depth_first_tree_traversal.rb

require "rubygems"
require "xml/libxml"
#require "active_support"



def traverse(node)
  children = node.children.select {|a| a.element?}
  txt = "<h1>HTML output</h1><ul>"
  last_depth, depth = 1, 1
  
  while child = children.shift
    depth = child.path.split("/").size.to_i - 2
    
    if depth > last_depth
      txt << "\n<ul>"
    elsif depth < last_depth
      txt << "</ul>\n" * (last_depth - depth)
    end    
      
    txt << "<li>#{child.name} : <i>#{child.content if child.children.all? {|a| a.text?}}</i></li>\n"
    
    a = child.children.select {|c| c.element?}
    unless a.empty?
      children.unshift(a).flatten!  
    end
    
    last_depth = depth
  end
  
  open("output.html", "w") do |f|
    f.write txt << "</ul>"
  end
end


xml = XML::Document.file("chaplin.xml") 
# p xml.root.namespaces
traverse(xml.root)