Re: [xsl] XPath expression that yields the same result as xsl:for-each-group?

["Martin Honnen martin.honnen@xxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

On 30.05.2019 15:06, Martin Honnen martin.honnen@xxxxxx wrote:

> > What XPath expression will yield the desired value for $groups?
> >
> > <xsl:variable name="groups" select="???" />
> >
> > Is there an XPath 2.0 expression that can be used?
>
> What kind of sequence type would you expect that XPath expression to
> return? You can't build sequences of sequences to somehow wrap the items
> belonging to a group.
>
> So unless you could move to XPath 3.1 with maps and/or arrays I don't
> see an XPath type constructed with pure XPath to hold groups. And of
> course even there it would be easier and smarter to use XSLT to create
> the map or the nested sequence/array or array/sequence structure than to
> rely on pure XPath I think.

A pure XPath 3.1 expression to build the groups as a sequence of
array(element(row)) would be

let $keys := distinct-values($rows/concat(ARPT__IDENT, '|', TRM__IDENT))
                    return
                      for $key in $keys
                      return array { $rows[$key = concat(ARPT__IDENT,
'|', TRM__IDENT)] }


you could use as


    <xsl:template match="Test">
        <xsl:variable name="rows" select="row" as="element(row)*"/>
        <xsl:variable name="groups" as="array(element(row))*"
            select="let $keys :=
distinct-values($rows/concat(ARPT__IDENT, '|', TRM__IDENT))
                    return
                      for $key in $keys
                      return array { $rows[$key = concat(ARPT__IDENT,
'|', TRM__IDENT)] }"/>
        <results>
            <xsl:for-each select="$groups">
                <group>
                    <xsl:sequence select="?*" />
                </group>
            </xsl:for-each>
        </results>
    </xsl:template>

https://xsltfiddle.liberty-development.net/jyRYYiQ

But I think using XSLT 2/3 grouping to build a grouping structure, be it
an XML one in XSLT 2 or such a nested sequence of arrays if needed in
XSLT 3 is much easier and probably more efficient anyway.