Sorry, if this has been answered previously. I checked the archives and sample
code and could not find the answer.
Is this the right pattern to execute a XPath Query on Xerces DOM? This code
used to work with the source in CVS repository that I downloaded couple of
months back. The official release causes an access violation on the following
line
XalanElement* rootElem = theWrapper.getDocumentElement();
I am using Xerces 2.2 and Xalan 1.5 on Windows platform. Any help/suggestions
would be really appreciated. Also, we plan to use XPath expressions heavily
(and call this method very often( so any pointers on better implementations to
improve performance would be greatly appreciated.
Thanks,
Ravin
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Declarations for objects used....
DOMDocument* xercesDocument;
std::wstring xPathQuery;
DOMNode* m_pDOMNode;
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XercesDOMSupport theDOMSupport;
XercesDocumentWrapper theWrapper(xercesDocument, false, false);
// Initialize the XPath subsystem
static XPathInit theInit;
// configure the objects needed for XPath to work with the Xerces DOM
XPathEnvSupportDefault theEnvSupport;
XObjectFactoryDefault theXObjectFactory;
XPathExecutionContextDefault theExecutionContext(theEnvSupport,
theDOMSupport, theXObjectFactory);
XPathFactoryDefault theXPathFactory;
XPathProcessorImpl theXPathProcessor;
XalanElement* rootElem = theWrapper.getDocumentElement();
XalanNode* currentNode = theWrapper.mapNode(m_pDOMNode);
// first get the context nodeset
XPath* const contextXPath = theXPathFactory.create(); //will be deleted by
theXPathFactory destructor
XPathConstructionContextDefault theXPathConstructionContext;
theXPathProcessor.initXPath(*contextXPath,
theXPathConstructionContext,
XalanDOMString(strQuery.c_str()),
ElementPrefixResolverProxy(rootElem,
theEnvSupport, theDOMSupport));
XObjectPtr xObj = contextXPath->execute(currentNode,
ElementPrefixResolverProxy(rootElem, theEnvSupport,
theDOMSupport),
theExecutionContext);
if( xObj->getType() != XObject::eTypeNodeSet )
{
//No results returned...
}
else
{
const NodeRefListBase& nodeset = xObj->nodeset();
//ok, now we get the matching xalan node, add to the vector
size_t len = nodeset.getLength();
for (size_t i=0; i<len; i++)
{
XalanNode* const node = nodeset.item(i);
//Push the results in XercesNodeVector using
Wrapper.mapNode(node) method.
}
}
