+#
+# $Id: Encode.pm,v 2.9 2004/12/03 19:16:40 dankogai Exp $
+#
package Encode;
use strict;
-our $VERSION = '0.40';
+# our $VERSION = do { my @r = (q$Revision: 2.9 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+our $VERSION = '2.0902_01';
+sub DEBUG () { 0 }
+use XSLoader ();
+XSLoader::load(__PACKAGE__, $VERSION);
-require DynaLoader;
require Exporter;
-
-our @ISA = qw(Exporter DynaLoader);
+use base qw/Exporter/;
# Public, encouraged API is exported by default
-our @EXPORT = qw (
- encode
- decode
- encode_utf8
- decode_utf8
- find_encoding
- encodings
+
+our @EXPORT = qw(
+ decode decode_utf8 encode encode_utf8
+ encodings find_encoding clone_encoding
);
+our @FB_FLAGS = qw(DIE_ON_ERR WARN_ON_ERR RETURN_ON_ERR LEAVE_SRC
+ PERLQQ HTMLCREF XMLCREF);
+our @FB_CONSTS = qw(FB_DEFAULT FB_CROAK FB_QUIET FB_WARN
+ FB_PERLQQ FB_HTMLCREF FB_XMLCREF);
+
our @EXPORT_OK =
- qw(
- define_encoding
- define_alias
- from_to
- is_utf8
- is_8bit
- is_16bit
- utf8_upgrade
- utf8_downgrade
- _utf8_on
- _utf8_off
- );
-
-bootstrap Encode ();
+ (
+ qw(
+ _utf8_off _utf8_on define_encoding from_to is_16bit is_8bit
+ is_utf8 perlio_ok resolve_alias utf8_downgrade utf8_upgrade
+ ),
+ @FB_FLAGS, @FB_CONSTS,
+ );
+
+our %EXPORT_TAGS =
+ (
+ all => [ @EXPORT, @EXPORT_OK ],
+ fallbacks => [ @FB_CONSTS ],
+ fallback_all => [ @FB_CONSTS, @FB_FLAGS ],
+ );
# Documentation moved after __END__ for speed - NI-S
-use Carp;
-
-# Make a %encoding package variable to allow a certain amount of cheating
-our %encoding;
-my @alias; # ordered matching list
-my %alias; # cached known aliases
-
- # 0 1 2 3 4 5 6 7 8 9 10
-our @latin2iso_num = ( 0, 1, 2, 3, 4, 9, 10, 13, 14, 15, 16 );
-
-our %winlatin2cp = (
- 'Latin1' => 1252,
- 'Latin2' => 1250,
- 'Cyrillic' => 1251,
- 'Greek' => 1253,
- 'Turkish' => 1254,
- 'Hebrew' => 1255,
- 'Arabic' => 1256,
- 'Baltic' => 1257,
- 'Vietnamese' => 1258,
- );
-
-our %external_tables = (
- 'euc-cn' => 'Encode/CN.pm',
- gb2312 => 'Encode/CN.pm',
- gb12345 => 'Encode/CN.pm',
- gbk => 'Encode/CN.pm',
- cp936 => 'Encode/CN.pm',
- 'iso-ir-165' => 'Encode/CN.pm',
- 'euc-jp' => 'Encode/JP.pm',
- shiftjis => 'Encode/JP.pm',
- macjapan => 'Encode/JP.pm',
- cp932 => 'Encode/JP.pm',
- 'euc-kr' => 'Encode/KR.pm',
- ksc5601 => 'Encode/KR.pm',
- cp949 => 'Encode/KR.pm',
- big5 => 'Encode/TW.pm',
- 'big5-hkscs' => 'Encode/TW.pm',
- cp950 => 'Encode/TW.pm',
- gb18030 => 'Encode/CN.pm', # HanExtra
- big5plus => 'Encode/TW.pm', # HanExtra
- 'euc-tw', => 'Encode/TW.pm', # HanExtra
-);
+our $ON_EBCDIC = (ord("A") == 193);
-sub encodings
-{
- my ($class) = @_;
- return
- map { $_->[0] }
- sort { $a->[1] cmp $b->[1] }
- map { [$_, lc $_] }
- grep { $_ ne 'Internal' }
- keys %encoding;
-}
+use Encode::Alias;
+
+# Make a %Encoding package variable to allow a certain amount of cheating
+our %Encoding;
+our %ExtModule;
+require Encode::Config;
+eval { require Encode::ConfigLocal };
-sub findAlias
+sub encodings
{
my $class = shift;
- local $_ = shift;
- # print "# findAlias $_\n";
- unless (exists $alias{$_})
- {
- for (my $i=0; $i < @alias; $i += 2)
- {
- my $alias = $alias[$i];
- my $val = $alias[$i+1];
- my $new;
- if (ref($alias) eq 'Regexp' && $_ =~ $alias)
- {
- $new = eval $val;
- }
- elsif (ref($alias) eq 'CODE')
- {
- $new = &{$alias}($val)
- }
- elsif (lc($_) eq lc($alias))
- {
- $new = $val;
- }
- if (defined($new))
- {
- next if $new eq $_; # avoid (direct) recursion on bugs
- my $enc = (ref($new)) ? $new : find_encoding($new);
- if ($enc)
- {
- $alias{$_} = $enc;
- last;
- }
+ my %enc;
+ if (@_ and $_[0] eq ":all"){
+ %enc = ( %Encoding, %ExtModule );
+ }else{
+ %enc = %Encoding;
+ for my $mod (map {m/::/o ? $_ : "Encode::$_" } @_){
+ DEBUG and warn $mod;
+ for my $enc (keys %ExtModule){
+ $ExtModule{$enc} eq $mod and $enc{$enc} = $mod;
}
}
}
- return $alias{$_};
+ return
+ sort { lc $a cmp lc $b }
+ grep {!/^(?:Internal|Unicode|Guess)$/o} keys %enc;
}
-sub define_alias
-{
- while (@_)
- {
- my ($alias,$name) = splice(@_,0,2);
- push(@alias, $alias => $name);
- }
+sub perlio_ok{
+ my $obj = ref($_[0]) ? $_[0] : find_encoding($_[0]);
+ $obj->can("perlio_ok") and return $obj->perlio_ok();
+ return 0; # safety net
}
-# Allow variants of iso-8859-1 etc.
-define_alias( qr/^iso[-_]?(\d+)[-_](\d+)$/i => '"iso-$1-$2"' );
-
-# At least HP-UX has these.
-define_alias( qr/^iso8859(\d+)$/i => '"iso-8859-$1"' );
-
-# More HP stuff.
-define_alias( qr/^(?:hp-)?(arabic|greek|hebrew|kana|roman|thai|turkish)8$/i => '"${1}8"' );
-
-# The Official name of ASCII.
-define_alias( qr/^ANSI[-_]?X3\.4[-_]?1968$/i => '"ascii"' );
-
-# This is a font issue, not an encoding issue.
-# (The currency symbol of the Latin 1 upper half
-# has been redefined as the euro symbol.)
-define_alias( qr/^(.+)\@euro$/i => '"$1"' );
-
-# Allow latin-1 style names as well
-define_alias( qr/^(?:iso[-_]?)?latin[-_]?(\d+)$/i => '"iso-8859-$latin2iso_num[$1]"' );
-
-# Allow winlatin1 style names as well
-define_alias( qr/^win(latin[12]|cyrillic|baltic|greek|turkish|hebrew|arabic|baltic|vietnamese)$/i => '"cp$winlatin2cp{\u$1}"' );
-
-# Common names for non-latin prefered MIME names
-define_alias( 'ascii' => 'US-ascii',
- 'cyrillic' => 'iso-8859-5',
- 'arabic' => 'iso-8859-6',
- 'greek' => 'iso-8859-7',
- 'hebrew' => 'iso-8859-8',
- 'thai' => 'iso-8859-11',
- 'tis620' => 'iso-8859-11',
- );
-
-# At least AIX has IBM-NNN (surprisingly...) instead of cpNNN.
-# And Microsoft has their own naming (again, surprisingly).
-define_alias( qr/^(?:ibm|ms)[-_]?(\d\d\d\d?)$/i => '"cp$1"');
-
-# Sometimes seen with a leading zero.
-define_alias( qr/^cp037$/i => '"cp37"');
-
-# Ououououou.
-define_alias( qr/^macRomanian$/i => '"macRumanian"');
-
-# Standardize on the dashed versions.
-define_alias( qr/^utf8$/i => 'utf-8' );
-define_alias( qr/^koi8r$/i => 'koi8-r' );
-define_alias( qr/^koi8u$/i => 'koi8-u' );
-
-# Seen in some Linuxes.
-define_alias( qr/^ujis$/i => 'euc-jp' );
-
-# CP936 doesn't have vendor-addon for GBK, so they're identical.
-define_alias( qr/^gbk$/i => '"cp936"');
-
-# TODO: HP-UX '8' encodings arabic8 greek8 hebrew8 kana8 thai8 turkish8
-# TODO: HP-UX '15' encodings japanese15 korean15 roi15
-# TODO: Cyrillic encoding ISO-IR-111 (useful?)
-# TODO: Armenian encoding ARMSCII-8
-# TODO: Hebrew encoding ISO-8859-8-1
-# 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
-# Kannada Khmer Korean Laotian Malayalam Mongolian
-# Oriya Sinhalese Symbol Tamil Telugu Tibetan Vietnamese
-
-# Map white space and _ to '-'
-define_alias( qr/^(\S+)[\s_]+(.*)$/i => '"$1-$2"' );
-
sub define_encoding
{
my $obj = shift;
my $name = shift;
- $encoding{$name} = $obj;
+ $Encoding{$name} = $obj;
my $lc = lc($name);
define_alias($lc => $obj) unless $lc eq $name;
- while (@_)
- {
+ while (@_){
my $alias = shift;
- define_alias($alias,$obj);
+ define_alias($alias, $obj);
}
return $obj;
}
sub getEncoding
{
- my ($class,$name) = @_;
- my $enc;
- if (ref($name) && $name->can('new_sequence'))
- {
- return $name;
- }
+ my ($class, $name, $skip_external) = @_;
+
+ ref($name) && $name->can('renew') and return $name;
+ exists $Encoding{$name} and return $Encoding{$name};
my $lc = lc $name;
- if (exists $encoding{$name})
- {
- return $encoding{$name};
- }
- if (exists $encoding{$lc})
- {
- return $encoding{$lc};
- }
- if (exists $external_tables{$lc})
+ exists $Encoding{$lc} and return $Encoding{$lc};
+
+ my $oc = $class->find_alias($name);
+ defined($oc) and return $oc;
+ $lc ne $name and $oc = $class->find_alias($lc);
+ defined($oc) and return $oc;
+
+ unless ($skip_external)
{
- require $external_tables{$lc};
- return $encoding{$name} if exists $encoding{$name};
+ if (my $mod = $ExtModule{$name} || $ExtModule{$lc}){
+ $mod =~ s,::,/,g ; $mod .= '.pm';
+ eval{ require $mod; };
+ exists $Encoding{$name} and return $Encoding{$name};
+ }
}
+ return;
+}
- my $oc = $class->findAlias($name);
- return $oc if defined $oc;
- return $class->findAlias($lc) if $lc ne $name;
+sub find_encoding($;$)
+{
+ my ($name, $skip_external) = @_;
+ return __PACKAGE__->getEncoding($name,$skip_external);
+}
+sub resolve_alias($){
+ my $obj = find_encoding(shift);
+ defined $obj and return $obj->name;
return;
}
-sub find_encoding
-{
- my ($name) = @_;
- return __PACKAGE__->getEncoding($name);
+sub clone_encoding($){
+ my $obj = find_encoding(shift);
+ ref $obj or return;
+ eval { require Storable };
+ $@ and return;
+ return Storable::dclone($obj);
}
-sub encode
+sub encode($$;$)
{
- my ($name,$string,$check) = @_;
+ my ($name, $string, $check) = @_;
+ return undef unless defined $string;
+ $string .= '' if ref $string; # stringify;
+ $check ||=0;
my $enc = find_encoding($name);
- croak("Unknown encoding '$name'") unless defined $enc;
+ unless(defined $enc){
+ require Carp;
+ Carp::croak("Unknown encoding '$name'");
+ }
my $octets = $enc->encode($string,$check);
- return undef if ($check && length($string));
+ $_[1] = $string if $check and !($check & LEAVE_SRC());
return $octets;
}
-sub decode
+sub decode($$;$)
{
my ($name,$octets,$check) = @_;
+ return undef unless defined $octets;
+ $octets .= '' if ref $octets;
+ $check ||=0;
my $enc = find_encoding($name);
- croak("Unknown encoding '$name'") unless defined $enc;
+ unless(defined $enc){
+ require Carp;
+ Carp::croak("Unknown encoding '$name'");
+ }
my $string = $enc->decode($octets,$check);
- $_[1] = $octets if $check;
+ $_[1] = $octets if $check and !($check & LEAVE_SRC());
return $string;
}
-sub from_to
+sub from_to($$$;$)
{
my ($string,$from,$to,$check) = @_;
+ return undef unless defined $string;
+ $check ||=0;
my $f = find_encoding($from);
- croak("Unknown encoding '$from'") unless defined $f;
+ unless (defined $f){
+ require Carp;
+ Carp::croak("Unknown encoding '$from'");
+ }
my $t = find_encoding($to);
- croak("Unknown encoding '$to'") unless defined $t;
+ unless (defined $t){
+ require Carp;
+ Carp::croak("Unknown encoding '$to'");
+ }
my $uni = $f->decode($string,$check);
return undef if ($check && length($string));
- $string = $t->encode($uni,$check);
+ $string = $t->encode($uni,$check);
return undef if ($check && length($uni));
- return length($_[0] = $string);
+ return defined($_[0] = $string) ? length($string) : undef ;
}
-sub encode_utf8
+sub encode_utf8($)
{
my ($str) = @_;
- utf8::encode($str);
+ utf8::encode($str);
return $str;
}
-sub decode_utf8
+sub decode_utf8($;$)
{
- my ($str) = @_;
- return undef unless utf8::decode($str);
- return $str;
+ my ($str, $check) = @_;
+ if ($check){
+ return decode("utf8", $str, $check);
+ }else{
+ return undef unless utf8::decode($str);
+ return $str;
+ }
}
-require Encode::Encoding;
-require Encode::XS;
-require Encode::Internal;
-require Encode::Unicode;
-require Encode::utf8;
-require Encode::iso10646_1;
-require Encode::ucs2_le;
+predefine_encodings(1);
+
+#
+# This is to restore %Encoding if really needed;
+#
+
+sub predefine_encodings{
+ use Encode::Encoding;
+ no warnings 'redefine';
+ my $use_xs = shift;
+ if ($ON_EBCDIC) {
+ # was in Encode::UTF_EBCDIC
+ package Encode::UTF_EBCDIC;
+ push @Encode::UTF_EBCDIC::ISA, 'Encode::Encoding';
+ *decode = sub{
+ my ($obj,$str,$chk) = @_;
+ my $res = '';
+ for (my $i = 0; $i < length($str); $i++) {
+ $res .=
+ chr(utf8::unicode_to_native(ord(substr($str,$i,1))));
+ }
+ $_[1] = '' if $chk;
+ return $res;
+ };
+ *encode = sub{
+ my ($obj,$str,$chk) = @_;
+ my $res = '';
+ for (my $i = 0; $i < length($str); $i++) {
+ $res .=
+ chr(utf8::native_to_unicode(ord(substr($str,$i,1))));
+ }
+ $_[1] = '' if $chk;
+ return $res;
+ };
+ $Encode::Encoding{Unicode} =
+ bless {Name => "UTF_EBCDIC"} => "Encode::UTF_EBCDIC";
+ } else {
+ package Encode::Internal;
+ push @Encode::Internal::ISA, 'Encode::Encoding';
+ *decode = sub{
+ my ($obj,$str,$chk) = @_;
+ utf8::upgrade($str);
+ $_[1] = '' if $chk;
+ return $str;
+ };
+ *encode = \&decode;
+ $Encode::Encoding{Unicode} =
+ bless {Name => "Internal"} => "Encode::Internal";
+ }
+
+ {
+ # was in Encode::utf8
+ package Encode::utf8;
+ push @Encode::utf8::ISA, 'Encode::Encoding';
+ #
+ if ($use_xs){
+ Encode::DEBUG and warn __PACKAGE__, " XS on";
+ *decode = \&decode_xs;
+ *encode = \&encode_xs;
+ }else{
+ Encode::DEBUG and warn __PACKAGE__, " XS off";
+ *decode = sub{
+ my ($obj,$octets,$chk) = @_;
+ my $str = Encode::decode_utf8($octets);
+ if (defined $str) {
+ $_[1] = '' if $chk;
+ return $str;
+ }
+ return undef;
+ };
+ *encode = sub {
+ my ($obj,$string,$chk) = @_;
+ my $octets = Encode::encode_utf8($string);
+ $_[1] = '' if $chk;
+ return $octets;
+ };
+ }
+ *cat_decode = sub{ # ($obj, $dst, $src, $pos, $trm, $chk)
+ my ($obj, undef, undef, $pos, $trm) = @_; # currently ignores $chk
+ my ($rdst, $rsrc, $rpos) = \@_[1,2,3];
+ use bytes;
+ if ((my $npos = index($$rsrc, $trm, $pos)) >= 0) {
+ $$rdst .= substr($$rsrc, $pos, $npos - $pos + length($trm));
+ $$rpos = $npos + length($trm);
+ return 1;
+ }
+ $$rdst .= substr($$rsrc, $pos);
+ $$rpos = length($$rsrc);
+ return '';
+ };
+ $Encode::Encoding{utf8} =
+ bless {Name => "utf8"} => "Encode::utf8";
+ $Encode::Encoding{"utf-8-strict"} =
+ bless {Name => "utf-8-strict", strict_utf8 => 1 } => "Encode::utf8";
+ }
+}
1;
use Encode;
+=head2 Table of Contents
+
+Encode consists of a collection of modules whose details are too big
+to fit in one document. This POD itself explains the top-level APIs
+and general topics at a glance. For other topics and more details,
+see the PODs below:
+
+ Name Description
+ --------------------------------------------------------
+ Encode::Alias Alias definitions to encodings
+ Encode::Encoding Encode Implementation Base Class
+ Encode::Supported List of Supported Encodings
+ Encode::CN Simplified Chinese Encodings
+ Encode::JP Japanese Encodings
+ Encode::KR Korean Encodings
+ Encode::TW Traditional Chinese Encodings
+ --------------------------------------------------------
+
=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>.
+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
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
+Traditionally, 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>).
+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 machine's 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".
=head2 TERMINOLOGY
-=over 4
+=over 2
=item *
=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.)
+(Term for bytes passed to or from a non-Perl context, e.g. a 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
+=head1 PERL ENCODING API
-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.
+=over 2
-=head2 Types of Encodings
+=item $octets = encode(ENCODING, $string [, CHECK])
-Encodings can be divided into the following types:
+Encodes a string from Perl's internal form into I<ENCODING> and returns
+a sequence of octets. ENCODING can be either a canonical name or
+an alias. For encoding names and aliases, see L</"Defining Aliases">.
+For CHECK, see L</"Handling Malformed Data">.
-=over 4
+For example, to convert a string from Perl's internal format to
+iso-8859-1 (also known as Latin1),
-=item * Fixed length 8-bit (or less) encodings.
+ $octets = encode("iso-8859-1", $string);
-Each character is a single octet so may have a repertoire of up to
-256 characters. ASCII and iso-8859-* are typical examples.
+B<CAVEAT>: When you run C<$octets = encode("utf8", $string)>, then $octets
+B<may not be equal to> $string. Though they both contain the same data, the utf8 flag
+for $octets is B<always> off. When you encode anything, utf8 flag of
+the result is always off, even when it contains completely valid utf8
+string. See L</"The UTF-8 flag"> below.
-=item * Fixed length 16-bit encodings
+If the $string is C<undef> then C<undef> is returned.
-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 $string = decode(ENCODING, $octets [, CHECK])
-=item * Fixed length 32-bit encodings.
+Decodes a sequence of octets assumed to be in I<ENCODING> into Perl's
+internal form and returns the resulting string. As in encode(),
+ENCODING can be either a canonical name or an alias. For encoding names
+and aliases, see L</"Defining Aliases">. For CHECK, see
+L</"Handling Malformed Data">.
-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.
+For example, to convert ISO-8859-1 data to a string in Perl's internal format:
-=item * Multi-byte encodings
+ $string = decode("iso-8859-1", $octets);
-The number of octets needed to represent a character varies.
-UTF-8 is a particularly complex but regular case of a multi-byte
-encoding. Several East Asian countries use a multi-byte encoding
-where 1-octet is used to cover western roman characters and Asian
-characters get 2-octets.
-(UTF-16 is strictly a multi-byte encoding taking either 2 or 4 octets
-to represent a Unicode code point.)
+B<CAVEAT>: When you run C<$string = decode("utf8", $octets)>, then $string
+B<may not be equal to> $octets. Though they both contain the same data,
+the utf8 flag for $string is on unless $octets entirely consists of
+ASCII data (or EBCDIC on EBCDIC machines). See L</"The UTF-8 flag">
+below.
-=item * "Escape" encodings.
+If the $string is C<undef> then C<undef> is returned.
-These encodings embed "escape sequences" into the octet sequence
-which describe how the following octets are to be interpreted.
-The iso-2022-* family is typical. Following the escape sequence
-octets are encoded by an "embedded" encoding (which will be one
-of the above types) until another escape sequence switches to
-a different "embedded" encoding.
+=item [$length =] from_to($octets, FROM_ENC, TO_ENC [, CHECK])
-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.
+Converts B<in-place> data between two encodings. The data in $octets
+must be encoded as octets and not as characters in Perl's internal
+format. For example, to convert ISO-8859-1 data to Microsoft's CP1250
+encoding:
-=back
+ from_to($octets, "iso-8859-1", "cp1250");
-=head2 Specifying Encodings
+and to convert it back:
-Encodings can be specified to the API described below in two ways:
+ from_to($octets, "cp1250", "iso-8859-1");
-=over 4
+Note that because the conversion happens in place, the data to be
+converted cannot be a string constant; it must be a scalar variable.
-=item 1. By name
+from_to() returns the length of the converted string in octets on
+success, I<undef> on error.
-Encoding names are strings with characters taken from a restricted
-repertoire. See L</"Encoding Names">.
+B<CAVEAT>: The following operations look the same but are not quite so;
-=item 2. As an object
+ from_to($data, "iso-8859-1", "utf8"); #1
+ $data = decode("iso-8859-1", $data); #2
-Encoding objects are returned by C<find_encoding($name)>.
+Both #1 and #2 make $data consist of a completely valid UTF-8 string
+but only #2 turns utf8 flag on. #1 is equivalent to
-=back
+ $data = encode("utf8", decode("iso-8859-1", $data));
-=head2 Encoding Names
+See L</"The UTF-8 flag"> below.
-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:
+=item $octets = encode_utf8($string);
-=over 4
+Equivalent to C<$octets = encode("utf8", $string);> The characters
+that comprise $string are encoded in Perl's internal format and the
+result is returned as a sequence of octets. All possible
+characters have a UTF-8 representation so this function cannot fail.
-=item * The MIME name as defined in IETF RFCs.
-=item * The name in the IANA registry.
+=item $string = decode_utf8($octets [, CHECK]);
-=item * The name used by the organization that defined it.
+equivalent to C<$string = decode("utf8", $octets [, CHECK])>.
+The sequence of octets represented by
+$octets 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
-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
+=head2 Listing available encodings
-(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>.)
+ use Encode;
+ @list = Encode->encodings();
-The PC codepages:
+Returns a list of the canonical names of the available encodings that
+are loaded. To get a list of all available encodings including the
+ones that are not loaded yet, say
- 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
+ @all_encodings = Encode->encodings(":all");
- WinLatin1 => CP1252
- WinLatin2 => CP1250
- WinCyrillic => CP1251
- WinGreek => CP1253
- WinTurkiskh => CP1254
- WinHebrew => CP1255
- WinArabic => CP1256
- WinBaltic => CP1257
- WinVietnamese => CP1258
+Or you can give the name of a specific module.
-(All the CPI<NNN...> are available also as IBMI<NNN...>.)
+ @with_jp = Encode->encodings("Encode::JP");
-The Mac codepages:
+When "::" is not in the name, "Encode::" is assumed.
- MacCentralEuropean MacJapanese
- MacCroatian MacRoman
- MacCyrillic MacRomanian
- MacDingbats MacSami
- MacGreek MacThai
- MacIcelandic MacTurkish
- MacUkraine
+ @ebcdic = Encode->encodings("EBCDIC");
-Miscellaneous:
+To find out in detail which encodings are supported by this package,
+see L<Encode::Supported>.
- 7bit-greek IR-197
- 7bit-kana NeXTstep
- 7bit-latin1 POSIX-BC
- DingBats Roman8
- GSM 0338 Symbol
+=head2 Defining Aliases
-=head1 PERL ENCODING API
+To add a new alias to a given encoding, use:
-=head2 Generic Encoding Interface
+ use Encode;
+ use Encode::Alias;
+ define_alias(newName => ENCODING);
-=over 4
+After that, newName can be used as an alias for ENCODING.
+ENCODING may be either the name of an encoding or an
+I<encoding object>
-=item *
+But before you do so, make sure the alias is nonexistent with
+C<resolve_alias()>, which returns the canonical name thereof.
+i.e.
- $bytes = encode(ENCODING, $string[, CHECK])
+ Encode::resolve_alias("latin1") eq "iso-8859-1" # true
+ Encode::resolve_alias("iso-8859-12") # false; nonexistent
+ Encode::resolve_alias($name) eq $name # true if $name is canonical
-Encodes string from Perl's internal form into I<ENCODING> and returns
-a sequence of octets. For CHECK see L</"Handling Malformed Data">.
+resolve_alias() does not need C<use Encode::Alias>; it can be
+exported via C<use Encode qw(resolve_alias)>.
-For example to convert (internally UTF-8 encoded) Unicode data
-to octets:
+See L<Encode::Alias> for details.
- $octets = encode("utf8", $unicode);
+=head1 Encoding via PerlIO
-=item *
+If your perl supports I<PerlIO> (which is the default), you can use a PerlIO layer to decode
+and encode directly via a filehandle. The following two examples
+are totally identical in their functionality.
- $string = decode(ENCODING, $bytes[, CHECK])
+ # via PerlIO
+ open my $in, "<:encoding(shiftjis)", $infile or die;
+ open my $out, ">:encoding(euc-jp)", $outfile or die;
+ while(<$in>){ print $out $_; }
-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">.
+ # via from_to
+ open my $in, "<", $infile or die;
+ open my $out, ">", $outfile or die;
+ while(<$in>){
+ from_to($_, "shiftjis", "euc-jp", 1);
+ print $out $_;
+ }
-For example to convert ISO 8859-1 data to UTF-8:
+Unfortunately, it may be that encodings are PerlIO-savvy. You can check
+if your encoding is supported by PerlIO by calling the C<perlio_ok>
+method.
- $utf8 = decode("latin1", $latin1);
+ Encode::perlio_ok("hz"); # False
+ find_encoding("euc-cn")->perlio_ok; # True where PerlIO is available
-=item *
+ use Encode qw(perlio_ok); # exported upon request
+ perlio_ok("euc-jp")
- from_to($string, FROM_ENCODING, TO_ENCODING[, CHECK])
+Fortunately, all encodings that come with Encode core are PerlIO-savvy
+except for hz and ISO-2022-kr. For gory details, see
+L<Encode::Encoding> and L<Encode::PerlIO>.
-Convert B<in-place> the data between two encodings. How did the data
-in $string originally get to be in FROM_ENCODING? Either using
-encode() or through PerlIO: See L</"Encoding and IO">. For CHECK
-see L</"Handling Malformed Data">.
+=head1 Handling Malformed Data
-For example to convert ISO 8859-1 data to UTF-8:
+The optional I<CHECK> argument is used as follows. When you omit it,
+Encode::FB_DEFAULT ( == 0 ) is assumed.
- from_to($data, "iso-8859-1", "utf-8");
+=over 2
-and to convert it back:
+=item B<NOTE:> Not all encoding suppport this feature
- 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.
+Some encodings ignore I<CHECK> argument. For example,
+L<Encode::Unicode> ignores I<CHECK> and it always croaks on error.
=back
-=head2 Handling Malformed Data
+Now here is the list of I<CHECK> values available
-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.
+=over 2
-It would desirable to have a way to indicate that transform should use
-the encodings "replacement character" - no such mechanism is defined yet.
+=item I<CHECK> = Encode::FB_DEFAULT ( == 0)
-It is also planned to allow I<CHECK> to be a code reference.
+If I<CHECK> is 0, (en|de)code will put a I<substitution character> in
+place of a malformed character. When you encode, E<lt>subcharE<gt>
+will be used. When you decode the code point C<0xFFFD> is used. If
+the data is supposed to be UTF-8, an optional lexical warning
+(category utf8) is given.
-This is not yet implemented as there are design issues with what its
-arguments should be and how it returns its results.
+=item I<CHECK> = Encode::FB_CROAK ( == 1)
-=over 4
+If I<CHECK> is 1, methods will die on error immediately with an error
+message. Therefore, when I<CHECK> is set to 1, you should trap the
+error with eval{} unless you really want to let it die.
-=item Scheme 1
+=item I<CHECK> = Encode::FB_QUIET
-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.
+If I<CHECK> is set to Encode::FB_QUIET, (en|de)code will immediately
+return the portion of the data that has been processed so far when an
+error occurs. The data argument will be overwritten with everything
+after that point (that is, the unprocessed part of data). This is
+handy when you have to call decode repeatedly in the case where your
+source data may contain partial multi-byte character sequences,
+(i.e. you are reading with a fixed-width buffer). Here is a sample
+code that does exactly this:
- sub fixup {
- my $ch = substr($_[0],0,1,'');
- return sprintf("\x{%02X}",ord($ch);
- }
+ my $buffer = ''; my $string = '';
+ while(read $fh, $buffer, 256, length($buffer)){
+ $string .= decode($encoding, $buffer, Encode::FB_QUIET);
+ # $buffer now contains the unprocessed partial character
+ }
-This scheme is close to how underlying C code for Encode works, but gives
-the fixup routine very little context.
+=item I<CHECK> = Encode::FB_WARN
-=item Scheme 2
+This is the same as above, except that it warns on error. Handy when
+you are debugging the mode above.
-Passed original string, and an index into it of the problem area, and
-output string so far. Appends what it will to output string and
-returns new index into original string. For example:
+=item perlqq mode (I<CHECK> = Encode::FB_PERLQQ)
- sub fixup {
- # my ($s,$i,$d) = @_;
- my $ch = substr($_[0],$_[1],1);
- $_[2] .= sprintf("\x{%02X}",ord($ch);
- return $_[1]+1;
- }
+=item HTML charref mode (I<CHECK> = Encode::FB_HTMLCREF)
-This scheme gives maximal control to the fixup routine but is more
-complicated to code, and may need internals of Encode to be tweaked to
-keep original string intact.
+=item XML charref mode (I<CHECK> = Encode::FB_XMLCREF)
-=item Other Schemes
+For encodings that are implemented by Encode::XS, CHECK ==
+Encode::FB_PERLQQ turns (en|de)code into C<perlqq> fallback mode.
-Hybrids of above.
+When you decode, C<\xI<HH>> will be inserted for a malformed character,
+where I<HH> is the hex representation of the octet that could not be
+decoded to utf8. And when you encode, C<\x{I<HHHH>}> will be inserted,
+where I<HHHH> is the Unicode ID of the character that cannot be found
+in the character repertoire of the encoding.
-Multiple return values rather than in-place modifications.
+HTML/XML character reference modes are about the same, in place of
+C<\x{I<HHHH>}>, HTML uses C<&#I<NNN>;> where I<NNN> is a decimal number and
+XML uses C<&#xI<HHHH>;> where I<HHHH> is the hexadecimal number.
-Index into the string could be pos($str) allowing s/\G...//.
+In Encode 2.10 or later, C<LEAVE_SRC> is also implied.
-=back
+=item The bitmask
-=head2 UTF-8 / utf8
+These modes are actually set via a bitmask. Here is how the FB_XX
+constants are laid out. You can import the FB_XX constants via
+C<use Encode qw(:fallbacks)>; you can import the generic bitmask
+constants via C<use Encode qw(:fallback_all)>.
-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">.
+ FB_DEFAULT FB_CROAK FB_QUIET FB_WARN FB_PERLQQ
+ DIE_ON_ERR 0x0001 X
+ WARN_ON_ERR 0x0002 X
+ RETURN_ON_ERR 0x0004 X X
+ LEAVE_SRC 0x0008 X
+ PERLQQ 0x0100 X
+ HTMLCREF 0x0200
+ XMLCREF 0x0400
=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.
+=head2 Unimplemented fallback schemes
-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
+In the future, you will be able to use a code reference to a callback
+function for the value of I<CHECK> but its API is still undecided.
- $hi = ($uni - 0x10000) / 0x400 + 0xD800;
- $lo = ($uni - 0x10000) % 0x400 + 0xDC00;
+The fallback scheme does not work on EBCDIC platforms.
-and the decoding is
+=head1 Defining Encodings
- $uni = 0x10000 + ($hi - 0xD8000) * 0x400 + ($lo - 0xDC00);
+To define a new encoding, use:
-Encode implements big-endian UCS-2 aliased to "iso-10646-1" as that
-happens to be the name used by that representation when used with X11
-fonts.
+ use Encode qw(define_encoding);
+ define_encoding($object, 'canonicalName' [, alias...]);
-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
+I<canonicalName> will be associated with I<$object>. The object
+should provide the interface described in L<Encode::Encoding>.
+If more than two arguments are provided then additional
+arguments are taken as aliases for I<$object>.
- pack('L*', unpack('U*', $string)); # native
- or
- pack('V*', unpack('U*', $string)); # little-endian
- or
- pack('N*', unpack('U*', $string)); # big-endian
+See L<Encode::Encoding> for more details.
-depending on the endianness required.
+=head1 The UTF-8 flag
-No UTF-32 encodings are implemented yet.
+Before the introduction of utf8 support in perl, The C<eq> operator
+just compared the strings represented by two scalars. Beginning with
+perl 5.8, C<eq> compares two strings with simultaneous consideration
+of I<the utf8 flag>. To explain why we made it so, I will quote page
+402 of C<Programming Perl, 3rd ed.>
-Both UCS-2 and UCS-4 style encodings can have "byte order marks" by
-representing the code point 0xFFFE as the very first thing in a file.
+=over 2
-=head2 Listing available encodings
-
- use Encode qw(encodings);
- @list = encodings();
-
-Returns a list of the canonical names of the available encodings.
-
-=head2 Defining Aliases
-
- use Encode qw(define_alias);
- define_alias( newName => ENCODING);
+=item Goal #1:
-Allows newName to be used as am alias for ENCODING. ENCODING may be
-either the name of an encoding or and encoding object (as above).
+Old byte-oriented programs should not spontaneously break on the old
+byte-oriented data they used to work on.
-Currently I<newName> can be specified in the following ways:
+=item Goal #2:
-=over 4
+Old byte-oriented programs should magically start working on the new
+character-oriented data when appropriate.
-=item As a simple string.
+=item Goal #3:
-=item As a qr// compiled regular expression, e.g.:
+Programs should run just as fast in the new character-oriented mode
+as in the old byte-oriented mode.
- define_alias( qr/^iso8859-(\d+)$/i => '"iso-8859-$1"' );
+=item Goal #4:
-In this case if I<ENCODING> is not a reference it is C<eval>-ed to
-allow C<$1> etc. to be subsituted. The example is one way to names as
-used in X11 font names to alias the MIME names for the iso-8859-*
-family.
-
-=item As a code reference, e.g.:
-
- define_alias( sub { return /^iso8859-(\d+)$/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.
+Perl should remain one language, rather than forking into a
+byte-oriented Perl and a character-oriented Perl.
=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>.
+Back when C<Programming Perl, 3rd ed.> was written, not even Perl 5.6.0
+was born and many features documented in the book remained
+unimplemented for a long time. Perl 5.8 corrected this and the introduction
+of the UTF-8 flag is one of them. You can think of this perl notion as of a
+byte-oriented mode (utf8 flag off) and a character-oriented mode (utf8
+flag on).
-=head1 Encoding and IO
+Here is how Encode takes care of the utf8 flag.
-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.
+=over 2
-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 $h, ">:encoding(latin9)") # iso-8859-15
-
-See L<PerlIO> for more information.
-
-See also L<encoding> for how to change the default encoding of the
-data in your script.
+=item *
-=head1 Encoding How to ...
+When you encode, the resulting utf8 flag is always off.
-To do:
+=item *
-=over 4
+When you decode, the resulting utf8 flag is on unless you can
+unambiguously represent data. Here is the definition of
+dis-ambiguity.
-=item * IO with mixed content (faking iso-2020-*)
+After C<$utf8 = decode('foo', $octet);>,
-=item * MIME's Content-Length:
+ When $octet is... The utf8 flag in $utf8 is
+ ---------------------------------------------
+ In ASCII only (or EBCDIC only) OFF
+ In ISO-8859-1 ON
+ In any other Encoding ON
+ ---------------------------------------------
-=item * UTF-8 strings in binary data.
+As you see, there is one exception, In ASCII. That way you can assue
+Goal #1. And with Encode Goal #2 is assumed but you still have to be
+careful in such cases mentioned in B<CAVEAT> paragraphs.
-=item * Perl/Encode wrappers on non-Unicode XS modules.
+This utf8 flag is not visible in perl scripts, exactly for the same
+reason you cannot (or you I<don't have to>) see if a scalar contains a
+string, integer, or floating point number. But you can still peek
+and poke these if you will. See the section below.
=back
-=head1 Messing with Perl's Internals
+=head2 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.
+implementation. As such, they are efficient but may change.
-=over 4
+=over 2
-=item * is_utf8(STRING [, CHECK])
+=item is_utf8(STRING [, CHECK])
-[INTERNAL] Test whether the UTF-8 flag is turned on in the STRING.
+[INTERNAL] Tests 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 * valid_utf8(STRING)
+As of perl 5.8.1, L<utf8> also has utf8::is_utf8().
-[INTERNAL] Test whether STRING is in a consistent state. Will return
-true if string is held as bytes, or is well-formed UTF-8 and has the
-UTF-8 flag on. Main reason for this routine is to allow Perl's
-testsuite to check that operations have left strings in a consistent
-state.
+=item _utf8_on(STRING)
-=item *
-
- _utf8_on(STRING)
-
-[INTERNAL] Turn on the UTF-8 flag in STRING. The data in STRING is
+[INTERNAL] Turns 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 *
+state of the UTF-8 flag (so please don't treat the return value as
+indicating success or failure), or C<undef> if STRING is not a string.
- _utf8_off(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
+[INTERNAL] Turns off the UTF-8 flag in STRING. Do not use frivolously.
+Returns the previous state of the UTF-8 flag (so please don't treat the
+return value as indicating success or failure), or C<undef> if STRING is
not a string.
=back
-=head1 IMPLEMENTATION CLASSES
+=head1 UTF-8 vs. utf8
-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.
+ ....We now view strings not as sequences of bytes, but as sequences
+ of numbers in the range 0 .. 2**32-1 (or in the case of 64-bit
+ computers, 0 .. 2**64-1) -- Programming Perl, 3rd ed.
-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.
+That has been the perl's notion of UTF-8 but official UTF-8 is more
+strict; Its ranges is much narrower (0 .. 10FFFF), some sequences are
+not allowed (i.e. Those used in the surrogate pair, 0xFFFE, et al).
-Once an encoding is loaded then value of the hash is object which
-implements the encoding. The object should provide the following
-interface:
+Now that is overruled by Larry Wall himself.
-=over 4
+ From: Larry Wall <larry@wall.org>
+ Date: December 04, 2004 11:51:58 JST
+ To: perl-unicode@perl.org
+ Subject: Re: Make Encode.pm support the real UTF-8
+ Message-Id: <20041204025158.GA28754@wall.org>
+
+ On Fri, Dec 03, 2004 at 10:12:12PM +0000, Tim Bunce wrote:
+ : I've no problem with 'utf8' being perl's unrestricted uft8 encoding,
+ : but "UTF-8" is the name of the standard and should give the
+ : corresponding behaviour.
+
+ For what it's worth, that's how I've always kept them straight in my
+ head.
-=item -E<gt>name
+ Also for what it's worth, Perl 6 will mostly default to strict but
+ make it easy to switch back to lax.
+
+ Larry
-Should return the string representing the canonical name of the encoding.
+Do you copy? As of Perl 5.8.7, B<UTF-8> means strict, official UTF-8
+while B<utf8> means liberal, lax, version thereof. And Encode version
+2.10 or later thus groks the difference between C<UTF-8> and C"utf8".
-=item -E<gt>new_sequence
+ encode("utf8", "\x{FFFF_FFFF}", 1); # okay
+ encode("UTF-8", "\x{FFFF_FFFF}", 1); # croaks
-This is a placeholder for encodings with state. It should return an
-object which implements this interface, all current implementations
-return the original object.
+C<UTF-8> in Encode is actually a canonical name for C<utf-8-strict>.
+Yes, the hyphen between "UTF" and "8" is important. Without it Encode
+goes "liberal"
-=item -E<gt>encode($string,$check)
+ find_encoding("UTF-8")->name # is 'utf-8-strict'
+ find_encoding("utf-8")->name # ditto. names are case insensitive
+ find_encoding("utf8")->name # ditto. "_" are treated as "-"
+ find_encoding("UTF8")->name # is 'utf8'.
-Should return the octet sequence representing I<$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.)
+=head1 SEE ALSO
-=back
+L<Encode::Encoding>,
+L<Encode::Supported>,
+L<Encode::PerlIO>,
+L<encoding>,
+L<perlebcdic>,
+L<perlfunc/open>,
+L<perlunicode>,
+L<utf8>,
+the Perl Unicode Mailing List E<lt>perl-unicode@perl.orgE<gt>
-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 MAINTAINER
-=head1 SEE ALSO
-
-L<perlunicode>, L<perlebcdic>, L<perlfunc/open>, L<PerlIO>, L<encoding>
+This project was originated by Nick Ing-Simmons and later maintained
+by Dan Kogai E<lt>dankogai@dan.co.jpE<gt>. See AUTHORS for a full
+list of people involved. For any questions, use
+E<lt>perl-unicode@perl.orgE<gt> so we can all share.
=cut
-
https://perl5.git.perl.org / perl5.git / blobdiff