| # |
| # $Id: Encode.pm,v 2.44 2011/08/09 07:49:44 dankogai Exp dankogai $ |
| # |
| package Encode; |
| use strict; |
| use warnings; |
| our $VERSION = sprintf "%d.%02d", q$Revision: 2.44 $ =~ /(\d+)/g; |
| use constant DEBUG => !!$ENV{PERL_ENCODE_DEBUG}; |
| 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/::/ ? $_ : "Encode::$_" } @_ ) { |
| 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 ) = @_; |
| |
| $name =~ s/\s+//g; # https://rt.cpan.org/Ticket/Display.html?id=65796 |
| |
| ref($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; |
| } |
| |
| my $utf8enc; |
| |
| sub decode_utf8($;$) { |
| my ( $octets, $check ) = @_; |
| return $octets if is_utf8($octets); |
| return undef unless defined $octets; |
| $octets .= '' if ref $octets; |
| $check ||= 0; |
| $utf8enc ||= find_encoding('utf8'); |
| my $string = $utf8enc->decode( $octets, $check ); |
| $_[0] = $octets if $check and !ref $check and !( $check & LEAVE_SRC() ); |
| return $string; |
| } |
| |
| # 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 in Perl |
| |
| =head1 SYNOPSIS |
| |
| use Encode; |
| |
| =head2 Table of Contents |
| |
| Encode consists of a collection of modules whose details are too extensive |
| to fit in one document. This one itself explains the top-level APIs |
| and general topics at a glance. For other topics and more details, |
| see the documentation for these modules: |
| |
| 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 interface between Perl strings |
| and the rest of the system. Perl strings are sequences of |
| I<characters>. |
| |
| The repertoire of characters that Perl can represent is a superset of those |
| defined by the Unicode Consortium. On most platforms the ordinal |
| values of a character as returned by C<ord(I<S>)> is the I<Unicode |
| codepoint> for that character. The exceptions are platforms where |
| the legacy encoding is some variant of EBCDIC rather than a superset |
| of ASCII; see L<perlebcdic>. |
| |
| During recent history, data is moved around a computer in 8-bit chunks, |
| often called "bytes" but also known as "octets" in standards documents. |
| 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: because 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, such as a disk file. |
| |
| =back |
| |
| =head1 THE PERL ENCODING API |
| |
| =over 2 |
| |
| =item $octets = encode(ENCODING, STRING[, CHECK]) |
| |
| Encodes the scalar value I<STRING> from Perl's internal form into |
| I<ENCODING> and returns a sequence of octets. I<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 into |
| 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 I<might not be equal to> $string. Though both contain the |
| same data, the UTF8 flag for $octets is I<always> off. When you |
| encode anything, the UTF8 flag on the result is always off, even when it |
| contains a 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]) |
| |
| This function returns the string that results from decoding the scalar |
| value I<OCTETS>, assumed to be a sequence of octets in I<ENCODING>, into |
| Perl's internal form. The returns the resulting string. As with encode(), |
| I<ENCODING> can be either a canonical name or an alias. For encoding names |
| and aliases, see L</"Defining Aliases">; for I<CHECK>, see L</"Handling |
| Malformed Data">. |
| |
| For example, to convert ISO-8859-1 data into 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 |
| I<might not be equal to> $octets. Though both contain the same data, the |
| UTF8 flag for $string is on unless $octets consists entirely of ASCII data |
| on ASCII machines 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 I<ENCODING>. Returns |
| C<undef> if no matching I<ENCODING> is find. The returned object is |
| what does the actual encoding or decoding. |
| |
| $utf8 = decode($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. |
| |
| You can therefore save time by reusing this object as follows; |
| |
| my $enc = find_encoding("iso-8859-1"); |
| while(<>) { |
| my $utf8 = $enc->decode($_); |
| ... # now do something 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 I<in-place> data between two encodings. The data in $octets |
| must be encoded as octets and I<not> as characters in Perl's internal |
| format. For example, to convert ISO-8859-1 data into Microsoft's CP1250 |
| encoding: |
| |
| from_to($octets, "iso-8859-1", "cp1250"); |
| |
| and to convert it back: |
| |
| from_to($octets, "cp1250", "iso-8859-1"); |
| |
| Because the conversion happens in place, the data to be |
| converted cannot be a string constant: it must be a scalar variable. |
| |
| from_to() returns the length of the converted string in octets on success, |
| and C<undef> on error. |
| |
| B<CAVEAT>: The following operations may look the same, but are not: |
| |
| from_to($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 the 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 t:o |
| |
| $octets = encode($to, decode($from, $octets), $check); |
| |
| Yes, it does I<not> respect the $check during decoding. It is |
| deliberately done that way. If you need minute control, use C<decode> |
| followed by 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 in |
| $string are encoded in Perl's internal format, and the result is returned |
| as a sequence of octets. Because all possible characters in Perl have a |
| (loose, not strict) UTF-8 representation, this function cannot fail. |
| |
| =item $string = decode_utf8($octets [, CHECK]); |
| |
| Equivalent to C<$string = decode("utf8", $octets [, CHECK])>. |
| The sequence of octets represented by $octets is decoded |
| from UTF-8 into a sequence of logical characters. |
| Because not all sequences of octets are valid UTF-8, |
| it is quite possible for this function to fail. |
| For CHECK, see L</"Handling Malformed Data">. |
| |
| =back |
| |
| =head2 Listing available encodings |
| |
| use Encode; |
| @list = Encode->encodings(); |
| |
| Returns a list of canonical names of available encodings that have already |
| been loaded. To get a list of all available encodings including those that |
| have not yet been loaded, say: |
| |
| @all_encodings = Encode->encodings(":all"); |
| |
| Or you can give the name of a specific module: |
| |
| @with_jp = Encode->encodings("Encode::JP"); |
| |
| When "C<::>" is not in the name, "C<Encode::>" is assumed. |
| |
| @ebcdic = Encode->encodings("EBCDIC"); |
| |
| To find out in detail which encodings are supported by this package, |
| see L<Encode::Supported>. |
| |
| =head2 Defining Aliases |
| |
| To add a new alias to a given encoding, use: |
| |
| use Encode; |
| use Encode::Alias; |
| define_alias(NEWNAME => ENCODING); |
| |
| After that, I<NEWNAME> can be used as an alias for I<ENCODING>. |
| <ENCODING> may be either the name of an encoding or an |
| I<encoding object>. |
| |
| Before you do that, first make sure the alias is nonexistent using |
| C<resolve_alias()>, which returns the canonical name thereof. |
| For example: |
| |
| Encode::resolve_alias("latin1") eq "iso-8859-1" # true |
| Encode::resolve_alias("iso-8859-12") # false; nonexistent |
| Encode::resolve_alias($name) eq $name # true if $name is canonical |
| |
| resolve_alias() does not need C<use Encode::Alias>; it can be |
| imported 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 Character Set Registry, commonly seen as C<< Content-Type: |
| text/plain; charset=I<WHATEVER> >>. For most cases, the canonical name |
| works, but sometimes it does not, most notably with "utf-8-strict". |
| |
| As of C<Encode> version 2.21, a new method C<mime_name()> is thereforeadded. |
| |
| 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 C<PerlIO> (which is the default), you can use a |
| C<PerlIO> layer to decode and encode directly via a filehandle. The |
| following two examples are fully identical in functionality: |
| |
| ### Version 1 via PerlIO |
| open(INPUT, "< :encoding(shiftjis)", $infile) |
| || die "Can't open < $infile for reading: $!"; |
| open(OUTPUT, "> :encoding(euc-jp)", $outfile) |
| || die "Can't open > $output for writing: $!"; |
| while (<INPUT>) { # auto decodes $_ |
| print OUTPUT; # auto encodes $_ |
| } |
| close(INPUT) || die "can't close $infile: $!"; |
| close(OUTPUT) || die "can't close $outfile: $!"; |
| |
| ### Version 2 via from_to() |
| open(INPUT, "< :raw", $infile) |
| || die "Can't open < $infile for reading: $!"; |
| open(OUTPUT, "> :raw", $outfile) |
| || die "Can't open > $output for writing: $!"; |
| |
| while (<INPUT>) { |
| from_to($_, "shiftjis", "euc-jp", 1); # switch encoding |
| print OUTPUT; # emit raw (but properly encoded) data |
| } |
| close(INPUT) || die "can't close $infile: $!"; |
| close(OUTPUT) || die "can't close $outfile: $!"; |
| |
| In the first version above, you let the appropriate encoding layer |
| handle the conversion. In the second, you explicitly translate |
| from one encoding to the other. |
| |
| Unfortunately, it may be that encodings are C<PerlIO>-savvy. You can check |
| to see whether your encoding is supported by C<PerlIO> by invoking the |
| C<perlio_ok> method on it: |
| |
| Encode::perlio_ok("hz"); # false |
| find_encoding("euc-cn")->perlio_ok; # true wherever PerlIO is available |
| |
| use Encode qw(perlio_ok); # imported upon request |
| perlio_ok("euc-jp") |
| |
| Fortunately, all encodings that come with C<Encode> core are C<PerlIO>-savvy |
| except for "hz" and "ISO-2022-kr". For the gory details, see |
| L<Encode::Encoding> and L<Encode::PerlIO>. |
| |
| =head1 Handling Malformed Data |
| |
| The optional I<CHECK> argument tells C<Encode> what to do when |
| encountering malformed data. Without I<CHECK>, C<Encode::FB_DEFAULT> |
| (== 0) is assumed. |
| |
| As of version 2.12, C<Encode> supports coderef values for C<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, encoding and decoding replace any malformed character |
| with a I<substitution character>. When you encode, I<SUBCHAR> is used. |
| When you decode, the Unicode REPLACEMENT CHARACTER, code point U+FFFD, is |
| used. If the data is supposed to be UTF-8, an optional lexical warning of |
| warning category C<"utf8"> is given. |
| |
| =item I<CHECK> = Encode::FB_CROAK ( == 1) |
| |
| If I<CHECK> is 1, methods immediately die with an error |
| message. Therefore, when I<CHECK> is 1, you should trap |
| exceptions with C<eval{}>, unless you really want to let it C<die>. |
| |
| =item I<CHECK> = Encode::FB_QUIET |
| |
| If I<CHECK> is set to C<Encode::FB_QUIET>, encoding and decoding immediately |
| return the portion of the data that has been processed so far when an |
| error occurs. The data argument is overwritten with everything |
| after that point; that is, the unprocessed portion of the data. This is |
| handy when you have to call C<decode> repeatedly in the case where your |
| source data may contain partial multi-byte character sequences, |
| (that is, you are reading with a fixed-width buffer). Here's some sample |
| code to do exactly that: |
| |
| my($buffer, $string) = ("", ""); |
| while (read($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 C<FB_QUIET> above, except that instead of being silent |
| on errors, it issues a warning. This is handy for when you are debugging. |
| |
| =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 the C<Encode::XS> module, C<CHECK> C<==> |
| C<Encode::FB_PERLQQ> puts C<encode> and C<decode> into C<perlqq> fallback mode. |
| |
| When you decode, C<\xI<HH>> is inserted for a malformed character, where |
| I<HH> is the hex representation of the octet that could not be decoded to |
| utf8. When you encode, C<\x{I<HHHH>}> will be inserted, where I<HHHH> is |
| the Unicode code point (in any number of hex digits) of the character that |
| cannot be found in the character repertoire of the encoding. |
| |
| The 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 C<Encode> 2.10 or later, C<LEAVE_SRC> is also implied. |
| |
| =item The bitmask |
| |
| These modes are all actually set via a bitmask. Here is how the C<FB_I<XXX>> |
| constants are laid out. You can import the C<FB_I<XXX>> constants via |
| C<use Encode qw(:fallbacks)>, and 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 I<not> set but I<CHECK> is set, then the |
| second argument to encode() or decode() will be overwritten in place. |
| If you're not interested in this, then bitwise-OR it with the bitmask. |
| |
| =back |
| |
| =head2 coderef for CHECK |
| |
| As of C<Encode> 2.12, C<CHECK> can also be a code reference which takes the |
| ordinal value of the unmapped caharacter as an argument and returns a string |
| that represents the fallback character. For instance: |
| |
| $ascii = encode("ascii", $utf8, sub{ sprintf "<U+%04X>", shift }); |
| |
| Acts like C<FB_PERLQQ> but U+I<XXXX> is used instead of C<\x{I<XXXX>}>. |
| |
| =head1 Defining Encodings |
| |
| To define a new encoding, use: |
| |
| use Encode qw(define_encoding); |
| define_encoding($object, CANONICAL_NAME [, alias...]); |
| |
| I<CANONICAL_NAME> will be associated with I<$object>. The object |
| should provide the interface described in L<Encode::Encoding>. |
| If more than two arguments are provided, additional |
| arguments are considered aliases for I<$object>. |
| |
| See L<Encode::Encoding> for 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 quote from page 402 of |
| I<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 |
| |
| When I<Programming Perl, 3rd ed.> was written, not even Perl 5.6.0 had been |
| born yet, many features documented in the book remained unimplemented for a |
| long time. Perl 5.8 corrected much of this, and the introduction of the |
| UTF8 flag is one of them. You can think of there being two fundamentally |
| different kinds of strings and string-operations in Perl: one a |
| byte-oriented mode for when the internal UTF8 flag is off, and the other a |
| character-oriented mode for when the internal UTF8 flag is on. |
| |
| Here is how C<Encode> handles the UTF8 flag. |
| |
| =over 2 |
| |
| =item * |
| |
| When you I<encode>, the resulting UTF8 flag is always B<off>. |
| |
| =item * |
| |
| When you I<decode>, the resulting UTF8 flag is B<on>--I<unless> you can |
| unambiguously represent data. Here is what we mean by "unambiguously". |
| 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 C<Encode>, Goal #2 is assumed but you still have to be |
| careful in the cases mentioned in the B<CAVEAT> paragraphs above. |
| |
| This UTF8 flag is not visible in Perl scripts, exactly for the same reason |
| you cannot (or rather, you I<don't have to>) see whether a scalar contains |
| a string, an integer, or a floating-point number. But you can still peek |
| and poke these if you will. See the next section. |
| |
| =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 in a future |
| release. |
| |
| =over 2 |
| |
| =item is_utf8(STRING [, CHECK]) |
| |
| [INTERNAL] Tests whether the UTF8 flag is turned on in the I<STRING>. |
| If I<CHECK> is true, also checks whether I<STRING> contains well-formed |
| UTF-8. Returns true if successful, false otherwise. |
| |
| As of Perl 5.8.1, L<utf8> also has the C<utf8::is_utf8> function. |
| |
| =item _utf8_on(STRING) |
| |
| [INTERNAL] Turns the I<STRING>'s internal UTF8 flag B<on>. The I<STRING> |
| is I<not> checked for containing only well-formed UTF-8. Do not use this |
| unless you I<know with absolute certainty> that the STRING holds only |
| 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 I<STRING> is not a string. |
| |
| B<NOTE>: For security reasons, this function does not work on tainted values. |
| |
| =item _utf8_off(STRING) |
| |
| [INTERNAL] Turns the I<STRING>'s internal UTF8 flag B<off>. Do not use |
| frivolously. Returns the previous state of the UTF8 flag, or C<undef> if |
| I<STRING> is not a string. Do not treat the return value as indicative of |
| success or failure, because that isn't what it means: it is only the |
| previous setting. |
| |
| B<NOTE>: For security reasons, 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 historically been Perl's notion of UTF-8, as that is how UTF-8 was |
| first conceived by Ken Thompson when he invented it. However, thanks to |
| later revisions to the applicable standards, official UTF-8 is now rather |
| stricter than that. For example, its range is much narrower (0 .. 0x10_FFFF |
| to cover only 21 bits instead of 32 or 64 bits) and some sequences |
| are not allowed, like those used in surrogate pairs, the 31 non-character |
| code points 0xFDD0 .. 0xFDEF, the last two code points in I<any> plane |
| (0xI<XX>_FFFE and 0xI<XX>_FFFF), all non-shortest encodings, etc. |
| |
| The former default in which Perl would always use a loose interpretation of |
| UTF-8 has now been overruled: |
| |
| 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 |
| |
| Got that? As of Perl 5.8.7, B<"UTF-8"> means UTF-8 in its current |
| sense, which is conservative and strict and security-conscious, whereas |
| B<"utf8"> means UTF-8 in its former sense, which was liberal and loose and |
| lax. C<Encode> version 2.10 or later thus groks this subtle but critically |
| important distinction between C<"UTF-8"> and C<"utf8">. |
| |
| encode("utf8", "\x{FFFF_FFFF}", 1); # okay |
| encode("UTF-8", "\x{FFFF_FFFF}", 1); # croaks |
| |
| In the C<Encode> module, C<"UTF-8"> is actually a canonical name for |
| C<"utf-8-strict">. That hyphen between the C<"UTF"> and the C<"8"> is |
| critical; without it, C<Encode> goes "liberal" and (perhaps overly-)permissive: |
| |
| 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'. |
| |
| Perl's internal UTF8 flag is called "UTF8", without a hyphen. It indicates |
| whether a string is internally encoded as "utf8", also without a hyphen. |
| |
| =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 the late Nick Ing-Simmons and later |
| maintained by Dan Kogai I<< <dankogai@dan.co.jp> >>. See AUTHORS |
| for a full list of people involved. For any questions, send mail to |
| I<< <perl-unicode@perl.org> >> so that we can all share. |
| |
| While Dan Kogai retains the copyright as a maintainer, credit |
| should go to all those involved. See AUTHORS for a list of those |
| who submitted code to the project. |
| |
| =head1 COPYRIGHT |
| |
| Copyright 2002-2011 Dan Kogai I<< <dankogai@dan.co.jp> >>. |
| |
| This library is free software; you can redistribute it and/or modify |
| it under the same terms as Perl itself. |
| |
| =cut |