Class ExpressionFactories

java.lang.Object

org.projog.core.predicate.builtin.clp.ExpressionFactories

public final class ExpressionFactories
extends Object

Maintains a collection of ExpressionFactory instances.

This class provides a mechanism for "plugging in" or "injecting" implementations of org.projog.clp.Expression at runtime. This mechanism provides an easy way to configure and extend the CLP expressions supported by Projog.

Each KnowledgeBase has at most one unique ClpExpressions instance.

Field Summary

Fields

Modifier and Type	Field	Description
private final Map<PredicateKey, String>	factoryClassNames
private final Map<PredicateKey, ExpressionFactory>	factoryInstances
private final KnowledgeBase	kb
private final Object	lock

Constructor Summary

Constructors

Constructor	Description
ExpressionFactories(KnowledgeBase kb)

Method Summary

Modifier and Type	Method	Description
void	addExpressionFactory(PredicateKey key, String operatorClassName)	Associates a ExpressionFactory with this KnowledgeBase.
private ExpressionFactory	getExpressionFactory(PredicateKey key)
private ExpressionFactory	instantiateExpressionFactory(String className)
private ExpressionFactory	instantiateExpressionFactory(PredicateKey key)
org.projog.clp.Expression	toExpression(Term t, Set<ClpVariable> vars)

Methods inherited from class Object

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

Field Details

kb

private final KnowledgeBase kb

lock

private final Object lock

factoryClassNames

private final Map<PredicateKey, String> factoryClassNames

factoryInstances

private final Map<PredicateKey, ExpressionFactory> factoryInstances

Constructor Details

ExpressionFactories

public ExpressionFactories(KnowledgeBase kb)

Method Details

addExpressionFactory

public void addExpressionFactory(PredicateKey key,
 String operatorClassName)

Associates a ExpressionFactory with this KnowledgeBase.

Parameters:

key - The name and arity to associate the ExpressionFactory with.

operatorClassName - The class name of the ExpressionFactory to be associated with key.

Throws:

ProjogException - if there is already a ExpressionFactory associated with the PredicateKey

toExpression

public org.projog.clp.Expression toExpression(Term t,
 Set<ClpVariable> vars)

getExpressionFactory

private ExpressionFactory getExpressionFactory(PredicateKey key)

instantiateExpressionFactory

private ExpressionFactory instantiateExpressionFactory(PredicateKey key)

instantiateExpressionFactory

private ExpressionFactory instantiateExpressionFactory(String className)