while arg = argv.shift
    case arg
    when /\A--(.*)/
      if $1.empty?      # xinit -- -bpp 24
  break
      end

      opt, val = $1.split('=', 2)

      if opt.size == 1
  argv.unshift arg
  return nil
      elsif valopts.key? opt    # imclean --src +trash
  valopts[opt] = val || argv.shift or return nil
      elsif boolopts.key? opt    # ruby --verbose
  boolopts[opt] = true
      else
  argv.unshift arg
  return nil
      end

      c += 1
    when /\A-(.+)/
      opts = $1

      until opts.empty?
  opt = opts.slice!(0, 1)

  if valopts.key? opt
    val = opts

    if val.empty?      # ruby -e 'p $:'
      valopts[opt] = argv.shift or return nil
    else        # cc -ohello ...
      valopts[opt] = val
    end

    c += 1
    break
  elsif boolopts.key? opt
    boolopts[opt] = true    # ruby -h
    c += 1
  else
    argv.unshift arg
    return nil
  end
      end
    else
      argv.unshift arg
      break
    end
  end