org.projog.core.predicate.builtin.compound

Class Once

java.lang.Object

org.projog.core.predicate.AbstractSingleResultPredicate

org.projog.core.predicate.builtin.compound.Once

All Implemented Interfaces:

KnowledgeBaseConsumer, PredicateFactory, PreprocessablePredicateFactory

public final class Once
extends AbstractSingleResultPredicate
implements PreprocessablePredicateFactory

once(X) - calls the goal represented by a term.

The once(X) goal succeeds if an attempt to satisfy the goal represented by the term X succeeds. No attempt is made to retry the goal during backtracking - it is only evaluated once.

Constructor Summary

Constructors

Constructor and Description
Once()

Method Summary

Modifier and Type	Method and Description
protected boolean	evaluate(Term t)
PredicateFactory	preprocess(Term term)

Methods inherited from class org.projog.core.predicate.AbstractSingleResultPredicate

evaluate, evaluate, evaluate, evaluate, evaluate, getArithmeticOperators, getFileHandles, getKnowledgeBase, getOperands, getPredicate, getPredicates, getProjogListeners, getSpyPoints, getTermFormatter, init, isRetryable, setKnowledgeBase

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

getPredicate, isAlwaysCutOnBacktrack, isRetryable

Constructor Detail

Once

public Once()

Method Detail

evaluate

protected boolean evaluate(Term t)

Overrides:

evaluate in class AbstractSingleResultPredicate

preprocess

public PredicateFactory preprocess(Term term)

Specified by:

preprocess in interface PreprocessablePredicateFactory