Am 08.07.2020 um 11:24 schrieb Matthieu RICAUD-DUSSARGET
m(_dot_)ricaud-dussarget(_at_)lefebvre-sarrut(_dot_)eu:
Hi all,
While teaching XSLT, someone ask if it was possible to have a kind of
generic function to group XML elements.
I first answer the only way to do it was to use (eventually nested)
<xsl:for-each-group> instruction with specific conditions according to
the data.
Later, as I was discovering XSLT3, I realize the grouping condition
might be sent as an higher-order-function parameter, which lead me to
write some generic grouping functions to wrap XML elements (see example
below).
The original code can be found on github at
https://github.com/ELSGestion/els-sie-xsl-lib/blob/master/src/main/xsl/els-common_xml.xsl
There’s also some generic xsl to nest titles
(https://github.com/ELSGestion/els-sie-xsl-lib/blob/master/src/main/xsl/nest-titles.xsl)
and a specific implementation of it to nest HTML titles
(https://github.com/ELSGestion/els-sie-xsl-lib/blob/master/src/main/xsl/nest-html-titles.xsl)
Working examples can be found in the test folder
https://github.com/ELSGestion/els-sie-xsl-lib/tree/master/src/test, as
xspec unit test or xspec driven integration tests.
I actually have a bug with Saxon 9.9
(https://saxonica.plan.io/issues/4636) on the generic starting-with
grouping function, but this is an occasion to share theses grouping
libraries J
Any comments, feedbacks or similar code implementation are welcome !
Cheers
Matthieu Ricaud-Dussarget
Example of generic adjacent grouping function used to define a specific
“by-name grouping” implementation (there’s a similar set of functions
for starting-with) :
<xd:doc>
<xd:desc>
<xd:p>Wrap adjacent elements into a new "wrapper" element</xd:p>
<xd:p>CAUTION : any text, pi, comments within context will be
loose</xd:p>
</xd:desc>
<xd:param name="context">Parent of the adjacent elements to
wrap</xd:param>
<xd:param name="adjacent.function">Xpath function to set the
adjacency condition</xd:param>
<xd:param name="wrapper">Element wrapper</xd:param>
<xd:param name="keep-context">Say if the context should be kept or
not in the result</xd:param>
<xd:return>context (or its content) with wrapped adjacent
element</xd:return>
</xd:doc>
<xsl:function name="els:wrap-elements-adjacent" as="node()*">
<xsl:param name="context" as="element()"/>
<xsl:param name="adjacent.function"/> <!--as="xs:string"-->
<xsl:param name="wrapper" as="element()"/>
<xsl:param name="keep-context" as="xs:boolean"/>
<xsl:variable name="content" as="item()*">
<xsl:for-each-group select="$context/*"
group-adjacent="$adjacent.function(.)">
I would certainly prefer to write a "generic" function that expects a
parameter with the grouping population as a sequence of nodes and then use
<xsl:for-each-group select="$population" ...
I don't think for-each-group adjacent is meant to be used only for child
elements of a parent, if you want to use it in a generic way then
provide a population sequence you want to group.
<xsl:choose>
<xsl:when test="current-grouping-key()">
<xsl:for-each select="$wrapper">
<xsl:copy>
<xsl:copy-of select="@*"/>
Doesn't
<xsl:copy select="$wrapper">
suffice in XSLT 3?
Why the xsl:for-each?
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