org.topbraid.jenax.util.JenaNodeUtil Maven / Gradle / Ivy
/*
* 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.
*
* See the NOTICE file distributed with this work for additional
* information regarding copyright ownership.
*/
package org.topbraid.jenax.util;
import java.util.LinkedList;
import java.util.List;
import org.apache.jena.atlas.iterator.Iter;
import org.apache.jena.graph.Graph;
import org.apache.jena.graph.Node;
import org.apache.jena.graph.Triple;
import org.apache.jena.rdf.model.Model;
import org.apache.jena.rdf.model.ModelFactory;
import org.apache.jena.rdf.model.Resource;
import org.apache.jena.util.iterator.ExtendedIterator;
/**
* Some utilities operating on Jena Node objects, bypassing the Model/RDFNode abstraction layer.
*
* There should be a cleaner and more complete API for this in the future.
*
* @author Holger Knublauch
*/
public class JenaNodeUtil {
public static Node getObject(Node subject, Node predicate, Graph graph) {
ExtendedIterator it = graph.find(subject, predicate, Node.ANY);
try {
return it.hasNext()
? it.next().getObject()
: null;
} finally {
it.close();
}
}
public static long getObjectCount(Node subject, Node predicate, Graph graph) {
return Iter.count(graph.find(subject, predicate, Node.ANY));
}
public static List getObjects(Node subject, Node predicate, Graph graph) {
List results = new LinkedList<>();
ExtendedIterator it = graph.find(subject, predicate, Node.ANY);
while(it.hasNext()) {
results.add(it.next().getObject());
}
return results;
}
public static long getSubjectCount(Node predicate, Node object, Graph graph) {
return Iter.count(graph.find(Node.ANY, predicate, object));
}
public static List getSubjects(Node predicate, Node object, Graph graph) {
List results = new LinkedList<>();
ExtendedIterator it = graph.find(Node.ANY, predicate, object);
while(it.hasNext()) {
results.add(it.next().getSubject());
}
return results;
}
public static boolean isInstanceOf(Node instance, Node type, Graph graph) {
// TODO: Use Node API only (maybe worth it)
Model model = ModelFactory.createModelForGraph(graph);
return JenaUtil.hasIndirectType((Resource)model.asRDFNode(instance), (Resource)model.asRDFNode(type));
}
}