* Kaz Kylheku <20090615105137....@gmail.com> :
Wrote on Wed, 3 Jun 2009 20:09:22 +0000 (UTC):

| On 2009-06-03, N. Raghavendra <ra...@mri.ernet.in> wrote:

|> I have written a basic C wrapper for libmxl2, which parses an XML
|> document, and prints a list containing the parsed data.  At the moment,
|> I save the printed sexp to a file, and READ it from Lisp.  I am thinking
|> it may be better to avoid the intermediate printing and READing, and
|> instead save the parsed data to a C struct; I can then try to use Lisp
|> to get the sexp from the C struct, using an FFI.  What is a good way to
|> store a sexp in C?  Is it common practice to pass through an
|> intermediate file like I am doing now?
|
| Why don't you just use an XML processing library for Common Lisp?

I'm sure there would be valid reasons to avoid depending on the recent
offerings of the free-common-lisp-library vendors in this department.

| It seems like your wrapper is a waste of effort.

If you looked at his posted example carefully. libxml2 has done extra
processing on his document: libxml2 has expanded this directive

  <xi:include href="urn:publicid:-:EXAMPLE:DOCUMENT+Section:EN"/>

and the results were included in the sexp output.

I'd imagine the OP would prefer to use libxml2 for its features.

To answer the OP, I'd expect that it may not be worth the effort to
construct lisp sexps directly from C code.

The next easiest thing would be to prepare a stream in C which lisp
could call READ on directly. But CL:READ would be likely be the slowest
step; I noticed you are dealing with UTF-8 strings and so any clever
speedups from munging 8bit-clean character arrays between C and lisp
will not be possible and you'd go through the extra copying/stream
layers in your lisp.

Are there any other characterestics of your XML data that you want to
avoid a file layer?