// Copyright (c) 2006 - 2008, Clark & Parsia, LLC. <http://www.clarkparsia.com>
// This source code is available under the terms of the Affero General Public License v3.
//
// Please see LICENSE.txt for full license terms, including the availability of proprietary exceptions.
// Questions, comments, or requests for clarification: licensing@clarkparsia.com
package com.clarkparsia.pellet.sparqldl.engine;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.mindswap.pellet.KnowledgeBase;
import org.mindswap.pellet.utils.ATermUtils;
import com.clarkparsia.pellet.sparqldl.model.Query;
import com.clarkparsia.pellet.sparqldl.model.QueryAtom;
import com.clarkparsia.pellet.sparqldl.model.QueryPredicate;
import com.clarkparsia.pellet.sparqldl.model.QueryResult;
import com.clarkparsia.pellet.sparqldl.model.QueryResultImpl;
import com.clarkparsia.pellet.sparqldl.model.ResultBinding;
import com.clarkparsia.pellet.sparqldl.model.ResultBindingImpl;
import aterm.ATermAppl;
/**
* <p>
* Title: SimpleQueryEngine
* </p>
* <p>
* Description:
* </p>
* <p>
* Copyright: Copyright (c) 2007
* </p>
* <p>
* Company: Clark & Parsia, LLC. <http://www.clarkparsia.com>
* </p>
*
* @author Petr Kremen
*/
public class OptimizedQueryEngine2 extends AbstractABoxEngineWrapper {
public static final Logger log = Logger.getLogger(QueryEngine.class.getName());
private QueryResult results;
private KnowledgeBase kb;
/**
* {@inheritDoc}
*/
public boolean supports(final Query q) {
return !q.getDistVars().isEmpty();
}
private void exec(final Query q, final ResultBinding binding,
final boolean first) {
if (q.getDistVars().isEmpty()) {
results.add(binding);
return;
}
final Iterator<ATermAppl> i = q.getDistVars().iterator();
final ATermAppl var = i.next();
Collection<ATermAppl> empty = Collections.emptySet();
final ATermAppl clazz = q.rollUpTo(var, empty, false);
if (log.isLoggable( Level.FINE )) {
log.fine("Rolling up " + var + " to " + clazz);
}
final Collection<ATermAppl> instances;
if (first) {
instances = new HashSet<ATermAppl>(kb.getIndividuals());
for (final QueryAtom atom : q.findAtoms(
QueryPredicate.PropertyValue, var, null, null)) {
instances.retainAll(kb.retrieveIndividualsWithProperty(atom
.getArguments().get(1)));
}
for (final QueryAtom atom : q.findAtoms(
QueryPredicate.PropertyValue, null, null, var)) {
instances.retainAll(kb
.retrieveIndividualsWithProperty(ATermUtils
.makeInv(atom.getArguments().get(1))));
}
} else {
instances = kb.getInstances(clazz);
}
for (final ATermAppl b : instances) {
if (log.isLoggable( Level.FINE )) {
log.fine("trying " + var + " --> " + b);
}
final ResultBinding newBinding = binding.duplicate();
newBinding.setValue(var, b);
final Query q2 = q.apply(newBinding);
exec(q2, newBinding, false);
}
}
@Override
public QueryResult execABoxQuery(final Query q) {
results = new QueryResultImpl(q);
this.kb = q.getKB();
long satCount = kb.getABox().stats.satisfiabilityCount;
long consCount = kb.getABox().stats.consistencyCount;
exec(q, new ResultBindingImpl(), true);
if (log.isLoggable( Level.FINE )) {
log.fine("Total satisfiability operations: "
+ (kb.getABox().stats.satisfiabilityCount - satCount));
log.fine("Total consistency operations: "
+ (kb.getABox().stats.consistencyCount - consCount));
log.fine("Results of ABox query : " + results);
}
return results;
}
}