/*
* $Header$
* $Revision: 982 $
* $Date: 2006-12-08 18:42:51 +1000 (Fri, 08 Dec 2006) $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 2003-2009 The JRDF Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* the JRDF Project (http://jrdf.sf.net/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The JRDF Project" and "JRDF" must not be used to endorse
* or promote products derived from this software without prior written
* permission. For written permission, please contact
* newmana@users.sourceforge.net.
*
* 5. Products derived from this software may not be called "JRDF"
* nor may "JRDF" appear in their names without prior written
* permission of the JRDF Project.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the JRDF Project. For more
* information on JRDF, please see <http://jrdf.sourceforge.net/>.
*
*/
package org.jrdf.graph.global.molecule.mem;
import static org.jrdf.graph.AnyPredicateNode.ANY_PREDICATE_NODE;
import static org.jrdf.graph.AnySubjectNode.ANY_SUBJECT_NODE;
import org.jrdf.graph.BlankNode;
import org.jrdf.graph.Graph;
import org.jrdf.graph.GraphException;
import org.jrdf.graph.ObjectNode;
import org.jrdf.graph.SubjectNode;
import org.jrdf.graph.Triple;
import org.jrdf.graph.global.molecule.FindEntryNode;
import static org.jrdf.graph.local.BlankNodeImpl.isBlankNode;
import org.jrdf.util.ClosableIterable;
import static java.util.Arrays.asList;
import java.util.HashSet;
import java.util.Set;
public class FindEntryNodeImpl implements FindEntryNode {
private Set<BlankNode> visitedNodes;
private Graph graph;
private Triple currentTriple;
public FindEntryNodeImpl() {
visitedNodes = new HashSet<BlankNode>();
}
public Triple find(Graph newGraph, Triple triple) throws GraphException {
this.graph = newGraph;
this.currentTriple = triple;
if (!isBlankNode(triple.getSubject())) {
return triple;
}
// TODO Work out if this needs to be kept.
addObjectNodeIfBlank(triple);
if (!graph.contains(triple)) {
throw new GraphException("Cannot find triple: " + triple);
} else {
findNextLevelOfNodes(new HashSet<BlankNode>(asList((BlankNode) triple.getSubject())));
return currentTriple;
}
}
private void addObjectNodeIfBlank(Triple triple) {
ObjectNode object = triple.getObject();
if (isBlankNode(object)) {
visitedNodes.add((BlankNode) object);
}
}
private BlankNode findNextLevelOfNodes(Set<BlankNode> currentLevelNodes) throws GraphException {
Set<BlankNode> newNodes = new HashSet<BlankNode>();
for (BlankNode bNode : currentLevelNodes) {
visitedNodes.add(bNode);
getNewBlankNodes(newNodes, graph.find(ANY_SUBJECT_NODE, ANY_PREDICATE_NODE, bNode));
}
if (newNodes.isEmpty()) {
return currentLevelNodes.iterator().next();
} else {
return findNextLevelOfNodes(newNodes);
}
}
private void getNewBlankNodes(Set<BlankNode> newNodes, ClosableIterable<Triple> triples) {
for (Triple triple : triples) {
SubjectNode newNode = triple.getSubject();
if (isBlankNode(newNode) && (!visitedNodes.contains((BlankNode) newNode))) {
currentTriple = triple;
newNodes.add((BlankNode) newNode);
}
}
triples.iterator().close();
}
}