mime::worddecoder(3)

NAME

MIME::WordDecoder - decode RFC-1522 encoded words to a
local representation

SYNOPSIS

See MIME::Words for the basics of encoded words.  See
"DESCRIPTION" for how this class works.
    use MIME::WordDecoder;
    ### Get the default word-decoder (used by unmime()):
    $wd = default MIME::WordDecoder;
    ###  Get  a  word-decoder  which  maps  to  ISO-8859-1
(Latin1):
    $wd = supported MIME::WordDecoder "ISO-8859-1";
    ###  Decode  a MIME string (e.g., into Latin1) via the
default decoder:
    $str = $wd->decode('To: =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <keld>');
    ###  Decode a string using the default decoder, non-OO
style:
    $str =  unmime('To:  =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <keld>');

DESCRIPTION

A MIME::WordDecoder consists, fundamentally, of a hash
which maps a character set name (US-ASCII, ISO-8859-1,
etc.) to a subroutine which knows how to take bytes in
that character set and turn them into the target string
representation. Ideally, this target representation would
be Unicode, but we don't want to overspecify the transla
tion that takes place: if you want to convert MIME strings
directly to Big5, that's your own decision.

The subroutine will be invoked with two arguments: DATA
(the data in the given character set), and CHARSET (the
upcased character set name).

For example:

### Keep 7-bit characters as-is, convert 8-bit charac

ters to '#':
sub keep7bit {

local $_ = shift;
tr/0-F/#/c;
$_;

}

Here's a decoder which uses that:

### Construct a decoder:
$wd = MIME::WordDecoder->new({'US-ASCII' => "KEEP",

### sub { $_[0] }

'ISO-8859-1' => keep7bit,
'ISO-8859-2' => keep7bit,
'Big5' => "WARN",
'*' => "DIE"});

### Convert some MIME text to a pure ASCII string...
$ascii = $wd->decode('To:

=?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <keld>');

### ...which will now hold: "To: Keld J#rn Simonsen

<keld>"

PUBLIC INTERFACE

default [DECODER]

Class method. Get/set the default DECODER object.

supported CHARSET, [DECODER]

Class method. If just CHARSET is given, returns a decoder object which maps data into that character set
(the character set is forced to all-uppercase).

$wd = supported MIME::WordDecoder "ISO-8859-1";

If DECODER is given, installs such an object:

MIME::WordDecoder->supported("ISO-8859-1" =>

(new MIME::WordDe

coder::ISO_8859 "1"));

You should not override this method.

new [@HANDLERS]

Class method, constructor. If @HANDLERS is given, then @HANDLERS is passed to handler() to initiallize the internal map.

handler CHARSET=>SUBREF, ...

Instance method. Set the handler SUBREF for a given CHARSET, for as many pairs as you care to supply.

When performing the translation of a MIME-encoded
string, a given SUBREF will be invoked when translat
ing a block of text in character set CHARSET. The
subroutine will be invoked with the following argu
ments:

DATA - the data in the given character set.
CHARSET - the upcased character set name, which

may prove useful

if you are using the same SUBREF for

multiple CHARSETs.

DECODER - the decoder itself, if it contains con

figuration information

that your handler function needs.

For example:

$wd = new MIME::WordDecoder;
$wd->handler('US-ASCII' => "KEEP");
$wd->handler('ISO-8859-1' => handle_latin1,

'ISO-8859-2' => handle_latin1,
'*' => "DIE");

Notice that, much as with %SIG, the SUBREF can also be
taken from a set of special keywords:

KEEP Pass data through unchanged.
IGNORE Ignore data in this character set, without

warning.
WARN Ignore data in this character set, with

warning.
DIE Fatal exception with "can't handle charac

ter set" message.

The subroutine for the special CHARSET of 'raw' is
used for raw (non-MIME-encoded) text, which is sup
posed to be US-ASCII. The handler for 'raw' defaults
to whatever was specified for 'US-ASCII' at the time
of construction.

The subroutine for the special CHARSET of '*' is used
for any unrecognized character set. The default
action for '*' is WARN.

decode STRING

Instance method. Decode a STRING which might contain MIME-encoded components into a local representation
(e.g., UTF-8, etc.).

unmime STRING

Function, exported. Decode the given STRING using the default() decoder. See default().

SUBCLASSES

MIME::WordDecoder::ISO_8859

A simple decoder which keeps US-ASCII and the 7-bit
characters of ISO-8859 character sets and UTF8, and
also keeps 8-bit characters from the indicated charac
ter set.

### Construct:
$wd = new MIME::WordDecoder::ISO_8859 2; ###

ISO-8859-2

### What to translate unknown characters to (can

also use empty):
### Default is "?".
$wd->unknown("?");

### Collapse runs of unknown characters to a sin

gle unknown()?
### Default is false.
$wd->collapse(1);

According to http://czyborra.com/charsets/iso8859.html (ca. November 2000):

ISO 8859 is a full series of 10 (and soon even more)
standardized multilingual single-byte coded (8bit)
graphic character sets for writing in alphabetic lan
guages:

1. Latin1 (West European)
2. Latin2 (East European)
3. Latin3 (South European)
4. Latin4 (North European)
5. Cyrillic
6. Arabic
7. Greek
8. Hebrew
9. Latin5 (Turkish)

10. Latin6 (Nordic)

The ISO 8859 charsets are not even remotely as com
plete as the truly great Unicode but they have been
around and usable for quite a while (first registered
Internet charsets for use with MIME) and have already
offered a major improvement over the plain 7bit
US-ASCII.

Characters 0 to 127 are always identical with US-ASCII
and the positions 128 to 159 hold some less used con
trol characters: the so-called C1 set from ISO 6429.

MIME::WordDecoder::US_ASCII
A subclass of the ISO-8859-1 decoder which discards
8-bit characters. You're probably better off using
ISO-8859-1.

AUTHOR

Eryq (eryq@zeegee.com), ZeeGee Software Inc (http://www.zeegee.com).

VERSION

$Revision: 5.403 $ $Date: 2000/11/23 05:04:03 $

perl v5.8.0 2000-11-23 MIME::WordDecoder(3)