/*
* eXist Open Source Native XML Database
* Copyright (C) 2007-09 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 program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* $Id$
*/
package org.exist.xquery.modules.ngram;
import org.exist.dom.NodeProxy;
import org.exist.dom.QName;
import org.exist.indexing.MatchListener;
import org.exist.indexing.ngram.NGramIndex;
import org.exist.indexing.ngram.NGramIndexWorker;
import org.exist.indexing.ngram.NGramMatchCallback;
import org.exist.memtree.DocumentBuilderReceiver;
import org.exist.memtree.MemTreeBuilder;
import org.exist.memtree.NodeImpl;
import org.exist.storage.serializers.Serializer;
import org.exist.util.serializer.Receiver;
import org.exist.xquery.BasicFunction;
import org.exist.xquery.Cardinality;
import org.exist.xquery.FunctionCall;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.FunctionReference;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.NodeValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceIterator;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.StringValue;
import org.exist.xquery.value.Type;
import org.exist.xquery.value.ValueSequence;
import org.xml.sax.SAXException;
/**
*/
public class HighlightMatches extends BasicFunction {
public final static FunctionSignature signature = new FunctionSignature(
new QName("filter-matches", NGramModule.NAMESPACE_URI, NGramModule.PREFIX),
"Highlight matching strings within text nodes that resulted from a ngram search. " +
"The function takes a sequence of nodes as first argument $nodes and a callback function (defined with " +
"util:function) as second parameter $function-reference. Each node in $nodes will be copied into a new document fragment. " +
"For each ngram match found while copying a node, the callback function in $function-reference will be called once. The " +
"callback function should take 2 arguments:\n\n1) the matching text string as xs:string,\n2) the node to which this " +
"text string belongs.\n\nThe callback function should return zero or more nodes, which will be inserted into the " +
"resulting node set at the place where the matching text sequence occurred.\n\n" +
"Note: a ngram match on mixed content may span multiple nodes. In this case, the callback function is called " +
"once for every text node which is part of the matching text sequence.",
new SequenceType[] {
new FunctionParameterSequenceType("nodes", Type.NODE, Cardinality.ZERO_OR_MORE, "The sequence of nodes"),
new FunctionParameterSequenceType("function-reference", Type.FUNCTION_REFERENCE, Cardinality.EXACTLY_ONE, "The callback function")
},
new FunctionReturnSequenceType(Type.NODE, Cardinality.ZERO_OR_MORE, "a resulting node set"));
public HighlightMatches(XQueryContext context) {
super(context, signature);
}
public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {
if (args[0].isEmpty())
return Sequence.EMPTY_SEQUENCE;
FunctionReference func = (FunctionReference) args[1].itemAt(0);
FunctionCall call = func.getFunctionCall();
NGramIndexWorker index = (NGramIndexWorker) context.getBroker().getIndexController().getWorkerByIndexId(NGramIndex.ID);
MemTreeBuilder builder = context.getDocumentBuilder();
DocumentBuilderReceiver docBuilder = new DocumentBuilderReceiver(builder);
MatchCallback matchCb = new MatchCallback(call, docBuilder);
Serializer serializer = context.getBroker().getSerializer();
serializer.reset();
ValueSequence result = new ValueSequence();
for (SequenceIterator i = args[0].iterate(); i.hasNext(); ) {
NodeValue v = (NodeValue) i.nextItem();
try {
int nodeNr = builder.getDocument().getLastNode();
if (v.getImplementationType() == NodeValue.IN_MEMORY_NODE) {
((NodeImpl)v).copyTo(context.getBroker(), docBuilder);
} else {
NodeProxy p = (NodeProxy) v;
MatchListener ml = index.getMatchListener(context.getBroker(), p, matchCb);
Receiver receiver;
if (ml == null)
receiver = docBuilder;
else {
ml.setNextInChain(docBuilder);
receiver = ml;
}
serializer.setReceiver(receiver);
serializer.toReceiver((NodeProxy) v, false);
}
result.add(builder.getDocument().getNode(++nodeNr));
} catch (SAXException e) {
LOG.warn(e.getMessage(), e);
throw new XPathException(this, e.getMessage());
}
}
return result;
}
private class MatchCallback implements NGramMatchCallback {
private FunctionCall callback;
private DocumentBuilderReceiver docBuilder;
private MatchCallback(FunctionCall callback, DocumentBuilderReceiver docBuilder) {
this.callback = callback;
this.docBuilder = docBuilder;
}
public void match(Receiver receiver, String matchingText, NodeProxy node) throws XPathException, SAXException {
Sequence params[] = {
new StringValue(matchingText),
node,
Sequence.EMPTY_SEQUENCE
};
context.pushDocumentContext();
Sequence seq = callback.evalFunction(null, null, params);
for (SequenceIterator i = seq.iterate(); i.hasNext(); ) {
Item next = i.nextItem();
next.copyTo(context.getBroker(), docBuilder);
}
context.popDocumentContext();
}
}
}