flat to hierarchy

wu4 · October 18th, 2005, 09:03 PM

I am convert a flat class file to a class hierarchy file. ie, every class only shows once.
If a class is subclass of other class, it will be show as subclass of that class and not show
as the direct child of classes.

I am new with xslt, please give me help.

The source file is like this

Code:

<classes>
    <class name="A"/>
    <class name="B"/>
    <class name="C">
       <class name="D"/>
    </class>
    <class name="D">
       <class name="E"/>
       <class name="F"/>
    </class>
    <class name="E">
       <class name="G"/>
    </class>
    <class name="F"/>
    <class name="G"/>
</classes>

The output file corresponding above file should be

Code:

<classes>
    <class name="A"/>
    <class name="B"/>
    <class name="C">
       <class name="D">
          <class name="E">
             <class name="G"/>
          </class>
          <class name="F"/>
       </class>
    </class>
</classes>

mhkay · October 19th, 2005, 02:13 AM

Do a recursive tree walk using apply-templates as you would to traverse a normal XML tree, but instead of following the physical hierarchy (i.e. processing the children of a node using the child axis), follow the logical hierarchy. It's useful to set up a key

<xsl:key name="n" match="class" use="@name"/>

and then you can process a node using

<xsl:template match="class">
  ...
  <xsl:apply-templates select="key('n', @name)/child::node()"/>
  ...
</xsl:template>

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

wu4 · October 19th, 2005, 12:52 PM

Could you please give more details.

When we use <xsl:apply-templates select="key('n', @name)/child::node()"/>, how we can prevent a node is processed more than once. Just like above example, we have to node with name attribute D. When we process /classes/class[@name='D'], we call <xsl:apply-templates select="key('n', @name)/child::node()"/>, then we process /classes/class/class[@name='D'], we call <xsl:apply-templates select="key('n', @name)/child::node()"/>,then we process /classes/class[@name='D'], ...., it seems that will enter a unlimited loop.

Don't langh at me if I am wrong. I am new with xslt, it drives me crazy.
Do you think it's convenient that I send you email directly? If yes, please send me a email.

Thanks

wu4 · October 19th, 2005, 03:36 PM

This is my code. I created it by using

Quote:

quote:
"Michael Kay The trick to this is to write a stylesheet with template rules that use <xsl:apply-templates> to process the children of the current element in the usual way, but instead of selecting the physical children of an element, you select its logical children, based on following the relationships in your data. The only other thing needed is to start processing at the logical root of the tree"

http://www.dpawson.co.uk/xsl/sect2/f....html#d4658e13

But the results I got was wrong. Could someone explain to me, why?

Code:

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="1.0">


  <xsl:key name="n" match="class" use="@name"/>

  <xsl:template match="/">
      <xsl:apply-templates/>
  </xsl:template>

  <xsl:template match="classes">
    <classes>

      <xsl:apply-templates select="class[count(key('n', @name))=1]"/>
    </classes>
  </xsl:template>

  <xsl:template match="class">
    <xsl:choose>
      <xsl:when test="class">
        <class>
          <xsl:apply-templates select="@* | Parameters"/>
          <xsl:for-each select="class">

             <xsl:variable name="myname">
               <xsl:value-of select="@name"/>
             </xsl:variable>

             <xsl:apply-templates select="/classes/class[@name=$myname]"/>
          </xsl:for-each>
        </class>
      </xsl:when>
      <xsl:otherwise>
        <xsl:copy-of select="."/>
      </xsl:otherwise>
    </xsl:choose>
  </xsl:template>


  <xsl:template match="@*">
    <xsl:copy-of select="."/>
  </xsl:template>

  <xsl:template match="Parameter">
    <xsl:copy-of select="."/>
  </xsl:template>
</xsl:stylesheet>