Performing chain of transformations in XSLT

Question

I am trying to transform an XML document through a series of XSL stylesheets transformations in oXygen. I found the question Is daisy chaining xslt an accepted practice? and Dimitre Novatchev's answer (below) is great: it works perfectly as set out for two pass. I can't seem to get this to work for a third pass however.

<xsl:stylesheet version="2.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 xmlns:xs="http://www.w3.org/2001/XMLSchema">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>

 <xsl:template match="/">
  <xsl:variable name="vPass1" >
   <xsl:apply-templates select="/*/*"/>
  </xsl:variable>
   <xsl:apply-templates mode="pass2"
        select="$vPass1/*"/>
 </xsl:template>

 <xsl:template match="num[. mod 2 = 1]">
  <xsl:copy-of select="."/>
 </xsl:template>

 <xsl:template match="num" mode="pass2">
  <xsl:copy>
    <xsl:value-of select=". *2"/>
  </xsl:copy>
 </xsl:template>
</xsl:stylesheet>

I've tried adding a second variable as below (in my problem I'm calling named templates instead of applying to the whole document). What I am calling template2 should be applied to the output of the transformation performed by template1.

Should I be declaring variable $vPass2 somewhere within template1 instead of in the same place as where i declare $vPass1? Or is there something else I'm not getting about how this works?

<xsl:template match="/">
  <xsl:variable name="vPass1" >
   <xsl:call-template name="template1"/>
  </xsl:variable>
   <xsl:apply-templates mode="pass2" select="$vPass1/*"/>
  <xsl:variable name="vPass2" >
   <xsl:call-template name="template2"/>
  </xsl:variable>
   <xsl:apply-templates mode="pass3" select="$vPass2/*"/>
 </xsl:template>

Thanks

Answer 1

When applying another step - here the third - you have to put the result of the second pass into a variable, too.

So, adding to the example from the linked answer, a three step solution could look like this:

<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xs="http://www.w3.org/2001/XMLSchema" version="2.0">
  <xsl:output omit-xml-declaration="yes" indent="yes" />

  <xsl:template match="/*">
    <xsl:copy>
      <xsl:variable name="vPass1">
        <xsl:apply-templates select="/*/*" />
      </xsl:variable>
      <xsl:variable name="vPass2">
        <xsl:apply-templates mode="pass2" select="$vPass1/*" />
      </xsl:variable>
      <xsl:variable name="vPass3">
        <xsl:apply-templates mode="pass3" select="$vPass2/*" />
      </xsl:variable>
      <!-- Display the final result -->
      <xsl:copy-of select="$vPass3"/>
    </xsl:copy>
  </xsl:template>

  <xsl:template match="num[. mod 2 = 1]">
    <xsl:copy-of select="."/>
  </xsl:template>

  <xsl:template match="num" mode="pass2">
    <xsl:copy>
      <xsl:value-of select=". *2"/>
    </xsl:copy>
  </xsl:template>

  <xsl:template match="num" mode="pass3">
    <xsl:copy>
      <xsl:value-of select=". + 1"/>
    </xsl:copy>
  </xsl:template>

</xsl:stylesheet>

Applied to this input XML

<nums>
  <num>01</num>
  <num>02</num>
  <num>03</num>
  <num>04</num>
  <num>05</num>
  <num>06</num>
  <num>07</num>
  <num>08</num>
  <num>09</num>
  <num>10</num>
</nums>

The result is (2*x+1)

<nums>
   <num>3</num>
   <num>7</num>
   <num>11</num>
   <num>15</num>
   <num>19</num>
</nums>

---

Relating to your special question, your second <xsl:apply-templates mode="pass2" select="$vPass1/*"/> is not in a variable - so its result will not be passed on to the third step.