svn commit: r983706 - /incubator/clerezza/trunk/org.apache.clerezza.parent/org.apache.clerezza.rdf.utils/src/main/java/org/apache/clerezza/rdf/utils/SeeAlsoExpander.java

[re...@apache.org]

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;
+	}
+
+}