route_from_path

# File lib/uri/generic.rb, line 806
    def route_from_path(src, dst)
      # RFC2396, Section 4.2
      return '' if src == dst

      src_path = split_path(src)
      dst_path = split_path(dst)

      # hmm... dst has abnormal absolute path, 
      # like "/./", "/../", "/x/../", ...
      if dst_path.include?('..') ||
          dst_path.include?('.')
        return dst.dup
      end

      src_path.pop

      # discard same parts
      while dst_path.first == src_path.first
        break if dst_path.empty?

        src_path.shift
        dst_path.shift
      end

      tmp = dst_path.join('/')

      # calculate
      if src_path.empty?
        if tmp.empty?
          return './'
        elsif dst_path.first.include?(':') # (see RFC2396 Section 5)
          return './' + tmp
        else
          return tmp
        end
      end

      return '../' * src_path.size + tmp
    end