/*
* $Header$
* $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.
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* 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.
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* 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"
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*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* ====================================================================
*
* 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/>.
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package org.jrdf.graph.global;
import org.jrdf.graph.AbstractBlankNode;
import org.jrdf.graph.BlankNode;
import org.jrdf.graph.GraphException;
import org.jrdf.graph.ObjectNode;
import org.jrdf.graph.PredicateNode;
import org.jrdf.graph.SubjectNode;
import org.jrdf.graph.Triple;
import org.jrdf.graph.TripleImpl;
import org.jrdf.graph.global.index.ReadableIndex;
import org.jrdf.graph.global.molecule.Molecule;
import org.jrdf.graph.global.molecule.MoleculeComparator;
import org.jrdf.graph.global.molecule.mem.MoleculeImpl;
import org.jrdf.graph.local.index.nodepool.NodePool;
import org.jrdf.util.ClosableIterator;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
/**
* @author Yuan-Fang Li
* @version :$
*/
public class MoleculeGraphHandlerImpl implements MoleculeGraphHandler {
private NodePool nodePool;
private ReadableIndex<Long> readableIndex;
private MoleculeComparator moleculeComparator;
public MoleculeGraphHandlerImpl(final NodePool newNodePool, final ReadableIndex<Long> newReadableIndex,
final MoleculeComparator newMoleculeComparator) {
this.nodePool = newNodePool;
this.readableIndex = newReadableIndex;
this.moleculeComparator = newMoleculeComparator;
}
public Molecule createMolecule(final Long pid, final Long mid) throws GraphException {
return reconstructMolecule(null, pid, mid);
}
// TODO if a sub molecule is to be returned, the isTopLevel field isn't correctly set when creating the molecule.
// TODO Maybe get the top-level molecule and return the subMolecule?
private Molecule reconstructMolecule(Molecule parentMolecule, Long pid, Long mid) throws GraphException {
Triple[] roots = iteratorAsTriples(readableIndex.findTriplesForMid(pid, mid));
Map<BlankNode, Triple> rootTripleMap = getBNodeToRootMap(parentMolecule);
Molecule molecule = new MoleculeImpl(moleculeComparator, roots);
molecule = createSubMolecules(mid, molecule);
if (null == parentMolecule) {
return molecule;
} else {
Triple linkingTriple = findLinkingTriple(parentMolecule, roots, rootTripleMap, molecule);
parentMolecule.add(linkingTriple, molecule);
return parentMolecule;
}
}
private Triple[] iteratorAsTriples(ClosableIterator<Long[]> iterator) {
try {
List<Triple> triples = new ArrayList<Triple>();
while (iterator.hasNext()) {
Long[] longs = iterator.next();
Triple triple = new TripleImpl((SubjectNode) nodePool.getNodeById(longs[0]),
(PredicateNode) nodePool.getNodeById(longs[1]), (ObjectNode) nodePool.getNodeById(longs[2]));
triples.add(triple);
}
Triple[] tripleArray = new Triple[triples.size()];
return triples.toArray(tripleArray);
} finally {
iterator.close();
}
}
private Map<BlankNode, Triple> getBNodeToRootMap(Molecule molecule) {
if (null == molecule) {
return null;
}
final Iterator<Triple> triples = molecule.getRootTriples();
Map<BlankNode, Triple> rootTripleMap = new HashMap<BlankNode, Triple>();
while (triples.hasNext()) {
Triple triple = triples.next();
ObjectNode obj = triple.getObject();
if (obj instanceof AbstractBlankNode) {
rootTripleMap.put((BlankNode) obj, triple);
}
}
return rootTripleMap;
}
private Molecule createSubMolecules(Long mid, Molecule molecule) throws GraphException {
ClosableIterator<Long> childIDs = readableIndex.findChildIds(mid);
while (childIDs.hasNext()) {
Long childID = childIDs.next();
molecule = reconstructMolecule(molecule, mid, childID);
}
childIDs.close();
return molecule;
}
// TODO YF a more robust version of findLinkingTriple is needed.
private Triple findLinkingTriple(Molecule parentMolecule, Triple[] roots, Map<BlankNode, Triple> rootTripleMap,
Molecule molecule) throws GraphException {
for (Triple triple : roots) {
SubjectNode sub = triple.getSubject();
if (AbstractBlankNode.isBlankNode(sub) && mapContainsBNode(rootTripleMap, sub)) {
return rootTripleMap.get(sub);
}
}
throw new GraphException("Cannot find the linking triple for parent : " + parentMolecule +
"\nand submolecule" + molecule);
}
private boolean mapContainsBNode(Map<BlankNode, Triple> nodeTripleMap, SubjectNode sub) {
return nodeTripleMap != null && nodeTripleMap.containsKey(sub);
}
}