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Re: data translation => descendants appear side by side in HTML-table


Joerg,

I'm afraid I didn't track the start of this thread, but there is a common 
"gotcha" here, and I think you're right, you may be observing a buglet in 
Xalan.

(.//description)[$pos] is an expansion of

(./descendant-or-self::node()/child::description)[position()=$pos]
translates into English as

 From the context node, collect all descendant description elements (i.e. 
all description elements that are children of the context node or its 
descendants), and of that set take the one in $pos position in document order.

.//description[$pos] expands

./descendant-or-self::node()/child::description[position()=$pos]
translates as

 From the context node, collect all description elements that are children 
of the context node or its descendants, and take those that are in $pos 
position *as children of their parents* (i.e. among their siblings).

Note that the presence of the parentheses grouping operator in the first 
case is critical, since it collects all those children and filters them as 
a group; whereas in the second case, the predicate operates only on the 
last step, 'child::description[position()=$pos]'.

Does that help clarify or confirm? It was tough enough for me to 
internalize this distinction when I was learning XPath that it stuck. I hope.

Cheers,
Wendell

At 09:25 AM 5/4/2002, you wrote:
>I searched for a different and more general approach (not limited to 2 
>base elements). The stylesheet is quite short:
>
><xsl:template match="root">
>   <html>
>     <head><title>Descriptions</title></head>
>     <body>
>       <table border="1">
>         <xsl:apply-templates 
> select="base[not(count(following-sibling::base//description) > 
> count(.//description))]//description"/>
>       </table>
>     </body>
>   </html>
></xsl:template>
>
><xsl:template match="description">
>   <xsl:variable name="pos" select="position()"/>
>   <tr>
>     <xsl:for-each select="/root/base">
>       <td>
>         <xsl:value-of select="(.//description)[$pos]"/>
>       </td>
>     </xsl:for-each>
>   </tr>
></xsl:template>
>
>But I found a bug in Xalan: When using <xsl:value-of 
>select=".//description[$pos]"/>, I already get the wanted result.
>
>But when I read in the spec
>
>"For example
>   appendix//ulist/item[position()=1]
>matches a node if and only if all of the following are true:
>* ...
>* evaluating the PredicateExpr position()=1 with the node as context node 
>and the *siblings* of the node that are item elements as the context node 
>list yields true
>* ..."
>
>I suspect this behaviour is wrong, isn't it?
>
>Regards,
>
>Joerg
>
>>should be transformed into:
>><table>
>>     <tr>
>>         <td>some_desc1</td>
>>         <td>some_desc1</td>
>>     </tr>
>>     <tr>
>>         <td>some_desc2</td>
>>         <td>some_add_desc2</td>
>>     </tr>
>>     <tr>
>>         <td>some_add_desc3</td>
>>         <td>some_desc3</td>
>>     </tr>
>>     <tr>
>>         <td>some_add_desc4</td>
>>         <td>some_desc4</td>
>>     </tr>
>>     <tr>
>>         <td></td>
>>         <td>some_add_desc5</td>
>>     </tr>
>></table>
>
>
>XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list


======================================================================
Wendell Piez                            mailto:wapiez@mulberrytech.com
Mulberry Technologies, Inc.                http://www.mulberrytech.com
17 West Jefferson Street                    Direct Phone: 301/315-9635
Suite 207                                          Phone: 301/315-9631
Rockville, MD  20850                                 Fax: 301/315-8285
----------------------------------------------------------------------
   Mulberry Technologies: A Consultancy Specializing in SGML and XML
======================================================================


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