2 # $Id: Encode.pm,v 1.63 2002/04/27 18:59:50 dankogai Exp $
6 our $VERSION = do { my @r = (q$Revision: 1.63 $ =~ /\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 The marker [INTERNAL] marks Internal Implementation Details, in
343 general meant only for those who think they know what they are doing,
344 and such details may change in future releases.
346 =head1 PERL ENCODING API
350 =item $octets = encode(ENCODING, $string[, CHECK])
352 Encodes a string from Perl's internal form into I<ENCODING> and returns
353 a sequence of octets. ENCODING can be either a canonical name or
354 an alias. For encoding names and aliases, see L</"Defining Aliases">.
355 For CHECK, see L</"Handling Malformed Data">.
357 For example, to convert (internally UTF-8 encoded) Unicode string to
358 iso-8859-1 (also known as Latin1),
360 $octets = encode("iso-8859-1", $utf8);
362 B<CAVEAT>: When you C<$octets = encode("utf8", $utf8)>, then $octets
363 B<ne> $utf8. Though they both contain the same data, the utf8 flag
364 for $octets is B<always> off. When you encode anything, utf8 flag of
365 the result is always off, even when it contains completely valid utf8
366 string. See L</"The UTF-8 flag"> below.
368 =item $string = decode(ENCODING, $octets[, CHECK])
370 Decodes a sequence of octets assumed to be in I<ENCODING> into Perl's
371 internal form and returns the resulting string. As in encode(),
372 ENCODING can be either a canonical name or an alias. For encoding names
373 and aliases, see L</"Defining Aliases">. For CHECK, see
374 L</"Handling Malformed Data">.
376 For example, to convert ISO-8859-1 data to UTF-8:
378 $utf8 = decode("iso-8859-1", $latin1);
380 B<CAVEAT>: When you C<$utf8 = encode("utf8", $octets)>, then $utf8
381 B<may not be equal to> $utf8. Though they both contain the same data,
382 the utf8 flag for $utf8 is on unless $octets entirely conststs of
383 ASCII data (or EBCDIC on EBCDIC machines). See L</"The UTF-8 flag">
386 =item [$length =] from_to($string, FROM_ENC, TO_ENC [, CHECK])
388 Converts B<in-place> data between two encodings. For example, to
389 convert ISO-8859-1 data to UTF-8:
391 from_to($data, "iso-8859-1", "utf8");
393 and to convert it back:
395 from_to($data, "utf8", "iso-8859-1");
397 Note that because the conversion happens in place, the data to be
398 converted cannot be a string constant; it must be a scalar variable.
400 from_to() returns the length of the converted string on success, undef
403 B<CAVEAT>: The following operations look the same but not quite so;
405 from_to($data, "iso-8859-1", "utf8"); #1
406 $data = decode("iso-8859-1", $data); #2
408 Both #1 and #2 makes $data consists of completely valid UTF-8 string
409 but only #2 turns utf8 flag on. #1 is equivalent to
411 $data = encode("utf8", decode("iso-8859-1", $data));
413 See L</"The UTF-8 flag"> below.
415 =item $octets = encode_utf8($string);
417 Equivalent to C<$octets = encode("utf8", $string);> The characters
418 that comprise $string are encoded in Perl's superset of UTF-8 and the
419 resulting octets are returned as a sequence of bytes. All possible
420 characters have a UTF-8 representation so this function cannot fail.
423 =item $string = decode_utf8($octets [, CHECK]);
425 equivalent to C<$string = decode("utf8", $octets [, CHECK])>.
426 decode_utf8($octets [, CHECK]); The sequence of octets represented by
427 $octets is decoded from UTF-8 into a sequence of logical
428 characters. Not all sequences of octets form valid UTF-8 encodings, so
429 it is possible for this call to fail. For CHECK, see
430 L</"Handling Malformed Data">.
434 =head2 Listing available encodings
437 @list = Encode->encodings();
439 Returns a list of the canonical names of the available encodings that
440 are loaded. To get a list of all available encodings including the
441 ones that are not loaded yet, say
443 @all_encodings = Encode->encodings(":all");
445 Or you can give the name of a specific module.
447 @with_jp = Encode->encodings("Encode::JP");
449 When "::" is not in the name, "Encode::" is assumed.
451 @ebcdic = Encode->encodings("EBCDIC");
453 To find out in detail which encodings are supported by this package,
454 see L<Encode::Supported>.
456 =head2 Defining Aliases
458 To add a new alias to a given encoding, use:
462 define_alias(newName => ENCODING);
464 After that, newName can be used as an alias for ENCODING.
465 ENCODING may be either the name of an encoding or an
468 But before you do so, make sure the alias is nonexistent with
469 C<resolve_alias()>, which returns the canonical name thereof.
472 Encode::resolve_alias("latin1") eq "iso-8859-1" # true
473 Encode::resolve_alias("iso-8859-12") # false; nonexistent
474 Encode::resolve_alias($name) eq $name # true if $name is canonical
476 resolve_alias() does not need C<use Encode::Alias>; it can be
477 exported via C<use Encode qw(resolve_alias)>.
479 See L<Encode::Alias> for details.
481 =head1 Encoding via PerlIO
483 If your perl supports I<PerlIO>, you can use a PerlIO layer to decode
484 and encode directly via a filehandle. The following two examples
485 are totally identical in their functionality.
488 open my $in, "<:encoding(shiftjis)", $infile or die;
489 open my $out, ">:encoding(euc-jp)", $outfile or die;
493 open my $in, "<", $infile or die;
494 open my $out, ">", $outfile or die;
496 from_to($_, "shiftjis", "euc-jp", 1);
499 Unfortunately, there may be encodings are PerlIO-savvy. You can check
500 if your encoding is supported by PerlIO by calling the C<perlio_ok>
503 Encode::perlio_ok("hz"); # False
504 find_encoding("euc-cn")->perlio_ok; # True where PerlIO is available
506 use Encode qw(perlio_ok); # exported upon request
509 Fortunately, all encodings that come with Encode core are PerlIO-savvy
510 except for hz and ISO-2022-kr. See L<Encode::Encoding> for details.
512 For gory details, see L<Encode::PerlIO>.
514 =head1 Handling Malformed Data
518 The I<CHECK> argument is used as follows. When you omit it,
519 the behaviour is the same as if you had passed a value of 0 for
522 =item I<CHECK> = Encode::FB_DEFAULT ( == 0)
524 If I<CHECK> is 0, (en|de)code will put a I<substitution character>
525 in place of a malformed character. For UCM-based encodings,
526 E<lt>subcharE<gt> will be used. For Unicode, "\x{FFFD}" is used.
527 If the data is supposed to be UTF-8, an optional lexical warning
528 (category utf8) is given.
530 =item I<CHECK> = Encode::FB_CROAK ( == 1)
532 If I<CHECK> is 1, methods will die immediately with an error
533 message. Therefore, when I<CHECK> is set to 1, you should trap the
534 fatal error with eval{} unless you really want to let it die on error.
536 =item I<CHECK> = Encode::FB_QUIET
538 If I<CHECK> is set to Encode::FB_QUIET, (en|de)code will immediately
539 return the portion of the data that has been processed so far when
540 an error occurs. The data argument will be overwritten with
541 everything after that point (that is, the unprocessed part of data).
542 This is handy when you have to call decode repeatedly in the case
543 where your source data may contain partial multi-byte character
544 sequences, for example because you are reading with a fixed-width
545 buffer. Here is some sample code that does exactly this:
548 while(defined(read $fh, $buffer, 256)){
549 # buffer may end in a partial character so we append
551 $utf8 .= decode($encoding, $data, ENCODE::FB_QUIET);
552 # $data now contains the unprocessed partial character
555 =item I<CHECK> = Encode::FB_WARN
557 This is the same as above, except that it warns on error. Handy when
558 you are debugging the mode above.
560 =item perlqq mode (I<CHECK> = Encode::FB_PERLQQ)
562 =item HTML charref mode (I<CHECK> = Encode::FB_HTMLCREF)
564 =item XML charref mode (I<CHECK> = Encode::FB_XMLCREF)
566 For encodings that are implemented by Encode::XS, CHECK ==
567 Encode::FB_PERLQQ turns (en|de)code into C<perlqq> fallback mode.
569 When you decode, '\xI<XX>' will be inserted for a malformed character,
570 where I<XX> is the hex representation of the octet that could not be
571 decoded to utf8. And when you encode, '\x{I<xxxx>}' will be inserted,
572 where I<xxxx> is the Unicode ID of the character that cannot be found
573 in the character repertoire of the encoding.
575 HTML/XML character reference modes are about the same, in place of
576 \x{I<xxxx>}, HTML uses &#I<1234>; where I<1234> is a decimal digit and
577 XML uses &#xI<abcd>; where I<abcd> is the hexadecimal digit.
581 These modes are actually set via a bitmask. Here is how the FB_XX
582 constants are laid out. You can import the FB_XX constants via
583 C<use Encode qw(:fallbacks)>; you can import the generic bitmask
584 constants via C<use Encode qw(:fallback_all)>.
586 FB_DEFAULT FB_CROAK FB_QUIET FB_WARN FB_PERLQQ
589 RETURN_ON_ERR 0x0004 X X
595 =head2 Unimplemented fallback schemes
597 In the future, you will be able to use a code reference to a callback
598 function for the value of I<CHECK> but its API is still undecided.
600 =head1 Defining Encodings
602 To define a new encoding, use:
604 use Encode qw(define_alias);
605 define_encoding($object, 'canonicalName' [, alias...]);
607 I<canonicalName> will be associated with I<$object>. The object
608 should provide the interface described in L<Encode::Encoding>.
609 If more than two arguments are provided then additional
610 arguments are taken as aliases for I<$object>, as for C<define_alias>.
612 See L<Encode::Encoding> for more details.
614 =head1 The UTF-8 flag
616 Before the introduction of utf8 support in perl, The C<eq> operator
617 just compares internal data of the scalars. Now C<eq> means internal
618 data equality AND I<the utf8 flag>. To explain why we made it so, I
619 will quote page 402 of C<Programming Perl, 3rd ed.>
625 Old byte-oriented programs should not spontaneously break on the old
626 byte-oriented data they used to work on.
630 Old byte-oriented programs should magically start working on the new
631 character-oriented data when appropriate.
635 Programs should run just as fast in the new character-oriented mode
636 as in the old byte-oriented mode.
640 Perl should remain one language, rather than forking into a
641 byte-oriented Perl and a character-oriented Perl.
645 Back when C<Programming Perl, 3rd ed.> was written, not even Perl 5.6.0
646 was born and many features documented in the book remained
647 unimplemented. Perl 5.8 hopefully correct this and the introduction
648 of UTF-8 flag is one of them. You can think this perl notion of
649 byte-oriented mode (utf8 flag off) and character-oriented mode (utf8
652 Here is how Encode takes care of the utf8 flag.
658 When you encode, the resulting utf8 flag is always off.
662 When you decode, the resuting utf8 flag is on unless you can
663 unambiguously represent data. Here is the definition of
666 After C<$utf8 = decode('foo', $octet);>,
668 When $octet is... The utf8 flag in $utf8 is
669 ---------------------------------------------
670 In ASCII only (or EBCDIC only) OFF
672 In any other Encoding ON
673 ---------------------------------------------
675 As you see, there is one exception, In ASCII. That way you can assue
676 Goal #1. And with Encode Goal #2 is assumed but you still have to be
677 careful in such cases mentioned in B<CAVEAT> paragraphs.
679 This utf8 flag is not visible in perl scripts, exactly for the same
680 reason you cannot (or you I<don't have to>) see if a scalar contains a
681 string, integer, or floating point number. But you can still peek
682 and poke these if you will. See the section below.
686 =head2 Messing with Perl's Internals
688 The following API uses parts of Perl's internals in the current
689 implementation. As such, they are efficient but may change.
693 =item is_utf8(STRING [, CHECK])
695 [INTERNAL] Tests whether the UTF-8 flag is turned on in the STRING.
696 If CHECK is true, also checks the data in STRING for being well-formed
697 UTF-8. Returns true if successful, false otherwise.
699 =item _utf8_on(STRING)
701 [INTERNAL] Turns on the UTF-8 flag in STRING. The data in STRING is
702 B<not> checked for being well-formed UTF-8. Do not use unless you
703 B<know> that the STRING is well-formed UTF-8. Returns the previous
704 state of the UTF-8 flag (so please don't treat the return value as
705 indicating success or failure), or C<undef> if STRING is not a string.
707 =item _utf8_off(STRING)
709 [INTERNAL] Turns off the UTF-8 flag in STRING. Do not use frivolously.
710 Returns the previous state of the UTF-8 flag (so please don't treat the
711 return value as indicating success or failure), or C<undef> if STRING is
719 L<Encode::Supported>,
726 the Perl Unicode Mailing List E<lt>perl-unicode@perl.orgE<gt>
730 This project was originated by Nick Ing-Simmons and later maintained
731 by Dan Kogai E<lt>dankogai@dan.co.jpE<gt>. See AUTHORS for a full
732 list of people involved. For any questions, use
733 E<lt>perl-unicode@perl.orgE<gt> so we can all share share.