Saxon

While trying to create a Java extension function (full interface) and use it via the command line, I've been unable to successfully register the extension when declaring it in a configuration file.

Configuration File¶

<configuration xmlns="http://saxon.sf.net/ns/configuration"
               edition="EE">
  <resources>
    <extensionFunction>com.example.ShiftLeft</extensionFunction>
  </resources>
</configuration>

Extension Function Definition¶

package com.example;

import net.sf.saxon.lib.ExtensionFunctionCall;
import net.sf.saxon.lib.ExtensionFunctionDefinition;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.om.StructuredQName;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.value.SequenceType;
import net.sf.saxon.value.IntegerValue;
import net.sf.saxon.value.Int64Value;

// Based upon:
//   http://www.saxonica.com/html/documentation/extensibility/integratedfunctions/ext-full-J.html

class ShiftLeft extends ExtensionFunctionDefinition {
    @Override
    public StructuredQName getFunctionQName() {
        return new StructuredQName("eg", "http://example.com/saxon-extension", "shift-left");
    }

    @Override
    public SequenceType[] getArgumentTypes() {
        return new SequenceType[]{SequenceType.SINGLE_INTEGER, SequenceType.SINGLE_INTEGER};
    }

    @Override
    public SequenceType getResultType(SequenceType[] suppliedArgumentTypes) {
        return SequenceType.SINGLE_INTEGER;
    }

    @Override
    public ExtensionFunctionCall makeCallExpression() {
        return new ExtensionFunctionCall() {
            @Override
            public Sequence call(XPathContext context, Sequence[] arguments) throws XPathException {
                long v0 = ((IntegerValue)arguments[0]).longValue();
                long v1 = ((IntegerValue)arguments[1]).longValue();
                long result = v0<<v1;
                return Int64Value.makeIntegerValue(result);
            }
        };
    }
}

Error¶

     [xslt] Warning on line 4 column 65 of saxon_config.xml:
     [xslt]   Invalid configuration property extensionFunction. Supplied value 'com.example.ShiftLeft',
     [xslt]   required value is the name of a class that implements
     [xslt]   'net.sf.saxon.lib.ExtensionFunctionDefinition': Failed to instantiate class
     [xslt]   com.example.ShiftLeft: class net.sf.saxon.trans.DynamicLoader cannot access a member of
     [xslt]   class com.example.ShiftLeft with modifiers ""

I've attached a complete, ant-driven example that exhibits the problem I'm having. Hope this helps in reproducing it, or (more likely) spotting the error in my ways.

Thank you,

Kenneth J Hughes