

public PredicateFactory preprocess(Term arg)

Specified by:

preprocess in interface PreprocessablePredicateFactory