[developers] differences between s-xml and pxml

[Ann Copestake]

Benjamin.Waldron at cl.cam.ac.uk said:
> I've checked in the S-XML XML module alongside the old pxml module. The  SMAF
> code now uses this new module under /all/ Common Lisps (because  it's that
> much more efficient and generates less garbage); the (R)MRS  and SPPP code
> still uses the old pxml module under Allegro Lisp, but  will use S-XML under
> any other Lisp. To achieve this I've used a  compiler macro (:pxml) which is
> set when we are compiling with pxml (eg.  under Allegro). When this compiler
> macro is set, the (R)MRS and SPPP  code will use the pxml module for XML
> processing. To access pxml it is  necessary to use the "net.xml.parser"
> package (the "xml" package comes  built-in to S-XML).

> Ann, I added the following patch rmrs/xml-utils.lsp:


I just ran the rmrs code with s-xml rather than pxml for the first time.  
Unfortunately this breaks RASP3-RMRS (the grammar and tag files won't load) - 
it appears that s-xml doesn't always give the same results as pxml (I believe 
it returns atoms in some contexts where pxml returns lists).  I have therefore 
reverted the changes alluded to above to require pxml until such time as we 
have a workaround.

Ann