Re: [xslt] URIs and Their Hacks

[Igor Zlatkovic <igor zlatkovic com>]

On Tue, 18 Feb 2003, Le grande pinguin wrote:
> Hmm, maybe i put too much into symbol names (that's what you get from programming
> in Scheme :) , but wouldn't  xmlCanonicPath be better name for that function?
> After all, what the code does is a hashing from pathes to a unique path ....
> This is an operation which seems neccesary on most plattforms that support relative
> pathes, i guess.

  The name is of secondary importance for me, call it xmlCanonicPath for all
I care :-) But, that functionality cannot completely be implemented on that
level. The SAX handler startDocument (where this function is used) does not
necessarily know anything about what it is actually parsing. Is it the
document specified to xmllint on the command-line? Is it a document
xincluded from another document? To build a really unique resource
identifier there, one woud need to know if there is a base URI for the
current document. That information is not available at the given level.

  The purpose of xmlURIFromPath is therefore not uniqueness, but
URI-conformness. If what xmlDoc.URL holds is not an URI, subsequent
manipulations through the functions from uri.c will fail. When, for example,
one document xincludes ahother and the corresponding code tries to build the
URI for the included document, it will fail if the xmlDoc.URL of the
including document is, say, a Windows path.

  The other thing, namely ensuring that more occurences of the same document
are represented by the same URI, that's another front.

> ... do they even _have_ to be paths? After all libxml has a pluggable IO layer
> (we use cms://bla/fup/oink .... inhouse :-)

And what you use is a proper URI :-) As said, IO layer has little to do with
this. The purpose is to ensure that URI processing regarding linked
documents succeeds in every case.

> Hmmm, thinking of that -- i think a real clean API would have a 'xmlCanonicURI'
> function as part of the IO layer ....

Everything will come in due time :-)

Ciao,
Igor