Class BacktrackEvaluator<QD extends QueryableData>

java.lang.Object

fr.inria.rules.integraal.query_evaluation.conjunction.backtrack.BacktrackEvaluator<QD>

Type Parameters:

QD - concrete QueryableData type

All Implemented Interfaces:

FOQueryEvaluator<FOFormulaConjunction, QD>, QueryEvaluator<FOQuery<? extends FOFormulaConjunction>, QD>

public class BacktrackEvaluator<QD extends QueryableData>
extends Object
implements FOQueryEvaluator<FOFormulaConjunction, QD>

Generic back-tracking evaluator for conjunctive first-order queries.

The implementation follows the algorithm introduced in chapter 5 of Jean-François Baget thesis (see http://www.lirmm.fr/~baget/publications/ thesis.pdf). All context-independent routines (equalities, function extraction, answer rebuilding) are delegated to the shared utility classes in fr.inria.rules.integraal.query_evaluation.util.

Author:

Guillaume Perution-Kihli

Constructor Summary

Constructors

Constructor	Description
BacktrackEvaluator(FOQueryEvaluator<FOFormula, QueryableData> evaluator)	Creates a backtrack evaluator using the default dynamic scheduler.
BacktrackEvaluator(FOQueryEvaluator<FOFormula, QueryableData> evaluator, Function<List<PreparedFOQuery<? extends FOFormula, QD>>, Scheduler<QD>> schedulerProvider)	Creates a backtrack evaluator with an explicit scheduler provider.

Method Summary

Modifier and Type	Method	Description
Stream<Substitution>	evaluate(FOQuery<? extends FOFormulaConjunction> query, QD queryableData, Collection<Variable> mustBeGround, Substitution preHomomorphism)	Evaluates a first-order query against a data source.
PreparedFOQuery<? extends FOFormulaConjunction, QD>	prepareQuery(FOQuery<? extends FOFormulaConjunction> query, QD queryableData, Collection<Variable> mustBeGround)	Creates a prepared first-order query bound to a data source and ground-term policy.

Methods inherited from class Object

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

Methods inherited from interface FOQueryEvaluator

prepareQuery

Methods inherited from interface QueryEvaluator

countAnswers, countHomomorphism, evaluate, evaluate, existAnswer, existAnswer, existHomomorphism, existHomomorphism, homomorphism, homomorphism, postprocessResult, postprocessResult

Constructor Details

BacktrackEvaluator

public BacktrackEvaluator(FOQueryEvaluator<FOFormula, QueryableData> evaluator,
 Function<List<PreparedFOQuery<? extends FOFormula, QD>>, Scheduler<QD>> schedulerProvider)

Creates a backtrack evaluator with an explicit scheduler provider.

Parameters:

evaluator - the delegated evaluator used for subqueries

schedulerProvider - the factory creating schedulers for prepared subqueries

BacktrackEvaluator

public BacktrackEvaluator(FOQueryEvaluator<FOFormula, QueryableData> evaluator)

Creates a backtrack evaluator using the default dynamic scheduler.

Parameters:

evaluator - the delegated evaluator used for subqueries

Method Details

evaluate

public Stream<Substitution> evaluate(FOQuery<? extends FOFormulaConjunction> query,
 QD queryableData,
 Collection<Variable> mustBeGround,
 Substitution preHomomorphism)
                              throws EvaluationException

Description copied from interface: FOQueryEvaluator

Evaluates a first-order query against a data source.

Specified by:

evaluate in interface FOQueryEvaluator<FOFormulaConjunction, QD extends QueryableData>

Specified by:

evaluate in interface QueryEvaluator<FOQuery<? extends FOFormulaConjunction>, QD extends QueryableData>

Parameters:

query - the query to evaluate

queryableData - the data source against which the query is evaluated

mustBeGround - variables constrained to constant answers

preHomomorphism - a partial substitution to extend

Returns:

a stream of substitutions answering the query

Throws:

EvaluationException - if the evaluation cannot be completed

prepareQuery

public PreparedFOQuery<? extends FOFormulaConjunction, QD> prepareQuery(FOQuery<? extends FOFormulaConjunction> query,
 QD queryableData,
 Collection<Variable> mustBeGround)

Description copied from interface: FOQueryEvaluator

Creates a prepared first-order query bound to a data source and ground-term policy.

Specified by:

prepareQuery in interface FOQueryEvaluator<FOFormulaConjunction, QD extends QueryableData>

Specified by:

prepareQuery in interface QueryEvaluator<FOQuery<? extends FOFormulaConjunction>, QD extends QueryableData>

Parameters:

query - the query to prepare

queryableData - the data source against which the query will run

mustBeGround - variables constrained to ground answers

Returns:

a prepared query wrapper