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diff --git a/Master/tlpkg/tlperl/lib/Encode.pm b/Master/tlpkg/tlperl/lib/Encode.pm new file mode 100644 index 00000000000..f1dff7820c2 --- /dev/null +++ b/Master/tlpkg/tlperl/lib/Encode.pm @@ -0,0 +1,963 @@ +# +# $Id: Encode.pm,v 2.39 2009/11/26 09:23:48 dankogai Exp $ +# +package Encode; +use strict; +use warnings; +our $VERSION = sprintf "%d.%02d", q$Revision: 2.39 $ =~ /(\d+)/g; +sub DEBUG () { 0 } +use XSLoader (); +XSLoader::load( __PACKAGE__, $VERSION ); + +require Exporter; +use base qw/Exporter/; + +# Public, encouraged API is exported by default + +our @EXPORT = qw( + decode decode_utf8 encode encode_utf8 str2bytes bytes2str + encodings find_encoding clone_encoding +); +our @FB_FLAGS = qw( + DIE_ON_ERR WARN_ON_ERR RETURN_ON_ERR LEAVE_SRC + PERLQQ HTMLCREF XMLCREF STOP_AT_PARTIAL +); +our @FB_CONSTS = qw( + FB_DEFAULT FB_CROAK FB_QUIET FB_WARN + FB_PERLQQ FB_HTMLCREF FB_XMLCREF +); +our @EXPORT_OK = ( + 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 ], + default => [ @EXPORT ], + fallbacks => [ @FB_CONSTS ], + fallback_all => [ @FB_CONSTS, @FB_FLAGS ], +); + +# Documentation moved after __END__ for speed - NI-S + +our $ON_EBCDIC = ( ord("A") == 193 ); + +use Encode::Alias; + +# Make a %Encoding package variable to allow a certain amount of cheating +our %Encoding; +our %ExtModule; +require Encode::Config; +# See +# https://bugzilla.redhat.com/show_bug.cgi?id=435505#c2 +# to find why sig handers inside eval{} are disabled. +eval { + local $SIG{__DIE__}; + local $SIG{__WARN__}; + require Encode::ConfigLocal; +}; + +sub encodings { + my $class = shift; + 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 sort { lc $a cmp lc $b } + grep { !/^(?:Internal|Unicode|Guess)$/o } keys %enc; +} + +sub perlio_ok { + my $obj = ref( $_[0] ) ? $_[0] : find_encoding( $_[0] ); + $obj->can("perlio_ok") and return $obj->perlio_ok(); + return 0; # safety net +} + +sub define_encoding { + my $obj = shift; + my $name = shift; + $Encoding{$name} = $obj; + my $lc = lc($name); + define_alias( $lc => $obj ) unless $lc eq $name; + while (@_) { + my $alias = shift; + define_alias( $alias, $obj ); + } + return $obj; +} + +sub getEncoding { + my ( $class, $name, $skip_external ) = @_; + + ref($name) && $name->can('renew') and return $name; + exists $Encoding{$name} and return $Encoding{$name}; + my $lc = lc $name; + 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) { + if ( my $mod = $ExtModule{$name} || $ExtModule{$lc} ) { + $mod =~ s,::,/,g; + $mod .= '.pm'; + eval { require $mod; }; + exists $Encoding{$name} and return $Encoding{$name}; + } + } + return; +} + +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 $obj->name; + return; +} + +sub clone_encoding($) { + my $obj = find_encoding(shift); + ref $obj or return; + eval { require Storable }; + $@ and return; + return Storable::dclone($obj); +} + +sub encode($$;$) { + my ( $name, $string, $check ) = @_; + return undef unless defined $string; + $string .= '' if ref $string; # stringify; + $check ||= 0; + unless ( defined $name ) { + require Carp; + Carp::croak("Encoding name should not be undef"); + } + my $enc = find_encoding($name); + unless ( defined $enc ) { + require Carp; + Carp::croak("Unknown encoding '$name'"); + } + my $octets = $enc->encode( $string, $check ); + $_[1] = $string if $check and !ref $check and !( $check & LEAVE_SRC() ); + return $octets; +} +*str2bytes = \&encode; + +sub decode($$;$) { + my ( $name, $octets, $check ) = @_; + return undef unless defined $octets; + $octets .= '' if ref $octets; + $check ||= 0; + my $enc = find_encoding($name); + unless ( defined $enc ) { + require Carp; + Carp::croak("Unknown encoding '$name'"); + } + my $string = $enc->decode( $octets, $check ); + $_[1] = $octets if $check and !ref $check and !( $check & LEAVE_SRC() ); + return $string; +} +*bytes2str = \&decode; + +sub from_to($$$;$) { + my ( $string, $from, $to, $check ) = @_; + return undef unless defined $string; + $check ||= 0; + my $f = find_encoding($from); + unless ( defined $f ) { + require Carp; + Carp::croak("Unknown encoding '$from'"); + } + my $t = find_encoding($to); + unless ( defined $t ) { + require Carp; + Carp::croak("Unknown encoding '$to'"); + } + my $uni = $f->decode($string); + $_[0] = $string = $t->encode( $uni, $check ); + return undef if ( $check && length($uni) ); + return defined( $_[0] ) ? length($string) : undef; +} + +sub encode_utf8($) { + my ($str) = @_; + utf8::encode($str); + return $str; +} + +sub decode_utf8($;$) { + my ( $str, $check ) = @_; + return $str if is_utf8($str); + if ($check) { + return decode( "utf8", $str, $check ); + } + else { + return decode( "utf8", $str ); + return $str; + } +} + +predefine_encodings(1); + +# +# This is to restore %Encoding if really needed; +# + +sub predefine_encodings { + require 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) + # currently ignores $chk + my ( $obj, undef, undef, $pos, $trm ) = @_; + 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; + +__END__ + +=head1 NAME + +Encode - character encodings + +=head1 SYNOPSIS + + 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>. + +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>). + +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 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 2 + +=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. a disk file.) + +=back + +=head1 PERL ENCODING API + +=over 2 + +=item $octets = encode(ENCODING, $string [, CHECK]) + +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">. + +For example, to convert a string from Perl's internal format to +iso-8859-1 (also known as Latin1), + + $octets = encode("iso-8859-1", $string); + +B<CAVEAT>: When you run C<$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 UTF8 flag"> below. + +If the $string is C<undef> then C<undef> is returned. + +=item $string = decode(ENCODING, $octets [, CHECK]) + +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">. + +For example, to convert ISO-8859-1 data to a string in Perl's internal format: + + $string = decode("iso-8859-1", $octets); + +B<CAVEAT>: When you run C<$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 UTF8 flag"> +below. + +If the $string is C<undef> then C<undef> is returned. + +=item [$obj =] find_encoding(ENCODING) + +Returns the I<encoding object> corresponding to ENCODING. Returns +undef if no matching ENCODING is find. + +This object is what actually does the actual (en|de)coding. + + $utf8 = decode($name, $bytes); + +is in fact + + $utf8 = do{ + $obj = find_encoding($name); + croak qq(encoding "$name" not found) unless ref $obj; + $obj->decode($bytes) + }; + +with more error checking. + +Therefore you can save time by reusing this object as follows; + + my $enc = find_encoding("iso-8859-1"); + while(<>){ + my $utf8 = $enc->decode($_); + # and do someting with $utf8; + } + +Besides C<< ->decode >> and C<< ->encode >>, other methods are +available as well. For instance, C<< -> name >> returns the canonical +name of the encoding object. + + find_encoding("latin1")->name; # iso-8859-1 + +See L<Encode::Encoding> for details. + +=item [$length =] from_to($octets, FROM_ENC, TO_ENC [, CHECK]) + +Converts B<in-place> data between two encodings. The data in $octets +must be encoded as octets and not as characters in Perl's internal +format. For example, to convert ISO-8859-1 data to Microsoft's CP1250 +encoding: + + from_to($octets, "iso-8859-1", "cp1250"); + +and to convert it back: + + from_to($octets, "cp1250", "iso-8859-1"); + +Note that because the conversion happens in place, the data to be +converted cannot be a string constant; it must be a scalar variable. + +from_to() returns the length of the converted string in octets on +success, I<undef> on error. + +B<CAVEAT>: The following operations look the same but are not quite so; + + from_to($data, "iso-8859-1", "utf8"); #1 + $data = decode("iso-8859-1", $data); #2 + +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 + + $data = encode("utf8", decode("iso-8859-1", $data)); + +See L</"The UTF8 flag"> below. + +Also note that + + from_to($octets, $from, $to, $check); + +is equivalent to + + $octets = encode($to, decode($from, $octets), $check); + +Yes, it does not respect the $check during decoding. It is +deliberately done that way. If you need minute control, C<decode> +then C<encode> as follows; + + $octets = encode($to, decode($from, $octets, $check_from), $check_to); + +=item $octets = encode_utf8($string); + +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 $string = decode_utf8($octets [, CHECK]); + +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 + +=head2 Listing available encodings + + use Encode; + @list = Encode->encodings(); + +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 + + @all_encodings = Encode->encodings(":all"); + +Or you can give the name of a specific module. + + @with_jp = Encode->encodings("Encode::JP"); + +When "::" is not in the name, "Encode::" is assumed. + + @ebcdic = Encode->encodings("EBCDIC"); + +To find out in detail which encodings are supported by this package, +see L<Encode::Supported>. + +=head2 Defining Aliases + +To add a new alias to a given encoding, use: + + use Encode; + use Encode::Alias; + define_alias(newName => ENCODING); + +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> + +But before you do so, make sure the alias is nonexistent with +C<resolve_alias()>, which returns the canonical name thereof. +i.e. + + 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 + +resolve_alias() does not need C<use Encode::Alias>; it can be +exported via C<use Encode qw(resolve_alias)>. + +See L<Encode::Alias> for details. + +=head2 Finding IANA Character Set Registry names + +The canonical name of a given encoding does not necessarily agree with +IANA IANA Character Set Registry, commonly seen as C<< Content-Type: +text/plain; charset=I<whatever> >>. For most cases canonical names +work but sometimes it does not (notably 'utf-8-strict'). + +Therefore as of Encode version 2.21, a new method C<mime_name()> is added. + + use Encode; + my $enc = find_encoding('UTF-8'); + warn $enc->name; # utf-8-strict + warn $enc->mime_name; # UTF-8 + +See also: L<Encode::Encoding> + +=head1 Encoding via PerlIO + +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. + + # via PerlIO + open my $in, "<:encoding(shiftjis)", $infile or die; + open my $out, ">:encoding(euc-jp)", $outfile or die; + while(<$in>){ print $out $_; } + + # 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 $_; + } + +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. + + Encode::perlio_ok("hz"); # False + find_encoding("euc-cn")->perlio_ok; # True where PerlIO is available + + use Encode qw(perlio_ok); # exported upon request + perlio_ok("euc-jp") + +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>. + +=head1 Handling Malformed Data + +The optional I<CHECK> argument tells Encode what to do when it +encounters malformed data. Without CHECK, Encode::FB_DEFAULT ( == 0 ) +is assumed. + +As of version 2.12 Encode supports coderef values for CHECK. See below. + +=over 2 + +=item B<NOTE:> Not all encoding support this feature + +Some encodings ignore I<CHECK> argument. For example, +L<Encode::Unicode> ignores I<CHECK> and it always croaks on error. + +=back + +Now here is the list of I<CHECK> values available + +=over 2 + +=item I<CHECK> = Encode::FB_DEFAULT ( == 0) + +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. + +=item I<CHECK> = Encode::FB_CROAK ( == 1) + +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 I<CHECK> = Encode::FB_QUIET + +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: + + 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 + } + +=item I<CHECK> = Encode::FB_WARN + +This is the same as above, except that it warns on error. Handy when +you are debugging the mode above. + +=item perlqq mode (I<CHECK> = Encode::FB_PERLQQ) + +=item HTML charref mode (I<CHECK> = Encode::FB_HTMLCREF) + +=item XML charref mode (I<CHECK> = Encode::FB_XMLCREF) + +For encodings that are implemented by Encode::XS, CHECK == +Encode::FB_PERLQQ turns (en|de)code into C<perlqq> fallback mode. + +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. + +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. + +In Encode 2.10 or later, C<LEAVE_SRC> is also implied. + +=item The bitmask + +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)>. + + 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 + +=over 2 + +=item Encode::LEAVE_SRC + +If the C<Encode::LEAVE_SRC> bit is not set, but I<CHECK> is, then the second +argument to C<encode()> or C<decode()> may be assigned to by the functions. If +you're not interested in this, then bitwise-or the bitmask with it. + +=back + +=head2 coderef for CHECK + +As of Encode 2.12 CHECK can also be a code reference which takes the +ord value of unmapped caharacter as an argument and returns a string +that represents the fallback character. For instance, + + $ascii = encode("ascii", $utf8, sub{ sprintf "<U+%04X>", shift }); + +Acts like FB_PERLQQ but E<lt>U+I<XXXX>E<gt> is used instead of +\x{I<XXXX>}. + +=head1 Defining Encodings + +To define a new encoding, use: + + use Encode qw(define_encoding); + define_encoding($object, 'canonicalName' [, alias...]); + +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>. + +See L<Encode::Encoding> for more details. + +=head1 The UTF8 flag + +Before the introduction of Unicode 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.> + +=over 2 + +=item Goal #1: + +Old byte-oriented programs should not spontaneously break on the old +byte-oriented data they used to work on. + +=item Goal #2: + +Old byte-oriented programs should magically start working on the new +character-oriented data when appropriate. + +=item Goal #3: + +Programs should run just as fast in the new character-oriented mode +as in the old byte-oriented mode. + +=item Goal #4: + +Perl should remain one language, rather than forking into a +byte-oriented Perl and a character-oriented Perl. + +=back + +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 UTF8 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). + +Here is how Encode takes care of the UTF8 flag. + +=over 2 + +=item * + +When you encode, the resulting UTF8 flag is always off. + +=item * + +When you decode, the resulting UTF8 flag is on unless you can +unambiguously represent data. Here is the definition of +dis-ambiguity. + +After C<$utf8 = decode('foo', $octet);>, + + 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 + --------------------------------------------- + +As you see, there is one exception, In ASCII. That way you can assume +Goal #1. And with Encode Goal #2 is assumed but you still have to be +careful in such cases mentioned in B<CAVEAT> paragraphs. + +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 + +=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. + +=over 2 + +=item is_utf8(STRING [, CHECK]) + +[INTERNAL] Tests whether the UTF8 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. + +As of perl 5.8.1, L<utf8> also has utf8::is_utf8(). + +=item _utf8_on(STRING) + +[INTERNAL] Turns on the UTF8 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 UTF8 flag (so please don't treat the return value as +indicating success or failure), or C<undef> if STRING is not a string. + +This function does not work on tainted values. + +=item _utf8_off(STRING) + +[INTERNAL] Turns off the UTF8 flag in STRING. Do not use frivolously. +Returns the previous state of the UTF8 flag (so please don't treat the +return value as indicating success or failure), or C<undef> if STRING is +not a string. + +This function does not work on tainted values. + +=back + +=head1 UTF-8 vs. utf8 vs. UTF8 + + ....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. + +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). + +Now that is overruled by Larry Wall himself. + + 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. + + Also for what it's worth, Perl 6 will mostly default to strict but + make it easy to switch back to lax. + + Larry + +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". + + encode("utf8", "\x{FFFF_FFFF}", 1); # okay + encode("UTF-8", "\x{FFFF_FFFF}", 1); # croaks + +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" + + find_encoding("UTF-8")->name # is 'utf-8-strict' + find_encoding("utf-8")->name # ditto. names are case insensitive + find_encoding("utf_8")->name # ditto. "_" are treated as "-" + find_encoding("UTF8")->name # is 'utf8'. + +The UTF8 flag is internally called UTF8, without a hyphen. It indicates +whether a string is internally encoded as utf8, also without a hypen. + +=head1 SEE ALSO + +L<Encode::Encoding>, +L<Encode::Supported>, +L<Encode::PerlIO>, +L<encoding>, +L<perlebcdic>, +L<perlfunc/open>, +L<perlunicode>, L<perluniintro>, L<perlunifaq>, L<perlunitut> +L<utf8>, +the Perl Unicode Mailing List E<lt>perl-unicode@perl.orgE<gt> + +=head1 MAINTAINER + +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. + +While Dan Kogai retains the copyright as a maintainer, the credit +should go to all those involoved. See AUTHORS for those submitted +codes. + +=head1 COPYRIGHT + +Copyright 2002-2006 Dan Kogai E<lt>dankogai@dan.co.jpE<gt> + +This library is free software; you can redistribute it and/or modify +it under the same terms as Perl itself. + +=cut |