Re: [xsl] sequence numbering.

[Jeni Tennison <jeni@xxxxxxxxxxxxxxxx>]

Hi William,

> Hi the solution Michael Suggested seems to fit my purpose, But Since
> i am a newbie to XSL , I do not know how to form a temporary tree
> that contains sorted sequence.

You can create a temporary tree by creating it within an xsl:variable:

  <xsl:variable name="temporary-tree">
    <xsl:for-each select="product">
      <xsl:sort select="color" />
      <xsl:copy-of select="." />
    </xsl:for-each>
  </xsl:variable>

This assigns to the $temporary-tree variable a result tree fragment
that contains a number of product elements, copies of the ones in your
original document, sorted in order of their color.

You can then convert the temporary tree into a node set using a
node-set extension function, for example exsl:node-set():

  exsl:node-set($temporary-tree)

Which extension function you use depends on what your processor
supports. Most processors support a node-set() extension function of
some form or another; check your processor's documentation to find out
what namespace you need to declare for it. If you have problems with
this, let us know, telling us which processor you're using.

When you've converted the result tree fragment (the temporary tree) to
a node set, you can operate over it in exactly the same way as you
normally do, and number them with judicious use of the count attribute
as Mike suggested:

  <xsl:for-each select="exsl:node-set($temporary-tree)/product">
    <xsl:variable name="this_color" select="color" />
    <xsl:number count="product[color = $this_color]" />
    ...
  </xsl:for-each>

What you're actually doing here is grouping the products together
based on their colour and then numbering them based on their position
within that group. If you find that the process described above goes
too slowly, you could use a grouping method instead. To give you an
idea of the process, the XSLT 2.0 grouping method would be:

  <xsl:for-each-group select="product" group-by="color">
    <xsl:sort select="color" />
    <xsl:for-each select="current-group()">
      <xsl:number value="position()" />
      ...
    </xsl:for-each>
  </xsl:for-each-group>

If you decide that you want to use this method, then have a read of
http://www.jenitennison.com/xslt/grouping/muenchian.html for a
description of how to do the grouping in XSLT 1.0.
  
Cheers,

Jeni

---
Jeni Tennison
http://www.jenitennison.com/


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