ext/Encode/encengine.c Encode extension
ext/Encode/encode.h Encode extension
ext/Encode/Encode.pm Encode extension
-ext/Encode/Encode.xs Encode extension
+ext/Encode/Encode.xs Encode extension
ext/Encode/Encode/11643-1.enc Encode table
ext/Encode/Encode/11643-2.enc Encode table
ext/Encode/Encode/2022-cn.enc Encode table
ext/Encode/KR/KR.pm Encode extension
ext/Encode/KR/Makefile.PL Encode extension
ext/Encode/lib/Encode/CN/HZ.pm Encode extension
+ext/Encode/lib/Encode/Description.pod Encode extension
ext/Encode/lib/Encode/Encoding.pm Encode extension
ext/Encode/lib/Encode/Internal.pm Encode extension
ext/Encode/lib/Encode/iso10646_1.pm Encode extension
#
# This list is in alphabetical order.
--
-Autrijus Tang <autrijus@autrijus.org>
-Dan Kogai <dankogai@dan.co.jp>
-Jarkko Hietaniemi <jhi@iki.fi>
-Nick Ing-Simmons <nick@ing-simmons.net>
+Anton Tagunov <tagunov@motor.ru>
+Autrijus Tang <autrijus@autrijus.org>
+Dan Kogai <dankogai@dan.co.jp>
+Jarkko Hietaniemi <jhi@iki.fi>
+Nick Ing-Simmons <nick@ing-simmons.net>
+SADAHIRO Tomoyuki <SADAHIRO@cpan.org>
package Encode::CN;
-our $VERSION = do { my @r = (q$Revision: 0.93 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+our $VERSION = do { my @r = (q$Revision: 0.94 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
use Encode;
use Encode::CN::HZ;
=head1 SYNOPSIS
- use Encode 'encode';
+ use Encode qw/encode decode/;
$euc_cn = encode("euc-cn", $utf8); # loads Encode::CN implicitly
$utf8 = decode("euc-cn", $euc_cn); # ditto
# Revision history for Perl extension Encode.
#
-# $Id$
+# $Id: Changes,v 0.94 2002/03/20 19:59:38 dankogai Exp dankogai $
#
+0.94 Thu Mar 21 2002
++ lib/Encode/Description.pod
+! lib/Encode/Encoding.pm
+ Now the pod in Encode.pm is abridged as programming references.
+ lib/Encode/Description.pod contains the original, detailed description
+ and Encode::Encoding explains how to write your own module to
+ add new encodings. So far, lib/Encode/Description.pod contains
+ the whole pod once in Encode.pm. This is intentional.
+! Encode.pm
+ Pod revisions by Anton Tagunov
+ Message-Id: <517178431.20020320174824@motor.ru>
+! lib/Encode/Tcl.pm
+ all occrance of Encode::Tcl::Extended removed including pod
+! t/CJKalias.t
+ test now checks $encoding->name only; $encoding->{name} are
+ no longer check to find the canonical name.
+! lib/Encode/JP/JIS.pm
+! lib/Encode/JP/ISO_2022_JP.pm
+ ->name() added to be more compliant with API
+! CN/CN.pm
+! JP/JP.pm
+! KR/KR.pm
+! TW/TW.pm
+! t/CJKalias.t
+ Patch by Autrijus to add aliases to TW and fixes to POD
+ Message-Id: <20020320090619.GA24774@not.autrijus.org>
+! AUTHORS
+ SADAHIRO Tomoyuki added as should. My apologies.
+
0.93 Wed Mar 20 2002
* First release to be uploaded to CPAN. For prehistoric changes,
please see Changes file of perl distibution as well as
package Encode;
use strict;
-our $VERSION = do { my @r = (q$Revision: 0.93 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+our $VERSION = do { my @r = (q$Revision: 0.94 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
require DynaLoader;
require Exporter;
# TODO: Thai encoding TCVN
# TODO: Korean encoding Johab
# TODO: Vietnamese encodings VPS
-# TODO: Japanese encoding JIS (not the same as SJIS)
# TODO: Mac Asian+African encodings: Arabic Armenian Bengali Burmese
# ChineseSimp ChineseTrad Devanagari Ethiopic ExtArabic
# Farsi Georgian Gujarati Gurmukhi Hebrew Japanese
The C<Encode> module provides the interfaces between Perl's strings
and the rest of the system. Perl strings are sequences of B<characters>.
-The repertoire of characters that Perl can represent is at least that
-defined by the Unicode Consortium. On most platforms the ordinal
-values of the characters (as returned by C<ord(ch)>) is the "Unicode
-codepoint" for the character (the exceptions are those platforms where
-the legacy encoding is some variant of EBCDIC rather than a super-set
-of ASCII - see L<perlebcdic>).
-
-Traditionaly computer data has been moved around in 8-bit chunks
-often called "bytes". These chunks are also known as "octets" in
-networking standards. Perl is widely used to manipulate data of
-many types - not only strings of characters representing human or
-computer languages but also "binary" data being the machines representation
-of numbers, pixels in an image - or just about anything.
-
-When Perl is processing "binary data" the programmer wants Perl to process
-"sequences of bytes". This is not a problem for Perl - as a byte has 256
-possible values it easily fits in Perl's much larger "logical character".
-
-Due to size concerns, each of B<CJK> (Chinese, Japanese & Korean) modules
-are not loaded in memory until the first time they're used. Although you
-don't have to C<use> the corresponding B<Encode::>(B<TW>|B<CN>|B<JP>|B<KR>)
-modules first, be aware that those encodings will not be in C<%encodings>
-until their module is loaded (either implicitly through using encodings
-contained in the same module, or via an explicit C<use>).
-
-=head2 TERMINOLOGY
-
-=over 4
-
-=item *
-
-I<character>: a character in the range 0..(2**32-1) (or more).
-(What Perl's strings are made of.)
-
-=item *
-
-I<byte>: a character in the range 0..255
-(A special case of a Perl character.)
-
-=item *
-
-I<octet>: 8 bits of data, with ordinal values 0..255
-(Term for bytes passed to or from a non-Perl context, e.g. disk file.)
-
-=back
-
-The marker [INTERNAL] marks Internal Implementation Details, in
-general meant only for those who think they know what they are doing,
-and such details may change in future releases.
-
-=head1 ENCODINGS
-
-=head2 Characteristics of an Encoding
-
-An encoding has a "repertoire" of characters that it can represent,
-and for each representable character there is at least one sequence of
-octets that represents it.
-
-=head2 Types of Encodings
-
-Encodings can be divided into the following types:
-
-=over 4
-
-=item * Fixed length 8-bit (or less) encodings.
-
-Each character is a single octet so may have a repertoire of up to
-256 characters. ASCII and iso-8859-* are typical examples.
-
-=item * Fixed length 16-bit encodings
-
-Each character is two octets so may have a repertoire of up to
-65 536 characters. Unicode's UCS-2 is an example. Also used for
-encodings for East Asian languages.
-
-=item * Fixed length 32-bit encodings.
-
-Not really very "encoded" encodings. The Unicode code points
-are just represented as 4-octet integers. None the less because
-different architectures use different representations of integers
-(so called "endian") there at least two disctinct encodings.
-
-=item * Multi-byte encodings
-
-The number of octets needed to represent a character varies.
-UTF-8 is a particularly complex but regular case of a multi-byte
-encoding. Several East Asian countries use a multi-byte encoding
-where 1-octet is used to cover western roman characters and Asian
-characters get 2-octets.
-(UTF-16 is strictly a multi-byte encoding taking either 2 or 4 octets
-to represent a Unicode code point.)
-
-=item * "Escape" encodings.
-
-These encodings embed "escape sequences" into the octet sequence
-which describe how the following octets are to be interpreted.
-The iso-2022-* family is typical. Following the escape sequence
-octets are encoded by an "embedded" encoding (which will be one
-of the above types) until another escape sequence switches to
-a different "embedded" encoding.
-
-These schemes are very flexible and can handle mixed languages but are
-very complex to process (and have state). No escape encodings are
-implemented for Perl yet.
-
-=back
-
-=head2 Specifying Encodings
-
-Encodings can be specified to the API described below in two ways:
-
-=over 4
-
-=item 1. By name
-
-Encoding names are strings with characters taken from a restricted
-repertoire. See L</"Encoding Names">.
-
-=item 2. As an object
-
-Encoding objects are returned by C<find_encoding($name, [$skip_external])>.
-If the second parameter is true, Encode will refrain from loading external
-modules for CJK encodings.
-
-=back
-
-=head2 Encoding Names
-
-Encoding names are case insensitive. White space in names is ignored.
-In addition an encoding may have aliases. Each encoding has one
-"canonical" name. The "canonical" name is chosen from the names of
-the encoding by picking the first in the following sequence:
-
-=over 4
-
-=item * The MIME name as defined in IETF RFCs.
-
-=item * The name in the IANA registry.
-
-=item * The name used by the organization that defined it.
-
-=back
-
-Because of all the alias issues, and because in the general case
-encodings have state C<Encode> uses the encoding object internally
-once an operation is in progress.
-
-As of Perl 5.8.0, at least the following encodings are recognized
-(the => marks aliases):
-
- ASCII
-
- US-ASCII => ASCII
-
-The Unicode:
-
- UTF-8
- UTF-16
- UCS-2
-
- ISO 10646-1 => UCS-2
-
-The ISO 8859 and KOI:
-
- ISO 8859-1 ISO 8859-6 ISO 8859-11 KOI8-F
- ISO 8859-2 ISO 8859-7 (12 doesn't exist) KOI8-R
- ISO 8859-3 ISO 8859-8 ISO 8859-13 KOI8-U
- ISO 8859-4 ISO 8859-9 ISO 8859-14
- ISO 8859-5 ISO 8859-10 ISO 8859-15
- ISO 8859-16
-
- Latin1 => 8859-1 Latin6 => 8859-10
- Latin2 => 8859-2 Latin7 => 8859-13
- Latin3 => 8859-3 Latin8 => 8859-14
- Latin4 => 8859-4 Latin9 => 8859-15
- Latin5 => 8859-9 Latin10 => 8859-16
-
- Cyrillic => 8859-5
- Arabic => 8859-6
- Greek => 8859-7
- Hebrew => 8859-8
- Thai => 8859-11
- TIS620 => 8859-11
-
-The CJKV: Chinese, Japanese, Korean, Vietnamese:
-
- ISO 2022 ISO 2022 JP-1 JIS 0201 GB 1988 Big5 EUC-CN
- ISO 2022 CN ISO 2022 JP-2 JIS 0208 GB 2312 HZ EUC-JP
- ISO 2022 JP ISO 2022 KR JIS 0210 GB 12345 CNS 11643 EUC-JP-0212
- Shift-JIS GBK Big5-HKSCS EUC-KR
- VISCII ISO-IR-165
-
-(Due to size concerns, additional Chinese encodings including C<GB 18030>,
-C<EUC-TW> and C<BIG5PLUS> are distributed separately on CPAN, under the name
-L<Encode::HanExtra>.)
-
-The PC codepages:
-
- CP37 CP852 CP861 CP866 CP949 CP1251 CP1256
- CP424 CP855 CP862 CP869 CP950 CP1252 CP1257
- CP737 CP856 CP863 CP874 CP1006 CP1253 CP1258
- CP775 CP857 CP864 CP932 CP1047 CP1254
- CP850 CP860 CP865 CP936 CP1250 CP1255
-
- WinLatin1 => CP1252
- WinLatin2 => CP1250
- WinCyrillic => CP1251
- WinGreek => CP1253
- WinTurkiskh => CP1254
- WinHebrew => CP1255
- WinArabic => CP1256
- WinBaltic => CP1257
- WinVietnamese => CP1258
-
-(All the CPI<NNN...> are available also as IBMI<NNN...>.)
-
-The Mac codepages:
-
- MacCentralEuropean MacJapanese
- MacCroatian MacRoman
- MacCyrillic MacRomanian
- MacDingbats MacSami
- MacGreek MacThai
- MacIcelandic MacTurkish
- MacUkraine
-
-Miscellaneous:
-
- 7bit-greek IR-197
- 7bit-kana NeXTstep
- 7bit-latin1 POSIX-BC
- DingBats Roman8
- GSM 0338 Symbol
+To find more about character encodings, please consult
+L<Encode::Description> . This document focuses on programming references.
=head1 PERL ENCODING API
internal form and returns the resulting string. For CHECK see
L</"Handling Malformed Data">.
-For example to convert ISO 8859-1 data to UTF-8:
+For example to convert ISO-8859-1 data to UTF-8:
$utf8 = decode("latin1", $latin1);
encode() or through PerlIO: See L</"Encoding and IO">. For CHECK
see L</"Handling Malformed Data">.
-For example to convert ISO 8859-1 data to UTF-8:
+For example to convert ISO-8859-1 data to UTF-8:
from_to($data, "iso-8859-1", "utf-8");
=back
-=head2 Other Encodings of Unicode
-
-UTF-16 is similar to UCS-2, 16 bit or 2-byte chunks. UCS-2 can only
-represent 0..0xFFFF, while UTF-16 has a I<surrogate pair> scheme which
-allows it to cover the whole Unicode range.
-
-Surrogates are code points set aside to encode the 0x01000..0x10FFFF
-range of Unicode code points in pairs of 16-bit units. The I<high
-surrogates> are the range 0xD800..0xDBFF, and the I<low surrogates>
-are the range 0xDC00..0xDFFFF. The surrogate encoding is
-
- $hi = ($uni - 0x10000) / 0x400 + 0xD800;
- $lo = ($uni - 0x10000) % 0x400 + 0xDC00;
-
-and the decoding is
-
- $uni = 0x10000 + ($hi - 0xD8000) * 0x400 + ($lo - 0xDC00);
-
-Encode implements big-endian UCS-2 aliased to "iso-10646-1" as that
-happens to be the name used by that representation when used with X11
-fonts.
-
-UTF-32 or UCS-4 is 32-bit or 4-byte chunks. Perl's logical characters
-can be considered as being in this form without encoding. An encoding
-to transfer strings in this form (e.g. to write them to a file) would
-need to
-
- pack('L*', unpack('U*', $string)); # native
- or
- pack('V*', unpack('U*', $string)); # little-endian
- or
- pack('N*', unpack('U*', $string)); # big-endian
-
-depending on the endianness required.
-
-No UTF-32 encodings are implemented yet.
-
-Both UCS-2 and UCS-4 style encodings can have "byte order marks" by
-representing the code point 0xFFFE as the very first thing in a file.
-
=head2 Listing available encodings
use Encode qw(encodings);
In this case if I<ENCODING> is not a reference it is C<eval>-ed to
allow C<$1> etc. to be subsituted. The example is one way to names as
used in X11 font names to alias the MIME names for the iso-8859-*
-family.
+family. Note the double quote inside the single quote. If you are
+using regex here, you have to do so or it won't work in this case.
=item As a code reference, e.g.:
=back
-=head2 Defining Encodings
+=head1 Defining Encodings
use Encode qw(define_alias);
define_encoding( $object, 'canonicalName' [,alias...]);
Causes I<canonicalName> to be associated with I<$object>. The object
-should provide the interface described in L</"IMPLEMENTATION CLASSES">
+should provide the interface described in L<Encode::Encoding>
below. If more than two arguments are provided then additional
arguments are taken as aliases for I<$object> as for C<define_alias>.
"character operations" (e.g. C<lc>, C</\W+/>, ...).
You can also use PerlIO to convert larger amounts of data you don't
-want to bring into memory. For example to convert between ISO 8859-1
+want to bring into memory. For example to convert between ISO-8859-1
(Latin 1) and UTF-8 (or UTF-EBCDIC in EBCDIC machines):
open(F, "<:encoding(iso-8859-1)", "data.txt") or die $!;
See also L<encoding> for how to change the default encoding of the
data in your script.
-=head1 Encoding How to ...
-
-To do:
-
-=over 4
-
-=item * IO with mixed content (faking iso-2020-*)
-
-=item * MIME's Content-Length:
-
-=item * UTF-8 strings in binary data.
-
-=item * Perl/Encode wrappers on non-Unicode XS modules.
-
-=back
-
=head1 Messing with Perl's Internals
The following API uses parts of Perl's internals in the current
=back
-=head1 IMPLEMENTATION CLASSES
-
-As mentioned above encodings are (in the current implementation at least)
-defined by objects. The mapping of encoding name to object is via the
-C<%encodings> hash.
-
-The values of the hash can currently be either strings or objects.
-The string form may go away in the future. The string form occurs
-when C<encodings()> has scanned C<@INC> for loadable encodings but has
-not actually loaded the encoding in question. This is because the
-current "loading" process is all Perl and a bit slow.
-
-Once an encoding is loaded then value of the hash is object which
-implements the encoding. The object should provide the following
-interface:
-
-=over 4
-
-=item -E<gt>name
-
-Should return the string representing the canonical name of the encoding.
-
-=item -E<gt>new_sequence
-
-This is a placeholder for encodings with state. It should return an
-object which implements this interface, all current implementations
-return the original object.
-
-=item -E<gt>encode($string,$check)
-
-Should return the octet sequence representing I<$string>. If I<$check>
-is true it should modify I<$string> in place to remove the converted
-part (i.e. the whole string unless there is an error). If an error
-occurs it should return the octet sequence for the fragment of string
-that has been converted, and modify $string in-place to remove the
-converted part leaving it starting with the problem fragment.
-
-If check is is false then C<encode> should make a "best effort" to
-convert the string - for example by using a replacement character.
-
-=item -E<gt>decode($octets,$check)
-
-Should return the string that I<$octets> represents. If I<$check> is
-true it should modify I<$octets> in place to remove the converted part
-(i.e. the whole sequence unless there is an error). If an error
-occurs it should return the fragment of string that has been
-converted, and modify $octets in-place to remove the converted part
-leaving it starting with the problem fragment.
-
-If check is is false then C<decode> should make a "best effort" to
-convert the string - for example by using Unicode's "\x{FFFD}" as a
-replacement character.
-
-=back
-
-It should be noted that the check behaviour is different from the
-outer public API. The logic is that the "unchecked" case is useful
-when encoding is part of a stream which may be reporting errors
-(e.g. STDERR). In such cases it is desirable to get everything
-through somehow without causing additional errors which obscure the
-original one. Also the encoding is best placed to know what the
-correct replacement character is, so if that is the desired behaviour
-then letting low level code do it is the most efficient.
-
-In contrast if check is true, the scheme above allows the encoding to
-do as much as it can and tell layer above how much that was. What is
-lacking at present is a mechanism to report what went wrong. The most
-likely interface will be an additional method call to the object, or
-perhaps (to avoid forcing per-stream objects on otherwise stateless
-encodings) and additional parameter.
-
-It is also highly desirable that encoding classes inherit from
-C<Encode::Encoding> as a base class. This allows that class to define
-additional behaviour for all encoding objects. For example built in
-Unicode, UCS-2 and UTF-8 classes use :
-
- package Encode::MyEncoding;
- use base qw(Encode::Encoding);
-
- __PACKAGE__->Define(qw(myCanonical myAlias));
-
-To create an object with bless {Name => ...},$class, and call
-define_encoding. They inherit their C<name> method from
-C<Encode::Encoding>.
-
-=head2 Compiled Encodings
-
-F<Encode.xs> provides a class C<Encode::XS> which provides the
-interface described above. It calls a generic octet-sequence to
-octet-sequence "engine" that is driven by tables (defined in
-F<encengine.c>). The same engine is used for both encode and
-decode. C<Encode:XS>'s C<encode> forces Perl's characters to their
-UTF-8 form and then treats them as just another multibyte
-encoding. C<Encode:XS>'s C<decode> transforms the sequence and then
-turns the UTF-8-ness flag as that is the form that the tables are
-defined to produce. For details of the engine see the comments in
-F<encengine.c>.
-
-The tables are produced by the Perl script F<compile> (the name needs
-to change so we can eventually install it somewhere). F<compile> can
-currently read two formats:
-
-=over 4
-
-=item *.enc
-
-This is a coined format used by Tcl. It is documented in
-Encode/EncodeFormat.pod.
-
-=item *.ucm
-
-This is the semi-standard format used by IBM's ICU package.
-
-=back
-
-F<compile> can write the following forms:
-
-=over 4
-
-=item *.ucm
-
-See above - the F<Encode/*.ucm> files provided with the distribution have
-been created from the original Tcl .enc files using this approach.
-
-=item *.c
-
-Produces tables as C data structures - this is used to build in encodings
-into F<Encode.so>/F<Encode.dll>.
-
-=item *.xs
-
-In theory this allows encodings to be stand-alone loadable Perl
-extensions. The process has not yet been tested. The plan is to use
-this approach for large East Asian encodings.
-
-=back
-
-The set of encodings built-in to F<Encode.so>/F<Encode.dll> is
-determined by F<Makefile.PL>. The current set is as follows:
-
-=over 4
-
-=item ascii and iso-8859-*
-
-That is all the common 8-bit "western" encodings.
-
-=item IBM-1047 and two other variants of EBCDIC.
-
-These are the same variants that are supported by EBCDIC Perl as
-"native" encodings. They are included to prove "reversibility" of
-some constructs in EBCDIC Perl.
-
-=item symbol and dingbats as used by Tk on X11.
-
-(The reason Encode got started was to support Perl/Tk.)
-
-=back
-
-That set is rather ad hoc and has been driven by the needs of the
-tests rather than the needs of typical applications. It is likely
-to be rationalized.
-
=head1 SEE ALSO
L<perlunicode>, L<perlebcdic>, L<perlfunc/open>, L<PerlIO>, L<encoding>,
-L<utf8>, the Perl Unicode Mailing List E<lt>perl-unicode@perl.orgE<gt>
+L<utf8>, L<Encode::Description>, L<Encode::Encoding> the Perl Unicode Mailing List E<lt>perl-unicode@perl.orgE<gt>
=cut
}
}
use Encode;
-our $VERSION = do { my @r = (q$Revision: 0.93 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+our $VERSION = do { my @r = (q$Revision: 0.94 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
use XSLoader;
XSLoader::load('Encode::JP',$VERSION);
=head1 SYNOPSIS
- use Encode 'encode';
+ use Encode qw/encode decode/;
$euc_jp = encode("euc-jp", $utf8); # loads Encode::JP implicitly
$utf8 = decode("euc-jp", $euc_jp); # ditto
package Encode::KR;
-our $VERSION = do { my @r = (q$Revision: 0.93 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+our $VERSION = do { my @r = (q$Revision: 0.94 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
use Encode;
use XSLoader;
=head1 SYNOPSIS
- use Encode 'encode';
+ use Encode qw/encode decode/;
$euc_kr = encode("euc-kr", $utf8); # loads Encode::KR implicitly
$utf8 = decode("euc-kr", $euc_kr); # ditto
encengine.c Encode extension
encode.h Encode extension
lib/Encode/CN/HZ.pm Encode extension
+lib/Encode/Description.pod General topics on character encodings
lib/Encode/Encoding.pm Encode extension
lib/Encode/Internal.pm Encode extension
lib/Encode/JP/Constants.pm Encode extension
package Encode::TW;
-our $VERSION = do { my @r = (q$Revision: 0.92 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+our $VERSION = do { my @r = (q$Revision: 0.94 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
use Encode;
use XSLoader;
XSLoader::load('Encode::TW',$VERSION);
+Encode::define_alias( qr/big-?5$/i => '"big5"' );
+Encode::define_alias( qr/big5-hk(?:scs)?/i => '"big5-hkscs"' );
+
1;
__END__
=head1 NAME
=head1 SYNOPSIS
- use Encode 'encode';
+ use Encode qw/encode decode/;
$big5 = encode("big5", $utf8); # loads Encode::TW implicitly
$utf8 = decode("big5", $big5); # ditto
This module implements Taiwan-based Chinese charset encodings.
Encodings supported are as follows.
- big5 The original Big5 encoding
- big5-hkscs Big5 plus Cantonese characters in Hong Kong
- cp950 Code Page 950 (Big5 + Microsoft vendor mappings)
+ Canonical Alias Description
+ --------------------------------------------------------------------
+ big5 /big-?5$/i The original Big5 encoding
+ big5-hkscs /big5-hk(scs)?$/i Big5 plus Cantonese characters in
+ Hong Kong
+ cp950 Code Page 950
+ (Big5 + Microsoft vendor mappings)
To find how to use this module in detail, see L<Encode>.
--- /dev/null
+
+=head1 NAME
+
+Encode - character encodings
+
+=head1 SYNOPSIS
+
+ use Encode;
+
+=head1 DESCRIPTION
+
+The C<Encode> module provides the interfaces between Perl's strings
+and the rest of the system. Perl strings are sequences of B<characters>.
+
+The repertoire of characters that Perl can represent is at least that
+defined by the Unicode Consortium. On most platforms the ordinal
+values of the characters (as returned by C<ord(ch)>) is the "Unicode
+codepoint" for the character (the exceptions are those platforms where
+the legacy encoding is some variant of EBCDIC rather than a super-set
+of ASCII - see L<perlebcdic>).
+
+Traditionaly computer data has been moved around in 8-bit chunks
+often called "bytes". These chunks are also known as "octets" in
+networking standards. Perl is widely used to manipulate data of
+many types - not only strings of characters representing human or
+computer languages but also "binary" data being the machines representation
+of numbers, pixels in an image - or just about anything.
+
+When Perl is processing "binary data" the programmer wants Perl to process
+"sequences of bytes". This is not a problem for Perl - as a byte has 256
+possible values it easily fits in Perl's much larger "logical character".
+
+Due to size concerns, each of B<CJK> (Chinese, Japanese & Korean) modules
+are not loaded in memory until the first time they're used. Although you
+don't have to C<use> the corresponding B<Encode::>(B<TW>|B<CN>|B<JP>|B<KR>)
+modules first, be aware that those encodings will not be in C<%encodings>
+until their module is loaded (either implicitly through using encodings
+contained in the same module, or via an explicit C<use>).
+
+=head2 TERMINOLOGY
+
+=over 4
+
+=item *
+
+I<character>: a character in the range 0..(2**32-1) (or more).
+(What Perl's strings are made of.)
+
+=item *
+
+I<byte>: a character in the range 0..255
+(A special case of a Perl character.)
+
+=item *
+
+I<octet>: 8 bits of data, with ordinal values 0..255
+(Term for bytes passed to or from a non-Perl context, e.g. disk file.)
+
+=back
+
+The marker [INTERNAL] marks Internal Implementation Details, in
+general meant only for those who think they know what they are doing,
+and such details may change in future releases.
+
+=head1 ENCODINGS
+
+=head2 Characteristics of an Encoding
+
+An encoding has a "repertoire" of characters that it can represent,
+and for each representable character there is at least one sequence of
+octets that represents it.
+
+=head2 Types of Encodings
+
+Encodings can be divided into the following types:
+
+=over 4
+
+=item * Fixed length 8-bit (or less) encodings.
+
+Each character is a single octet so may have a repertoire of up to
+256 characters. ASCII and iso-8859-* are typical examples.
+
+=item * Fixed length 16-bit encodings
+
+Each character is two octets so may have a repertoire of up to
+65 536 characters. Unicode's UCS-2 is an example. Also used for
+encodings for East Asian languages.
+
+=item * Fixed length 32-bit encodings.
+
+Not really very "encoded" encodings. The Unicode code points
+are just represented as 4-octet integers. None the less because
+different architectures use different representations of integers
+(so called "endian") there at least two disctinct encodings.
+
+=item * Multi-byte encodings
+
+The number of octets needed to represent a character varies.
+UTF-8 is a particularly complex but regular case of a multi-byte
+encoding. Several East Asian countries use a multi-byte encoding
+where 1-octet is used to cover western roman characters and Asian
+characters get 2-octets.
+(UTF-16 is strictly a multi-byte encoding taking either 2 or 4 octets
+to represent a Unicode code point.)
+
+=item * "Escape" encodings.
+
+These encodings embed "escape sequences" into the octet sequence
+which describe how the following octets are to be interpreted.
+The iso-2022-* family is typical. Following the escape sequence
+octets are encoded by an "embedded" encoding (which will be one
+of the above types) until another escape sequence switches to
+a different "embedded" encoding.
+
+These schemes are very flexible and can handle mixed languages but are
+very complex to process (and have state). No escape encodings are
+implemented for Perl yet.
+
+=back
+
+=head2 Specifying Encodings
+
+Encodings can be specified to the API described below in two ways:
+
+=over 4
+
+=item 1. By name
+
+Encoding names are strings with characters taken from a restricted
+repertoire. See L</"Encoding Names">.
+
+=item 2. As an object
+
+Encoding objects are returned by C<find_encoding($name, [$skip_external])>.
+If the second parameter is true, Encode will refrain from loading external
+modules for CJK encodings.
+
+=back
+
+=head2 Encoding Names
+
+Encoding names are case insensitive. White space in names is ignored.
+In addition an encoding may have aliases. Each encoding has one
+"canonical" name. The "canonical" name is chosen from the names of
+the encoding by picking the first in the following sequence:
+
+=over 4
+
+=item * The MIME name as defined in IETF RFCs.
+
+=item * The name in the IANA registry.
+
+=item * The name used by the organization that defined it.
+
+=back
+
+Because of all the alias issues, and because in the general case
+encodings have state C<Encode> uses the encoding object internally
+once an operation is in progress.
+
+As of Perl 5.8.0, at least the following encodings are recognized
+(the => marks aliases):
+
+ ASCII
+
+ US-ASCII => ASCII
+
+The Unicode:
+
+ UTF-8
+ UTF-16
+ UCS-2
+
+ ISO 10646-1 => UCS-2
+
+The ISO 8859 and KOI:
+
+ ISO 8859-1 ISO 8859-6 ISO 8859-11 KOI8-F
+ ISO 8859-2 ISO 8859-7 (12 doesn't exist) KOI8-R
+ ISO 8859-3 ISO 8859-8 ISO 8859-13 KOI8-U
+ ISO 8859-4 ISO 8859-9 ISO 8859-14
+ ISO 8859-5 ISO 8859-10 ISO 8859-15
+ ISO 8859-16
+
+ Latin1 => 8859-1 Latin6 => 8859-10
+ Latin2 => 8859-2 Latin7 => 8859-13
+ Latin3 => 8859-3 Latin8 => 8859-14
+ Latin4 => 8859-4 Latin9 => 8859-15
+ Latin5 => 8859-9 Latin10 => 8859-16
+
+ Cyrillic => 8859-5
+ Arabic => 8859-6
+ Greek => 8859-7
+ Hebrew => 8859-8
+ Thai => 8859-11
+ TIS620 => 8859-11
+
+The CJKV: Chinese, Japanese, Korean, Vietnamese:
+
+ ISO 2022 ISO 2022 JP-1 JIS 0201 GB 1988 Big5 EUC-CN
+ ISO 2022 CN ISO 2022 JP-2 JIS 0208 GB 2312 HZ EUC-JP
+ ISO 2022 JP ISO 2022 KR JIS 0210 GB 12345 CNS 11643 EUC-JP-0212
+ Shift-JIS GBK Big5-HKSCS EUC-KR
+ VISCII ISO-IR-165
+
+(Due to size concerns, additional Chinese encodings including C<GB 18030>,
+C<EUC-TW> and C<BIG5PLUS> are distributed separately on CPAN, under the name
+L<Encode::HanExtra>.)
+
+The PC codepages:
+
+ CP37 CP852 CP861 CP866 CP949 CP1251 CP1256
+ CP424 CP855 CP862 CP869 CP950 CP1252 CP1257
+ CP737 CP856 CP863 CP874 CP1006 CP1253 CP1258
+ CP775 CP857 CP864 CP932 CP1047 CP1254
+ CP850 CP860 CP865 CP936 CP1250 CP1255
+
+ WinLatin1 => CP1252
+ WinLatin2 => CP1250
+ WinCyrillic => CP1251
+ WinGreek => CP1253
+ WinTurkiskh => CP1254
+ WinHebrew => CP1255
+ WinArabic => CP1256
+ WinBaltic => CP1257
+ WinVietnamese => CP1258
+
+(All the CPI<NNN...> are available also as IBMI<NNN...>.)
+
+The Mac codepages:
+
+ MacCentralEuropean MacJapanese
+ MacCroatian MacRoman
+ MacCyrillic MacRomanian
+ MacDingbats MacSami
+ MacGreek MacThai
+ MacIcelandic MacTurkish
+ MacUkraine
+
+Miscellaneous:
+
+ 7bit-greek IR-197
+ 7bit-kana NeXTstep
+ 7bit-latin1 POSIX-BC
+ DingBats Roman8
+ GSM 0338 Symbol
+
+=head2 Encoding Classification
+
+Encodings
+
+ US-ASCII UTF-8 KOI8-R ISO-8859-*
+ ISO-2022-CN ISO-2022-JP ISO-2022-KR Big5
+ EUC-CN EUC-JP EUC-KR
+
+are L<http://www.iana.org/assignments/character-sets>-registered
+as preferred MIME names and may probably be used over the Internet.
+So is
+
+ Shift_JIS
+
+but despite its wide spread it bears the label of being
+Microsft proprietary.
+
+ UTF-16 KOI8-U ISO-2022-JP-2
+
+are IANA-registered preferred MIME names but probably shoule
+be avoided as encoding for web pages due to lack of browser
+support.
+
+
+ ISO-2022 (http://www.ecma.ch/ecma1/STAND/ECMA-035.HTM)
+ ISO-2022-JP-1 (http://www.faqs.org/rfcs/rfc2237.html)
+ ISO-IR-165 (http://www.faqs.org/rfcs/rfc1345.html)
+ GBK
+ VISCII
+ GB 12345 (only plains 1 and 2 available)
+ GB 18030
+ CNS 11643
+
+are totally valid encodings but not registered at IANA.
+
+ BIG5PLUS
+ EUC-JP-0212 (Encode::lib::Encode::Tcl::Extended)
+
+are a bit proprietary
+
+You may probably get some info on CJK encodings at
+
+ brief description for most of the mentioned CJK encodings
+ http://www.debian.org.ru/doc/manuals/intro-i18n/ch-codes.html
+
+ several years old, but still useful
+ http://www.oreilly.com/people/authors/lunde/cjk_inf.html
+
+ and some in-depth reading for the heroes :-)
+ http://www.ecma.ch/ecma1/STAND/ECMA-035.HTM (eq ISO-2022)
+ http://www.faqs.org/rfcs/rfc1345.txt
+
+
+=head1 PERL ENCODING API
+
+=head2 Generic Encoding Interface
+
+=over 4
+
+=item *
+
+ $bytes = encode(ENCODING, $string[, CHECK])
+
+Encodes string from Perl's internal form into I<ENCODING> and returns
+a sequence of octets. For CHECK see L</"Handling Malformed Data">.
+
+For example to convert (internally UTF-8 encoded) Unicode data
+to octets:
+
+ $octets = encode("utf8", $unicode);
+
+=item *
+
+ $string = decode(ENCODING, $bytes[, CHECK])
+
+Decode sequence of octets assumed to be in I<ENCODING> into Perl's
+internal form and returns the resulting string. For CHECK see
+L</"Handling Malformed Data">.
+
+For example to convert ISO-8859-1 data to UTF-8:
+
+ $utf8 = decode("latin1", $latin1);
+
+=item *
+
+ from_to($string, FROM_ENCODING, TO_ENCODING[, CHECK])
+
+Convert B<in-place> the data between two encodings. How did the data
+in $string originally get to be in FROM_ENCODING? Either using
+encode() or through PerlIO: See L</"Encoding and IO">. For CHECK
+see L</"Handling Malformed Data">.
+
+For example to convert ISO-8859-1 data to UTF-8:
+
+ from_to($data, "iso-8859-1", "utf-8");
+
+and to convert it back:
+
+ from_to($data, "utf-8", "iso-8859-1");
+
+Note that because the conversion happens in place, the data to be
+converted cannot be a string constant, it must be a scalar variable.
+
+=back
+
+=head2 Handling Malformed Data
+
+If CHECK is not set, C<undef> is returned. If the data is supposed to
+be UTF-8, an optional lexical warning (category utf8) is given. If
+CHECK is true but not a code reference, dies.
+
+It would desirable to have a way to indicate that transform should use
+the encodings "replacement character" - no such mechanism is defined yet.
+
+It is also planned to allow I<CHECK> to be a code reference.
+
+This is not yet implemented as there are design issues with what its
+arguments should be and how it returns its results.
+
+=over 4
+
+=item Scheme 1
+
+Passed remaining fragment of string being processed.
+Modifies it in place to remove bytes/characters it can understand
+and returns a string used to represent them.
+e.g.
+
+ sub fixup {
+ my $ch = substr($_[0],0,1,'');
+ return sprintf("\x{%02X}",ord($ch);
+ }
+
+This scheme is close to how underlying C code for Encode works, but gives
+the fixup routine very little context.
+
+=item Scheme 2
+
+Passed original string, and an index into it of the problem area, and
+output string so far. Appends what it will to output string and
+returns new index into original string. For example:
+
+ sub fixup {
+ # my ($s,$i,$d) = @_;
+ my $ch = substr($_[0],$_[1],1);
+ $_[2] .= sprintf("\x{%02X}",ord($ch);
+ return $_[1]+1;
+ }
+
+This scheme gives maximal control to the fixup routine but is more
+complicated to code, and may need internals of Encode to be tweaked to
+keep original string intact.
+
+=item Other Schemes
+
+Hybrids of above.
+
+Multiple return values rather than in-place modifications.
+
+Index into the string could be pos($str) allowing s/\G...//.
+
+=back
+
+=head2 UTF-8 / utf8
+
+The Unicode consortium defines the UTF-8 standard as a way of encoding
+the entire Unicode repertiore as sequences of octets. This encoding is
+expected to become very widespread. Perl can use this form internaly
+to represent strings, so conversions to and from this form are
+particularly efficient (as octets in memory do not have to change,
+just the meta-data that tells Perl how to treat them).
+
+=over 4
+
+=item *
+
+ $bytes = encode_utf8($string);
+
+The characters that comprise string are encoded in Perl's superset of UTF-8
+and the resulting octets returned as a sequence of bytes. All possible
+characters have a UTF-8 representation so this function cannot fail.
+
+=item *
+
+ $string = decode_utf8($bytes [,CHECK]);
+
+The sequence of octets represented by $bytes is decoded from UTF-8
+into a sequence of logical characters. Not all sequences of octets
+form valid UTF-8 encodings, so it is possible for this call to fail.
+For CHECK see L</"Handling Malformed Data">.
+
+=back
+
+=head2 Other Encodings of Unicode
+
+UTF-16 is similar to UCS-2, 16 bit or 2-byte chunks. UCS-2 can only
+represent 0..0xFFFF, while UTF-16 has a I<surrogate pair> scheme which
+allows it to cover the whole Unicode range.
+
+Surrogates are code points set aside to encode the 0x01000..0x10FFFF
+range of Unicode code points in pairs of 16-bit units. The I<high
+surrogates> are the range 0xD800..0xDBFF, and the I<low surrogates>
+are the range 0xDC00..0xDFFFF. The surrogate encoding is
+
+ $hi = ($uni - 0x10000) / 0x400 + 0xD800;
+ $lo = ($uni - 0x10000) % 0x400 + 0xDC00;
+
+and the decoding is
+
+ $uni = 0x10000 + ($hi - 0xD8000) * 0x400 + ($lo - 0xDC00);
+
+Encode implements big-endian UCS-2 aliased to "iso-10646-1" as that
+happens to be the name used by that representation when used with X11
+fonts.
+
+UTF-32 or UCS-4 is 32-bit or 4-byte chunks. Perl's logical characters
+can be considered as being in this form without encoding. An encoding
+to transfer strings in this form (e.g. to write them to a file) would
+need to
+
+ pack('L*', unpack('U*', $string)); # native
+ or
+ pack('V*', unpack('U*', $string)); # little-endian
+ or
+ pack('N*', unpack('U*', $string)); # big-endian
+
+depending on the endianness required.
+
+No UTF-32 encodings are implemented yet.
+
+Both UCS-2 and UCS-4 style encodings can have "byte order marks" by
+representing the code point 0xFFFE as the very first thing in a file.
+
+=head2 Listing available encodings
+
+ use Encode qw(encodings);
+ @list = encodings();
+
+Returns a list of the canonical names of the available encodings.
+
+=head2 Defining Aliases
+
+ use Encode qw(define_alias);
+ define_alias( newName => ENCODING);
+
+Allows newName to be used as am alias for ENCODING. ENCODING may be
+either the name of an encoding or and encoding object (as above).
+
+Currently I<newName> can be specified in the following ways:
+
+=over 4
+
+=item As a simple string.
+
+=item As a qr// compiled regular expression, e.g.:
+
+ define_alias( qr/^iso8859-(\d+)$/i => '"iso-8859-$1"' );
+
+In this case if I<ENCODING> is not a reference it is C<eval>-ed to
+allow C<$1> etc. to be subsituted. The example is one way to names as
+used in X11 font names to alias the MIME names for the iso-8859-*
+family. Note the double quote inside the single quote. If you are
+using regex here, y ou have to do so or it won't work in this case.
+
+=item As a code reference, e.g.:
+
+ define_alias( sub { return /^iso8859-(\d+)$/i ? "iso-8859-$1" : undef } , '');
+
+In this case C<$_> will be set to the name that is being looked up and
+I<ENCODING> is passed to the sub as its first argument. The example
+is another way to names as used in X11 font names to alias the MIME
+names for the iso-8859-* family.
+
+=back
+
+=head2 Defining Encodings
+
+ use Encode qw(define_alias);
+ define_encoding( $object, 'canonicalName' [,alias...]);
+
+Causes I<canonicalName> to be associated with I<$object>. The object
+should provide the interface described in L</"IMPLEMENTATION CLASSES">
+below. If more than two arguments are provided then additional
+arguments are taken as aliases for I<$object> as for C<define_alias>.
+
+=head1 Encoding and IO
+
+It is very common to want to do encoding transformations when
+reading or writing files, network connections, pipes etc.
+If Perl is configured to use the new 'perlio' IO system then
+C<Encode> provides a "layer" (See L<perliol>) which can transform
+data as it is read or written.
+
+Here is how the blind poet would modernise the encoding:
+
+ use Encode;
+ open(my $iliad,'<:encoding(iso-8859-7)','iliad.greek');
+ open(my $utf8,'>:utf8','iliad.utf8');
+ my @epic = <$iliad>;
+ print $utf8 @epic;
+ close($utf8);
+ close($illiad);
+
+In addition the new IO system can also be configured to read/write
+UTF-8 encoded characters (as noted above this is efficient):
+
+ open(my $fh,'>:utf8','anything');
+ print $fh "Any \x{0021} string \N{SMILEY FACE}\n";
+
+Either of the above forms of "layer" specifications can be made the default
+for a lexical scope with the C<use open ...> pragma. See L<open>.
+
+Once a handle is open is layers can be altered using C<binmode>.
+
+Without any such configuration, or if Perl itself is built using
+system's own IO, then write operations assume that file handle accepts
+only I<bytes> and will C<die> if a character larger than 255 is
+written to the handle. When reading, each octet from the handle
+becomes a byte-in-a-character. Note that this default is the same
+behaviour as bytes-only languages (including Perl before v5.6) would
+have, and is sufficient to handle native 8-bit encodings
+e.g. iso-8859-1, EBCDIC etc. and any legacy mechanisms for handling
+other encodings and binary data.
+
+In other cases it is the programs responsibility to transform
+characters into bytes using the API above before doing writes, and to
+transform the bytes read from a handle into characters before doing
+"character operations" (e.g. C<lc>, C</\W+/>, ...).
+
+You can also use PerlIO to convert larger amounts of data you don't
+want to bring into memory. For example to convert between ISO-8859-1
+(Latin 1) and UTF-8 (or UTF-EBCDIC in EBCDIC machines):
+
+ open(F, "<:encoding(iso-8859-1)", "data.txt") or die $!;
+ open(G, ">:utf8", "data.utf") or die $!;
+ while (<F>) { print G }
+
+ # Could also do "print G <F>" but that would pull
+ # the whole file into memory just to write it out again.
+
+More examples:
+
+ open(my $f, "<:encoding(cp1252)")
+ open(my $g, ">:encoding(iso-8859-2)")
+ open(my $h, ">:encoding(latin9)") # iso-8859-15
+
+See L<PerlIO> for more information.
+
+See also L<encoding> for how to change the default encoding of the
+data in your script.
+
+=head1 Encoding How to ...
+
+To do:
+
+=over 4
+
+=item * IO with mixed content (faking iso-2022-*)
+
+Encode::JP implements its own iso-2022 routines, however.
+
+=item * MIME's Content-Length:
+
+=item * UTF-8 strings in binary data.
+
+=item * Perl/Encode wrappers on non-Unicode XS modules.
+
+=back
+
+=head1 Messing with Perl's Internals
+
+The following API uses parts of Perl's internals in the current
+implementation. As such they are efficient, but may change.
+
+=over 4
+
+=item * is_utf8(STRING [, CHECK])
+
+[INTERNAL] Test whether the UTF-8 flag is turned on in the STRING.
+If CHECK is true, also checks the data in STRING for being well-formed
+UTF-8. Returns true if successful, false otherwise.
+
+=item *
+
+ _utf8_on(STRING)
+
+[INTERNAL] Turn on the UTF-8 flag in STRING. The data in STRING is
+B<not> checked for being well-formed UTF-8. Do not use unless you
+B<know> that the STRING is well-formed UTF-8. Returns the previous
+state of the UTF-8 flag (so please don't test the return value as
+I<not> success or failure), or C<undef> if STRING is not a string.
+
+=item *
+
+ _utf8_off(STRING)
+
+[INTERNAL] Turn off the UTF-8 flag in STRING. Do not use frivolously.
+Returns the previous state of the UTF-8 flag (so please don't test the
+return value as I<not> success or failure), or C<undef> if STRING is
+not a string.
+
+=back
+
+=head1 IMPLEMENTATION CLASSES
+
+As mentioned above encodings are (in the current implementation at least)
+defined by objects. The mapping of encoding name to object is via the
+C<%encodings> hash.
+
+The values of the hash can currently be either strings or objects.
+The string form may go away in the future. The string form occurs
+when C<encodings()> has scanned C<@INC> for loadable encodings but has
+not actually loaded the encoding in question. This is because the
+current "loading" process is all Perl and a bit slow.
+
+Once an encoding is loaded then value of the hash is object which
+implements the encoding. The object should provide the following
+interface:
+
+=over 4
+
+=item -E<gt>name
+
+Should return the string representing the canonical name of the encoding.
+
+=item -E<gt>new_sequence
+
+This is a placeholder for encodings with state. It should return an
+object which implements this interface, all current implementations
+return the original object.
+
+=item -E<gt>encode($string,$check)
+
+Should return the octet sequence representing I<$string>. If I<$check>
+is true it should modify I<$string> in place to remove the converted
+part (i.e. the whole string unless there is an error). If an error
+occurs it should return the octet sequence for the fragment of string
+that has been converted, and modify $string in-place to remove the
+converted part leaving it starting with the problem fragment.
+
+If check is is false then C<encode> should make a "best effort" to
+convert the string - for example by using a replacement character.
+
+=item -E<gt>decode($octets,$check)
+
+Should return the string that I<$octets> represents. If I<$check> is
+true it should modify I<$octets> in place to remove the converted part
+(i.e. the whole sequence unless there is an error). If an error
+occurs it should return the fragment of string that has been
+converted, and modify $octets in-place to remove the converted part
+leaving it starting with the problem fragment.
+
+If check is is false then C<decode> should make a "best effort" to
+convert the string - for example by using Unicode's "\x{FFFD}" as a
+replacement character.
+
+=back
+
+It should be noted that the check behaviour is different from the
+outer public API. The logic is that the "unchecked" case is useful
+when encoding is part of a stream which may be reporting errors
+(e.g. STDERR). In such cases it is desirable to get everything
+through somehow without causing additional errors which obscure the
+original one. Also the encoding is best placed to know what the
+correct replacement character is, so if that is the desired behaviour
+then letting low level code do it is the most efficient.
+
+In contrast if check is true, the scheme above allows the encoding to
+do as much as it can and tell layer above how much that was. What is
+lacking at present is a mechanism to report what went wrong. The most
+likely interface will be an additional method call to the object, or
+perhaps (to avoid forcing per-stream objects on otherwise stateless
+encodings) and additional parameter.
+
+It is also highly desirable that encoding classes inherit from
+C<Encode::Encoding> as a base class. This allows that class to define
+additional behaviour for all encoding objects. For example built in
+Unicode, UCS-2 and UTF-8 classes use :
+
+ package Encode::MyEncoding;
+ use base qw(Encode::Encoding);
+
+ __PACKAGE__->Define(qw(myCanonical myAlias));
+
+To create an object with bless {Name => ...},$class, and call
+define_encoding. They inherit their C<name> method from
+C<Encode::Encoding>.
+
+=head2 Compiled Encodings
+
+F<Encode.xs> provides a class C<Encode::XS> which provides the
+interface described above. It calls a generic octet-sequence to
+octet-sequence "engine" that is driven by tables (defined in
+F<encengine.c>). The same engine is used for both encode and
+decode. C<Encode:XS>'s C<encode> forces Perl's characters to their
+UTF-8 form and then treats them as just another multibyte
+encoding. C<Encode:XS>'s C<decode> transforms the sequence and then
+turns the UTF-8-ness flag as that is the form that the tables are
+defined to produce. For details of the engine see the comments in
+F<encengine.c>.
+
+The tables are produced by the Perl script F<compile> (the name needs
+to change so we can eventually install it somewhere). F<compile> can
+currently read two formats:
+
+=over 4
+
+=item *.enc
+
+This is a coined format used by Tcl. It is documented in
+Encode/EncodeFormat.pod.
+
+=item *.ucm
+
+This is the semi-standard format used by IBM's ICU package.
+
+=back
+
+F<compile> can write the following forms:
+
+=over 4
+
+=item *.ucm
+
+See above - the F<Encode/*.ucm> files provided with the distribution have
+been created from the original Tcl .enc files using this approach.
+
+=item *.c
+
+Produces tables as C data structures - this is used to build in encodings
+into F<Encode.so>/F<Encode.dll>.
+
+=item *.xs
+
+In theory this allows encodings to be stand-alone loadable Perl
+extensions. The process has not yet been tested. The plan is to use
+this approach for large East Asian encodings.
+
+=back
+
+The set of encodings built-in to F<Encode.so>/F<Encode.dll> is
+determined by F<Makefile.PL>. The current set is as follows:
+
+=over 4
+
+=item ascii and iso-8859-*
+
+That is all the common 8-bit "western" encodings.
+
+=item IBM-1047 and two other variants of EBCDIC.
+
+These are the same variants that are supported by EBCDIC Perl as
+"native" encodings. They are included to prove "reversibility" of
+some constructs in EBCDIC Perl.
+
+=item symbol and dingbats as used by Tk on X11.
+
+(The reason Encode got started was to support Perl/Tk.)
+
+=back
+
+That set is rather ad hoc and has been driven by the needs of the
+tests rather than the needs of typical applications. It is likely
+to be rationalized.
+
+=head1 SEE ALSO
+
+L<perlunicode>, L<perlebcdic>, L<perlfunc/open>, L<PerlIO>, L<encoding>,
+L<utf8>, the Perl Unicode Mailing List E<lt>perl-unicode@perl.orgE<gt>
+
+
+=cut
+
package Encode::Encoding;
# Base class for classes which implement encodings
use strict;
-our $VERSION = do { my @r = (q$Revision: 0.92 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+our $VERSION = do { my @r = (q$Revision: 0.94 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
sub Define
{
1;
__END__
+
+=head1 NAME
+
+Encode::Encoding - Encode Implementation Base Class
+
+=head1 SYNOPSIS
+
+ package Encode::MyEncoding;
+ use base qw(Encode::Encoding);
+
+ __PACKAGE__->Define(qw(myCanonical myAlias));
+
+=head 1 DESCRIPTION
+
+As mentioned in L<Encode>, encodings are (in the current
+implementation at least) defined by objects. The mapping of encoding
+name to object is via the C<%encodings> hash.
+
+The values of the hash can currently be either strings or objects.
+The string form may go away in the future. The string form occurs
+when C<encodings()> has scanned C<@INC> for loadable encodings but has
+not actually loaded the encoding in question. This is because the
+current "loading" process is all Perl and a bit slow.
+
+Once an encoding is loaded then value of the hash is object which
+implements the encoding. The object should provide the following
+interface:
+
+=over 4
+
+=item -E<gt>name
+
+Should return the string representing the canonical name of the encoding.
+
+=item -E<gt>new_sequence
+
+This is a placeholder for encodings with state. It should return an
+object which implements this interface, all current implementations
+return the original object.
+
+=item -E<gt>encode($string,$check)
+
+Should return the octet sequence representing I<$string>. If I<$check>
+is true it should modify I<$string> in place to remove the converted
+part (i.e. the whole string unless there is an error). If an error
+occurs it should return the octet sequence for the fragment of string
+that has been converted, and modify $string in-place to remove the
+converted part leaving it starting with the problem fragment.
+
+If check is is false then C<encode> should make a "best effort" to
+convert the string - for example by using a replacement character.
+
+=item -E<gt>decode($octets,$check)
+
+Should return the string that I<$octets> represents. If I<$check> is
+true it should modify I<$octets> in place to remove the converted part
+(i.e. the whole sequence unless there is an error). If an error
+occurs it should return the fragment of string that has been
+converted, and modify $octets in-place to remove the converted part
+leaving it starting with the problem fragment.
+
+If check is is false then C<decode> should make a "best effort" to
+convert the string - for example by using Unicode's "\x{FFFD}" as a
+replacement character.
+
+=back
+
+It should be noted that the check behaviour is different from the
+outer public API. The logic is that the "unchecked" case is useful
+when encoding is part of a stream which may be reporting errors
+(e.g. STDERR). In such cases it is desirable to get everything
+through somehow without causing additional errors which obscure the
+original one. Also the encoding is best placed to know what the
+correct replacement character is, so if that is the desired behaviour
+then letting low level code do it is the most efficient.
+
+In contrast if check is true, the scheme above allows the encoding to
+do as much as it can and tell layer above how much that was. What is
+lacking at present is a mechanism to report what went wrong. The most
+likely interface will be an additional method call to the object, or
+perhaps (to avoid forcing per-stream objects on otherwise stateless
+encodings) and additional parameter.
+
+It is also highly desirable that encoding classes inherit from
+C<Encode::Encoding> as a base class. This allows that class to define
+additional behaviour for all encoding objects. For example built in
+Unicode, UCS-2 and UTF-8 classes use :
+
+ package Encode::MyEncoding;
+ use base qw(Encode::Encoding);
+
+ __PACKAGE__->Define(qw(myCanonical myAlias));
+
+To create an object with bless {Name => ...},$class, and call
+define_encoding. They inherit their C<name> method from
+C<Encode::Encoding>.
+
+=head2 Compiled Encodings
+
+F<Encode.xs> provides a class C<Encode::XS> which provides the
+interface described above. It calls a generic octet-sequence to
+octet-sequence "engine" that is driven by tables (defined in
+F<encengine.c>). The same engine is used for both encode and
+decode. C<Encode:XS>'s C<encode> forces Perl's characters to their
+UTF-8 form and then treats them as just another multibyte
+encoding. C<Encode:XS>'s C<decode> transforms the sequence and then
+turns the UTF-8-ness flag as that is the form that the tables are
+defined to produce. For details of the engine see the comments in
+F<encengine.c>.
+
+The tables are produced by the Perl script F<compile> (the name needs
+to change so we can eventually install it somewhere). F<compile> can
+currently read two formats:
+
+=over 4
+
+=item *.enc
+
+This is a coined format used by Tcl. It is documented in
+Encode/EncodeFormat.pod.
+
+=item *.ucm
+
+This is the semi-standard format used by IBM's ICU package.
+
+=back
+
+F<compile> can write the following forms:
+
+=over 4
+
+=item *.ucm
+
+See above - the F<Encode/*.ucm> files provided with the distribution have
+been created from the original Tcl .enc files using this approach.
+
+=item *.c
+
+Produces tables as C data structures - this is used to build in encodings
+into F<Encode.so>/F<Encode.dll>.
+
+=item *.xs
+
+In theory this allows encodings to be stand-alone loadable Perl
+extensions. The process has not yet been tested. The plan is to use
+this approach for large East Asian encodings.
+
+=back
+
+The set of encodings built-in to F<Encode.so>/F<Encode.dll> is
+determined by F<Makefile.PL>. The current set is as follows:
+
+=over 4
+
+=item ascii and iso-8859-*
+
+That is all the common 8-bit "western" encodings.
+
+=item IBM-1047 and two other variants of EBCDIC.
+
+These are the same variants that are supported by EBCDIC Perl as
+"native" encodings. They are included to prove "reversibility" of
+some constructs in EBCDIC Perl.
+
+=item symbol and dingbats as used by Tk on X11.
+
+(The reason Encode got started was to support Perl/Tk.)
+
+=back
+
+That set is rather ad hoc and has been driven by the needs of the
+tests rather than the needs of typical applications. It is likely
+to be rationalized.
+
+=cut
use base 'Encode::Encoding';
use vars qw($VERSION);
-$VERSION = do { my @r = (q$Revision: 0.92 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+$VERSION = do { my @r = (q$Revision: 0.94 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
my $canon = 'iso-2022-jp';
my $obj = bless {name => $canon}, __PACKAGE__;
$obj->Define($canon);
+sub name { return $_[0]->{name}; }
+
#
# decode is identical to 7bit-jis
#
use strict;
use vars qw($VERSION);
-$VERSION = do { my @r = (q$Revision: 0.92 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+$VERSION = do { my @r = (q$Revision: 0.94 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
# Just for the time being, we implement jis-7bit
# encoding via EUC
my $obj = bless {name => $canon}, __PACKAGE__;
$obj->Define($canon);
+sub name { return $_[0]->{name}; }
+
sub decode
{
my ($obj,$str,$chk) = @_;
}
}
use strict;
-our $VERSION = do { my @r = (q$Revision: 0.92 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+our $VERSION = do { my @r = (q$Revision: 0.94 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
use Encode qw(find_encoding);
use base 'Encode::Encoding';
L<Encode::Tcl::Escape>
-L<Encode::Tcl::Extended>
-
=cut
use strict;
-#use Test::More tests => 27;
+#use Test::More tests => 29;
use Test::More qw(no_plan);
use Encode::CN;
use Encode::JP;
Shift_JIS shiftjis
x-sjis shiftjis
jis 7bit-jis
+ big-5 big5
+ zh_TW.Big5 big5
+ big5-hk big5-hkscs
);
foreach my $a (keys %a2c){
my $e = Encode::find_encoding($a);
- my $n = $e->name || $e->{name};
- is($n, $a2c{$a});
+ is($e->name, $a2c{$a});
}
https://perl5.git.perl.org / perl5.git / commitdiff