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package fr.boreal.model.kb.api;
import java.util.Collection;
import java.util.Iterator;
import fr.boreal.model.logicalElements.api.Substitution;
import fr.boreal.model.query.api.FOQuery;
import fr.boreal.model.rule.api.FORule;
/**
* This interface represents storage systems that can directly apply datalog
* rules as part of their implementation. Datalog rules are rules without
* existential variables.
*
* This is extended to the direct evaluation of conjunctive queries.
*
*/
public interface DatalogDelegable extends Readable, Writeable {
/**
* Apply all the given (datalog) rules.
*
* @param rules the rules to apply
* @return true iff at least one atom have been produced by the application of
* the rules
* @throws Exception if a given rule is not datalog. The exact type is depending
* on the implementation
*/
boolean delegate(Collection rules) throws Exception;
/**
* Evaluate the given (conjunctive) query
*
* @param query the query to evaluate
* @param countAnswersOnly true iff the query has to return only the number of
* answers
* @return an {@link Iterator} of {@link Substitution} over all the answers of
* the given query with respect to the query answer variables.
* @throws Exception if the given query is not conjunctive. The exact type is
* depending on the implementation
*/
Iterator delegate(FOQuery query, boolean countAnswersOnly) throws Exception;
/**
* Evaluate the given (conjunctive) query
*
* @param query the query to evaluate
* @return an {@link Iterator} of {@link Substitution} over all the answers of
* the given query with respect to the query answer variables.
* @throws Exception if the given query is not conjunctive. The exact type is
**/
default Iterator delegate(FOQuery query) throws Exception {
return delegate(query, false);
}
}