/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-2009 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.functions.fn;
import java.io.StringWriter;
import java.io.Writer;
import org.exist.dom.QName;
import org.exist.storage.serializers.Serializer;
import org.exist.xquery.BasicFunction;
import org.exist.xquery.Cardinality;
import org.exist.xquery.Function;
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.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.Type;
import org.exist.xquery.value.ValueSequence;
import org.xml.sax.SAXException;
/**
* @author Dannes Wessels
* @author Wolfgang Meier (wolfgang@exist-db.org)
*/
public class FunTrace extends BasicFunction {
public final static FunctionSignature signature =
new FunctionSignature(
new QName("trace", Function.BUILTIN_FUNCTION_NS),
"This function is intended to be used in debugging queries by "
+"providing a trace of their execution. The input $value is "
+"returned, unchanged, as the result of the function. "
+"In addition, the inputs $value, converted to an xs:string, "
+"and $label is directed to a trace data set in the eXist log files.",
new SequenceType[] {
new FunctionParameterSequenceType("value", Type.ITEM, Cardinality.ZERO_OR_MORE, "The value"),
new FunctionParameterSequenceType("label", Type.STRING, Cardinality.EXACTLY_ONE, "The label in the log file")
},
new FunctionReturnSequenceType(Type.ITEM, Cardinality.ZERO_OR_MORE, "the labelled $value in the log")
);
public FunTrace(XQueryContext context) {
super(context, signature);
}
/*
* (non-Javadoc)
* @see org.exist.xquery.BasicFunction#eval(Sequence[], Sequence)
*/
public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {
// TODO Add TRACE log statements using log4j
// TODO Figure out why XQTS still does not work
// TODO Remove unneeded comments
String label = args[1].getStringValue();
if(label==null){
label="";
}
final Serializer serializer= context.getBroker().getSerializer();
Sequence result ;
if(args[0].isEmpty()){
result = Sequence.EMPTY_SEQUENCE;
} else {
// Copy all Items from input to output sequence
result = new ValueSequence();
int position = 0;
for (final SequenceIterator i = args[0].iterate(); i.hasNext();) {
// Get item
final Item next = i.nextItem();
// Only write if debug mode
if (true) {
String value = null;
position++;
final int type = next.getType();
// Serialize an element type
if (Type.ELEMENT == type) {
final Writer sw = new StringWriter();
try {
serializer.serialize((NodeValue) next, sw);
} catch (final SAXException ex) {
LOG.error(ex.getMessage());
}
value = sw.toString();
// Get string value for other types
} else {
value = next.getStringValue();
}
// Write to log
LOG.info(label + " [" + position + "]: " + Type.getTypeName(type) + ": " + value);
}
// Add to result
result.add(next);
}
}
return result;
}
}