RE: Nested for-each-group

group-starting-with and group-ending-with partition the population: the
first/last item in the population starts/ends a group whether or not it
matches the pattern. 

The simplest way to discard the spurious groups in this case is probably to
do 

xsl:if test="position()=last()" 

in the outer group, and

xsl:if test="position()=1"

in the inner group.

An interesting way of tackling the problem. I think I would have used
"intersect":

<div>
 <xsl:value-of select="
    sum (    
      (col[@colname=$s]/(.|following-sibling::col)
               intersect
       col[@colname=$e]/(.|preceding-sibling::col))/@width)"/>
</div>

Unless I thought about it more carefully (!), in which case I would use a
predicate of the form:

sum(col[. is $S or . is $E or (. >> $S and . << $E)])

Yet another solution:

for $s in index-of(col/@colname, $start),
    $e in index-of(col/@colname, $end)
return
    sum(subsequence(col/@width, $s, $e - $s + 1)), 


Michael Kay
http://www.saxonica.com/


> -----Original Message-----
> From: Andrew Welch [mailto:ajwelch@xxxxxxxxxxxxxxx] 
> Sent: 28 September 2004 11:38
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  Nested for-each-group
> 
> 
> Hi all,
> 
> Given this xml:
> 
> <tgroup>
> 	<col colname="C.HPC" width="17"/>
> 	<col colname="C.HPB" width="23"/>
> 	<col colname="C.HPA" width="29"/>
> 	<col colname="C.I0F" width="17"/>
> 	<col colname="C.I0E" width="14"/>
> 	<spanspec namest="C.HPC" nameend="C.I0F"/>
> 	<spanspec namest="C.HPC" nameend="C.I0E"/>
> </tgroup>
> 
> I'm trying to sum the colwidths specified by the spanspecs.  I used to
> use a recursive template, which I'm trying to replace using a nested
> for-each-group:
> 
> <xsl:template match="spanspec">
>     <xsl:variable name="namest" select="@namest"/>
>     <xsl:variable name="nameend" select="@nameend"/>
> 
>     <xsl:for-each-group select="preceding-sibling::col"
> group-starting-with="*[@colname = $namest]">
>         <xsl:for-each-group select="current-group()"
> group-ending-with="*[@colname = $nameend]">
>       		<div><xsl:value-of
> select="sum(current-group()/@width)"/></div>
>       	</xsl:for-each-group>
>     </xsl:for-each-group>
> 
> </xsl:template>
> 
> However, this produces:
> 
> 	<div>86</div><div>14</div>
> 	<div>100</div>
> 
> I don't understand why I'm getting the "<div>14</div>" output?  I know
> it's part of the outer group, but it shouldn't be part of the inner
> group.  Any ideas why its there?
> 
> cheers
> andrew