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Re: looping problem, <xsl: for-each>??

2003-10-09 13:36:41
Mukul,

Nice job with this.

At 01:05 PM 10/9/2003, you wrote:
I applied your suggestion to store an intermediate
tree fragment in a variable, and then converting the
variable into a nodeset. By iterating the nodeset, I
am able to generate numbers 1,2,3,4..

The XSL is --

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
xmlns:xalan="http://xml.apache.org/xalan";>
<xsl:output method="xml" version="1.0"
encoding="UTF-8" indent="yes"/>

<xsl:key name="x" match="/rss/channel/item"
use="category"/>
<xsl:template match="/">
  <xsl:variable name="treeFrag">
    <rootelem>
      <xsl:for-each select="rss/channel/item">
        <xsl:if test="generate-id(.) = generate-id(key('x',
category)[1])">
<h1> <xsl:value-of select="category"/>
          </h1>
          <xsl:for-each select="key('x', category)">
            <desc>
              <xsl:value-of select="description"/>
            </desc>
          </xsl:for-each>
        </xsl:if>
      </xsl:for-each>
    </rootelem>
  </xsl:variable>

  <xsl:for-each
select="xalan:nodeset($treeFrag)/rootelem/desc">
    <xsl:if test="name(preceding-sibling::*[1]) =
'h1'">
      <h1>
        <xsl:value-of select="preceding-sibling::*[1]" />
      </h1>
    </xsl:if>
    ITEM<xsl:value-of select="position()"/>
<xsl:value-of select="."/>
  </xsl:for-each>
</xsl:template>

</xsl:stylesheet>

In the above solution, though numbers are getting
generated properly, but to output <h1> tags at the
right place, I had to write a slightly complex syntax
* xsl:if test="name(preceding-sibling::*[1]) = 'h1'" *

Yes. This could be improved by using plain old templates to process this stuff, as in:

<xsl:template match="/">
<xsl:variable name="treeFrag"> [construct as you have it...] </xsl:variable>

  <xsl:apply-templates
    select="xalan:nodeset($treeFrag)/rootelem" mode="treefrag">
  </xsl:for-each>
</xsl:template>

<xsl:template match="item" mode="treefrag">
ITEM<xsl:number level="any"/> <!-- I changed it to xsl:number: more dependable -->
  <xsl:value-of select="."/>
</xsl:template>

<xsl:template match="h1" mode="treefrag">
  <xsl:copy-of select="."/>
</xsl:template>

This can also be generalized further to handle a greater range of input structures.

I still think an XPath-based counting solution may be possible here, but it's highly dependent on the structure of the input (and hence, rather more brittle), and in the meantime I think I lost the input sample (it's around here somewhere).

Cheers,
Wendell


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Wendell Piez                            
mailto:wapiez(_at_)mulberrytech(_dot_)com
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