Root.java

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.