package client.net.sf.saxon.ce.functions;
import client.net.sf.saxon.ce.expr.*;
import client.net.sf.saxon.ce.om.Item;
import client.net.sf.saxon.ce.om.NodeInfo;
import client.net.sf.saxon.ce.trans.XPathException;
/**
* Implement the XPath 2.0 root() function
*/
public class Root extends SystemFunction {
public Root newInstance() {
return new Root();
}
/**
* Simplify and validate.
* @param visitor an expression visitor
*/
public Expression simplify(ExpressionVisitor visitor) throws XPathException {
useContextItemAsDefault();
return simplifyArguments(visitor);
}
/**
* Get the static properties of this expression (other than its type). The result is
* bit-significant. These properties are used for optimizations. In general, if
* property bit is set, it is true, but if it is unset, the value is unknown.
*/
public int computeSpecialProperties() {
int prop = StaticProperty.ORDERED_NODESET |
StaticProperty.SINGLE_DOCUMENT_NODESET |
StaticProperty.NON_CREATIVE;
if ((getNumberOfArguments() == 0) ||
(argument[0].getSpecialProperties() & StaticProperty.CONTEXT_DOCUMENT_NODESET) != 0) {
prop |= StaticProperty.CONTEXT_DOCUMENT_NODESET;
}
return prop;
}
/**
* Evaluate in a general context
*/
public Item evaluateItem(XPathContext c) throws XPathException {
NodeInfo start = (NodeInfo)argument[0].evaluateItem(c);
if (start==null) {
return null;
}
return start.getRoot();
}
}
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is “Incompatible With Secondary Licenses”, as defined by the Mozilla Public License, v. 2.0.