Re: [xml] Refactoring of the SAX interface for namespace support

[Daniel Veillard <veillard redhat com>]

On Wed, Aug 13, 2003 at 04:12:53PM +0200, Toni Uusitalo wrote:
> I think there could be some benefits implementing SAX interface as close to 
> existing Java/C++ SAX2 interface as you can get with poor old C:

  For me C is not poor.

> - For example namespace info for callbacks has been well thought over and 
> tested
> - Existing documentation on SAX can be more easy to grasp when callbacks 
> are similar (in the limits of C of course)

  Well I think it's a trivial change actually. The point is to have
a clear description on how this changed and I will do this.

> Of course performance issues are on the scale too but I think little 
> performance benefit over usability isn't worth it.

  Well for me performances are a critical aspect at this point, after
conformance to standards (note that if SAX actually had gone through due
standard process I would feel far more annoyed to break it !).

> p.s. I myself have written minimal SAX2 based XML parser in ANSI C with 
> namespace support and API similar to
> SAX2

  Looked at it:

--------------
startElementHandler
int (*XML_START_ELEMENT_HANDLER)(void *UserData, const XMLCH *uri, const XMLCH *localName, 
                                 const XMLCH *qName, LPXMLVECTOR atts);

endElementHandler
int (*XML_END_ELEMENT_HANDLER)(void *UserData, const XMLCH *uri, const XMLCH *localName,
                               const XMLCH *qName);
--------------

  This looks very close to proposal #1, I still prefer having per attributes
callbacks to avoid the complication of walking over the atts vector. But this
is one more vote toward the first option.

--------------
Similar to SAX2 events, note that uri or localName parameter doesn't have value NULL when unavailable but 
their values are empty string, this can be tested with

if (!*uri) ...
--------------

  Bahh, this is not common for C, and force and indirect memory reference
instead of just a register test, I'm not thrilled ? Is that supposed to 
help programmers, I can't see why.

--------------
of course. Difference from SAX is that qName has always valid value. localName is empty string when element 
doesn't belong to any namespace or belongs to default namespace.
--------------

   Localname empty when in default namespace ? that sounds very misleading.

Daniel

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