Charset(3) User Contributed Perl Documentation Charset(3)NAMEMIME::Charset - Charset Informations for MIME
SYNOPSIS
use MIME::Charset:
$charset = MIME::Charset->new("euc-jp");
Getting charset informations:
$benc = $charset->body_encoding; # e.g. "Q"
$cset = $charset->as_string; # e.g. "US-ASCII"
$henc = $charset->header_encoding; # e.g. "S"
$cset = $charset->output_charset; # e.g. "ISO-2022-JP"
Translating text data:
($text, $charset, $encoding) =
$charset->header_encode(
"\xc9\xc2\xc5\xaa\xc0\xde\xc3\xef\xc5\xaa".
"\xc7\xd1\xca\xaa\xbd\xd0\xce\xcf\xb4\xef",
Charset => 'euc-jp');
# ...returns e.g. (<converted>, "ISO-2022-JP", "B").
($text, $charset, $encoding) =
$charset->body_encode(
"Collectioneur path\xe9tiquement ".
"\xe9clectique de d\xe9chets",
Charset => 'latin1');
# ...returns e.g. (<original>, "ISO-8859-1", "QUOTED-PRINTABLE").
$len = $charset->encoded_header_len(
"Perl\xe8\xa8\x80\xe8\xaa\x9e",
Charset => 'utf-8',
Encoding => "b");
# ...returns e.g. 28.
Manipulating module defaults:
MIME::Charset::alias("csEUCKR", "euc-kr");
MIME::Charset::default("iso-8859-1");
MIME::Charset::fallback("us-ascii");
Non-OO functions (may be deprecated in near future):
use MIME::Charset qw(:info);
$benc = body_encoding("iso-8859-2"); # "Q"
$cset = canonical_charset("ANSI X3.4-1968"); # "US-ASCII"
$henc = header_encoding("utf-8"); # "S"
$cset = output_charset("shift_jis"); # "ISO-2022-JP"
use MIME::Charset qw(:trans);
($text, $charset, $encoding) =
header_encode(
"\xc9\xc2\xc5\xaa\xc0\xde\xc3\xef\xc5\xaa".
"\xc7\xd1\xca\xaa\xbd\xd0\xce\xcf\xb4\xef",
"euc-jp");
# ...returns (<converted>, "ISO-2022-JP", "B");
($text, $charset, $encoding) =
body_encode(
"Collectioneur path\xe9tiquement ".
"\xe9clectique de d\xe9chets",
"latin1");
# ...returns (<original>, "ISO-8859-1", "QUOTED-PRINTABLE");
$len = encoded_header_len(
"Perl\xe8\xa8\x80\xe8\xaa\x9e", "b", "utf-8"); # 28
DESCRIPTIONMIME::Charset provides informations about character sets used for MIME
messages on Internet.
Definitions
The charset is ``character set'' used in MIME to refer to a method of
converting a sequence of octets into a sequence of characters. It
includes both concepts of ``coded character set'' (CCS) and ``character
encoding scheme'' (CES) of ISO/IEC.
The encoding is that used in MIME to refer to a method of representing
a body part or a header body as sequence(s) of printable US-ASCII
characters.
Constructor
$charset = MIME::Charset->new([CHARSET [, OPTS]])
Create charset object.
OPTS may accept following key-value pair. NOTE: When
Unicode/multibyte support is disabled (see "USE_ENCODE"),
conversion will not be performed. So this option do not have any
effects.
Mapping => MAPTYPE
Whether to extend mappings actually used for charset names or
not. "EXTENDED" uses extended mappings. "STANDARD" uses
standardized strict mappings. Default is "EXTENDED".
Getting Informations of Charsets
$charset->body_encoding
body_encoding CHARSET
Get recommended transfer-encoding of CHARSET for message body.
Returned value will be one of "B" (BASE64), "Q" (QUOTED-PRINTABLE),
"S" (shorter one of either) or "undef" (might not be transfer-
encoded; either 7BIT or 8BIT). This may not be same as encoding
for message header.
$charset->as_string
canonical_charset CHARSET
Get canonical name for charset.
$charset->decoder
Get "Encode::Encoding" object to decode strings to Unicode by
charset. If charset is not specified or not known by this module,
undef will be returned.
$charset->dup
Get a copy of charset object.
$charset->encoder([CHARSET])
Get "Encode::Encoding" object to encode Unicode string using
compatible charset recommended to be used for messages on Internet.
If optional CHARSET is specified, replace encoder (and output
charset name) of $charset object with those of CHARSET, therefore,
$charset object will be a converter between original charset and
new CHARSET.
$charset->header_encoding
header_encoding CHARSET
Get recommended encoding scheme of CHARSET for message header.
Returned value will be one of "B", "Q", "S" (shorter one of either)
or "undef" (might not be encoded). This may not be same as
encoding for message body.
$charset->output_charset
output_charset CHARSET
Get a charset which is compatible with given CHARSET and is
recommended to be used for MIME messages on Internet (if it is
known by this module).
When Unicode/multibyte support is disabled (see "USE_ENCODE"), this
function will simply return the result of "canonical_charset".
Translating Text Data
$charset->body_encode(STRING [, OPTS])
body_encode STRING, CHARSET [, OPTS]
Get converted (if needed) data of STRING and recommended transfer-
encoding of that data for message body. CHARSET is the charset by
which STRING is encoded.
OPTS may accept following key-value pairs. NOTE: When
Unicode/multibyte support is disabled (see "USE_ENCODE"),
conversion will not be performed. So these options do not have any
effects.
Detect7bit => YESNO
Try auto-detecting 7-bit charset when CHARSET is not given.
Default is "YES".
Replacement => REPLACEMENT
Specifies error handling scheme. See "Error Handling".
3-item list of (converted string, charset for output, transfer-
encoding) will be returned. Transfer-encoding will be either
"BASE64", "QUOTED-PRINTABLE", "7BIT" or "8BIT". If charset for
output could not be determined and converted string contains non-
ASCII byte(s), charset for output will be "undef" and transfer-
encoding will be "BASE64". Charset for output will be "US-ASCII"
if and only if string does not contain any non-ASCII bytes.
$charset->decode(STRING [,CHECK])
Decode STRING to Unicode.
Note: When Unicode/multibyte support is disabled (see
"USE_ENCODE"), this function will die.
detect_7bit_charset STRING
Guess 7-bit charset that may encode a string STRING.
$charset->encode(STRING [,CHECK])
Encode STRING (Unicode or non-Unicode) using compatible charset
recommended to be used for messages on Internet (if this module
knows it). Note that string will be decoded to Unicode then
encoded even if compatible charset was equal to original charset.
Note: When Unicode/multibyte support is disabled (see
"USE_ENCODE"), this function will die.
$charset->encoded_header_len(STRING [, ENCODING])
encoded_header_len STRING, ENCODING, CHARSET
Get length of encoded STRING for message header (without folding).
ENCODING may be one of "B", "Q" or "S" (shorter one of either "B"
or "Q").
$charset->header_encode(STRING [, OPTS])
header_encode STRING, CHARSET [, OPTS]
Get converted (if needed) data of STRING and recommended encoding
scheme of that data for message headers. CHARSET is the charset by
which STRING is encoded.
OPTS may accept following key-value pairs. NOTE: When
Unicode/multibyte support is disabled (see "USE_ENCODE"),
conversion will not be performed. So these options do not have any
effects.
Detect7bit => YESNO
Try auto-detecting 7-bit charset when CHARSET is not given.
Default is "YES".
Replacement => REPLACEMENT
Specifies error handling scheme. See "Error Handling".
3-item list of (converted string, charset for output, encoding
scheme) will be returned. Encoding scheme will be either "B", "Q"
or "undef" (might not be encoded). If charset for output could not
be determined and converted string contains non-ASCII byte(s),
charset for output will be "8BIT" (this is not charset name but a
special value to represent unencodable data) and encoding scheme
will be "undef" (should not be encoded). Charset for output will
be "US-ASCII" if and only if string does not contain any non-ASCII
bytes.
$charset->undecode(STRING [,CHECK])
Encode Unicode string STRING to byte string by input charset of
$charset. This is equivalent to "$charset->decoder->encode()".
Note: When Unicode/multibyte support is disabled (see
"USE_ENCODE"), this function will die.
Manipulating Module Defaults
alias ALIAS [, CHARSET]
Get/set charset alias for canonical names determined by
"canonical_charset".
If CHARSET is given and isn't false, ALIAS will be assigned as an
alias of CHARSET. Otherwise, alias won't be changed. In both
cases, current charset name that ALIAS is assigned will be
returned.
default [CHARSET]
Get/set default charset.
Default charset is used by this module when charset context is
unknown. Modules using this module are recommended to use this
charset when charset context is unknown or implicit default is
expected. By default, it is "US-ASCII".
If CHARSET is given and isn't false, it will be set to default
charset. Otherwise, default charset won't be changed. In both
cases, current default charset will be returned.
NOTE: Default charset should not be changed.
fallback [CHARSET]
Get/set fallback charset.
Fallback charset is used by this module when conversion by given
charset is failed and "FALLBACK" error handling scheme is
specified. Modules using this module may use this charset as last
resort of charset for conversion. By default, it is "UTF-8".
If CHARSET is given and isn't false, it will be set to fallback
charset. If CHARSET is "NONE", fallback charset will be undefined.
Otherwise, fallback charset won't be changed. In any cases,
current fallback charset will be returned.
NOTE: It is useful that "US-ASCII" is specified as fallback
charset, since result of conversion will be readable without
charset informations.
recommended CHARSET [, HEADERENC, BODYENC [, ENCCHARSET]]
Get/set charset profiles.
If optional arguments are given and any of them are not false,
profiles for CHARSET will be set by those arguments. Otherwise,
profiles won't be changed. In both cases, current profiles for
CHARSET will be returned as 3-item list of (HEADERENC, BODYENC,
ENCCHARSET).
HEADERENC is recommended encoding scheme for message header. It
may be one of "B", "Q", "S" (shorter one of either) or "undef"
(might not be encoded).
BODYENC is recommended transfer-encoding for message body. It may
be one of "B", "Q", "S" (shorter one of either) or "undef" (might
not be transfer-encoded).
ENCCHARSET is a charset which is compatible with given CHARSET and
is recommended to be used for MIME messages on Internet. If
conversion is not needed (or this module doesn't know appropriate
charset), ENCCHARSET is "undef".
NOTE: This function in the future releases can accept more optional
arguments (for example, properties to handle character widths, line
folding behavior, ...). So format of returned value may probably
be changed. Use "header_encoding", "body_encoding" or
"output_charset" to get particular profile.
Constants
USE_ENCODE
Unicode/multibyte support flag. Non-empty string will be set when
Unicode and multibyte support is enabled. Currently, this flag
will be non-empty on Perl 5.7.3 or later and empty string on
earlier versions of Perl.
Error Handling
"body_encode" and "header_encode" accept following "Replacement"
options:
"DEFAULT"
Put a substitution character in place of a malformed character.
For UCM-based encodings, <subchar> will be used.
"FALLBACK"
Try "DEFAULT" scheme using fallback charset (see "fallback"). When
fallback charset is undefined and conversion causes error, code
will die on error with an error message.
"CROAK"
Code will die on error immediately with an error message.
Therefore, you should trap the fatal error with eval{} unless you
really want to let it die on error. Synonym is "STRICT".
"PERLQQ"
"HTMLCREF"
"XMLCREF"
Use "FB_PERLQQ", "FB_HTMLCREF" or "FB_XMLCREF" scheme defined by
Encode module.
numeric values
Numeric values are also allowed. For more details see "Handling
Malformed Data" in Encode.
If error handling scheme is not specified or unknown scheme is
specified, "DEFAULT" will be assumed.
Configuration File
Built-in defaults for option parameters can be overridden by
configuration file: MIME/Charset/Defaults.pm. For more details read
MIME/Charset/Defaults.pm.sample.
VERSION
Consult $VERSION variable.
Development versions of this module may be found at
http://hatuka.nezumi.nu/repos/MIME-Charset/
<http://hatuka.nezumi.nu/repos/MIME-Charset/>.
Incompatible Changes
Release 1.001
· new() method returns an object when CHARSET argument is not
specified.
Release 1.005
· Restrict characters in encoded-word according to RFC 2047
section 5 (3). This also affects return value of
encoded_header_len() method.
Release 1.008.2
· body_encoding() method may also returns "S".
· Return value of body_encode() method for UTF-8 may include
"QUOTED-PRINTABLE" encoding item that in earlier versions was
fixed to "BASE64".
SEE ALSO
Multipurpose Internet Mail Extensions (MIME).
AUTHOR
Hatuka*nezumi - IKEDA Soji <hatuka(at)nezumi.nu>
COPYRIGHT
Copyright (C) 2006-2011 Hatuka*nezumi - IKEDA Soji. This program is
free software; you can redistribute it and/or modify it under the same
terms as Perl itself.
perl v5.14.1 2011-06-08 Charset(3)
