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

- If order of the sequence must be maintained, consider fold-left() or

fold-right() I suppose

  - but test it!


I would definitely prefer the index-of() - based solution: for being:
  -  shortest
  - with least moving parts and surface
  - shown in actual performance measurements to be not slower (actually,
was slightly faster) than the fold - based solutions provided in this thread
  - shown to work with both BaseX and Saxon (while one of the fold-based
solutions was being evaluated incorrectly in Saxon due to a bug)

Thanks Eliot and everyone! Happy New Year!
Dimitre

On Thu, Dec 30, 2021 at 6:46 AM Wendell Piez wapiez(_at_)wendellpiez(_dot_)com <
xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

Hmm....

Takeaways for me seem to be:

- For the operation in question, prefer "$nodes/." or perhaps
"$nodes/self::node()" or $nodes/self::* as appropriate, plus a comment
- If order of the sequence must be maintained, consider fold-left() or
fold-right() I suppose
  - but test it!
- except and intersect (to say nothing of union) also have some
interesting uses and applications

Meanwhile it is very reassuring and an education to see these things
worked out. This problem actually has real-world applications for me too -
and the $nodes in question could be documents....

Thanks Eliot! Happy New Year!
Wendell


On Wed, Dec 29, 2021 at 6:25 PM Dimitre Novatchev 
dnovatchev(_at_)gmail(_dot_)com <
xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

No, it doesn't seem to be fixed, Mike's implementation seems to try be
smarter than the spec allows and his own coding assumes :)


Seems BaseX rules!

And glad to be a contributor to the eventual future improvement of Saxon
:)

Cheers,
Dimitre

On Wed, Dec 29, 2021 at 12:17 PM Martin Honnen 
martin(_dot_)honnen(_at_)gmx(_dot_)de <
xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

On 29.12.2021 20:59, Dimitre Novatchev dnovatchev(_at_)gmail(_dot_)com 
wrote:

  document (fragments?) are involved.

Yes, bugs happen...

Just trying to evaluate Dr. Kay's fold-left solution with Saxon

(EE9.1.7

via Oxygen) I am getting a result of 20 nodes but the correct must be
just 3 nodes. BaseX correctly evaluates the XPath expression and
produces the right 3-nodes result.

Xml document:
<t>
   <a/>
   <b/>
   <c/>
</t>

XSLT stylesheet:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform
<http://www.w3.org/1999/XSL/Transform>" version="3.0">
   <xsl:output omit-xml-declaration="yes"/>
   <xsl:template match="/">
     <xsl:sequence select=
       "let $xml := /,
       $nodes := (/*/a, /*/c, /*/b, /*/a, /*/b, /*/a, /*/c, /*/b, /*/a,
/*/b,
       /*/a, /*/c, /*/b, /*/a, /*/b, /*/a, /*/c, /*/b, /*/a, /*/b,
       /*/a, /*/c, /*/b, /*/a, /*/b, /*/a, /*/c, /*/b, /*/a, /*/b,
       /*/a, /*/c, /*/b, /*/a, /*/b, /*/a, /*/c, /*/b, /*/a, /*/b,
       /*/a, /*/c, /*/b, /*/a, /*/b )
       return
         $nodes => fold-left((), function($all, $this) {$all, $this
except $all})"/>
   </xsl:template>
</xsl:stylesheet>

Result produced when run with Saxon-EE (and also PE) 9.9.1.7 via

Oxygen:

<a/><c/><b/><b/><b/><b/><b/><b/><b/><b/><b/><b/><b/><b/><b/><b/><b/><b/><b/><b/>


Evaluating the below expression with Saxon-EE XQuery9.9.1.7 also
produces the same unexpected result:

let $xml := parse-xml("<t><a/><b/><c/></t>"),
     $nodes := ($xml/*/a, $xml/*/c, $xml/*/b, $xml/*/a, $xml/*/b,
$xml/*/a, $xml/*/c, $xml/*/b, $xml/*/a, $xml/*/b, $xml/*/a, $xml/*/c,
$xml/*/b, $xml/*/a, $xml/*/b, $xml/*/a, $xml/*/c, $xml/*/b, $xml/*/a,
$xml/*/b, $xml/*/a, $xml/*/c, $xml/*/b, $xml/*/a, $xml/*/b, $xml/*/a,
$xml/*/c, $xml/*/b, $xml/*/a, $xml/*/b,$xml/*/a, $xml/*/c, $xml/*/b,
$xml/*/a, $xml/*/b, $xml/*/a, $xml/*/c, $xml/*/b, $xml/*/a, $xml/*/b,
$xml/*/a, $xml/*/c, $xml/*/b, $xml/*/a, $xml/*/b )
   return
     $nodes => fold-left((), function($all, $this) {$all, $this except
$all})

Hopefully this is fixed in the next versions of Saxon?


No, it doesn't seem to be fixed, Mike's implementation seems to try be
smarter than the spec allows and his own coding assumes :)

Saxon-JS 2.3 gets

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
version="3.0">
   <xsl:output omit-xml-declaration="yes"/>
   <xsl:template match="/">
     <xsl:sequence select=
       "let $xml := /,
       $nodes := (/*/a, /*/c, /*/b, /*/a, /*/b, /*/a, /*/c, /*/b, /*/a,
/*/b,
       /*/a, /*/c, /*/b, /*/a, /*/b, /*/a, /*/c, /*/b, /*/a, /*/b,
       /*/a, /*/c, /*/b, /*/a, /*/b, /*/a, /*/c, /*/b, /*/a, /*/b,
       /*/a, /*/c, /*/b, /*/a, /*/b, /*/a, /*/c, /*/b, /*/a, /*/b,
       /*/a, /*/c, /*/b, /*/a, /*/b )
       return
         fold-left($nodes, (), function($all, $this) {$all, $this except
$all})"/>
   </xsl:template>
</xsl:stylesheet>

right but SaxonCS and Saxon HE 10.6 don't.


--
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
-------------------------------------
To avoid situations in which you might make mistakes may be the
biggest mistake of all
------------------------------------
Quality means doing it right when no one is looking.
-------------------------------------
You've achieved success in your field when you don't know whether what
you're doing is work or play
-------------------------------------
To achieve the impossible dream, try going to sleep.
-------------------------------------
Facts do not cease to exist because they are ignored.
-------------------------------------
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-------------------------------------
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-------------------------------------
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-- 
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
-------------------------------------
To avoid situations in which you might make mistakes may be the
biggest mistake of all
------------------------------------
Quality means doing it right when no one is looking.
-------------------------------------
You've achieved success in your field when you don't know whether what
you're doing is work or play
-------------------------------------
To achieve the impossible dream, try going to sleep.
-------------------------------------
Facts do not cease to exist because they are ignored.
-------------------------------------
Typing monkeys will write all Shakespeare's works in 200yrs.Will they write
all patents, too? :)
-------------------------------------
Sanity is madness put to good use.
-------------------------------------
I finally figured out the only reason to be alive is to enjoy it.
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