Pipe XSLT in C++ to get JSON

This is a snippet of my c++ which pumps out XML nodes:

    for (auto& ea: mapa) {
    std::cout << "Removed:" << std::endl;
    ea.second.print(std::cout);
}

for (auto& eb: mapb) {
    std::cout << "Added:" << std::endl;
    eb.second.print(std::cout);
}

I have an XSLT template which can convert this XML into JSON. I'm confused about how I can pipe the printed XML node into the XSLT template and capture the JSON result.

Can anyone give me some pointers as to how this might be achieved?