Actually, I don't think this is quite so impossible. Given the evaluate()
and node-set() extensions, it seems quite feasible to write a recursive
process that reads an XPath expression, creates a new tree that modifies the
nodes selected by that expression in some way, and then continues by reading
the next XPath expression to create another new tree and so on. Whether it's
a good application design is another matter, but I don't think it's
infeasible.
Michael Kay
http://www.saxonica.com/
-----Original Message-----
From: Wendell Piez [mailto:wapiez(_at_)mulberrytech(_dot_)com]
Sent: 11 August 2005 23:29
To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
Subject: Re: [xsl] How recursively iterate over entire document?
Chris,
What you are trying to accomplish in a single pass defies the
processing
model for XSLT 1.0. If you could map out the dependencies between the
different settings explicitly, it might not be completely
inconceivable
under XSLT 2.0, but it's not a task I'd relish. I'd probably
be inclined to
start with the assumption that N passes over the data may be
needed, where
N is the number of assertions you are making.
While evaluate() may be handy, I'd suggest you try thinking
through how
you'd do this without it -- writing a stylesheet to generate
stylesheets.
You could, in fact, generate a suite of stylesheets to be executed
consecutively over your data in a (longish) pipeline (they'd all be
variants of the identity transform, except amended with logic
from your
settings). This would have the virtue of clarifying the
dependencies. Your
process expects x to happen before y -- but the XSLT processing model
doesn't support that specification explicitly (it's designed
so processors
can execute steps in parallel if they like).
This is sort of like trying to repair your engine while your
car is moving
at 65mph on the highway.
Cheers,
Wendell
At 06:04 PM 8/11/2005, you wrote:
Hi List,
It's kind of strange what I'm doing, so it's hard to explain. I'll
try to keep it simple. In my document that I'm
trasnforming, I have a
sequence of elements that contain some xpath queries in them.... that
will be dynamically evaluated using evaluate().
These can't be evaluated consecutively on the same document, because
one will cause changes to the document that the next one has to see,
etc.
So in other words, I need to iterate over a sequence and for each
iteration, make changes to a document and pass it on to the next
iteration. In the end, I want only the single document with all the
changes to it. I'm probably making no sense, so I'll try to
illustrate and example.
Source Documents
------------------------------
<settings>
<setting xpath="/company/departments">
<department name="c"/>
</setting>
<setting xpath="/company/departments/department[(_at_)name='c']">
<employees count="10"/>
</setting>
</settings>
<company>
<departments>
<department name="a"/>
<department name="b"/>
</departments>
</company>
Output Doc
------------------------------
<company>
<departments>
<department name="c">
<employees count="10"/>
</department>
<department name="a"/>
<department name="b"/>
</departments>
</company>
---------------------------
Please ignore the worthlessness of this example... it's just a
simplified example to illustrate what I'm trying to do.
As you can see, the first 'setting' element is adding a new element
to the doc at the location specified by the 'xpath'
attribute. I have
no problem with doing just one. The problem I have, is that the
second setting element has an xpath that is depended on the first one
already having been completed because, for example, department C does
not exist until it has been added.... and since this is not DOM, it's
getting a little complicated for me to conceptualize how to
do this...
This doesn't work, but maybe will give some ideas....
<xsl:variable name="doc" select="document(company.xml)">
<xsl:for-each select="settings/setting">
<xsl:variable name="doc">
<xsl:apply-templates select="$doc">
(tunnel setting element param...)
</xsl:apply-templates>
</xsl:variable>
</xsl:for-each>
<xsl:sequence select="$doc"/>
Any ideas?
Thanks!
======================================================================
Wendell Piez
mailto:wapiez(_at_)mulberrytech(_dot_)com
Mulberry Technologies, Inc. http://www.mulberrytech.com
17 West Jefferson Street Direct Phone: 301/315-9635
Suite 207 Phone: 301/315-9631
Rockville, MD 20850 Fax: 301/315-8285
----------------------------------------------------------------------
Mulberry Technologies: A Consultancy Specializing in SGML and XML
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