Package org.projog.core.predicate

Class AbstractPredicateFactory

java.lang.Object

org.projog.core.predicate.AbstractPredicateFactory

All Implemented Interfaces:

KnowledgeBaseConsumer, PredicateFactory

Direct Known Subclasses:

Append, AtomConcat, BagOf, Between, CharType, Conjunction, Conjunction.OptimisedRetryableConjuction, CurrentPredicate, Cut, Disjunction, Fold, IfThen, Inspect, Last, Length, Limit, Member, Nth, Recorded, RepeatInfinitely, RepeatSetAmount, Resolve, Reverse, Select, SetOf

public abstract class AbstractPredicateFactory
extends java.lang.Object
implements PredicateFactory, KnowledgeBaseConsumer

Field Summary

Fields

Modifier and Type	Field	Description
private KnowledgeBase	knowledgeBase

Constructor Summary

Constructors

Constructor	Description
AbstractPredicateFactory()

Method Summary

Modifier and Type	Method	Description
private java.lang.IllegalArgumentException	createWrongNumberOfArgumentsException(int numberOfArguments)
protected ArithmeticOperators	getArithmeticOperators()
protected FileHandles	getFileHandles()
protected KnowledgeBase	getKnowledgeBase()
protected Operands	getOperands()
protected Predicate	getPredicate()
protected Predicate	getPredicate(Term arg)
Predicate	getPredicate(Term[] args)	Returns a Predicate to be used in the evaluation of a goal.
protected Predicate	getPredicate(Term arg1, Term arg2)
protected Predicate	getPredicate(Term arg1, Term arg2, Term arg3)
protected Predicate	getPredicate(Term arg1, Term arg2, Term arg3, Term arg4)
protected Predicates	getPredicates()
protected ProjogListeners	getProjogListeners()
protected SpyPoints	getSpyPoints()
protected TermFormatter	getTermFormatter()
protected void	init()	This method is called by setKnowledgeBase(KnowledgeBase).
boolean	isRetryable()	Should instances of this implementation be re-evaluated when backtracking?
void	setKnowledgeBase(KnowledgeBase knowledgeBase)	Provides a reference to a KnowledgeBase.

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

knowledgeBase

private KnowledgeBase knowledgeBase

Constructor Detail

AbstractPredicateFactory

public AbstractPredicateFactory()

Method Detail

getPredicate

public final 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()

getPredicate

protected Predicate getPredicate()

getPredicate

protected Predicate getPredicate(Term arg)

getPredicate

protected Predicate getPredicate(Term arg1,
                                 Term arg2)

getPredicate

protected Predicate getPredicate(Term arg1,
                                 Term arg2,
                                 Term arg3)

getPredicate

protected Predicate getPredicate(Term arg1,
                                 Term arg2,
                                 Term arg3,
                                 Term arg4)

createWrongNumberOfArgumentsException

private java.lang.IllegalArgumentException createWrongNumberOfArgumentsException(int numberOfArguments)

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

setKnowledgeBase

public final void setKnowledgeBase(KnowledgeBase knowledgeBase)

Description copied from interface: KnowledgeBaseConsumer

Provides a reference to a KnowledgeBase.

Specified by:

setKnowledgeBase in interface KnowledgeBaseConsumer

init

protected void init()

This method is called by setKnowledgeBase(KnowledgeBase).

Can be overridden by subclasses to perform initialisation before any calls to getPredicate(Term[]) are made. As setKnowledgeBase(KnowledgeBase) will have already been called before this method is invoked, overridden versions will be able to access the KnowledgeBase using getKnowledgeBase().

getKnowledgeBase

protected final KnowledgeBase getKnowledgeBase()

getPredicates

protected final Predicates getPredicates()

getArithmeticOperators

protected final ArithmeticOperators getArithmeticOperators()

getProjogListeners

protected final ProjogListeners getProjogListeners()

getOperands

protected final Operands getOperands()

getTermFormatter

protected final TermFormatter getTermFormatter()

getSpyPoints

protected final SpyPoints getSpyPoints()

getFileHandles

protected final FileHandles getFileHandles()