Re: [xml] XPath with no XML Doc

[Daniel Veillard <veillard redhat com>]

On Wed, Mar 20, 2002 at 03:16:53PM -0000, Cyberthymia wrote:
> Hi

  Hi,

> One of the test documents I'm using to test my integration of libxml into
> our program consists of XPath statements with no associated XML Document.
> The purpose of this test is to check the format of the results from XPath
> statements and to act as a regression test against out old hand-coded XML /
> XPath implementation.
>
> [Sidetrack: In effect our test doc fires XPath statements like
> "string(0123.4560)" or "substring-after('13/10/2000','/')" or "1 div
> round(-0.49)" into the XPath processor (either libxml or our original one),
> and check the values are the same / correct. We have a different doc to test
> the node set functions, with an associated XML doc.]
>
> Anyway, what I wanted to check was is there any way to get XPath to work
> without creating a dummy XML document for the statements to work against?
> If I create an XPath context with a NULL document and try using it, I get
> the following error:
> C:\src\xml\libxml\xpath.c:9855 Internal error: no document
> I noticed that the testxpath prog always parses the built in XML document
> and uses that if one isn't specified.

  Hum, right it is a bit extreme :-)

> In theory, there isn't any need for the Internal error to be generated
> unless the XPath statement requires access to an XML document (e.g. for node
> set functions), and it seems unnecessary to create an empty dummy document
> just to use a few simple XPath statements.

  Well in theory, XPath wasn't supposed to be used standalone :-)
But I agree with your point, I just never considered that XPath would
seriously be used without a context document.

> Have I missed anything obvious, or should I start tweaking the XPath code?

  I take patches, the hardest is to actually make sure the document is 
really present when needed and that this won't create a relibility 
problem to remove the test from the context creation.

Daniel

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