/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-09 The eXist Project
* http://exist-db.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* \$Id\$
*/
package org.exist.xquery.modules.lucene;
import org.apache.log4j.Logger;
import org.exist.xquery.BasicFunction;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.Cardinality;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.XPathException;
import org.exist.xquery.value.*;
import org.exist.dom.QName;
import org.exist.dom.NodeProxy;
import org.exist.dom.Match;
import org.exist.indexing.lucene.LuceneIndex;
import org.exist.indexing.lucene.LuceneIndexWorker;
public class Score extends BasicFunction {
protected static final Logger logger = Logger.getLogger(Score.class);
public final static FunctionSignature signature =
new FunctionSignature(
new QName("score", LuceneModule.NAMESPACE_URI, LuceneModule.PREFIX),
"Returns a computed relevance score for the given node. The score is the sum of all " +
"relevance scores provided by Lucene for the node and its descendants. In general, the score " +
"will be a number between 0.0 and 1.0 if the query had $node as context. If the query targeted " +
"multiple descendants of $node (e.g. 'title' and 'author' within a 'book'), the score will be the " +
"sum of all sub-scores and may thus be greater than 1.",
new SequenceType[] {
new FunctionParameterSequenceType("node", Type.NODE, Cardinality.EXACTLY_ONE,
"the context node")
},
new FunctionReturnSequenceType(Type.FLOAT, Cardinality.ZERO_OR_MORE,
"sum of all relevance scores provided by Lucene for all matches below the given context node")
);
public Score(XQueryContext context) {
super(context, signature);
}
public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {
NodeValue nodeValue = (NodeValue) args[0].itemAt(0);
if (nodeValue.getImplementationType() != NodeValue.PERSISTENT_NODE) {
return Sequence.EMPTY_SEQUENCE;
}
NodeProxy proxy = (NodeProxy) nodeValue;
Match match = proxy.getMatches();
float score = 0.0f;
while (match != null) {
if (match.getIndexId() == LuceneIndex.ID) {
float currentScore = ((LuceneIndexWorker.LuceneMatch)match).getScore();
score += currentScore;
}
match = match.getNextMatch();
}
return new FloatValue(score);
}
}