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C++ Cookbook
book

C++ Cookbook

by D. Ryan Stephens, Christopher Diggins, Jonathan Turkanis, Jeff Cogswell
November 2005
Beginner to intermediate content levelBeginner to intermediate
594 pages
16h 23m
English
O'Reilly Media, Inc.
Content preview from C++ Cookbook

14.8. Evaluating an XPath Expression

Problem

You want to extract information from a parsed XML document by evaluating an XPath expression.

Solution

Use the Xalan library. First, parse the XML document to obtain a pointer to a xalanc::XalanDocument. This can be done by using instances of XalanSourceTreeInit, XalanSourceTreeDOMSupport, and XalanSourceTreeParserLiaison—each defined in the namespace xalanc—like so:

#include <xercesc/framework/LocalFileInputSource.hpp>
#include <xalanc/XalanSourceTree/XalanSourceTreeDOMSupport.hpp>
#include <xalanc/XalanSourceTree/XalanSourceTreeInit.hpp>
#include <xalanc/XalanSourceTree/XalanSourceTreeParserLiaison.hpp>
...
int main()
{
     ...
     // Initialize the XalanSourceTree subsystem
     XalanSourceTreeInit           init;
     XalanSourceTreeDOMSupport     support; 

     // Interface to the parser
     XalanSourceTreeParserLiaison  liaison(support);

     // Hook DOMSupport to ParserLiaison
     support.setParserLiaison(&liaison);  
     LocalFileInputSource          src(document-location);
     XalanDocument*                doc = liason.ParseXMLStream(doc);
    ...
}

Alternatively, you can use the Xerces DOM parser to obtain a pointer to a DOMDocument, as in Example 14-14, and then use instances of XercesDOMSupport, XercesParserLiaison, and XercesDOMWrapperParsedSource — each defined in namespace xalanc — to obtain a pointer to a XalanDocument corresponding to the DOMDocument:

#include <xercesc/dom/DOM.hpp> #include <xalanc/XalanTransformer/XercesDOMWrapperParsedSource.hpp> #include <xalanc/XercesParserLiaison/XercesParserLiaison.hpp> ...
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Publisher Resources

ISBN: 0596007612Supplemental ContentErrata Page