AbsolutizeUrl.java

package com.va.harvest.normalize.saxon;

import com.va.harvest.web.contrib.CommonUtil;
import net.sf.saxon.expr.StaticProperty;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.functions.ExtensionFunctionCall;
import net.sf.saxon.functions.ExtensionFunctionDefinition;
import net.sf.saxon.om.*;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.SequenceType;
import net.sf.saxon.value.StringValue;

/**
 * Author: Tejus Parikh
 * Date: Mar 29, 2010 2:25:01 PM
 */
public class AbsolutizeUrl extends ExtensionFunctionDefinition {
    private static final StructuredQName qName =
            new StructuredQName("", 
                    "http://vijedi.net/", 
                    "absolutizeUrl");

    private final static SequenceType[] argumentTypes = new SequenceType[] {
            SequenceType.SINGLE_STRING,
            SequenceType.OPTIONAL_STRING
    };

    @Override
    public StructuredQName getFunctionQName() {
        return qName; 
    }

    @Override
    public int getMinimumNumberOfArguments() {
        return 1;
    }

    @Override
    public int getMaximumNumberOfArguments() {
        return 2;
    }

    @Override
    public SequenceType[] getArgumentTypes() {
        return argumentTypes;  
    }

    @Override
    public SequenceType getResultType(SequenceType[] suppliedArgumentTypes) {
        return SequenceType.makeSequenceType(
                suppliedArgumentTypes[0].getPrimaryType(), StaticProperty.ALLOWS_ZERO_OR_ONE);
    }

    @Override
    public ExtensionFunctionCall makeCallExpression() {
        return new AbsolutizeUrlCall(); 
    }

    private static class AbsolutizeUrlCall extends ExtensionFunctionCall {

        @Override
        public SequenceIterator call(SequenceIterator[] arguments, XPathContext xPathContext) throws XPathException {

            StringValue pageUrlSV = (StringValue) arguments[0].next();
            if(null == pageUrlSV) {
                return EmptyIterator.getInstance();
            }

            StringValue hrefUrlSV = null;
            if(arguments.length > 1) {
                hrefUrlSV = (StringValue) arguments[1].next();
                if(null == hrefUrlSV) {
                    return EmptyIterator.getInstance();
                }
            }
            
            String pageUrl = pageUrlSV.getStringValue();
            String hrefUrl = hrefUrlSV.getStringValue();

            // Url transformation magic goes here

            Item item = new StringValue(fullUrl);
            return SingletonIterator.makeIterator(item);  
        }
    }
}

This is really cool, thanks. Could you please provide a .xsl snippet to show how to declare and use this function ?