One question -- what does the attribute @files mean on
the folder element whose @id="dir1"? It has @files="4",
but that doesn't seem to enter into the calculation you're
doing. So the semantics of the XML are a little unclear to me.

> -----Original Message-----
> From: owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> [mailto:owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx]On Behalf Of
> annirack@xxxxxxx
> Sent: Wednesday, January 14, 2004 2:41 PM
> To: XSL-List@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  recursive addition
> 
> 
> I have a structure (much like a file system) where elements 
> of the same type are linked together via IDs rather than the 
> XML structure--i.e. all directory elements are at the same level.
> 
> For an arbitrary directory level element, I want to sum a 
> numeric attribute for all linked elements and so on down the tree.

To rephrase the above question, are you just summing the attributes
of leaf folders (as you appear to be in your example where you
expect the answer to be 9)?
 
> Is there any way to do this?  I know that recursion is the 
> first step, but what I don't know how to sum an arbitrary 
> number of parallel level attributes in different elements.
> 
> Here's an example:
> <root>
>    <folder files="2" id="dir0">
>       <file id="dir1" />
> 
>       <file id="dir4" />
>    </folder>
> 
>    <folder files="4" id="dir1">
>       <file id="dir2" />
> 
>       <file id="dir3" />
>    </folder>
> 
>    <folder files="3" id="dir2" />
> 
>    <folder files="6" id="dir3" />
> 
>    <folder files="7" id="dir4" />
> 
>    <folder files="5" id="dir5" />
> </root>
> 
> If my arbitrary element id is "dir1", then the result should 
> be 9. (folder[@id='dir2']/@files + folder[@id='dir3']/@files)
> 
> How do I do that with xsl?

Assuming you're only summing the @files attributes of folders
that have no subfolders, here's some pseudo code:

with parameter folderID

main template 
  variable folder = /root/folder[@id = $folderID]
  call template sumFiles(folder, 1)

template name=sumFiles
  params folder, startFrom

  if not(child::file) return @files
  else if not(child::file[startFrom]) return "0"
  else {
    variable firstChild = child::file[startFrom]
    firstSum = sumFiles(/root/folder[@id = $firstChild/@id], 1)
    restSum = sumFiles(., startFrom+1)
    return xsl:value-of select="$firstSum + $restSum";    
  }

Does that help?

Of course you could make it more efficient by using keys/id's.

You could probably also make the code simpler by using an extension
function to build a nodeset and then use sum() on it.

Lars


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