1 # $Id: encoding.pm,v 1.44 2003/03/09 20:07:37 dankogai Exp $
3 our $VERSION = do { my @r = (q$Revision: 1.44 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
10 if (ord("A") == 193) {
12 Carp::croak("encoding pragma does not support EBCDIC platforms");
17 eval { require PerlIO::encoding };
19 $HAS_PERLIO = (PerlIO::encoding->VERSION >= 0.02);
24 $] > 5.008 and return 0; # 5.8.1 then no
25 my %utfs = map {$_=>1}
26 qw(utf8 UCS-2BE UCS-2LE UTF-16 UTF-16BE UTF-16LE
27 UTF-32 UTF-32BE UTF-32LE);
28 $utfs{$name} or return 0; # UTFs or no
29 require Config; Config->import(); our %Config;
30 return $Config{perl_patchlevel} == 0 # maintperl then no
37 $name ||= $ENV{PERL_ENCODING};
38 my $enc = find_encoding($name);
39 unless (defined $enc) {
41 Carp::croak("Unknown encoding '$name'");
43 $name = $enc->name; # canonize
44 unless ($arg{Filter}) {
45 $DEBUG and warn "_exception($name) = ", _exception($name);
46 _exception($name) or ${^ENCODING} = $enc;
47 $HAS_PERLIO or return 1;
49 defined(${^ENCODING}) and undef ${^ENCODING};
50 # implicitly 'use utf8'
51 require utf8; # to fetch $utf8::hint_bits;
52 $^H |= $utf8::hint_bits;
54 require Filter::Util::Call ;
55 Filter::Util::Call->import ;
57 my $status = filter_read();
60 $_ = $enc->decode($_, 1);
66 } $DEBUG and warn "Filter installed";
67 defined ${^UNICODE} and ${^UNICODE} != 0 and return 1;
68 for my $h (qw(STDIN STDOUT)){
70 unless (defined find_encoding($arg{$h})) {
72 Carp::croak("Unknown encoding for $h, '$arg{$h}'");
74 eval { binmode($h, ":raw :encoding($arg{$h})") };
76 unless (exists $arg{$h}){
78 no warnings 'uninitialized';
79 binmode($h, ":raw :encoding($name)");
88 return 1; # I doubt if we need it, though
95 binmode(STDIN, ":raw");
96 binmode(STDOUT, ":raw");
101 if ($INC{"Filter/Util/Call.pm"}){
102 eval { filter_del() };
113 encoding - allows you to write your script in non-ascii or non-utf8
117 use encoding "greek"; # Perl like Greek to you?
118 use encoding "euc-jp"; # Jperl!
120 # or you can even do this if your shell supports your native encoding
122 perl -Mencoding=latin2 -e '...' # Feeling centrally European?
123 perl -Mencoding=euc-kr -e '...' # Or Korean?
127 # A simple euc-cn => utf-8 converter
128 use encoding "euc-cn", STDOUT => "utf8"; while(<>){print};
130 # "no encoding;" supported (but not scoped!)
133 # an alternate way, Filter
134 use encoding "euc-jp", Filter=>1;
135 # now you can use kanji identifiers -- in euc-jp!
139 Let's start with a bit of history: Perl 5.6.0 introduced Unicode
140 support. You could apply C<substr()> and regexes even to complex CJK
141 characters -- so long as the script was written in UTF-8. But back
142 then, text editors that supported UTF-8 were still rare and many users
143 instead chose to write scripts in legacy encodings, giving up a whole
144 new feature of Perl 5.6.
146 Rewind to the future: starting from perl 5.8.0 with the B<encoding>
147 pragma, you can write your script in any encoding you like (so long
148 as the C<Encode> module supports it) and still enjoy Unicode support.
149 This pragma achieves that by doing the following:
155 Internally converts all literals (C<q//,qq//,qr//,qw///, qx//>) from
156 the encoding specified to utf8. In Perl 5.8.1 and later, literals in
157 C<tr///> and C<DATA> pseudo-filehandle are also converted.
161 Changing PerlIO layers of C<STDIN> and C<STDOUT> to the encoding
166 =head2 Literal Conversions
168 You can write code in EUC-JP as follows:
170 my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji
171 #<-char-><-char-> # 4 octets
172 s/\bCamel\b/$Rakuda/;
174 And with C<use encoding "euc-jp"> in effect, it is the same thing as
177 my $Rakuda = "\x{99F1}\x{99DD}"; # two Unicode Characters
178 s/\bCamel\b/$Rakuda/;
180 =head2 PerlIO layers for C<STD(IN|OUT)>
182 The B<encoding> pragma also modifies the filehandle layers of
183 STDIN and STDOUT to the specified encoding. Therefore,
185 use encoding "euc-jp";
186 my $message = "Camel is the symbol of perl.\n";
187 my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji
188 $message =~ s/\bCamel\b/$Rakuda/;
191 Will print "\xF1\xD1\xF1\xCC is the symbol of perl.\n",
192 not "\x{99F1}\x{99DD} is the symbol of perl.\n".
194 You can override this by giving extra arguments; see below.
196 =head1 FEATURES THAT REQUIRE 5.8.1
198 Some of the features offered by this pragma requires perl 5.8.1. Most
199 of these are done by Inaba Hiroto. Any other features and changes
204 =item "NON-EUC" doublebyte encodings
206 Because perl needs to parse script before applying this pragma, such
207 encodings as Shift_JIS and Big-5 that may contain '\' (BACKSLASH;
208 \x5c) in the second byte fails because the second byte may
209 accidentally escape the quoting character that follows. Perl 5.8.1
210 or later fixes this problem.
214 C<tr//> was overlooked by Perl 5 porters when they released perl 5.8.0
215 See the section below for details.
217 =item DATA pseudo-filehandle
219 Another feature that was overlooked was C<DATA>.
227 =item use encoding [I<ENCNAME>] ;
229 Sets the script encoding to I<ENCNAME>. And unless ${^UNICODE}
230 exists and non-zero, PerlIO layers of STDIN and STDOUT are set to
231 ":encoding(I<ENCNAME>)".
233 Note that STDERR WILL NOT be changed.
235 Also note that non-STD file handles remain unaffected. Use C<use
236 open> or C<binmode> to change layers of those.
238 If no encoding is specified, the environment variable L<PERL_ENCODING>
239 is consulted. If no encoding can be found, the error C<Unknown encoding
240 'I<ENCNAME>'> will be thrown.
242 =item use encoding I<ENCNAME> [ STDIN =E<gt> I<ENCNAME_IN> ...] ;
244 You can also individually set encodings of STDIN and STDOUT via the
245 C<< STDIN => I<ENCNAME> >> form. In this case, you cannot omit the
246 first I<ENCNAME>. C<< STDIN => undef >> turns the IO transcoding
249 When ${^UNICODE} exists and non-zero, these options will completely
250 ignored. ${^UNICODE} is a variable introduced in perl 5.8.1. See
251 L<perlrun> see L<perlvar/"${^UNICODE}"> and L<perlrun/"-C"> for
252 details (perl 5.8.1 and later).
254 =item use encoding I<ENCNAME> Filter=E<gt>1;
256 This turns the encoding pragma into a source filter. While the
257 default approach just decodes interpolated literals (in qq() and
258 qr()), this will apply a source filter to the entire source code. See
259 L</"The Filter Option"> below for details.
263 Unsets the script encoding. The layers of STDIN, STDOUT are
264 reset to ":raw" (the default unprocessed raw stream of bytes).
268 =head1 The Filter Option
270 The magic of C<use encoding> is not applied to the names of
271 identifiers. In order to make C<${"\x{4eba}"}++> ($human++, where human
272 is a single Han ideograph) work, you still need to write your script
273 in UTF-8 -- or use a source filter. That's what 'Filter=>1' does.
275 What does this mean? Your source code behaves as if it is written in
276 UTF-8 with 'use utf8' in effect. So even if your editor only supports
277 Shift_JIS, for example, you can still try examples in Chapter 15 of
278 C<Programming Perl, 3rd Ed.>. For instance, you can use UTF-8
281 This option is significantly slower and (as of this writing) non-ASCII
282 identifiers are not very stable WITHOUT this option and with the
283 source code written in UTF-8.
285 =head2 Filter-related changes at Encode version 1.87
291 The Filter option now sets STDIN and STDOUT like non-filter options.
292 And C<< STDIN=>I<ENCODING> >> and C<< STDOUT=>I<ENCODING> >> work like
297 C<use utf8> is implicitly declared so you no longer have to C<use
298 utf8> to C<${"\x{4eba}"}++>.
306 The pragma is a per script, not a per block lexical. Only the last
307 C<use encoding> or C<no encoding> matters, and it affects
308 B<the whole script>. However, the <no encoding> pragma is supported and
309 B<use encoding> can appear as many times as you want in a given script.
310 The multiple use of this pragma is discouraged.
312 By the same reason, the use this pragma inside modules is also
313 discouraged (though not as strongly discouranged as the case above.
316 If you still have to write a module with this pragma, be very careful
317 of the load order. See the codes below;
320 package Module_IN_BAR;
322 # stuff in "bar" encoding here
328 # surprise! use encoding "bar" is in effect.
330 The best way to avoid this oddity is to use this pragma RIGHT AFTER
331 other modules are loaded. i.e.
336 =head2 DO NOT MIX MULTIPLE ENCODINGS
338 Notice that only literals (string or regular expression) having only
339 legacy code points are affected: if you mix data like this
343 the data is assumed to be in (Latin 1 and) Unicode, not in your native
344 encoding. In other words, this will match in "greek":
350 "\xDF\x{100}" =~ /\x{3af}\x{100}/
352 since the C<\xDF> (ISO 8859-7 GREEK SMALL LETTER IOTA WITH TONOS) on
353 the left will B<not> be upgraded to C<\x{3af}> (Unicode GREEK SMALL
354 LETTER IOTA WITH TONOS) because of the C<\x{100}> on the left. You
355 should not be mixing your legacy data and Unicode in the same string.
357 This pragma also affects encoding of the 0x80..0xFF code point range:
358 normally characters in that range are left as eight-bit bytes (unless
359 they are combined with characters with code points 0x100 or larger,
360 in which case all characters need to become UTF-8 encoded), but if
361 the C<encoding> pragma is present, even the 0x80..0xFF range always
364 After all, the best thing about this pragma is that you don't have to
365 resort to \x{....} just to spell your name in a native encoding.
366 So feel free to put your strings in your encoding in quotes and
369 =head2 tr/// with ranges
371 The B<encoding> pragma works by decoding string literals in
372 C<q//,qq//,qr//,qw///, qx//> and so forth. In perl 5.8.0, this
373 does not apply to C<tr///>. Therefore,
375 use encoding 'euc-jp';
377 $kana =~ tr/\xA4\xA1-\xA4\xF3/\xA5\xA1-\xA5\xF3/;
378 # -------- -------- -------- --------
382 $kana =~ tr/\x{3041}-\x{3093}/\x{30a1}-\x{30f3}/;
386 =item Legend of characters above
388 utf8 euc-jp charnames::viacode()
389 -----------------------------------------
390 \x{3041} \xA4\xA1 HIRAGANA LETTER SMALL A
391 \x{3093} \xA4\xF3 HIRAGANA LETTER N
392 \x{30a1} \xA5\xA1 KATAKANA LETTER SMALL A
393 \x{30f3} \xA5\xF3 KATAKANA LETTER N
397 This counterintuitive behavior has been fixed in perl 5.8.1.
399 =head3 workaround to tr///;
401 In perl 5.8.0, you can work aroud as follows;
403 use encoding 'euc-jp';
405 eval qq{ \$kana =~ tr/\xA4\xA1-\xA4\xF3/\xA5\xA1-\xA5\xF3/ };
407 Note the C<tr//> expression is surronded by C<qq{}>. The idea behind
408 is the same as classic idiom that makes C<tr///> 'interpolate'.
410 tr/$from/$to/; # wrong!
411 eval qq{ tr/$from/$to/ }; # workaround.
413 Nevertheless, in case of B<encoding> pragma even C<q//> is affected so
414 C<tr///> not being decoded was obviously against the will of Perl5
415 Porters so it has been fixed in Perl 5.8.1 or later.
417 =head1 EXAMPLE - Greekperl
419 use encoding "iso 8859-7";
421 # \xDF in ISO 8859-7 (Greek) is \x{3af} in Unicode.
426 printf "%#x\n", ord($a); # will print 0x3af, not 0xdf
430 # $c will be "\x{3af}\x{100}", not "\x{df}\x{100}".
432 # chr() is affected, and ...
434 print "mega\n" if ord(chr(0xdf)) == 0x3af;
436 # ... ord() is affected by the encoding pragma ...
438 print "tera\n" if ord(pack("C", 0xdf)) == 0x3af;
440 # ... as are eq and cmp ...
442 print "peta\n" if "\x{3af}" eq pack("C", 0xdf);
443 print "exa\n" if "\x{3af}" cmp pack("C", 0xdf) == 0;
445 # ... but pack/unpack C are not affected, in case you still
446 # want to go back to your native encoding
448 print "zetta\n" if unpack("C", (pack("C", 0xdf))) == 0xdf;
450 =head1 KNOWN PROBLEMS
454 =item literals in regex that are longer than 127 bytes
456 For native multibyte encodings (either fixed or variable length),
457 the current implementation of the regular expressions may introduce
458 recoding errors for regular expression literals longer than 127 bytes.
462 The encoding pragma is not supported on EBCDIC platforms.
463 (Porters who are willing and able to remove this limitation are
468 This pragma doesn't work well with format because PerlIO does not
469 get along very well with it. When format contains non-ascii
470 characters it prints funny or gets "wide character warnings".
471 To understand it, try the code below.
473 # Save this one in utf8
474 # replace *non-ascii* with a non-ascii string
480 $camel = "*non-ascii*";
481 binmode(STDOUT=>':encoding(utf8)'); # bang!
483 print $camel, "\n"; # fine
485 Without binmode this happens to work but without binmode, print()
486 fails instead of write().
488 At any rate, the very use of format is questionable when it comes to
489 unicode characters since you have to consider such things as character
490 width (i.e. double-width for ideographs) and directions (i.e. BIDI for
497 This pragma first appeared in Perl 5.8.0. For features that require
498 5.8.1 and better, see above.
502 L<perlunicode>, L<Encode>, L<open>, L<Filter::Util::Call>,
504 Ch. 15 of C<Programming Perl (3rd Edition)>
505 by Larry Wall, Tom Christiansen, Jon Orwant;
506 O'Reilly & Associates; ISBN 0-596-00027-8