xml2json.rb

#!/usr/bin/env ruby

require 'rexml/document'
require 'json'

file = ARGV[0]

class REXML::Element
  def to_h
    hash = {}
    if self.has_elements?
      self.elements.each do |e|
        if e.has_elements?
          if hash[e.name].nil?
            hash[e.name] = e.to_h
          elsif hash[e.name].is_a?(Array)
            hash[e.name].push( e.to_h )
          else
            hash[e.name] = [ hash[e.name] ]
            hash[e.name].push( e.to_h )
          end
        elsif e.has_text?
          hash[e.name] = e.text
        end
      end
    else
      hash[self.name] = self.text
    end
    hash
  end
end

doc = REXML::Document.new open(file).read
obj = doc.root.to_h
puts JSON.dump(obj)