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Data Model WD: infoitem-to-text-nodes() function

From: Jeni Tennison <jeni@jenitennison.com>
Date: Mon, 19 Aug 2002 20:05:41 +0100
Message-ID: <67624967605.20020819200541@jenitennison.com>
To: public-qt-comments@w3.org

Hi,

I might be missing something, but I think that the definition of
infoitem-to-text-nodes() function is wonky. The definition in the Data
Model WD is:

define function infoitem-to-text-nodes(Node* $nodes)
       returns Node* 
{
  if (xf:empty($nodes)) then return empty-sequence()
  else
    let $head:= op:item-at($nodes, 1), 
        $tail:= xf:subsequence($nodes, 2)
    return
      if (dm:node-kind($head) = "text") then
        /* Collapse two consecutive text nodes and apply 
           infoitem-to-text-nodes recursively */
        if (xf:empty($tail)) then $head
        else if (dm:node-kind(op:item-at($tail,1))="text") then 
          infoitem-to-text-nodes(
            op:concatenate(
              dm:text-node(xf:concat(dm:string-value($head),
                   dm:string-value(op:item-at($tail,1)))), 
              xf:subsequence($tail, 2)
            )
          )
        else op:concatenate($head,
               op:concatenate(op:item-at($tail,1),
                              infoitem-to-text-nodes($tail)))
      else op:concatenate($head, infoitem-to-text-nodes($tail))
  }

Consider the operation over the content of the foo element in:

  <foo> blah <bar /></foo>

Here, the sequences of nodes is a text node, followed by a bar
element. I'll call these $node[1] and $node[2]. Running through the
function we get:

1st recursion:
  $head = ( $node[1] )
  $tail = ( $node[2] )

  // $head is text; $tail[1] isn't empty and isn't text
  
  return
    op:concatenate($node[1],
      op:concatenate($node[2],
                     infoitem-to-text-nodes( ($node[2]) )))

2nd recursion:
  $head = ( $node[2] )
  $tail = ()

  // $head isn't text
  
  return
    op:concatenate( $node[2], () )

So we end up with:

  ( $node[1], $node[2], $node[2] )

whereas I think we want:

  ( $node[1], $node[2] )

The problem is here:

        else op:concatenate($head,
               op:concatenate(op:item-at($tail,1),
                              infoitem-to-text-nodes($tail)))

which I think should be:

        else op:concatenate($head,
               op:concatenate(op:item-at($tail, 1),
                 infoitem-to-text-nodes(xf:subsequence($tail, 2))))

or possibly, for simplicity:

        else op:concatenate($head,
                            infoitem-to-text-nodes($tail))
  
Cheers,

Jeni
---
Jeni Tennison
http://www.jenitennison.com/
Received on Monday, 19 August 2002 15:05:43 UTC

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