STLL tries to be indepentend of the XML library to use for parsing the XHTML code. This is achieved by a little XML abstraction layer that contains functions to access a DOM tree parsed by a certain library.

For each library to support STLL must provide this interface.

The XHTML parser is written with C++ templates and instantiated once for each library

Right now STLL supports libxml2 and pugixml as XML libraries. The library support is checked at compile time. When a library is available the instance is compiled in, if not it will be left out. If you want to add support for a different library you need to recompile

If you want to add support for a new library that is not yet supported by STLL you have to do the following:

add check for the library to CMakeList.txt and define a compiler variable USE_xxx for your library
open xmllibraries.h and add overloaded functions for your library (copy paste adapt)
create a new file layouterXHTML_xxx for your library and inside create an instantiation of the parser for your library (copy paste adapt)
add your new parser function to the layouterXHTML.h header file (copy paste adapt)
add a new runtest instance for your library to CMakeList.txt and make sure all tests pass (copy paste adapt)
send in a patch so that others can profit from your work

Most of it is simple stuff, the hardest is step 2 to create the overloaded functions.