# File lib/webrick/httputils.rb, line 351
    def _make_regex!(str) /([^#{Regexp.escape(str)}])/n end
    def _escape(str, regex) str.gsub(regex){ "%%%02X" % $1[0] } end
    def _unescape(str, regex) str.gsub(regex){ $1.hex.chr } end

    UNESCAPED = _make_regex(control+space+delims+unwise+nonascii)
    UNESCAPED_FORM = _make_regex(reserved+control+delims+unwise+nonascii)
    NONASCII  = _make_regex(nonascii)
    ESCAPED   = /%([0-9a-fA-F]{2})/
    UNESCAPED_PCHAR = _make_regex!(unreserved+":@&=+$,")

    def escape(str)
      _escape(str, UNESCAPED)
    end

    def unescape(str)
      _unescape(str, ESCAPED)
    end

    def escape_form(str)
      ret = _escape(str, UNESCAPED_FORM)
      ret.gsub!(/ /, "+")
      ret
    end

    def unescape_form(str)
      _unescape(str.gsub(/\+/, " "), ESCAPED)
    end

    def escape_path(str)
      result = ""
      str.scan(%r{/([^/]*)}).each{|i|
        result << "/" << _escape(i[0], UNESCAPED_PCHAR)
      }
      return result
    end

    def escape8bit(str)
      _escape(str, NONASCII)
    end
  end