/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-09 The eXist Team
*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
*/
package org.exist.xquery.functions.util;
import java.util.List;
import org.apache.log4j.Logger;
import org.exist.dom.NodeSet;
import org.exist.dom.QName;
import org.exist.storage.Indexable;
import org.exist.storage.NativeValueIndex;
import org.exist.xquery.AnalyzeContextInfo;
import org.exist.xquery.Cardinality;
import org.exist.xquery.Constants;
import org.exist.xquery.Dependency;
import org.exist.xquery.DynamicCardinalityCheck;
import org.exist.xquery.Expression;
import org.exist.xquery.Function;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.RootNode;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.util.Error;
import org.exist.xquery.util.Messages;
import org.exist.xquery.value.AtomicValue;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.QNameValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;
/**
* @author J.M. Vanel
* @author Loren Cahlander
*/
public class QNameIndexLookup extends Function {
protected static final Logger logger = Logger.getLogger(QNameIndexLookup.class);
public final static FunctionSignature signature = new FunctionSignature(
new QName("qname-index-lookup", UtilModule.NAMESPACE_URI, UtilModule.PREFIX),
"Can be used to query existing qname indexes defined on a set of nodes. ",
new SequenceType[] {
new FunctionParameterSequenceType("qname", Type.QNAME, Cardinality.EXACTLY_ONE, "The QName"),
new FunctionParameterSequenceType("comparison-value", Type.ATOMIC, Cardinality.EXACTLY_ONE, "The comparison value") },
new FunctionReturnSequenceType(Type.NODE, Cardinality.ZERO_OR_MORE, "the result"));
public QNameIndexLookup(XQueryContext context) {
super(context, signature);
}
/**
* Overwritten: function can process the whole context sequence at once.
*
* @see org.exist.xquery.Expression#getDependencies()
*/
public int getDependencies() {
return Dependency.CONTEXT_SET;
}
/**
* Overwritten to disable automatic type checks. We check manually.
*
* @see org.exist.xquery.Function#setArguments(java.util.List)
*/
public void setArguments(List<Expression> arguments) throws XPathException {
// wrap arguments into a cardinality check, so an error will be generated if
// one of the arguments returns an empty sequence
Expression arg = arguments.get(0);
arg = new DynamicCardinalityCheck(context, Cardinality.ONE_OR_MORE, arg,
new Error(Error.FUNC_PARAM_CARDINALITY, "1", mySignature));
steps.add(arg);
arg = arguments.get(1);
arg = new DynamicCardinalityCheck(context, Cardinality.ONE_OR_MORE, arg,
new Error(Error.FUNC_PARAM_CARDINALITY, "2", mySignature));
steps.add(arg);
}
public void analyze(AnalyzeContextInfo contextInfo) throws XPathException {
contextInfo.setParent(this);
// call analyze for each argument
inPredicate = (contextInfo.getFlags() & IN_PREDICATE) > 0;
for(int i = 0; i < getArgumentCount(); i++) {
getArgument(i).analyze(contextInfo);
}
}
public Sequence eval(Sequence contextSequence, Item contextItem) throws XPathException {
if (contextSequence == null || contextSequence.isEmpty()) {
// if the context sequence is empty, we create a default context
final RootNode rootNode = new RootNode(context);
contextSequence = rootNode.eval(null, null);
}
final Sequence[] args = getArguments(null, null);
final Item item = args[0].itemAt(0);
QNameValue qval;
try {
// attempt to convert the first argument to a QName
qval = (QNameValue) item.convertTo(Type.QNAME);
} catch (final XPathException e) {
// wrong type: generate a diagnostic error
throw new XPathException(this,
Messages.formatMessage(Error.FUNC_PARAM_TYPE,
new Object[] { "1", mySignature.toString(), null,
Type.getTypeName(Type.QNAME), Type.getTypeName(item.getType()) }
));
}
final QName qname = qval.getQName();
final AtomicValue comparisonCriterium = args[1].itemAt(0).atomize();
Sequence result = Sequence.EMPTY_SEQUENCE;
if (comparisonCriterium instanceof Indexable) {
final NativeValueIndex valueIndex = context.getBroker().getValueIndex();
result =
valueIndex.find(context.getWatchDog(), Constants.EQ, contextSequence.getDocumentSet(), null, NodeSet.ANCESTOR,
qname, comparisonCriterium);
} else {
final String message = "The comparison criterium must be an Indexable: " +
"boolean, numeric, string; instead your criterium has type " +
Type.getTypeName(comparisonCriterium.getType());
throw new XPathException(this, message);
}
return result;
}
}