Re: [xml] seeking help with namespaces and SAX

[Daniel Veillard <veillard redhat com>]

On Thu, Jan 10, 2002 at 11:04:44PM -0500, Alex Graveley wrote:
> Hi,
>
> I need to be able to tell if an element or attribute is in a specific
> namespace using the SAX parser.  Is there any good sample code for a
> state machine that would do this?
>
> I was essentially thinking that I would keep an array of lists of valid
> namespace prefixes (one entry in the array for each parent node).  I
> would walk up the array looking for the current element/attributes'
> prefix.  On startElement the index into the array would be incremented,
> and an array constructed of new prefixes for my namespace.  The reverse
> would happen on endElement.  

  More complex than that, I think you need one dictionary per level.
Well you need at least to keep all the informations from the parents
nodes, including their level.

> Hmm... this doesn't cover the redefine of a parent node's valid prefix
> to another namespace... uggg... I guess I could keep an allow list and a
> deny list for each node.  Anyways, every way I can think of seems gross
> and makes way too many allocations.  

A child node can remove a prefix from the subtree scope by using
    xmlns:foo = ""
or simply redefine foo to a new value (same applies to default namespaces too)
so you can't just pass the same array/dictionary underneath.

  The spec is short. You should read it.
    http://www.w3.org/TR/REC-xml-names/

> Someone must have dealt with this before, whats the best solution?

Look in the Java code, they tend to use SAX a lot.

Daniel

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