| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.jena.sparql.graph; |
| |
| import java.util.Collection; |
| import java.util.Iterator; |
| import java.util.Map; |
| import java.util.Map.Entry; |
| import java.util.function.Consumer; |
| |
| import org.apache.jena.atlas.iterator.Iter; |
| import org.apache.jena.atlas.iterator.IteratorConcat; |
| import org.apache.jena.atlas.lib.CollectionUtils; |
| import org.apache.jena.graph.Graph; |
| import org.apache.jena.graph.Node; |
| import org.apache.jena.graph.TransactionHandler; |
| import org.apache.jena.graph.Triple; |
| import org.apache.jena.graph.impl.GraphBase; |
| import org.apache.jena.shared.AddDeniedException; |
| import org.apache.jena.shared.DeleteDeniedException; |
| import org.apache.jena.shared.PrefixMapping; |
| import org.apache.jena.shared.impl.PrefixMappingImpl; |
| import org.apache.jena.sparql.core.*; |
| import org.apache.jena.util.iterator.ExtendedIterator; |
| import org.apache.jena.util.iterator.NullIterator; |
| import org.apache.jena.util.iterator.WrappedIterator; |
| |
| /** Immutable graph that is the view of a union of graphs in a dataset. |
| * This union can be a fixed set of graph or all named graph. |
| * This union iterates over graphs. |
| * <p> |
| * {@link GraphView} provides a view over a dataset and does support union graph but |
| * assumes quad access is efficient and does not end up looping. |
| * |
| * @see GraphView |
| * @see DatasetGraphMap |
| */ |
| public class GraphUnionRead extends GraphBase { |
| private final DatasetGraph dataset; |
| private final Collection<Node> graphs; |
| // Special case. |
| private final Node graphName; |
| |
| /** Read-only graph view of all named graphs in the dataset. |
| * If graphs are added after this view if created, then this is reflected in |
| * the {@code find} call. |
| */ |
| public GraphUnionRead(DatasetGraph dsg) { |
| this(dsg, null); |
| } |
| |
| /** Read-only graph view of a set of graphs from the dataset */ |
| public GraphUnionRead(DatasetGraph dsg, Collection<Node> graphs) { |
| this.dataset = dsg; |
| this.graphs = graphs; |
| // Special case. |
| if ( graphs != null && graphs.size() == 1 ) { |
| // No need to suppress duplicates because there aren't any. |
| // Assumes the dataset handles Quad.unionGraph. |
| graphName = CollectionUtils.oneElt(graphs); |
| } |
| else |
| graphName = null; |
| } |
| |
| @Override |
| protected PrefixMapping createPrefixMapping() { |
| PrefixMapping pmap = new PrefixMappingImpl(); |
| forEachGraph((g) -> { |
| Map<String, String> map = g.getPrefixMapping().getNsPrefixMap(); |
| for (Entry<String, String> e: map.entrySet()) { |
| try { |
| // PrefixMapping protects against RDF/XML illegal prefixes. |
| pmap.setNsPrefix( e.getKey(), e.getValue() ); |
| } catch (PrefixMapping.IllegalPrefixException ex) { /* ignore unacceptable prefixes */ } |
| } |
| }); |
| return pmap; |
| } |
| |
| @Override |
| protected ExtendedIterator<Triple> graphBaseFind(Triple m) { |
| if ( graphs == null ) { |
| // This produces unique quads with the same graph node, |
| // hence the triples are distinct. |
| return quadsToTriples(dataset, Quad.unionGraph, m); |
| } |
| if ( graphs.isEmpty() ) |
| return NullIterator.instance(); |
| if ( graphName != null ) { |
| if ( ! dataset.containsGraph(graphName) ) |
| // Avoid auto-creation. |
| return NullIterator.instance(); |
| // Avoid needing distinct. |
| return dataset.getGraph(graphName).find(m); |
| } |
| // Only certain graphs. |
| IteratorConcat<Triple> iter = new IteratorConcat<>(); |
| forEachGraph((g) -> iter.add(g.find(m))); |
| return WrappedIterator.createNoRemove(Iter.distinct(iter)); |
| } |
| |
| private static ExtendedIterator<Triple> quadsToTriples(DatasetGraph dsg, Node graphName, Triple m) { |
| Iterator<Quad> qIter = dsg.findNG(graphName, m.getSubject(), m.getPredicate(), m.getObject()); |
| Iterator<Triple> tIter = Iter.map(qIter, quad->quad.asTriple()); |
| return WrappedIterator.createNoRemove(tIter); |
| } |
| |
| /** Execute action for each graph that exists */ |
| private void forEachGraph(Consumer<Graph> action) { |
| if ( graphs == null ) { |
| // Fast-path the dynamic union of all named graphs. |
| dataset.listGraphNodes().forEachRemaining((gn) -> action.accept(dataset.getGraph(gn))); |
| return; |
| } |
| |
| graphs.stream() |
| // Need to check to avoid auto-creation. |
| .filter(gn -> dataset.containsGraph(gn)) |
| // For the explicit name of the default graph. |
| .map(gn -> Quad.isDefaultGraph(gn) ? dataset.getDefaultGraph() : dataset.getGraph(gn)) |
| .forEach(action); |
| } |
| |
| @Override public TransactionHandler getTransactionHandler() { |
| return new TransactionHandlerView(dataset); |
| } |
| |
| // Override to give more specific message. |
| |
| @Override |
| public void performAdd(Triple t) { |
| throw new AddDeniedException("GraphUnionRead::performAdd - Read-only graph"); |
| } |
| |
| @Override |
| public void performDelete(Triple t) { |
| throw new DeleteDeniedException("GraphUnionRead::performDelete - Read-only graph"); |
| } |
| } |