require 'nokogiri'

class DocumentHandler < Nokogiri::XML::SAX::Document
  attr_reader :opened, :closed
  def initialize
    @level = 0
    @opened = 0
    @closed = 0
  end

  def start_element(name, attributes)
    @level += 1
    @opened += 1
    puts %Q{start_element -->>> #{"\t"*@level}name=[#{name}], attributes=[#{attributes.inspect}] -> level=[#{@level}]}
  end

  def end_element(name)
    @closed += 1
    puts %Q{end_element -->>> #{"\t"*@level}name=[#{name}] -> level=[#{@level}]}
    @level -= 1
  end
end

file=ARGV.shift
sax_handler = DocumentHandler.new
parser = Nokogiri::XML::SAX::Parser.new(sax_handler)
parser.parse_file(file)
puts "sax_handler.opened=[#{sax_handler.opened}]"
puts "sax_handler.closed=[#{sax_handler.closed}]"