Generate an XSL file for a simple XML file (See related posts)

#!/usr/bin/ruby
# file: xml2xsl.rb

# author: jrobertson
# created: 31-Dec-07
# description: 
#   Converts an xml file into another xml file in 'xml2xsl' format.
#   This new xml file can then be transformed with the stylesheet 
#   xml2xsl.xsl into a multi-purpose xsl file template for the original 
#   xml file.

 
require 'rexml/document'
include REXML

class PreXml2Xsl

  def pre_xml2xsl(doc)
    puts '<xsl>'
    puts "  <template name='" + doc.root.name + "'>"
    build_xml(doc.root)
    puts '    </template>'
    puts '</xsl>'
  end
  
  def build_xml(node)
    previous_name = ''
    node.each_child do |child| 
      if child.length > 1 
        build_template(child.name)
        build_xml(child) 
      else
        build_value(child.name) if child.name != previous_name
        previous_name = child.name
      end
    end
  end
      
  def build_template(element)
    puts '  ' + "<select name=\"#{element}\" />"
    puts "</template>"
    puts "<template name=\"#{element}\">"
  end

  def build_value(element)
    puts '  ' + "<value name=\"#{element}\" />"
  end

  if __FILE__ == $0
    xml_language = '<languages><programming><name>C++</name><name>C Sharp</name
><name>Ruby</name></programming></languages>'
    doc = Document.new(xml_language)
    px = PreXml2Xsl.new
    px.pre_xml2xsl(doc)
  end
end

<xsl>
  <template name="languages">
    <select name="programming"/>
  </template>
  <template name="programming">
    <value name="name"/>
  </template>
</xsl>

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

  <xsl:template match="xsl">
  <xsl:variable name="colon"><xsl:text>:</xsl:text></xsl:variable>
    <xsl:element name="xsl:stylesheet">
      <xsl:attribute name="xmlns{$colon}xsl">
        <xsl:text>http://www.w3.org/1999/XSL/Transform</xsl:text>
      </xsl:attribute>
      <xsl:attribute name="version">
        <xsl:text>1.0</xsl:text>
      </xsl:attribute>
      
      <xsl:apply-templates select="*" />
    
  </xsl:element>

  </xsl:template>
  
  <xsl:template match="template">
  <xsl:text>
  </xsl:text>
        <xsl:element name="xsl:template">
        <xsl:attribute name="match">
          <xsl:value-of select="@name"/>
        </xsl:attribute>

        <xsl:apply-templates select="*" />
  <xsl:text>
  </xsl:text>
    </xsl:element>
<xsl:text>
</xsl:text>

  </xsl:template>
  
  <xsl:template match="select">
    <xsl:text>
    </xsl:text>
  <xsl:element name="xsl:element">
    <xsl:attribute name="name">
      <xsl:value-of select="@name"/>
    </xsl:attribute>
    <xsl:text>
    </xsl:text>
    <xsl:text>  </xsl:text><xsl:element name="xsl:apply-templates">
      <xsl:attribute name="select">
        <xsl:value-of select="@name"/>
      </xsl:attribute>
    </xsl:element>
    <xsl:text>
    </xsl:text>
  </xsl:element>


  </xsl:template>
  
  <xsl:template match="value">
    <xsl:text>
    </xsl:text>
  <xsl:element name="xsl:element">
    <xsl:attribute name="name">
      <xsl:value-of select="@name"/>
    </xsl:attribute>
      <xsl:text>
      </xsl:text>
    <xsl:element name="xsl:value-of">
      <xsl:attribute name="select">
        <xsl:value-of select="@name"/>
      </xsl:attribute>
    </xsl:element>
    <xsl:text>
    </xsl:text>
  </xsl:element>
</xsl:template>
</xsl:stylesheet>

<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
  <xsl:template match="languages">
    <xsl:element name="programming">
      <xsl:apply-templates select="programming"/>
    </xsl:element>
  </xsl:template>

  <xsl:template match="programming">
    <xsl:element name="name">
      <xsl:value-of select="name"/>
    </xsl:element>
  </xsl:template>
</xsl:stylesheet>