Author: reto
Date: Mon Aug 9 16:10:31 2010
New Revision: 983706
URL: http://svn.apache.org/viewvc?rev=983706&view=rev
Log:
Added utility class to expand a GraphNode using rdfs:seeAlso properties
Added:
incubator/clerezza/trunk/org.apache.clerezza.parent/org.apache.clerezza.rdf.utils/src/main/java/org/apache/clerezza/rdf/utils/SeeAlsoExpander.java
Added:
incubator/clerezza/trunk/org.apache.clerezza.parent/org.apache.clerezza.rdf.utils/src/main/java/org/apache/clerezza/rdf/utils/SeeAlsoExpander.java
URL:
http://svn.apache.org/viewvc/incubator/clerezza/trunk/org.apache.clerezza.parent/org.apache.clerezza.rdf.utils/src/main/java/org/apache/clerezza/rdf/utils/SeeAlsoExpander.java?rev=983706&view=auto
==============================================================================
---
incubator/clerezza/trunk/org.apache.clerezza.parent/org.apache.clerezza.rdf.utils/src/main/java/org/apache/clerezza/rdf/utils/SeeAlsoExpander.java
(added)
+++
incubator/clerezza/trunk/org.apache.clerezza.parent/org.apache.clerezza.rdf.utils/src/main/java/org/apache/clerezza/rdf/utils/SeeAlsoExpander.java
Mon Aug 9 16:10:31 2010
@@ -0,0 +1,113 @@
+/*
+ * 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.clerezza.rdf.utils;
+
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Set;
+import java.util.concurrent.locks.Lock;
+import org.apache.clerezza.rdf.core.Resource;
+import org.apache.clerezza.rdf.core.TripleCollection;
+import org.apache.clerezza.rdf.core.UriRef;
+import org.apache.clerezza.rdf.core.access.NoSuchEntityException;
+import org.apache.clerezza.rdf.core.access.TcManager;
+import org.apache.clerezza.rdf.ontologies.RDFS;
+
+/**
+ * Expands a GraphNode expanding SeeAlso-References of the node.
+ *
+ * @author reto
+ */
+public class SeeAlsoExpander {
+ /**
+ * using TcManger instead of TcProvider as this ensures LockableMGraphs
+ */
+ private final TcManager tcManager;
+ public SeeAlsoExpander(TcManager tcManager) {
+ this.tcManager = tcManager;
+
+ }
+
+ /**
+ * expands a node dereferencing its rdfs:seeAlso references using the
+ * tcManager associated to this instance. If the added TripleCollections
+ * also associate rdfs:seeAlso properties to node this are expanded till
+ * the maximum recursion depth specified.
+ *
+ * @param node the node to be expanded
+ * @param recursion the maximum recursion depth
+ * @return a new GraphNode over the union of the original and all
expansion graphs
+ */
+ public GraphNode expand(GraphNode node, int recursion) {
+ Set<UriRef> alreadyVisited = new HashSet();
+ Set<TripleCollection> resultTripleCollections = new
HashSet<TripleCollection>();
+ resultTripleCollections.add(node.getGraph());
+ for (UriRef uriRef : expand(node, alreadyVisited, recursion)) {
+ try {
+
resultTripleCollections.add(tcManager.getTriples(uriRef));
+ } catch (NoSuchEntityException e) {
+ //ignore
+ }
+ }
+ return new GraphNode(node.getNode(),
+ new UnionMGraph(resultTripleCollections.toArray(
+ new
TripleCollection[resultTripleCollections.size()])));
+
+ }
+
+ private Set<UriRef> getSeeAlsoObjectUris(GraphNode node) {
+ Set<UriRef> result = new HashSet<UriRef>();
+ Lock l = node.readLock();
+ l.lock();
+ try {
+ Iterator<Resource> objects =
node.getObjects(RDFS.seeAlso);
+ while (objects.hasNext()) {
+ Resource next = objects.next();
+ if (next instanceof UriRef) {
+ result.add((UriRef)next);
+ }
+ }
+ } finally {
+ l.unlock();
+ }
+ return result;
+ }
+
+ private Set<UriRef> expand(GraphNode node, Set<UriRef> alreadyVisited,
int recursion) {
+ Set<UriRef> rdfSeeAlsoTargets = getSeeAlsoObjectUris(node);
+ Set<UriRef> result = new HashSet<UriRef>();
+ result.addAll(rdfSeeAlsoTargets);
+ recursion++;
+ if (recursion > 0) {
+ rdfSeeAlsoTargets.removeAll(alreadyVisited);
+ alreadyVisited.addAll(rdfSeeAlsoTargets);
+ for (UriRef target : rdfSeeAlsoTargets) {
+ try {
+ result.addAll(expand(new
GraphNode(node.getNode(),
+ tcManager.getTriples(target)),
alreadyVisited, recursion));
+ } catch (NoSuchEntityException e) {
+ //ignore
+ }
+ }
+ }
+ return result;
+ }
+
+}
