Interface FOQueryEvaluator<Formula extends FOFormula, QD extends QueryableData>

Type Parameters:

Formula - The type of FOFormula that the evaluator can evaluate

QD - The type of QueryableData evaluated by this evaluator

All Superinterfaces:

QueryEvaluator<FOQuery<? extends Formula>, QD>

All Known Implementing Classes:

AtomicFOQueryEvaluator, BacktrackEvaluator, FOQueryEvaluatorWithDBMSDelegation, GenericFOQueryEvaluator, InfAtomicFOQueryEvaluator, IntersectFOQueryConjunctionEvaluator, LegacyBacktrackEvaluator, NegationFOQueryEvaluator, UnfoldingAtomicFOQueryEvaluator

public interface FOQueryEvaluator<Formula extends FOFormula, QD extends QueryableData>
extends QueryEvaluator<FOQuery<? extends Formula>, QD>

An FOQuery evaluator is one possible algorithm to evaluate a FOQuery.
Evaluating a FOQuery means retrieving all the Substitution of the answer variables from the query with respect to the atoms from the Readable.

Method Summary

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

Methods inherited from interface QueryEvaluator

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

Method Details

evaluate

Stream<Substitution> evaluate(FOQuery<? extends Formula> query,
 QD queryableData,
 Collection<Variable> variablesThatMustBeMappedToConstants,
 Substitution preHomomorphism)
                       throws EvaluationException

Evaluates a first-order query against a data source.

Specified by:

evaluate in interface QueryEvaluator<Formula extends FOFormula, QD extends QueryableData>

Parameters:

query - the query to evaluate

queryableData - the data source against which the query is evaluated

variablesThatMustBeMappedToConstants - 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

default PreparedFOQuery<? extends Formula, QD> prepareQuery(FOQuery<? extends Formula> query,
 QD queryableData,
 Collection<Variable> variablesThatMustBeMappedToGroundTerms)

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

Specified by:

prepareQuery in interface QueryEvaluator<Formula extends FOFormula, QD extends QueryableData>

Parameters:

query - the query to prepare

queryableData - the data source against which the query will run

variablesThatMustBeMappedToGroundTerms - variables constrained to ground answers

Returns:

a prepared query wrapper

prepareQuery

default PreparedFOQuery<? extends Formula, QD> prepareQuery(FOQuery<? extends Formula> query,
 QD queryableData,
 boolean answerVariablesMustBeGround)

Creates a prepared first-order query bound to a data source.

Specified by:

prepareQuery in interface QueryEvaluator<Formula extends FOFormula, QD extends QueryableData>

Parameters:

query - the query to prepare

queryableData - the data source against which the query will run

answerVariablesMustBeGround - whether answer variables must map to ground terms

Returns:

a prepared query wrapper