Thread: [Docstring-develop] Validation from Python code?

In the Docstring Processing System, there is a class library module [1]_
with one class for each element in the DTDs [2]_. The nodes (text & element
objects) have an asdom() method, which constructs an xml.dom.minidom tree. I
would like to implement a validate() method, which would verify that the
content of each element node adheres to the content models from the DTDs. I
could manually code each validate() method, but thought that there must be
some way to encode the content models in the classes such that they can be
automatically validated (without running an external parser). Basically I'm
looking for the XML/DOM equivalent of regular expression matching, something
that can answer the question: "given a pattern P, is DOM tree D valid?"

Does anybody know of ways to accomplish this validation? Pointers to
existing standards and/or implementations would be much appreciated. Any
Python implementations out there?

Thanks in advance.

David Goodger

.. _[1] http://docstring.sourceforge.net/dps/nodes.py

.. _[2] http://docstring.sourceforge.net/spec/gpdi.dtd,
   http://docstring.sourceforge.net/spec/ppdi.dtd,
   http://docstring.sourceforge.net/spec/soextblx.dtd

-- 
David Goodger    dgo...@bi...    Open-source projects:
 - Python Docstring Processing System: http://docstring.sourceforge.net
 - reStructuredText: http://structuredtext.sourceforge.net
 - The Go Tools Project: http://gotools.sourceforge.net

> Basically I'm
> looking for the XML/DOM equivalent of regular expression matching, something
> that can answer the question: "given a pattern P, is DOM tree D valid?"

Sounds like you want pytrex.
	/r$

> > Basically I'm looking for the XML/DOM equivalent of regular
> > expression matching, something that can answer the question:
> > "given a pattern P, is DOM tree D valid?"
>
> Sounds like you want pytrex.

PyTREX looks like it can nicely validate the parser output (via
``.asdom().toxml()``), but doesn't seem to provide tools for
automatically generating the patterns from the DTD.

Can anyone suggest a way of filling the gap so that we don't have to
hand-maintain the tests in sync with the DTD?

Suspicions: if we switch to using an XML schema, perhaps we can pull
PyTREX patterns out of the schema using XSLT. Perhaps we can build the
schema from the PyTREX patterns. Perhaps we can establish some
middle-format from which we can derive both schema and patterns --
`permittedContents` attributes in ``nodes.py``, or something. It's a fun
problem to mull over, that's for sure.

I can understand David's reluctance to use an external parser if he can
possibly avoid it; it just took me Much Work to get PyXML and 4Suite to
build and install under Cygwin.

David, are you intending your tests to be run only during testing, or as
an optional "paranoid mode" for dps and restructuredtext where people
can have all of their output checked for validity versus the DTD? Both?

Regards,
Garth.

on 2001-07-29 7:02 PM, Garth T Kidd (ga...@de...) wrote:
> PyTREX looks like it can nicely validate the parser output (via
> ``.asdom().toxml()``), but doesn't seem to provide tools for
> automatically generating the patterns from the DTD.

I'm not worried about that. There are tools out there, and it shouldn't be a
frequent task. Incremental maintenance should be easy.

> I can understand David's reluctance to use an external parser if he can
> possibly avoid it; it just took me Much Work to get PyXML and 4Suite to
> build and install under Cygwin.

Yes, and I'm loathe to include anything but pure Python in the project. I
work on a compiler-challenged OS, so feel like a second-class citizen when
I'd like to use some C extension. Not to mention that I haven't done any C
programming for 10 years.

> David, are you intending your tests to be run only during testing, or as
> an optional "paranoid mode" for dps and restructuredtext where people
> can have all of their output checked for validity versus the DTD? Both?

Both. Just having "paranoid mode" automatically means that it's available
for testing too.

David