org.projog.core.math

Class ArithmeticOperators

java.lang.Object

org.projog.core.math.ArithmeticOperators

public final class ArithmeticOperators
extends Object

Maintains a collection of ArithmeticOperator instances.

This class provides a mechanism for "plugging in" or "injecting" implementations of ArithmeticOperator at runtime. This mechanism provides an easy way to configure and extend the arithmetic operations supported by Projog.

Each KnowledgeBase has a single unique ArithmeticOperators instance.

Constructor Summary

Constructors

Constructor and Description
ArithmeticOperators(KnowledgeBase kb)

Method Summary

Modifier and Type	Method and Description
void	addArithmeticOperator(PredicateKey key, ArithmeticOperator operator) Associates a ArithmeticOperator with this KnowledgeBase.
void	addArithmeticOperator(PredicateKey key, String operatorClassName) Associates a ArithmeticOperator with this KnowledgeBase.
ArithmeticOperator	getArithmeticOperator(PredicateKey key)
Numeric	getNumeric(Term t) Returns the result of evaluating the specified arithmetic expression.
ArithmeticOperator	getPreprocessedArithmeticOperator(Term argument)

Methods inherited from class java.lang.Object

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

Constructor Detail

ArithmeticOperators

public ArithmeticOperators(KnowledgeBase kb)

Method Detail

addArithmeticOperator

public void addArithmeticOperator(PredicateKey key,
                                  ArithmeticOperator operator)

Associates a ArithmeticOperator with this KnowledgeBase.

Parameters:

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

operator - The instance of ArithmeticOperator to be associated with key.

Throws:

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

addArithmeticOperator

public void addArithmeticOperator(PredicateKey key,
                                  String operatorClassName)

Associates a ArithmeticOperator with this KnowledgeBase.

Parameters:

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

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

Throws:

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

getNumeric

public Numeric getNumeric(Term t)

Returns the result of evaluating the specified arithmetic expression.

Parameters:

t - a Term that can be evaluated as an arithmetic expression (e.g. a Structure of the form +(1,2) or a Numeric)

Returns:

the result of evaluating the specified arithmetic expression

Throws:

ProjogException - if the specified term does not represent an arithmetic expression

getPreprocessedArithmeticOperator

public ArithmeticOperator getPreprocessedArithmeticOperator(Term argument)

Returns:

null if not found

getArithmeticOperator

public ArithmeticOperator getArithmeticOperator(PredicateKey key)

Throws:

ProjogException - if not found