package net.sf.saxon.functions;
import net.sf.saxon.expr.ReversibleIterator;
import net.sf.saxon.expr.StaticProperty;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.AnyItemType;
import net.sf.saxon.type.ItemType;
import net.sf.saxon.type.TypeHierarchy;
import net.sf.saxon.value.SequenceExtent;
/**
* Implement XPath function fn:reverse()
*/
public class Reverse extends SystemFunction {
// /**
// * Simplify and validate.
// * @param visitor an expression visitor
// */
// public Expression simplify(ExpressionVisitor visitor) throws XPathException {
// Reverser a = new Reverser(argument[0]);
// ExpressionTool.copyLocationInfo(this, a);
// return visitor.simplify(a);
// }
/**
* Determine the item type of the value returned by the function
*
* @param th the type hierarchy cache
*/
public ItemType getItemType(TypeHierarchy th) {
return argument[0].getItemType(th); //AUTO
}
public int computeSpecialProperties() {
int baseProps = argument[0].getSpecialProperties();
if ((baseProps & StaticProperty.REVERSE_DOCUMENT_ORDER) != 0) {
return (baseProps &
(~StaticProperty.REVERSE_DOCUMENT_ORDER)) |
StaticProperty.ORDERED_NODESET;
} else if ((baseProps & StaticProperty.ORDERED_NODESET) != 0) {
return (baseProps &
(~StaticProperty.ORDERED_NODESET)) |
StaticProperty.REVERSE_DOCUMENT_ORDER;
} else {
return baseProps;
}
}
public SequenceIterator iterate(XPathContext context) throws XPathException {
SequenceIterator forwards = argument[0].iterate(context);
if (forwards instanceof ReversibleIterator) {
return ((ReversibleIterator)forwards).getReverseIterator();
} else {
SequenceExtent extent = new SequenceExtent(forwards);
return extent.reverseIterate();
}
}
public boolean effectiveBooleanValue(XPathContext context) throws XPathException {
// EBV is independent of sequence order unless the sequence mixes atomic values and nodes
ItemType type = argument[0].getItemType(context.getConfiguration().getTypeHierarchy());
if (type == AnyItemType.getInstance()) {
return super.effectiveBooleanValue(context);
} else {
return argument[0].effectiveBooleanValue(context);
}
}
}
//
// 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.
//