[xslt] Document on libxslt internals

[Daniel Veillard <veillard redhat com>]

  I tried to document how libxslt actually works:

    http://xmlsoft.org/XSLT/internals.html

I hope this will be an useful resource for those planning to hack on
or with libxslt, and people trying to evaluate it.
Actually writing this had lead me to the following:
   - well libxslt is not well optimized, there were parts where some
     trade-off where made but there is also obvious innefficiencies.
     The fact that libxslt compares relatively favorably preformance
     wise with other engines tends to prove that XSLT implementations
     are either not matures or that Java is still has performance
     problem since Saxon seems far better optimized than libxslt.
   - I did spot a serious problem in the way I handle templates
     variables and parameters, this part will probably need to be
     completely rewritten
   - I found a number of things to improve, depending on time and
     pressure they may come in faster or slower

  As always this is probably full of typos errors of all sorts, etc.
feedback to fix them is very welcome :-)

  I think the 3 things i will focuse on in the near future are:
    - fix the parameter/variable stack handling
    - write a decent framework and doc for writing extensions
    - change the way the result is built to allow a SAX like 
      event interface to be used instead of a DOM tree generation

Daniel

-- 
Daniel Veillard      | Red Hat Network http://redhat.com/products/network/
veillard@redhat.com  | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/