org.projog.core.kb

Class KnowledgeBaseUtils

java.lang.Object

org.projog.core.kb.KnowledgeBaseUtils

public final class KnowledgeBaseUtils
extends Object

Helper methods for performing common tasks on KnowledgeBase instances.

Field Summary

Fields

Modifier and Type	Field and Description
static String	CONJUNCTION_PREDICATE_NAME The functor of structures representing conjunctions (,).
static String	IMPLICATION_PREDICATE_NAME The functor of structures representing implications (:-).
static String	QUESTION_PREDICATE_NAME The functor of structures representing questions (i.e.

Method Summary

Modifier and Type	Method and Description
static void	bootstrap(KnowledgeBase kb) Consults the ProjogProperties.getBootstrapScript() for the KnowledgeBase.
static KnowledgeBase	createKnowledgeBase() Constructs a new KnowledgeBase object using ProjogDefaultProperties
static KnowledgeBase	createKnowledgeBase(ProjogProperties projogProperties) Constructs a new KnowledgeBase object using the specified ProjogProperties
static List<PredicateKey>	getPredicateKeysByName(KnowledgeBase kb, String predicateName) Returns list of all user defined predicates with the specified name.
static <T> T	instantiate(KnowledgeBase knowledgeBase, String input) Returns a new object created using reflection.
static boolean	isConjunction(Term t) Returns true if the specified Term represent a conjunction, else false.
static boolean	isQuestionOrDirectiveFunctionCall(Term t) Returns true if the specified Term represents a question or directive, else false.
static boolean	isSingleAnswer(KnowledgeBase kb, Term term) Returns true if the predicate represented by the specified Term never succeeds on re-evaluation.
static Term[]	toArrayOfConjunctions(Term t) Returns an array of all Terms that make up the conjunction represented by the specified Term.

Methods inherited from class java.lang.Object

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

Field Detail

CONJUNCTION_PREDICATE_NAME

public static final String CONJUNCTION_PREDICATE_NAME

The functor of structures representing conjunctions (,).

See Also:

Constant Field Values

IMPLICATION_PREDICATE_NAME

public static final String IMPLICATION_PREDICATE_NAME

The functor of structures representing implications (:-).

See Also:

Constant Field Values

QUESTION_PREDICATE_NAME

public static final String QUESTION_PREDICATE_NAME

The functor of structures representing questions (i.e. queries) (?-).

See Also:

Constant Field Values

Method Detail

createKnowledgeBase

public static KnowledgeBase createKnowledgeBase()

Constructs a new KnowledgeBase object using ProjogDefaultProperties

createKnowledgeBase

public static KnowledgeBase createKnowledgeBase(ProjogProperties projogProperties)

Constructs a new KnowledgeBase object using the specified ProjogProperties

bootstrap

public static void bootstrap(KnowledgeBase kb)

Consults the ProjogProperties.getBootstrapScript() for the KnowledgeBase.

This is a way to configure a new KnowledgeBase (i.e. plugging in ArithmeticOperator and PredicateFactory instances).

When using ProjogDefaultProperties the resource parsed will be projog-bootstrap.pl (contained in projog-core.jar).

See Also:

ProjogSourceReader.parseResource(KnowledgeBase, String)

getPredicateKeysByName

public static List<PredicateKey> getPredicateKeysByName(KnowledgeBase kb,
                                                        String predicateName)

Returns list of all user defined predicates with the specified name.

isQuestionOrDirectiveFunctionCall

public static boolean isQuestionOrDirectiveFunctionCall(Term t)

Returns true if the specified Term represents a question or directive, else false.

A Term is judged to represent a question if it is a structure a single argument and with a functor QUESTION_PREDICATE_NAME or IMPLICATION_PREDICATE_NAME.

isSingleAnswer

public static boolean isSingleAnswer(KnowledgeBase kb,
                                     Term term)

Returns true if the predicate represented by the specified Term never succeeds on re-evaluation.

toArrayOfConjunctions

public static Term[] toArrayOfConjunctions(Term t)

Returns an array of all Terms that make up the conjunction represented by the specified Term.

If the specified Term does not represent a conjunction then it will be used as the only element in the returned array.

isConjunction

public static boolean isConjunction(Term t)

Returns true if the specified Term represent a conjunction, else false.

A Term is judged to represent a conjunction if is a structure with a functor of CONJUNCTION_PREDICATE_NAME and exactly two arguments.

instantiate

public static <T> T instantiate(KnowledgeBase knowledgeBase,
                                String input)
                         throws ReflectiveOperationException

Returns a new object created using reflection.

The input parameter can be in one of two formats:

1. The class name - e.g. java.lang.String - this will cause an attempt to create a new instance of the specified class using its no argument constructor.
2. The class name and a method name (separated by a /) - e.g. java.util.Calendar/getInstance - this will cause an attempt to create a new instance of the class by invoking the specified method (as a no argument static method) of the specified class.

Throws:

ReflectiveOperationException