| /* |
| * 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.apache.zest.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.apache.zest.api.common.Optional; |
| import org.apache.zest.api.entity.EntityReference; |
| import org.apache.zest.api.injection.scope.Service; |
| import org.apache.zest.api.mixin.Mixins; |
| import org.apache.zest.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; |
| } |
| } |
| } |