XercesDOMSupport: Converting between Xalan nodes and Xerces DOM nodes for removal

[Keith Reynolds <ch...@yahoo.com>]

Hello,
  I have seen some other postings with similar questions.  In general
there was agreement to work up a sample but none exists - that I can
find.  
  I would like to use Xalan for XPATH searching and then allow removal
of some nodes.  I have tried using the wrapper and haven't had any
success.  The wrapper's function removeChild() fails with
NO_MODIFICATION_ALLOWED_ERR and I apparently can't call on the
XercesNode::removeChild() - because it's returned 'const' from
mapNode().

  I have the code shown below.
  
  As an alternative approach (one that I less favor) could the selected
nodes be passed into a XSLT transformation to achieve the same result?

Thanks,
Keith Reynolds


<code>
// Using Xalan-C 1.10
// Using Xerces-C 2.7

XALAN_USING_XALAN(FormatterToXercesDOM)
XALAN_USING_XALAN(NodeRefList)
XALAN_USING_XALAN(XPathEvaluator)
XALAN_USING_XALAN(XalanDOMString)
XALAN_USING_XALAN(XalanDocument)
XALAN_USING_XALAN(XalanDocumentPrefixResolver)
XALAN_USING_XALAN(XalanNode)
XALAN_USING_XALAN(XercesDOMSupport)
XALAN_USING_XALAN(XercesDOMWrapperParsedSource)
XALAN_USING_XALAN(XercesDocumentWrapper)
XALAN_USING_XALAN(XercesParserLiaison)
XALAN_USING_XERCES(MemBufInputSource);
XALAN_USING_XALAN(XalanElement)
XALAN_USING_XERCES(DOMNode)

bool retval = false;

char szXML[] =
"<DET><Filelist><File><ID>001</ID><Filename>\\\\server\\workspace\\file1.wav</Filename></File><File><ID>002</ID><Filename>\\\\server\\workspace\\file2.wav</Filename></File></Filelist></DET>";
int nSize = sizeof(szXML);

MemBufInputSource memBuf((const XMLByte*)szXML, nSize, "memory_buffer",
false);

XercesDOMSupport theDOMSupport;
XercesParserLiaison theLiaison(theDOMSupport);

theLiaison.setBuildWrapperNodes(true);
theLiaison.setBuildMaps(true);

XalanDocument* xalan_document = theLiaison.parseXMLStream(memBuf);
assert(xalan_document != 0);

XercesDocumentWrapper* docWrapper =
theLiaison.mapDocumentToWrapper(xalan_document); 
assert(docWrapper != 0);

XalanNode * contextNode = xalan_document;
assert(contextNode != 0);

XalanElement * namespace_node = xalan_document->getDocumentElement();
assert(namespace_node != 0);

XPathEvaluator theEvaluator;

XalanNode * xalan_node = theEvaluator.selectSingleNode(
	theDOMSupport, 
	contextNode,
	XalanDOMString("DET//File[ID = '001']").c_str(),
	XalanDocumentPrefixResolver(docWrapper)
	);

if (xalan_node)
{
	XalanDOMString nodeName = xalan_node->getNodeName();
	std::cout << "Found node" << std::endl;

	const DOMNode * xerces_node = docWrapper->mapNode(xalan_node);


//////////////////////////////////////////////////////////////////////////
	// If I try this, the exception 'NO_MODIFICATION_ALLOWED_ERR' is
thrown
	docWrapper->removeChild(xalan_node);

//////////////////////////////////////////////////////////////////////////

	if (NULL != xerces_node)
	{
		const XMLCh * pName = xerces_node->getNodeName();

		DOMNode* xerces_parent = xerces_node->getParentNode();
		if (NULL != xerces_parent)
		{
		
//////////////////////////////////////////////////////////////////////////
			// this call is not valid because child is 'const'
			xerces_parent->removeChild(xerces_node);
		
//////////////////////////////////////////////////////////////////////////
		}
	}
}




// todo: return the modified DOM in some manner - MemBuf?
// todo: how do we reload the wrapper if necessary?

</code>


		
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