Re: data translation => descendants appear side by sid

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Subject: Re: data translation => descendants appear side by side in HTML-table
From: Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>
Date: Mon, 06 May 2002 12:40:14 -0400

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

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Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
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
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======================================================================

XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list

Current Thread
Re: xpath - how to return all nodes but the node matching avalue in an arbitrary tree?, (continued) Joerg Heinicke - Sat, 4 May 2002 14:19:15 -0400 (EDT) Jeni Tennison - Sat, 4 May 2002 13:49:55 -0400 (EDT) G. Ken Holman - Sat, 4 May 2002 22:49:41 -0400 (EDT) Joerg Heinicke - Sat, 4 May 2002 09:19:39 -0400 (EDT) Wendell Piez - Mon, 6 May 2002 12:36:12 -0400 (EDT) <=

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