Class BooleanConstraintPredicate

java.lang.Object

org.projog.core.predicate.builtin.clp.BooleanConstraintPredicate

All Implemented Interfaces:

KnowledgeBaseConsumer, ConstraintFactory, PredicateFactory

public final class BooleanConstraintPredicate
extends Object
implements PredicateFactory, ConstraintFactory, KnowledgeBaseConsumer

CLP predicates for comparing boolean values.

Integer values are used to represent boolean values. 1 repesents true and 0 represents false.

• #/\ and
• #\/ or
• #\ exclusive or
• #<==> equivalent
• #==> implication

Method Summary

Modifier and Type	Method	Description
static BooleanConstraintPredicate	and()
org.projog.clp.Constraint	createConstraint(Term term, Set<org.projog.core.predicate.builtin.clp.ClpVariable> vars)
static BooleanConstraintPredicate	equivalent()
Predicate	getPredicate(Term term)	Returns a Predicate to be used in the evaluation of a goal.
boolean	isRetryable()	Should instances of this implementation be re-evaluated when backtracking?
static BooleanConstraintPredicate	leftImpliesRight()
static BooleanConstraintPredicate	not()
static BooleanConstraintPredicate	or()
static BooleanConstraintPredicate	rightImpliesLeft()
void	setKnowledgeBase(KnowledgeBase knowledgeBase)	Provides a reference to a KnowledgeBase.
static BooleanConstraintPredicate	xor()

Methods inherited from class Object

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

Methods inherited from interface PredicateFactory

isAlwaysCutOnBacktrack, preprocess

Method Details

equivalent

public static BooleanConstraintPredicate equivalent()

leftImpliesRight

public static BooleanConstraintPredicate leftImpliesRight()

rightImpliesLeft

public static BooleanConstraintPredicate rightImpliesLeft()

and

public static BooleanConstraintPredicate and()

or

public static BooleanConstraintPredicate or()

xor

public static BooleanConstraintPredicate xor()

not

public static BooleanConstraintPredicate not()

getPredicate

public Predicate getPredicate(Term term)

Description copied from interface: PredicateFactory

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

Specified by:

getPredicate in interface PredicateFactory

Parameters:

term - the term containing 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

createConstraint

public org.projog.clp.Constraint createConstraint(Term term,
 Set<org.projog.core.predicate.builtin.clp.ClpVariable> vars)

Specified by:

createConstraint in interface ConstraintFactory

setKnowledgeBase

public void setKnowledgeBase(KnowledgeBase knowledgeBase)

Description copied from interface: KnowledgeBaseConsumer

Provides a reference to a KnowledgeBase.

Specified by:

setKnowledgeBase in interface KnowledgeBaseConsumer