Re: [xsl] Universally quantified test of child attribute presence/absence

[Abel Braaksma <abel.online@xxxxxxxxx>]

Yves Forkl wrote:
> 1) There are element children, and they all have the attribute.
>
> 2) Each of the element children, if any, does not have the attribute.
>
> 3) Some element children do have the attribute, some don't.
>
> The solution I have found (thanks again to you and David) is to 
> explicitly couple the existence of children with attribute presence 
> for case 1, then proceed to case 2 where I just test for attribute 
> absence before passing on to the "otherwise" clause representing case 3:
>
> <xsl:choose>
>   <xsl:when
>     test="* and (every $child in * satisfies $child[@my_attribute])">
>   </xsl:when>
>   <xsl:when
>     test="every $child in * satisfies $child[not(@my_attribute)]">
>   </xsl:when>
>   <xsl:otherwise>
>   </xsl:otherwise>
> <xsl:choose>
>
> Relying on the evaluation order of the instructions within xsl:choose 
> spares me from having to use more complicated (or less familiar :-)) 
> test expressions.
>
> Note that for case 2, testing revealed that I can't test for
>
> not(every $child in * satisfies $child[@my_attribute])

Your second test can be simplified if you make the third test to be your 
second:

<xsl:when test="*[@my_attribute]">

which will leave your <xsl:otherwise /> to catch what's now in "every 
$child in ... not(@my..." (you can remove that altogether). Of course, 
it is a matter of taste. I dislike the 'every' and 'some' expressions, 
because they tend to be very confusing, even on second read, and 
especially when used with negation:

<xsl:choose>
 <xsl:when
   test="* and (every $child in * satisfies $child[@my_attribute])">
    <!-- all children have @my_attribute -->
 </xsl:when>
 <xsl:when test="*[@my_attribute]">
     <!-- some children have @my_attribute -->
 </xsl:when>
 <xsl:otherwise>
     <!-- zero children, or none have @my_attribute -->
 </xsl:otherwise>
<xsl:choose>


Cheers,
-- Abel Braaksma
  http://www.nuntia.nl