Re: Building a tree from path-like strings

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Subject: Re: Building a tree from path-like strings
From: "G. Ken Holman" <gkholman@xxxxxxxxxxxxxxxxxxxx>
Date: Sat, 03 Jan 2009 14:11:15 -0500

At 2009-01-03 18:38 +0000, Richard Lewis wrote:

Hi there,

I'm trying to make a tree-hierarchic document from a flat
list of elements which have id-like values which define
the hierarchy I need.

So here is simplified version of the source document:
...
which should become this after transformation:
...
  <li id="FOO/2">
    FOO/3
  </li>

I'm assuming you really want id="FOO/3" there.

So far I have the following:
...
This attempt at a solution is not only protracted and incomprehensible, it
doesn't actually work either.

I chose to start from scratch.

Can anyone think of a solution to this? Preferably disregarding my
existing attempt.

A complete solution to your supplied data is below whose output matches what you specified, modulo some indentation controlled by the XSLT processor.

Note my use of recursion, rather than re-application. I felt that dealing with axes when applying templates would be more cumbersome than dealing with progressively smaller subsets of records. Each subset is an ordered list. The result is quite compact, and when dealing with recursion I often find the more compact the result the more robust it usually is ... once you start dealing with exceptions, problems can creep in unexpectedly.

I hope this helps.

. . . . . . . . . . . . Ken

T:\ftemp>type richard.xml
<btc>
<record table="works">
  <record table="external_records">
    <field name="external_id"><value>FOO/1</value></field>
    <field name="ds_name"><value>ms-sources</value></field>
  </record>
  <record table="external_records">
    <field name="external_id"><value>FOO/1/1</value></field>
    <field name="ds_name"><value>ms-sources</value></field>
  </record>
  <record table="external_records">
    <field name="external_id"><value>FOO/1/2</value></field>
    <field name="ds_name"><value>ms-sources</value></field>
  </record>
  <record table="external_records">
    <field name="external_id"><value>FOO/2</value></field>
    <field name="ds_name"><value>ms-sources</value></field>
  </record>
  <record table="external_records">
    <field name="external_id"><value>FOO/2/1</value></field>
    <field name="ds_name"><value>ms-sources</value></field>
  </record>
  <record table="external_records">
    <field name="external_id"><value>FOO/2/1/1</value></field>
    <field name="ds_name"><value>ms-sources</value></field>
  </record>
  <record table="external_records">
    <field name="external_id"><value>FOO/2/1/2</value></field>
    <field name="ds_name"><value>ms-sources</value></field>
  </record>
  <record table="external_records">
    <field name="external_id"><value>FOO/2/2</value></field>
    <field name="ds_name"><value>ms-sources</value></field>
  </record>
  <record table="external_records">
    <field name="external_id"><value>FOO/3</value></field>
    <field name="ds_name"><value>ms-sources</value></field>
  </record>
</record>
</btc>

T:\ftemp>call xslt richard.xml richard.xsl richard.out

T:\ftemp>type richard.out
<?xml version="1.0" encoding="utf-8"?>
<ol>
   <li id="FOO/1">FOO/1<ol>
         <li id="FOO/1/1">FOO/1/1</li>
         <li id="FOO/1/2">FOO/1/2</li>
      </ol>
   </li>
   <li id="FOO/2">FOO/2<ol>
         <li id="FOO/2/1">FOO/2/1<ol>
               <li id="FOO/2/1/1">FOO/2/1/1</li>
               <li id="FOO/2/1/2">FOO/2/1/2</li>
            </ol>
         </li>
         <li id="FOO/2/2">FOO/2/2</li>
      </ol>
   </li>
   <li id="FOO/3">FOO/3</li>
</ol>
T:\ftemp>type richard.xsl
<?xml version="1.0" encoding="US-ASCII"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="1.0">

<xsl:output indent="yes"/>

<xsl:template match="/">
  <xsl:call-template name="recurse-this">
    <xsl:with-param name="records" select="btc/record/record"/>
  </xsl:call-template>
</xsl:template>

<xsl:template name="recurse-this"> <xsl:param name="records"/> <ol>  <xsl:for-each select="$records"> <xsl:variable name="this-id" select="field[@name='external_id']/value"/> <xsl:if test="count($records[starts-with($this-id, field[@name='external_id']/value)]) = 1">  <li id="{$this-id}"> <xsl:value-of select="$this-id"/>  <xsl:if test="count($records[ starts-with(field[@name='external_id']/value,$this-id)]) > 1">  <xsl:call-template name="recurse-this">  <xsl:with-param name="records" select="$records[ starts-with(field[@name='external_id']/value,$this-id) and field[@name='external_id']/value!=$this-id]"/> </xsl:call-template> </xsl:if> </li> </xsl:if> </xsl:for-each> </ol> </xsl:template>

</xsl:stylesheet>

T:\ftemp>rem Done!


--
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Current Thread
Building a tree from path-like strings Richard Lewis - 3 Jan 2009 18:38:48 -0000 G. Ken Holman - 3 Jan 2009 19:11:45 -0000 <= Dimitre Novatchev - 3 Jan 2009 23:05:22 -0000

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Building a tree from path-lik, Richard Lewis	Thread	Re: Building a tree from path, Dimitre Novatchev
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