/*
* Copyright 2009 Niclas Hedhman.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied.
*
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.qi4j.index.rdf.query;
import java.util.HashMap;
import java.util.Map;
import org.openrdf.model.Value;
import org.openrdf.model.impl.ValueFactoryImpl;
import org.openrdf.query.*;
import org.openrdf.repository.Repository;
import org.openrdf.repository.RepositoryConnection;
import org.openrdf.repository.RepositoryException;
import org.qi4j.api.common.Optional;
import org.qi4j.api.entity.EntityReference;
import org.qi4j.api.injection.scope.Service;
import org.qi4j.api.mixin.Mixins;
import org.qi4j.spi.query.EntityFinderException;
@Mixins( TupleQueryExecutor.TupleQueryExecutorMixin.class )
public interface TupleQueryExecutor
{
long performTupleQuery( QueryLanguage language, String query, @Optional Map<String, Object> bindings, @Optional QualifiedIdentityResultCallback callback )
throws EntityFinderException;
class TupleQueryExecutorMixin
implements TupleQueryExecutor
{
@Service
private Repository repository;
@Override
public long performTupleQuery( QueryLanguage language, String query, Map<String, Object> bindings, QualifiedIdentityResultCallback callback )
throws EntityFinderException
{
try
{
RepositoryConnection connection = repository.getConnection();
TupleQueryResult result = null;
try
{
TupleQuery tupleQuery = connection.prepareTupleQuery( language, query );
for (Map.Entry<String, Value> stringValueEntry : getBindings( bindings ).entrySet())
{
tupleQuery.setBinding(stringValueEntry.getKey(), stringValueEntry.getValue());
}
tupleQuery.setIncludeInferred( false );
result = tupleQuery.evaluate();
long row = 0;
while( result.hasNext() )
{
if( handleCallbacks( callback, result, row ) )
{
break;
}
row++;
}
return row;
}
finally
{
if( result != null )
{
result.close();
}
if( connection != null )
{
connection.close();
}
}
}
catch( RepositoryException e )
{
throw new EntityFinderException( e );
}
catch( MalformedQueryException e )
{
throw new EntityFinderException( e );
}
catch( QueryEvaluationException e )
{
throw new EntityFinderException( e );
}
catch( Exception e )
{
throw new EntityFinderException( e );
}
}
private boolean handleCallbacks( QualifiedIdentityResultCallback callback, TupleQueryResult result, long row )
throws Exception
{
BindingSet bindingSet = result.next();
if( callback != null )
{
if( !processRow( row, bindingSet, callback ) )
{
return true;
}
}
return false;
}
private boolean processRow( long row, BindingSet bindingSet, QualifiedIdentityResultCallback callback )
{
final Value identifier = bindingSet.getValue( "identity" );
//TODO Shall we throw an exception if there is no binding for identifier = query parser is not right
if( identifier == null )
{
return true;
}
final String identity = identifier.stringValue();
final EntityReference entityReference = new EntityReference( identity );
return callback.processRow( row, entityReference );
}
private Map<String, Value> getBindings(Map<String, Object> variables)
{
Map<String, Value> bindings = new HashMap<String, Value>();
for (Map.Entry<String, Object> stringObjectEntry : variables.entrySet())
{
if (!stringObjectEntry.getValue().getClass().equals(Object.class))
bindings.put(stringObjectEntry.getKey(), ValueFactoryImpl.getInstance().createLiteral(stringObjectEntry.getValue().toString()));
}
return bindings;
}
}
}