org.deri.iris.builtins
Class ArithmeticBuiltin

java.lang.Object
  org.deri.iris.builtins.AbstractBuiltin
      org.deri.iris.builtins.ArithmeticBuiltin

All Implemented Interfaces:

Comparable<IAtom>, IAtom, IBuiltinAtom

Direct Known Subclasses:

AddBuiltin, DivideBuiltin, EqualBuiltin, ExactEqualBuiltin, MaxBuiltin, ModulusBuiltin, MultiplyBuiltin, SubtractBuiltin

public abstract class ArithmeticBuiltin
extends AbstractBuiltin

Base class of arithmetic built-in predicates. This kind of built-in has: a) can have any arity b) can be evaluated with up to 1 unknown variable c) the unknown variable can be at any position d) if all terms are known at evaluation time, the result is checked to indicate true or false

Field Summary

Fields inherited from class org.deri.iris.builtins.AbstractBuiltin

EMPTY_TERM

Constructor Summary

ArithmeticBuiltin(IPredicate predicate, ITerm... terms)
Constructor.

Method Summary

protected abstract ITerm	computeMissingTerm(int missingTermIndex, ITerm[] terms) Compute the missing term when the other two are known.
protected ITerm	evaluateTerms(ITerm[] terms, int[] variableIndexes) Evaluate the predicate once the terms and variable indexes have been found.
int	maxUnknownVariables() The maximum number of unknown variables allowed such that the predicate can still be evaluated.
protected boolean	testForEquality(ITerm t1, ITerm t2)

Methods inherited from class org.deri.iris.builtins.AbstractBuiltin

compareTo, equals, evaluate, getPredicate, getTuple, hashCode, isBuiltin, isGround, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ArithmeticBuiltin

public ArithmeticBuiltin(IPredicate predicate,
                         ITerm... terms)

Constructor.

Parameters:

predicate - The predicate that identifies this built-in.

terms - The terms of the instance. Must be 3.

Method Detail

evaluateTerms

protected ITerm evaluateTerms(ITerm[] terms,
                              int[] variableIndexes)
                       throws EvaluationException

Description copied from class: AbstractBuiltin

Evaluate the predicate once the terms and variable indexes have been found.

Overrides:

evaluateTerms in class AbstractBuiltin

Parameters:

terms - The array of all terms for this evaluation.

variableIndexes - the indexes of the terms which should be computed (starting at 0)

Returns:

The result of the evaluation.

Throws:

EvaluationException

testForEquality

protected boolean testForEquality(ITerm t1,
                                  ITerm t2)

computeMissingTerm

protected abstract ITerm computeMissingTerm(int missingTermIndex,
                                            ITerm[] terms)
                                     throws EvaluationException

Compute the missing term when the other two are known.

Parameters:

terms - The collection of all terms.

Returns:

The computed value.

Throws:

EvaluationException

maxUnknownVariables

public int maxUnknownVariables()

Description copied from interface: IBuiltinAtom

The maximum number of unknown variables allowed such that the predicate can still be evaluated.

Specified by:

maxUnknownVariables in interface IBuiltinAtom

Overrides:

maxUnknownVariables in class AbstractBuiltin

Returns:

The maximum number of unknown variables.