gistfile1.rb

require 'nokogiri'

ENTER_PROMPT = 'Running. Press <Enter> to pause.'

def ui
  loop do
    puts '(c)ontinue'
    puts '(n)ext'
    puts '(q)uit'
    print '> '
    case STDIN.gets.chop
    when 'c'
      puts ENTER_PROMPT
      break
      when 'n' then return true
    when 'q' then exit
    end
  end
end

def listen_loop
  puts ENTER_PROMPT
  loop do
    begin
      STDIN.read_nonblock(1)
    rescue Errno::EAGAIN
      yield
    else
      break if ui
    end
  end
end

def mem_push_parser_document
  html = <<END
<?xml version="1.0"?>
<!DOCTYPE staff SYSTEM "staff.dtd" [
  <!ENTITY ent1 "es">
]>
<staff></staff>
END

  doc = Nokogiri::XML::SAX::Document.new
  
  listen_loop do
    parser = Nokogiri::XML::SAX::PushParser.new(doc)
    parser.write(html)
  end
end

mem_push_parser_document