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, $decrement, 3)" />
</xsl:template>
</xsl:stylesheet>
/Roger
Nice, Roger,
The naming of the last argument makes the code *look* like ordinary recursion.
And this could deceive some people! :) Also, the name of this
argument will have to change for a new function to match the function
name.
I would personally prefer a more standard and unchangeable name, such
as "_step".
To go further, the type of the "_step" argument could be specified as
function()+ .
This could be used to implement "non-deterministic" functions, where
at each step, the next processing step is randomly determined from the
available choices ($_step functions).
I feel overwhelmed at what can be accomplished with pure XPath 3.0
anonymous functions.
--
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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