[xml] XPath and DTD default values

["Jonas Holmberg" <jonas holmberg frontlinesystem com>]

Hi.

I have a question about the XPath implementation.
I have tried to get the default attributes from the DTD:s to work with the 
XPath lookups.
I am very new to libxml, so if there is a very well known answer, I'm 
sorry...

Consider the following document:

<?xml version="1.0"?>
<!DOCTYPE root SYSTEM "root.dtd" [
<!ELEMENT elem (#PCDATA)>
<!ATTLIST elem test CDATA "nothing">
<!ELEMENT root (elem)>
]>
<root>
<elem>data1</elem>
<elem>data2</elem>
<elem test="something">data3</elem>
</root>

with this code:

void doXPath(xmlDocPtr doc,xmlChar* xpathExpr)
{
  xmlXPathContextPtr xpathCtx = xmlXPathNewContext(doc);
  xmlXPathObjectPtr xpathObj = xmlXPathEvalExpression(xpathExpr,xpathCtx);
  xmlNodeSetPtr nodes = xpathObj->nodesetval;
  for (int i = 0; i < nodes->nodeNr; i++) {
     if (nodes->nodeTab[i]->type == XML_ELEMENT_NODE) {
        xmlNodePtr node = nodes->nodeTab[i];
        xmlChar* pProp = xmlGetProp(node,BAD_CAST "test");
        xmlChar* pContent = xmlNodeGetContent(node);
        std::cout << "Node: " << node->name << ", Data: " << pContent << ", 
test = " << pProp << endl;
        xmlFree((void*) pContent);
        xmlFree((void*) pProp);
     }
  }
  xmlXPathFreeObject(xpathObjPtr);
  xmlXPathFreeContext(xpathContextPtr);
}

doXPath(doc,(xmlChar*) "//root/*");
gives me:
Node: elem, Data: data1, test = nothing
Node: elem, Data: data2, test = nothing
Node: elem, Data: data3, test = something

So, xmlGetProp works great, giving me the default value of "nothing"

doXPath(doc,(xmlChar*) "//root/*[ test=\"something\"");
gives me:
Node: elem, Data: data3, test = something

Still, as expected.

But.
doXPath(doc,(xmlChar*) "//root/*[ test=\"nothing\"");
gives me no results...


Am I wrong in expecting xpath to work with default values, or can anybody 
help me out?

Regards
Jonas Holmberg