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Re: [xsl] XPath 3.0: Is it possible to do recursion in an anonymous function?


Subject: Re: [xsl] XPath 3.0: Is it possible to do recursion in an anonymous function?
From: Dimitre Novatchev <dnovatchev@xxxxxxxxx>
Date: Mon, 8 Apr 2013 20:04:55 -0700

Something new in addition to the treatment of this subject in the
current thread -- tail-call optimization and how to survive its
complete lack in current XPath 3.0 processors:

http://dnovatchev.wordpress.com/2013/04/08/recursion-with-anonymous-inline-functions-in-xpath-3-0-part-ii/




On Sun, Oct 14, 2012 at 9:44 AM, Costello, Roger L. <costello@xxxxxxxxx> wrote:
>
> Thank you very much Dimitre. That is a fantastic technique.
>
> Using Dimitre's technique, I implemented the "until" function:
>
> <?xml version="1.0" encoding="UTF-8"?>
> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>                             xmlns:xs="http://www.w3.org/2001/XMLSchema"
>                             version="3.0">
>
>     <xsl:output method="text"/>
>
>     <xsl:variable name="isNegative" select="function($x as xs:integer) {$x lt 0}" />
>     <xsl:variable name="decrement" select="function($x as xs:integer) {$x - 1}" />
>     <xsl:variable name="_until" select="
>                   function(
>                                     $p as function(item()*) as xs:boolean,
>                                     $f as function(item()*) as item()*,
>                                     $x as item()*,
>                                     $_until as function(function(), function(), item()*, function()) as item()*
>                                  ) as item()*
>                      {if ($p($x)) then $x else $_until($p, $f, $f($x), $_until)}
>         " />
>
>     <xsl:variable name="until" select="
>                   function(
>                                      $p as function(item()*) as xs:boolean,
>                                      $f as function(item()*) as item()*,
>                                      $x as item()*
>                                   ) as item()*
>                       {$_until($p, $f, $x, $_until)}
>           " />
>
>     <xsl:template match="/">
>         <xsl:value-of select="$until($isNegative, $decrement, 3)" />
>     </xsl:template>
>
> </xsl:stylesheet>
>
> /Roger
>



--
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
-------------------------------------
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? :)
-------------------------------------
I finally figured out the only reason to be alive is to enjoy it.


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