Fix for using acts_as_solr with libxml-ruby 0.8.1

xml.rb

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module Solr::XML
end

begin
  
  # If we can load rubygems and libxml-ruby...
  require 'rubygems'
  require 'xml/libxml'
  
  # then make a few modifications to XML::Node so it can stand in for REXML::Element
  #
  # There is a problem with libxml-ruby 0.8.1 where XML::Node cannot be monkeypatched
  # with just `class XML::Node`; to workaround this, we can use class_eval instead.
  XML::Node.class_eval do
    # element.add_element(another_element) should work
    alias_method :add_element, :<<

    # element.attributes['blah'] should work
    def attributes
      self
    end

    # element.text = "blah" should work
    def text=(x)
      self << x.to_s
    end
  end
  
  # And use XML::Node for our XML generation
  Solr::XML::Element = XML::Node
  
rescue LoadError => e # If we can't load either rubygems or libxml-ruby
  
  # Just use REXML.
  require 'rexml/document'
  Solr::XML::Element = REXML::Element
  
end