Class LegacyBacktrackEvaluator<QD extends QueryableData>

java.lang.Object

fr.inria.rules.integraal.query_evaluation.conjunction.backtrack.legacy.LegacyBacktrackEvaluator<QD>

Type Parameters:

QD - the type of queryable data evaluated by this backtracker

All Implemented Interfaces:

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

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

Evaluates a query with a conjunctive formula by using homomorphism computing using backtrack algorithm to aggregate the result of each sub-query
To evaluate a given query, a sub-query is chosen and evaluated. The first result is assumed correct and the next sub-query is evaluated. If the results of the second sub-query are consistent with the first (assumed correct) result, the next sub-query is evaluated and so on. When a sub-query result is not consistent with the previous results, a step of backtrack is used to go back on the assumed result and take the next answer. If there is no more answer to go back to, it is also considered inconsistent.
This Backtrack algorithm is inspired by the Baget Jean-François Thesis (Chapter 5) See ... for more information

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	LegacyBacktrackEvaluator.BacktrackIterator	The BacktrackIterator is used to redefine the iterator return as an answer to the query.

Field Summary

Fields

Modifier and Type	Field	Description
protected final FOQueryEvaluator<FOFormula, QD>	evaluator	Query evaluator used to evaluate the sub-queries
protected BiFunction<FOQuery<? extends FOFormulaConjunction>, QD, Scheduler>	schedulerBuilder	Function for creating Scheduler instances based on the query and queryableData

Constructor Summary

Constructors

Constructor	Description
LegacyBacktrackEvaluator(FOQueryEvaluator<FOFormula, QD> evaluator)	Creates a new evaluator using the given evaluator to evaluate sub-queries
LegacyBacktrackEvaluator(FOQueryEvaluator<FOFormula, QD> evaluator, BiFunction<FOQuery<? extends FOFormulaConjunction>, QD, Scheduler> schedulerBuilder)	Creates a new evaluator using the given evaluator to evaluate sub-queries and a function to create Schedulers

Method Summary

Modifier and Type	Method	Description
Stream<Substitution>	evaluate(FOQuery<? extends FOFormulaConjunction> query, QD queryableData, Collection<Variable> vars, Substitution preHomomorphism)	//////////////////////////////////////////////

Methods inherited from class Object

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

Methods inherited from interface FOQueryEvaluator

prepareQuery, prepareQuery

Methods inherited from interface QueryEvaluator

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

Field Details

evaluator

protected final FOQueryEvaluator<FOFormula, QD extends QueryableData> evaluator

Query evaluator used to evaluate the sub-queries

schedulerBuilder

protected BiFunction<FOQuery<? extends FOFormulaConjunction>, QD extends QueryableData, Scheduler> schedulerBuilder

Function for creating Scheduler instances based on the query and queryableData

Constructor Details

LegacyBacktrackEvaluator

public LegacyBacktrackEvaluator(FOQueryEvaluator<FOFormula, QD> evaluator,
 BiFunction<FOQuery<? extends FOFormulaConjunction>, QD, Scheduler> schedulerBuilder)

Creates a new evaluator using the given evaluator to evaluate sub-queries and a function to create Schedulers

Parameters:

evaluator - the query evaluator to use for recursive calls

schedulerBuilder - the function to create Scheduler instances based on the query and queryableData

LegacyBacktrackEvaluator

public LegacyBacktrackEvaluator(FOQueryEvaluator<FOFormula, QD> evaluator)

Creates a new evaluator using the given evaluator to evaluate sub-queries

Parameters:

evaluator - the query evaluator to use for recursive calls

Method Details

evaluate

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

//////////////////////////////////////////////

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

vars - variables constrained to constant answers

preHomomorphism - a partial substitution to extend

Returns:

a stream of substitutions answering the query