// Copyright (c) Keith D Gregory, all rights reserved
package com.kdgregory.example.xml.xpath;

import java.io.StringReader;

import javax.xml.namespace.QName;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathFactory;
import javax.xml.xpath.XPathVariableResolver;

import org.w3c.dom.Document;

import org.xml.sax.InputSource;

import net.sf.practicalxml.xpath.SimpleNamespaceResolver;


public class VariableExample
{
    public static void main(String[] argv) throws Exception
    {
        String xml = "<foo>"
                   + "    <bar name='argle'>"
                   +          "Argle"
                   + "    </bar>"
                   + "    <bar name='bargle'>"
                   +          "Bargle"
                   + "        <baz>Baz</baz>"
                   + "    </bar>"
                   + "</foo>";

        Document dom = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new InputSource(new StringReader(xml)));

        XPath xpath = XPathFactory.newInstance().newXPath();
        xpath.setNamespaceContext(new SimpleNamespaceResolver("ns", "foo"));
        xpath.setXPathVariableResolver(new XPathVariableResolver()
        {
            @Override
            public Object resolveVariable(QName var)
            {
                if (var.getLocalPart().equals("name"))
                    return "argle";
                else
                    return "";
            }
        });

        String result = xpath.evaluate("//bar[@name=$ns:name]", dom);
        System.out.println("selected content: \"" + result + "\"");
    }
}