Re: [xsl] XQuery/XPath 3.1: Node List to Node Set ("distinct nodes")

Eliot and XSL-List,

Along similar lines to $nodes | (), consider

$nodes except ()
$nodes intersect $nodes

I'm finding it difficult to argue what's most intuitive but I kind of like
'intersect'. Can't vouch for performance though. :-)

Best wishes for 2022 --
Wendell




On Tue, Dec 28, 2021 at 4:56 PM Michael Kay mike(_at_)saxonica(_dot_)com <
xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

You might consider

$nodes | ()

a bit more intuitive.

Michael Kay
Saxonica

On 28 Dec 2021, at 19:23, Eliot Kimber 
eliot(_dot_)kimber(_at_)servicenow(_dot_)com <
xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

Hmph.

That is certainly much more efficient 😊 but is not necessarily obvious
(at least not to me).

Thanks!

E.

_____________________________________________
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*From: *Martin Honnen martin(_dot_)honnen(_at_)gmx(_dot_)de <
xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com>
*Date: *Tuesday, December 28, 2021 at 1:15 PM
*To: *xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com 
<xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com>
*Subject: *Re: [xsl] XQuery/XPath 3.1: Node List to Node Set ("distinct
nodes")

[External Email]


On 28.12.2021 20:10, Eliot Kimber 
eliot(_dot_)kimber(_at_)servicenow(_dot_)com wrote:

I couldn’t find an answer in my google and markmail searching so I
thought I’d ask here:

Given an arbitrary list of nodes that may contain duplicates, what is
the most efficient way to reduce the node list to a set?

The solution I came up with is a recursive function:

(:

Get the unique nodes from the supplied sequence

@param nodes The sequence of nodes to evaluate

@return A sequence of nodes such that each node in $nodes exists exactly
once.

:)

declare function dutils:distinctNodes($nodes as node()*) as node()* {

   dutils:_getDistinctNodes($nodes, ())

};

declare function dutils:_getDistinctNodes($nodes as node()*, $resultList
as node()*) as node()* {

   if (exists($nodes))

   then

   let $node := head($nodes)

   return dutils:_getDistinctNodes(tail($nodes), ($resultList | $node))

   else $resultList

};

Which works but I feel like I’m missing some obvious way to do this more
directly, but I’m not seeing it.

Am I missing a better solution?


$nodes/.
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