RE: [xsl] XSL - using for-each with sort

Jeff,

Below appears an example stripped down from a working stylesheet. It does something a bit different from what you need, but it illustrates two passes using a node-set extension.

The function in this case is bound to the exslt namespace. Check out exslt.org for more on this, as well as your processor's documentation on available extension functions.

The first pass here processes a bunch of <meta> elements assembled from various files, whose names are assigned to the $files variable. (In the actual stylesheet this assembly is more complex; this is simplified here.) The second pass will be processing this aggregated metadata for display; but it can't simply process the nodes in their original form, in part since the aggregation will be sorted, but the sort criteria are not all explicit in the data. (This is the reverse of your case, in which the sorting would happen in the first pass.) In order to generate these sort criteria, the <meta> elements are processed in a special mode, "init" (mostly not shown here). The result is then made into a node-set and bound to a variable, which can then be processed further.

The running version of this code may be seen at sonneteer.xmlshoestring.com, a demonstration project of mine. (All this runs on XML source server-side in 4Suite, an XML application framework. One sort criterion of interest here is a poem's rhyme scheme: although the rhyme scheme of each poem is not actually explicit, as such, in its tagging, it can easily be derived from it, which is one of the things that happens in the "init" phase. In fact, strictly speaking this particular sort can be achieved in one pass; but there are a couple of other things happening, including parameterizing to handle other sort orders, that make it very convenient to do in two.)

Here's the code, stripped down to illustrate the principle:

<xsl:stylesheet version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
    xmlns:exslt="http://exslt.org/common";
    extension-element-prefixes="exslt">

<xsl:variable name="files" select="//file"/>

<xsl:variable name="metaRTF">
  <xsl:apply-templates select="document($files)/*/meta" mode="init"/>
</xsl:variable>

<xsl:template match="meta" mode="init">
  <!-- ... selects stuff out of the meta elements at the top level,
           and adds some special stuff ... -->
</xsl:template>

<!-- trimming the metadata model not to include
     this stuff -->
<xsl:template match="source | remark" mode="init"/>

<!-- most of the init mode is an identity transform -->
<xsl:template match="node()|@*" mode="init">
  <xsl:copy>
    <xsl:copy-of select="@*"/>
    <xsl:apply-templates mode="init"/>
  </xsl:copy>
</xsl:template>

<!-- the variable declaration to create a node-set we can process
     out of the result of the 'init' pass -->
<xsl:variable name="meta-collection"
  select="exslt:node-set($metaRTF)"/>

<!-- leaving this around just in case we need it -->
<xsl:template match="/" mode="debug">
  <xsl:copy-of select="$meta-collection"/>
</xsl:template>

<xsl:template match="/">
  <html>
    <!-- html stuff goes here-->
    <body>
      <!-- more html stuff goes here -->
      <div class="portfolio">
        <xsl:apply-templates select="$meta-collection/meta">
      </div>
   </body>
  </html>
</xsl:template>

<!-- we process our "initialized" node set in the unnamed mode -->
<xsl:template match="meta">
  <!-- etc.... -->
</xsl:template>



</xsl:stylesheet>

This is the kind of thing David was talking about.

I hope this helps,
Wendell

At 07:01 PM 11/25/2003, you wrote:

Would it be too
much trouble to ask either of you for an example of a two-pass process?


======================================================================
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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======================================================================

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