On Fri, Apr 16, 2010 at 1:53 PM, Michael Kay <mike(_at_)saxonica(_dot_)com>
wrote:
Given the following source XML document and a data-driven (push
style) XSLT transformation:
<a1>
<a2>
<a3>
<a4/>
</a3>
</a2>
</a1>
then the start of processing <a{N}> will be after the start
of processing of <a{N-1}>.
As far as the language semantics are concerned, a4 is a subexpression of a3
and is therefore evaluated first. Evaluation of a4 produces an element node;
evaluation of a3 copies this element node to create the child of the new a3
element. Evaluation of a2 then copies the new a3, and so on. So contrary to
your description, evaluation of a4 happens BEFORE a3.
Seems like a misunderstanding.
I meant this:
There was an <xsl:apply-templates> instruction that caused a template
to be selected and applied on <a4>. This <xsl:apply-templates>
instruction was processed as part of processing the parent of <a4>.
Therefore, the processing of <a3> (the parent of <a4>) started, then
the <xsl:apply-templates> was part of this processing and it caused
the processing of <a4>.
What is wrong with this?
--
Cheers,
Dimitre Novatchev
---------------------------------------
Truly great madness cannot be achieved without significant intelligence.
---------------------------------------
To invent, you need a good imagination and a pile of junk
-------------------------------------
Never fight an inanimate object
-------------------------------------
You've achieved success in your field when you don't know whether what
you're doing is work or play
Now a real XSLT processor might behave quite differently. Saxon, for
example, might compile this into a sequence of internal instructions:
emit startElement(a1)
emit startElement(a2)
emit startElement(a3)
emit startElement(a4)
emit endElement(a4)
emit endElement(a3)
emit endElement(a2)
emit endElement(a1)
This is sufficiently far removed from the abstract syntax tree that to ask
what order the source expressions are evaluated in is not very meaningful.
It becomes even less meaningful once you have some real expressions to
compute the names and content of the elements. For example, if the logic
were:
<xsl:template match="x">
<xsl:variable name="this" select="."/>
<a1 name="{concat($p, 1)}">
<xsl:for-each select="*">
<a2 name="{concat($p, $this/@id)}"/>
</
</
</
then the expression concat($p, 1) will be turned into a global variable that
is computed once, the first time it is used, while the expression concat($p,
$this/@id) will be calculated once, during the first iteration of the
xsl:for-each loop.
Regards,
Michael Kay
http://www.saxonica.com/
http://twitter.com/michaelhkay
--~------------------------------------------------------------------
XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
To unsubscribe, go to: http://lists.mulberrytech.com/xsl-list/
or e-mail:
<mailto:xsl-list-unsubscribe(_at_)lists(_dot_)mulberrytech(_dot_)com>
--~--
--~------------------------------------------------------------------
XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
To unsubscribe, go to: http://lists.mulberrytech.com/xsl-list/
or e-mail: <mailto:xsl-list-unsubscribe(_at_)lists(_dot_)mulberrytech(_dot_)com>
--~--