Package org.projog.core.predicate.builtin.compound

Class Disjunction.OptimisedIfThenElse

java.lang.Object

org.projog.core.predicate.builtin.compound.Disjunction.OptimisedIfThenElse

All Implemented Interfaces:

PredicateFactory

Enclosing class:

Disjunction

private static class Disjunction.OptimisedIfThenElse
extends java.lang.Object
implements PredicateFactory

Field Summary

Fields

Modifier and Type	Field	Description
private PredicateFactory	condition
private PredicateFactory	elsePf
private PredicateFactory	thenPf

Constructor Summary

Constructors

Constructor	Description
OptimisedIfThenElse(PredicateFactory condition, PredicateFactory thenPf, PredicateFactory elsePf)

Method Summary

Modifier and Type	Method	Description
Predicate	getPredicate(Term[] args)	Returns a Predicate to be used in the evaluation of a goal.
boolean	isAlwaysCutOnBacktrack()	Will attempting to re-evaluate this implementation always result in a cut?
boolean	isRetryable()	Should instances of this implementation be re-evaluated when backtracking?

Methods inherited from class java.lang.Object

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

Field Detail

condition

private final PredicateFactory condition

thenPf

private final PredicateFactory thenPf

elsePf

private final PredicateFactory elsePf

Constructor Detail

OptimisedIfThenElse

OptimisedIfThenElse(PredicateFactory condition,
                    PredicateFactory thenPf,
                    PredicateFactory elsePf)

Method Detail

getPredicate

public Predicate 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

isAlwaysCutOnBacktrack

public boolean isAlwaysCutOnBacktrack()

Description copied from interface: PredicateFactory

Will attempting to re-evaluate this implementation always result in a cut?

Specified by:

isAlwaysCutOnBacktrack in interface PredicateFactory

Returns:

true if a cut will always be encountered when attempting to re-evaluate, false otherwise