// 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.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.mindswap.pellet.KnowledgeBase;
import com.clarkparsia.pellet.sparqldl.model.Query;
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 com.clarkparsia.pellet.sparqldl.model.Query.VarType;
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 OptimizedQueryEngine3 extends AbstractABoxEngineWrapper {
public static final Logger log = Logger.getLogger(QueryEngine.class.getName());
public boolean supports(final Query q) {
return true; // TODO
}
@Override
public QueryResult execABoxQuery(final Query q) {
final QueryResult results = new QueryResultImpl(q);
final KnowledgeBase kb = q.getKB();
long satCount = kb.getABox().stats.satisfiabilityCount;
long consCount = kb.getABox().stats.consistencyCount;
if (q.getDistVars().isEmpty()) {
if (QueryEngine.execBooleanABoxQuery(q)) {
results.add(new ResultBindingImpl());
}
} else {
final Map<ATermAppl, Set<ATermAppl>> varBindings = new HashMap<ATermAppl, Set<ATermAppl>>();
for (final ATermAppl currVar : q
.getDistVarsForType(VarType.INDIVIDUAL)) {
ATermAppl rolledUpClass = q.rollUpTo(currVar,
Collections.EMPTY_SET, false);
if (log.isLoggable( Level.FINER ))
log.finer("Rolled up class " + rolledUpClass);
varBindings.put(currVar, kb.getInstances(rolledUpClass));
}
if (log.isLoggable( Level.FINER ))
log.finer("Var bindings: " + varBindings);
final List<ATermAppl> varList = new ArrayList<ATermAppl>(
varBindings.keySet()); // TODO
final Map<ATermAppl, Collection<ResultBinding>> goodLists = new HashMap<ATermAppl, Collection<ResultBinding>>();
final ATermAppl first = varList.get(0);
final Collection<ResultBinding> c = new HashSet<ResultBinding>();
for (final ATermAppl a : varBindings.get(first)) {
final ResultBinding bind = new ResultBindingImpl();
bind.setValue(first, a);
c.add(bind);
}
goodLists.put(first, c);
Collection<ResultBinding> previous = goodLists.get(first);
for (int i = 1; i < varList.size(); i++) {
final ATermAppl next = varList.get(i);
final Collection<ResultBinding> newBindings = new HashSet<ResultBinding>();
for (final ResultBinding binding : previous) {
for (final ATermAppl testBind : varBindings.get(next)) {
final ResultBinding bindingCandidate = binding.duplicate();
bindingCandidate.setValue(next, testBind);
boolean queryTrue = QueryEngine.execBooleanABoxQuery(q
.apply(bindingCandidate));
if (queryTrue) {
newBindings.add(bindingCandidate);
if (log.isLoggable( Level.FINER )) {
log.finer("Accepted binding: "
+ bindingCandidate);
}
} else {
if (log.isLoggable( Level.FINER )) {
log.finer("Rejected binding: "
+ bindingCandidate);
}
}
}
}
previous = newBindings;
}
// no var. should be marked as both INDIVIDUAL and LITERAL in an
// ABox query.
boolean hasLiterals = !q.getDistVarsForType(VarType.LITERAL)
.isEmpty();
if (hasLiterals) {
for (final ResultBinding b : previous) {
for (final Iterator<ResultBinding> i = new LiteralIterator(
q, b); i.hasNext();) {
results.add(i.next());
}
}
} else {
for (final ResultBinding b : previous) {
results.add(b);
}
}
if (log.isLoggable( Level.FINE )) {
log.fine("Results: "
+ results);
log.fine("Total satisfiability operations: "
+ (kb.getABox().stats.satisfiabilityCount - satCount));
log.fine("Total consistency operations: "
+ (kb.getABox().stats.consistencyCount - consCount));
}
}
return results;
}
}