Jarkko Hietaniemi > perl > Encode::Guess

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Module Version: 1.09   Source  

NAME ^

Encode::Guess -- Guesses encoding from data

SYNOPSIS ^

  # if you are sure $data won't contain anything bogus

  use Encode;
  use Encode::Guess qw/euc-jp shiftjis 7bit-jis/;
  my $utf8 = decode("Guess", $data);
  my $data = encode("Guess", $utf8);   # this doesn't work!

  # more elaborate way
  use Encode::Guess;
  my $enc = guess_encoding($data, qw/euc-jp shiftjis 7bit-jis/);
  ref($enc) or die "Can't guess: $enc"; # trap error this way
  $utf8 = $enc->decode($data);
  # or
  $utf8 = decode($enc->name, $data)

ABSTRACT ^

Encode::Guess enables you to guess in what encoding a given data is encoded, or at least tries to.

DESCRIPTION ^

By default, it checks only ascii, utf8 and UTF-16/32 with BOM.

  use Encode::Guess; # ascii/utf8/BOMed UTF

To use it more practically, you have to give the names of encodings to check (suspects as follows). The name of suspects can either be canonical names or aliases.

 # tries all major Japanese Encodings as well
  use Encode::Guess qw/euc-jp shiftjis 7bit-jis/;

If the $Encode::Guess::NoUTFAutoGuess variable is set to a true value, no heuristics will be applied to UTF8/16/32, and the result will be limited to the suspects and ascii.

Encode::Guess->set_suspects

You can also change the internal suspects list via set_suspects method.

  use Encode::Guess;
  Encode::Guess->set_suspects(qw/euc-jp shiftjis 7bit-jis/);
Encode::Guess->add_suspects

Or you can use add_suspects method. The difference is that set_suspects flushes the current suspects list while add_suspects adds.

  use Encode::Guess;
  Encode::Guess->add_suspects(qw/euc-jp shiftjis 7bit-jis/);
  # now the suspects are euc-jp,shiftjis,7bit-jis, AND
  # euc-kr,euc-cn, and big5-eten
  Encode::Guess->add_suspects(qw/euc-kr euc-cn big5-eten/);
Encode::decode("Guess" ...)

When you are content with suspects list, you can now

  my $utf8 = Encode::decode("Guess", $data);
Encode::Guess->guess($data)

But it will croak if:

  • Two or more suspects remain
  • No suspects left

So you should instead try this;

  my $decoder = Encode::Guess->guess($data);

On success, $decoder is an object that is documented in Encode::Encoding. So you can now do this;

  my $utf8 = $decoder->decode($data);

On failure, $decoder now contains an error message so the whole thing would be as follows;

  my $decoder = Encode::Guess->guess($data);
  die $decoder unless ref($decoder);
  my $utf8 = $decoder->decode($data);
guess_encoding($data, [, list of suspects])

You can also try guess_encoding function which is exported by default. It takes $data to check and it also takes the list of suspects by option. The optional suspect list is not reflected to the internal suspects list.

  my $decoder = guess_encoding($data, qw/euc-jp euc-kr euc-cn/);
  die $decoder unless ref($decoder);
  my $utf8 = $decoder->decode($data);
  # check only ascii and utf8
  my $decoder = guess_encoding($data);

CAVEATS ^

It is, after all, just a guess. You should alway be explicit when it comes to encodings. But there are some, especially Japanese, environment that guess-coding is a must. Use this module with care.

TO DO ^

Encode::Guess does not work on EBCDIC platforms.

SEE ALSO ^

Encode, Encode::Encoding

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