NAME
    Convert::DUDE - Conversion between Unicode and DUDE

SYNOPSIS
      use Convert::DUDE ':all';

      # handles 'dq--' prefix
      $domain  = to_dude($utf8);
      $utf8    = from_dude($domain);

      # don't care about 'dq--' prefix
      # not exported by default           
      $dudestr = dude_encode($utf8);
      $utf8    = dude_decode($dudestr);

DESCRIPTION
    This module provides functions to convert between DUDE (Differential
    Unicode Domain Encoding) and Unicode encodings.

    Quoted from http://www.i-d-n.net/draft/draft-ietf-idn-dude-02.txt

      DUDE is a reversible transformation from a sequence of nonnegative
      integer values to a sequence of letters, digits, and hyphens (LDH
      characters).  DUDE provides a simple and efficient ASCII-Compatible
      Encoding (ACE) of Unicode strings for use with Internationalized
      Domain Names.

FUNCTIONS
    Following two functions are exported to your package when you use
    Convert::DUDE.

    to_dude
          $domain = to_dude($utf8);

        takes UTF8-encoded string, encodes it in DUDE and adds 'dq--' prefix
        in front.

    from_dude
          $utf8 = from_dude($domain);

        takes 'dq--' prefixed DUDE encoded string and decodes it to original
        UTF8 strings.

    Following two functions can be exported to your package when you import
    them explicitly.

    dude_encode
          $dude = dude_encode($utf8);

        takes UTF8-encoded string, encodes it in DUDE. Note that it doesn't
        care about 'dq--' prefix.

    dude_decode
          $utf8 = dude_decode($dude);

        takes DUDE encoded string and decodes it to original UTF8 strings.
        Note that it doesn't care about 'dq--' prefix.

    Those functions above may throw exeptions in case of error. You may have
    to catch 'em with eval block.

CLASS METHODS
    prefix
          $prefix = Convert::DUDE->prefix;
          Convert::DUDE->prefix('xx--');

        gets/sets DUDE prefix. 'dq--' for default.

EXAMPLES
    Here's a sample code which does RACE-DUDE conversion.

      use Convert::RACE;
      use Convert::DUDE;
      use Unicode::String qw(utf16);
               
      my $race = "bq--aewrcsy";

      eval {
          my $utf16 = from_race($race);
          my $dude = to_dude(utf16($utf16)->utf8);
          print "RACE: $race => DUDE: $dude\n";
      };

      if ($@) {
          warn "Conversion failed: $@";
      }
  
CAVEATS
    *   There's no constraints on the input. See internet draft for nameprep
        about IDN input validation.

TODO
    *   Consider mixed-case annotation. See internet draft for DUDE for
        details.

AUTHOR
    Tatsuhiko Miyagawa <miyagawa@bulknews.net>

    This library is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

    This module comes without warranty of any kind.

SEE ALSO
    the Convert::RACE manpage, http://www.i-d-n.net/,
    http://www.i-d-n.net/draft/draft-ietf-idn-dude-02.txt, the
    Unicode::String manpage, the Jcode manpage