2 # $Id: Encode.pm,v 1.64 2002/04/29 06:54:06 dankogai Exp $
6 our $VERSION = do { my @r = (q$Revision: 1.64 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
9 XSLoader::load(__PACKAGE__, $VERSION);
12 use base qw/Exporter/;
14 # Public, encouraged API is exported by default
17 decode decode_utf8 encode encode_utf8
18 encodings find_encoding
21 our @FB_FLAGS = qw(DIE_ON_ERR WARN_ON_ERR RETURN_ON_ERR LEAVE_SRC
22 PERLQQ HTMLCREF XMLCREF);
23 our @FB_CONSTS = qw(FB_DEFAULT FB_CROAK FB_QUIET FB_WARN
24 FB_PERLQQ FB_HTMLCREF FB_XMLCREF);
29 _utf8_off _utf8_on define_encoding from_to is_16bit is_8bit
30 is_utf8 perlio_ok resolve_alias utf8_downgrade utf8_upgrade
32 @FB_FLAGS, @FB_CONSTS,
37 all => [ @EXPORT, @EXPORT_OK ],
38 fallbacks => [ @FB_CONSTS ],
39 fallback_all => [ @FB_CONSTS, @FB_FLAGS ],
42 # Documentation moved after __END__ for speed - NI-S
44 our $ON_EBCDIC = (ord("A") == 193);
48 # Make a %Encoding package variable to allow a certain amount of cheating
51 require Encode::Config;
52 eval { require Encode::ConfigLocal };
58 if (@_ and $_[0] eq ":all"){
59 %enc = ( %Encoding, %ExtModule );
62 for my $mod (map {m/::/o ? $_ : "Encode::$_" } @_){
64 for my $enc (keys %ExtModule){
65 $ExtModule{$enc} eq $mod and $enc{$enc} = $mod;
70 sort { lc $a cmp lc $b }
71 grep {!/^(?:Internal|Unicode|Guess)$/o} keys %enc;
75 my $obj = ref($_[0]) ? $_[0] : find_encoding($_[0]);
76 $obj->can("perlio_ok") and return $obj->perlio_ok();
77 return 0; # safety net
84 $Encoding{$name} = $obj;
86 define_alias($lc => $obj) unless $lc eq $name;
89 define_alias($alias, $obj);
96 my ($class, $name, $skip_external) = @_;
98 ref($name) && $name->can('new_sequence') and return $name;
99 exists $Encoding{$name} and return $Encoding{$name};
101 exists $Encoding{$lc} and return $Encoding{$lc};
103 my $oc = $class->find_alias($name);
104 defined($oc) and return $oc;
105 $lc ne $name and $oc = $class->find_alias($lc);
106 defined($oc) and return $oc;
108 unless ($skip_external)
110 if (my $mod = $ExtModule{$name} || $ExtModule{$lc}){
111 $mod =~ s,::,/,g ; $mod .= '.pm';
112 eval{ require $mod; };
113 exists $Encoding{$name} and return $Encoding{$name};
121 my ($name, $skip_external) = @_;
122 return __PACKAGE__->getEncoding($name,$skip_external);
126 my $obj = find_encoding(shift);
127 defined $obj and return $obj->name;
133 my ($name,$string,$check) = @_;
135 my $enc = find_encoding($name);
136 unless(defined $enc){
138 Carp::croak("Unknown encoding '$name'");
140 my $octets = $enc->encode($string,$check);
141 return undef if ($check && length($string));
147 my ($name,$octets,$check) = @_;
149 my $enc = find_encoding($name);
150 unless(defined $enc){
152 Carp::croak("Unknown encoding '$name'");
154 my $string = $enc->decode($octets,$check);
155 $_[1] = $octets if $check;
161 my ($string,$from,$to,$check) = @_;
163 my $f = find_encoding($from);
166 Carp::croak("Unknown encoding '$from'");
168 my $t = find_encoding($to);
171 Carp::croak("Unknown encoding '$to'");
173 my $uni = $f->decode($string,$check);
174 return undef if ($check && length($string));
175 $string = $t->encode($uni,$check);
176 return undef if ($check && length($uni));
177 return defined($_[0] = $string) ? length($string) : undef ;
190 return undef unless utf8::decode($str);
194 predefine_encodings();
197 # This is to restore %Encoding if really needed;
200 sub predefine_encodings{
201 use Encode::Encoding;
203 # was in Encode::UTF_EBCDIC
204 package Encode::UTF_EBCDIC;
205 push @Encode::UTF_EBCDIC::ISA, 'Encode::Encoding';
207 my ($obj,$str,$chk) = @_;
209 for (my $i = 0; $i < length($str); $i++) {
211 chr(utf8::unicode_to_native(ord(substr($str,$i,1))));
217 my ($obj,$str,$chk) = @_;
219 for (my $i = 0; $i < length($str); $i++) {
221 chr(utf8::native_to_unicode(ord(substr($str,$i,1))));
226 $Encode::Encoding{Unicode} =
227 bless {Name => "UTF_EBCDIC"} => "Encode::UTF_EBCDIC";
229 package Encode::Internal;
230 push @Encode::Internal::ISA, 'Encode::Encoding';
232 my ($obj,$str,$chk) = @_;
238 $Encode::Encoding{Unicode} =
239 bless {Name => "Internal"} => "Encode::Internal";
243 # was in Encode::utf8
244 package Encode::utf8;
245 push @Encode::utf8::ISA, 'Encode::Encoding';
247 my ($obj,$octets,$chk) = @_;
248 my $str = Encode::decode_utf8($octets);
256 my ($obj,$string,$chk) = @_;
257 my $octets = Encode::encode_utf8($string);
261 $Encode::Encoding{utf8} =
262 bless {Name => "utf8"} => "Encode::utf8";
272 Encode - character encodings
278 =head2 Table of Contents
280 Encode consists of a collection of modules whose details are too big
281 to fit in one document. This POD itself explains the top-level APIs
282 and general topics at a glance. For other topics and more details,
286 --------------------------------------------------------
287 Encode::Alias Alias definitions to encodings
288 Encode::Encoding Encode Implementation Base Class
289 Encode::Supported List of Supported Encodings
290 Encode::CN Simplified Chinese Encodings
291 Encode::JP Japanese Encodings
292 Encode::KR Korean Encodings
293 Encode::TW Traditional Chinese Encodings
294 --------------------------------------------------------
298 The C<Encode> module provides the interfaces between Perl's strings
299 and the rest of the system. Perl strings are sequences of
302 The repertoire of characters that Perl can represent is at least that
303 defined by the Unicode Consortium. On most platforms the ordinal
304 values of the characters (as returned by C<ord(ch)>) is the "Unicode
305 codepoint" for the character (the exceptions are those platforms where
306 the legacy encoding is some variant of EBCDIC rather than a super-set
307 of ASCII - see L<perlebcdic>).
309 Traditionally, computer data has been moved around in 8-bit chunks
310 often called "bytes". These chunks are also known as "octets" in
311 networking standards. Perl is widely used to manipulate data of many
312 types - not only strings of characters representing human or computer
313 languages but also "binary" data being the machine's representation of
314 numbers, pixels in an image - or just about anything.
316 When Perl is processing "binary data", the programmer wants Perl to
317 process "sequences of bytes". This is not a problem for Perl - as a
318 byte has 256 possible values, it easily fits in Perl's much larger
327 I<character>: a character in the range 0..(2**32-1) (or more).
328 (What Perl's strings are made of.)
332 I<byte>: a character in the range 0..255
333 (A special case of a Perl character.)
337 I<octet>: 8 bits of data, with ordinal values 0..255
338 (Term for bytes passed to or from a non-Perl context, e.g. a disk file.)
342 =head1 PERL ENCODING API
346 =item $octets = encode(ENCODING, $string [, CHECK])
348 Encodes a string from Perl's internal form into I<ENCODING> and returns
349 a sequence of octets. ENCODING can be either a canonical name or
350 an alias. For encoding names and aliases, see L</"Defining Aliases">.
351 For CHECK, see L</"Handling Malformed Data">.
353 For example, to convert a string from Perl's internal format to
354 iso-8859-1 (also known as Latin1),
356 $octets = encode("iso-8859-1", $string);
358 B<CAVEAT>: When you run C<$octets = encode("utf8", $string)>, then $octets
359 B<may not be equal to> $string. Though they both contain the same data, the utf8 flag
360 for $octets is B<always> off. When you encode anything, utf8 flag of
361 the result is always off, even when it contains completely valid utf8
362 string. See L</"The UTF-8 flag"> below.
364 =item $string = decode(ENCODING, $octets [, CHECK])
366 Decodes a sequence of octets assumed to be in I<ENCODING> into Perl's
367 internal form and returns the resulting string. As in encode(),
368 ENCODING can be either a canonical name or an alias. For encoding names
369 and aliases, see L</"Defining Aliases">. For CHECK, see
370 L</"Handling Malformed Data">.
372 For example, to convert ISO-8859-1 data to a string in Perl's internal format:
374 $string = decode("iso-8859-1", $octets);
376 B<CAVEAT>: When you run C<$string = decode("utf8", $octets)>, then $string
377 B<may not be equal to> $octets. Though they both contain the same data,
378 the utf8 flag for $string is on unless $octets entirely consists of
379 ASCII data (or EBCDIC on EBCDIC machines). See L</"The UTF-8 flag">
382 =item [$length =] from_to($octets, FROM_ENC, TO_ENC [, CHECK])
384 Converts B<in-place> data between two encodings. The data in $octets
385 must be encoded as octets and not as characters in Perl's internal
386 format. For example, to convert ISO-8859-1 data to Microsoft's CP1250 encoding:
388 from_to($octets, "iso-8859-1", "cp1250");
390 and to convert it back:
392 from_to($octets, "cp1250", "iso-8859-1");
394 Note that because the conversion happens in place, the data to be
395 converted cannot be a string constant; it must be a scalar variable.
397 from_to() returns the length of the converted string in octets on success, undef
400 B<CAVEAT>: The following operations look the same but are not quite so;
402 from_to($data, "iso-8859-1", "utf8"); #1
403 $data = decode("iso-8859-1", $data); #2
405 Both #1 and #2 make $data consist of a completely valid UTF-8 string
406 but only #2 turns utf8 flag on. #1 is equivalent to
408 $data = encode("utf8", decode("iso-8859-1", $data));
410 See L</"The UTF-8 flag"> below.
412 =item $octets = encode_utf8($string);
414 Equivalent to C<$octets = encode("utf8", $string);> The characters
415 that comprise $string are encoded in Perl's internal format and the
416 result is returned as a sequence of octets. All possible
417 characters have a UTF-8 representation so this function cannot fail.
420 =item $string = decode_utf8($octets [, CHECK]);
422 equivalent to C<$string = decode("utf8", $octets [, CHECK])>.
423 The sequence of octets represented by
424 $octets is decoded from UTF-8 into a sequence of logical
425 characters. Not all sequences of octets form valid UTF-8 encodings, so
426 it is possible for this call to fail. For CHECK, see
427 L</"Handling Malformed Data">.
431 =head2 Listing available encodings
434 @list = Encode->encodings();
436 Returns a list of the canonical names of the available encodings that
437 are loaded. To get a list of all available encodings including the
438 ones that are not loaded yet, say
440 @all_encodings = Encode->encodings(":all");
442 Or you can give the name of a specific module.
444 @with_jp = Encode->encodings("Encode::JP");
446 When "::" is not in the name, "Encode::" is assumed.
448 @ebcdic = Encode->encodings("EBCDIC");
450 To find out in detail which encodings are supported by this package,
451 see L<Encode::Supported>.
453 =head2 Defining Aliases
455 To add a new alias to a given encoding, use:
459 define_alias(newName => ENCODING);
461 After that, newName can be used as an alias for ENCODING.
462 ENCODING may be either the name of an encoding or an
465 But before you do so, make sure the alias is nonexistent with
466 C<resolve_alias()>, which returns the canonical name thereof.
469 Encode::resolve_alias("latin1") eq "iso-8859-1" # true
470 Encode::resolve_alias("iso-8859-12") # false; nonexistent
471 Encode::resolve_alias($name) eq $name # true if $name is canonical
473 resolve_alias() does not need C<use Encode::Alias>; it can be
474 exported via C<use Encode qw(resolve_alias)>.
476 See L<Encode::Alias> for details.
478 =head1 Encoding via PerlIO
480 If your perl supports I<PerlIO> (which is the default), you can use a PerlIO layer to decode
481 and encode directly via a filehandle. The following two examples
482 are totally identical in their functionality.
485 open my $in, "<:encoding(shiftjis)", $infile or die;
486 open my $out, ">:encoding(euc-jp)", $outfile or die;
487 while(<$in>){ print $out $_; }
490 open my $in, "<", $infile or die;
491 open my $out, ">", $outfile or die;
493 from_to($_, "shiftjis", "euc-jp", 1);
497 Unfortunately, it may be that encodings are PerlIO-savvy. You can check
498 if your encoding is supported by PerlIO by calling the C<perlio_ok>
501 Encode::perlio_ok("hz"); # False
502 find_encoding("euc-cn")->perlio_ok; # True where PerlIO is available
504 use Encode qw(perlio_ok); # exported upon request
507 Fortunately, all encodings that come with Encode core are PerlIO-savvy
508 except for hz and ISO-2022-kr. For gory details, see L<Encode::Encoding> and L<Encode::PerlIO>.
510 =head1 Handling Malformed Data
514 The I<CHECK> argument is used as follows. When you omit it,
515 the behaviour is the same as if you had passed a value of 0 for
518 =item I<CHECK> = Encode::FB_DEFAULT ( == 0)
520 If I<CHECK> is 0, (en|de)code will put a I<substitution character>
521 in place of a malformed character. For UCM-based encodings,
522 E<lt>subcharE<gt> will be used. For Unicode, the code point C<0xFFFD> is used.
523 If the data is supposed to be UTF-8, an optional lexical warning
524 (category utf8) is given.
526 =item I<CHECK> = Encode::FB_CROAK ( == 1)
528 If I<CHECK> is 1, methods will die on error immediately with an error
529 message. Therefore, when I<CHECK> is set to 1, you should trap the
530 fatal error with eval{} unless you really want to let it die on error.
532 =item I<CHECK> = Encode::FB_QUIET
534 If I<CHECK> is set to Encode::FB_QUIET, (en|de)code will immediately
535 return the portion of the data that has been processed so far when
536 an error occurs. The data argument will be overwritten with
537 everything after that point (that is, the unprocessed part of data).
538 This is handy when you have to call decode repeatedly in the case
539 where your source data may contain partial multi-byte character
540 sequences, for example because you are reading with a fixed-width
541 buffer. Here is some sample code that does exactly this:
543 my $data = ''; my $utf8 = '';
544 while(defined(read $fh, $buffer, 256)){
545 # buffer may end in a partial character so we append
547 $utf8 .= decode($encoding, $data, ENCODE::FB_QUIET);
548 # $data now contains the unprocessed partial character
551 =item I<CHECK> = Encode::FB_WARN
553 This is the same as above, except that it warns on error. Handy when
554 you are debugging the mode above.
556 =item perlqq mode (I<CHECK> = Encode::FB_PERLQQ)
558 =item HTML charref mode (I<CHECK> = Encode::FB_HTMLCREF)
560 =item XML charref mode (I<CHECK> = Encode::FB_XMLCREF)
562 For encodings that are implemented by Encode::XS, CHECK ==
563 Encode::FB_PERLQQ turns (en|de)code into C<perlqq> fallback mode.
565 When you decode, C<\xI<HH>> will be inserted for a malformed character,
566 where I<HH> is the hex representation of the octet that could not be
567 decoded to utf8. And when you encode, C<\x{I<HHHH>}> will be inserted,
568 where I<HHHH> is the Unicode ID of the character that cannot be found
569 in the character repertoire of the encoding.
571 HTML/XML character reference modes are about the same, in place of
572 C<\x{I<HHHH>}>, HTML uses C<&#I<NNNN>>; where I<NNNN> is a decimal digit and
573 XML uses C<&#xI<HHHH>>; where I<HHHH> is the hexadecimal digit.
577 These modes are actually set via a bitmask. Here is how the FB_XX
578 constants are laid out. You can import the FB_XX constants via
579 C<use Encode qw(:fallbacks)>; you can import the generic bitmask
580 constants via C<use Encode qw(:fallback_all)>.
582 FB_DEFAULT FB_CROAK FB_QUIET FB_WARN FB_PERLQQ
585 RETURN_ON_ERR 0x0004 X X
591 =head2 Unimplemented fallback schemes
593 In the future, you will be able to use a code reference to a callback
594 function for the value of I<CHECK> but its API is still undecided.
596 =head1 Defining Encodings
598 To define a new encoding, use:
600 use Encode qw(define_encoding);
601 define_encoding($object, 'canonicalName' [, alias...]);
603 I<canonicalName> will be associated with I<$object>. The object
604 should provide the interface described in L<Encode::Encoding>.
605 If more than two arguments are provided then additional
606 arguments are taken as aliases for I<$object>.
608 See L<Encode::Encoding> for more details.
610 =head1 The UTF-8 flag
612 Before the introduction of utf8 support in perl, The C<eq> operator
613 just compared the strings represented by two scalars. Beginning with
614 perl 5.8, C<eq> compares two strings with simultaneous consideration
615 of I<the utf8 flag>. To explain why we made it so, I will quote page
616 402 of C<Programming Perl, 3rd ed.>
622 Old byte-oriented programs should not spontaneously break on the old
623 byte-oriented data they used to work on.
627 Old byte-oriented programs should magically start working on the new
628 character-oriented data when appropriate.
632 Programs should run just as fast in the new character-oriented mode
633 as in the old byte-oriented mode.
637 Perl should remain one language, rather than forking into a
638 byte-oriented Perl and a character-oriented Perl.
642 Back when C<Programming Perl, 3rd ed.> was written, not even Perl 5.6.0
643 was born and many features documented in the book remained
644 unimplemented for a long time. Perl 5.8 corrected this and the introduction
645 of the UTF-8 flag is one of them. You can think of this perl notion as of a
646 byte-oriented mode (utf8 flag off) and a character-oriented mode (utf8
649 Here is how Encode takes care of the utf8 flag.
655 When you encode, the resulting utf8 flag is always off.
659 When you decode, the resulting utf8 flag is on unless you can
660 unambiguously represent data. Here is the definition of
663 After C<$utf8 = decode('foo', $octet);>,
665 When $octet is... The utf8 flag in $utf8 is
666 ---------------------------------------------
667 In ASCII only (or EBCDIC only) OFF
669 In any other Encoding ON
670 ---------------------------------------------
672 As you see, there is one exception, In ASCII. That way you can assue
673 Goal #1. And with Encode Goal #2 is assumed but you still have to be
674 careful in such cases mentioned in B<CAVEAT> paragraphs.
676 This utf8 flag is not visible in perl scripts, exactly for the same
677 reason you cannot (or you I<don't have to>) see if a scalar contains a
678 string, integer, or floating point number. But you can still peek
679 and poke these if you will. See the section below.
683 =head2 Messing with Perl's Internals
685 The following API uses parts of Perl's internals in the current
686 implementation. As such, they are efficient but may change.
690 =item is_utf8(STRING [, CHECK])
692 [INTERNAL] Tests whether the UTF-8 flag is turned on in the STRING.
693 If CHECK is true, also checks the data in STRING for being well-formed
694 UTF-8. Returns true if successful, false otherwise.
696 =item _utf8_on(STRING)
698 [INTERNAL] Turns on the UTF-8 flag in STRING. The data in STRING is
699 B<not> checked for being well-formed UTF-8. Do not use unless you
700 B<know> that the STRING is well-formed UTF-8. Returns the previous
701 state of the UTF-8 flag (so please don't treat the return value as
702 indicating success or failure), or C<undef> if STRING is not a string.
704 =item _utf8_off(STRING)
706 [INTERNAL] Turns off the UTF-8 flag in STRING. Do not use frivolously.
707 Returns the previous state of the UTF-8 flag (so please don't treat the
708 return value as indicating success or failure), or C<undef> if STRING is
716 L<Encode::Supported>,
723 the Perl Unicode Mailing List E<lt>perl-unicode@perl.orgE<gt>
727 This project was originated by Nick Ing-Simmons and later maintained
728 by Dan Kogai E<lt>dankogai@dan.co.jpE<gt>. See AUTHORS for a full
729 list of people involved. For any questions, use
730 E<lt>perl-unicode@perl.orgE<gt> so we can all share.