package net.sf.saxon.functions;
import net.sf.saxon.expr.*;
import net.sf.saxon.om.EmptyIterator;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.sort.GroupIterator;
import net.sf.saxon.trans.XPathException;
/**
* Implements the XSLT functions current-group() and current-grouping-key()
*/
public class CurrentGroup extends SystemFunction {
public static final int CURRENT_GROUP = 0;
public static final int CURRENT_GROUPING_KEY = 1;
/**
* preEvaluate: this method suppresses compile-time evaluation by doing nothing
* (because the value of the expression depends on the runtime context)
* @param visitor an expression visitor
*/
public Expression preEvaluate(ExpressionVisitor visitor) {
return this;
}
/**
* Evaluate the expression
*/
public Item evaluateItem(XPathContext c) throws XPathException {
if (operation==CURRENT_GROUPING_KEY) {
GroupIterator gi = c.getCurrentGroupIterator();
if (gi==null) {
return null;
}
return gi.getCurrentGroupingKey();
} else {
return super.evaluateItem(c);
}
}
/**
* Return an iteration over the result sequence
*/
public SequenceIterator iterate(XPathContext c) throws XPathException {
if (operation==CURRENT_GROUP) {
GroupIterator gi = c.getCurrentGroupIterator();
if (gi==null) {
return EmptyIterator.getInstance();
}
return gi.iterateCurrentGroup();
} else {
return super.iterate(c);
}
}
/**
* Determine the dependencies
*/
public int getIntrinsicDependencies() {
return StaticProperty.DEPENDS_ON_CURRENT_GROUP;
}
}
//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
// you may not use this file except in compliance with the License. You may obtain a copy of the
// License at http://www.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file.
//
// The Initial Developer of the Original Code is Michael H. Kay.
//
// Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
//
// Contributor(s): none.
//