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Re: [xsl] XTTE1100: A sequence of more than one item is not allowed as the @group-adjacent attribute


Subject: Re: [xsl] XTTE1100: A sequence of more than one item is not allowed as the @group-adjacent attribute
From: Ihe Onwuka <ihe.onwuka@xxxxxxxxx>
Date: Mon, 13 May 2013 02:49:52 +0100

On Mon, May 13, 2013 at 2:20 AM, G. Ken Holman
<gkholman@xxxxxxxxxxxxxxxxxxxx> wrote:
> At 2013-05-13 02:08 +0100, Ihe Onwuka wrote:
>>
>> On Mon, May 13, 2013 at 1:55 AM, G. Ken Holman
>> <gkholman@xxxxxxxxxxxxxxxxxxxx> wrote:
>> > At 2013-05-13 01:50 +0100, Ihe Onwuka wrote:
>> >>
>> >> I am getting the above error on the following line of code
>> >>
>> >> <xsl:for-each-group select="*" group-adjacent="data(
>> >> descendant::*/local-name())">
>> >>
>> >> I originally tried it without wrapping it in the data function and
>> >> have also tried casting it to string (where I get a different but
>> >> similar answer).
>> >>
>> >> I'm sure there is a simple answer out there.
>> >
>> >
>> > Yes, both the data() function the group-adjacent= attribute are each
>> > expecting a singleton evaluation and you are supplying a sequence
>> > expression
>> > that returns more than a singleton value.
>> >
>> > The expression is evaluated from the context of the member of the
>> > population
>> > being grouped.  The expression descendant::*/local-name() returns a
>> > sequence
>> > of strings being the local name of all of the descendant elements of
>> > each
>> > element of the population.  The error message is quite explicit in what
>> > is
>> > wrong.
>> >
>> > What is it you are trying to do
>>
>> I am trying to group the children of each element by the  local name
>> of all of the descendant elements of each child.
>
>
> I can read that from your expression, but it doesn't make sense to me on a
> number of levels.
>
> First, your sentence implies you should be using group= instead of
> group-adjacent= ... do you want *all* elements that are "the same" in one
> group, or do you want them split up into groups of elements that are
> adjacent members of the population?
>
> Second, by "the same" being your definition of "the local name of all of the
> descendants" do you mean the "ordered set of local names of the descendants
> in document order" or "the unordered set of unique local names without
> duplicates" or something else?
>
> When I asked what you were trying to do I was looking for a sentence
> describing the *reason* why you wrote the expression, not what the
> expression was in a sentence.  What is the nature of these elements with
> descendants that they need to be grouped?  Is this an academic exercise or
> is there a reason the names are important to the grouping?  By trying to
> understand the problem being solved, someone on the list may be able to help
> you better than trying to fix something you've started that may turn out to
> have been an inappropriate way to start given the problem at hand.
>
> . . . . . . . . . . Ken
>

I understand but what I described is what I want to do - no it is not
an academic exercise.

See an example of the required grouping - attribute and text nodes may
be present but are ignored for the purpose of grouping.

<A>
  <!-- start group>
  <B>
     <C>
     <D>
  </B>
  <B>
     <C>
     <D>
  </B>
  <! --end group>
  <B>  *** singleton group
  <C>  *** singleton group
  <!-- start group>
  <D>
    <E>
    <E>
      <F>
     <E>
   </D>
   <D>
    <E>
    <E>
      <F>
     <E>
   </D>
   <!-- end group>
     <!-- start group>
  <B>
     <C>
     <D>
  </B>
  <B>
     <C>
     <D>
  </B>
  <! --end group>
  </A>


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