class RDoc::Markup::Formatter

def self.gen_relative_url(path, target)
  from        = File.dirname path
  to, to_file = File.split target
  from = from.split "/"
  to   = to.split "/"
  from.delete '.'
  to.delete '.'
  while from.size > 0 and to.size > 0 and from[0] == to[0] do
    from.shift
    to.shift
  end
  from.fill ".."
  from.concat to
  from << to_file
  File.join(*from)
end