Commit | Line | Data |
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742555bd | 1 | # $Id: encoding.pm,v 2.6 2007/04/22 14:56:12 dankogai Exp $ |
3ef515df | 2 | package encoding; |
44b3b9c7 | 3 | our $VERSION = do { my @r = ( q$Revision: 2.6 $ =~ /\d+/g ); sprintf "%d." . "%02d" x $#r, @r }; |
3ef515df JH |
4 | |
5 | use Encode; | |
046f36bf | 6 | use strict; |
656ebd29 | 7 | use warnings; |
b1aeb384 | 8 | |
8f139f4c | 9 | sub DEBUG () { 0 } |
3ef515df JH |
10 | |
11 | BEGIN { | |
d1256cb1 RGS |
12 | if ( ord("A") == 193 ) { |
13 | require Carp; | |
14 | Carp::croak("encoding: pragma does not support EBCDIC platforms"); | |
3ef515df JH |
15 | } |
16 | } | |
17 | ||
0ab8f81e JH |
18 | our $HAS_PERLIO = 0; |
19 | eval { require PerlIO::encoding }; | |
d1256cb1 RGS |
20 | unless ($@) { |
21 | $HAS_PERLIO = ( PerlIO::encoding->VERSION >= 0.02 ); | |
0ab8f81e | 22 | } |
b2704119 | 23 | |
d1256cb1 | 24 | sub _exception { |
151b5d36 | 25 | my $name = shift; |
d1256cb1 RGS |
26 | $] > 5.008 and return 0; # 5.8.1 or higher then no |
27 | my %utfs = map { $_ => 1 } | |
28 | qw(utf8 UCS-2BE UCS-2LE UTF-16 UTF-16BE UTF-16LE | |
29 | UTF-32 UTF-32BE UTF-32LE); | |
30 | $utfs{$name} or return 0; # UTFs or no | |
31 | require Config; | |
32 | Config->import(); | |
33 | our %Config; | |
34 | return $Config{perl_patchlevel} ? 0 : 1 # maintperl then no | |
151b5d36 | 35 | } |
fa6f41cf | 36 | |
d1256cb1 | 37 | sub in_locale { $^H & ( $locale::hint_bits || 0 ) } |
b1aeb384 JH |
38 | |
39 | sub _get_locale_encoding { | |
40 | my $locale_encoding; | |
41 | ||
42 | # I18N::Langinfo isn't available everywhere | |
43 | eval { | |
d1256cb1 RGS |
44 | require I18N::Langinfo; |
45 | I18N::Langinfo->import(qw(langinfo CODESET)); | |
46 | $locale_encoding = langinfo( CODESET() ); | |
b1aeb384 | 47 | }; |
d1256cb1 | 48 | |
b1aeb384 JH |
49 | my $country_language; |
50 | ||
51 | no warnings 'uninitialized'; | |
52 | ||
d1256cb1 RGS |
53 | if ( not $locale_encoding && in_locale() ) { |
54 | if ( $ENV{LC_ALL} =~ /^([^.]+)\.([^.]+)$/ ) { | |
55 | ( $country_language, $locale_encoding ) = ( $1, $2 ); | |
56 | } | |
57 | elsif ( $ENV{LANG} =~ /^([^.]+)\.([^.]+)$/ ) { | |
58 | ( $country_language, $locale_encoding ) = ( $1, $2 ); | |
59 | } | |
60 | ||
61 | # LANGUAGE affects only LC_MESSAGES only on glibc | |
62 | } | |
63 | elsif ( not $locale_encoding ) { | |
64 | if ( $ENV{LC_ALL} =~ /\butf-?8\b/i | |
65 | || $ENV{LANG} =~ /\butf-?8\b/i ) | |
66 | { | |
67 | $locale_encoding = 'utf8'; | |
68 | } | |
69 | ||
70 | # Could do more heuristics based on the country and language | |
71 | # parts of LC_ALL and LANG (the parts before the dot (if any)), | |
72 | # since we have Locale::Country and Locale::Language available. | |
73 | # TODO: get a database of Language -> Encoding mappings | |
74 | # (the Estonian database at http://www.eki.ee/letter/ | |
75 | # would be excellent!) --jhi | |
b1aeb384 | 76 | } |
d1256cb1 RGS |
77 | if ( defined $locale_encoding |
78 | && lc($locale_encoding) eq 'euc' | |
79 | && defined $country_language ) | |
80 | { | |
81 | if ( $country_language =~ /^ja_JP|japan(?:ese)?$/i ) { | |
82 | $locale_encoding = 'euc-jp'; | |
83 | } | |
84 | elsif ( $country_language =~ /^ko_KR|korean?$/i ) { | |
85 | $locale_encoding = 'euc-kr'; | |
86 | } | |
5a1dbf39 | 87 | elsif ( $country_language =~ /^zh_CN|chin(?:a|ese)$/i ) { |
d1256cb1 RGS |
88 | $locale_encoding = 'euc-cn'; |
89 | } | |
90 | elsif ( $country_language =~ /^zh_TW|taiwan(?:ese)?$/i ) { | |
91 | $locale_encoding = 'euc-tw'; | |
92 | } | |
93 | else { | |
94 | require Carp; | |
95 | Carp::croak( | |
96 | "encoding: Locale encoding '$locale_encoding' too ambiguous" | |
97 | ); | |
98 | } | |
b1aeb384 JH |
99 | } |
100 | ||
101 | return $locale_encoding; | |
102 | } | |
103 | ||
3ef515df JH |
104 | sub import { |
105 | my $class = shift; | |
106 | my $name = shift; | |
d1256cb1 RGS |
107 | if ( $name eq ':_get_locale_encoding' ) { # used by lib/open.pm |
108 | my $caller = caller(); | |
b1aeb384 | 109 | { |
d1256cb1 RGS |
110 | no strict 'refs'; |
111 | *{"${caller}::_get_locale_encoding"} = \&_get_locale_encoding; | |
112 | } | |
113 | return; | |
b1aeb384 JH |
114 | } |
115 | $name = _get_locale_encoding() if $name eq ':locale'; | |
3ef515df | 116 | my %arg = @_; |
b1aeb384 | 117 | $name = $ENV{PERL_ENCODING} unless defined $name; |
3ef515df | 118 | my $enc = find_encoding($name); |
d1256cb1 RGS |
119 | unless ( defined $enc ) { |
120 | require Carp; | |
121 | Carp::croak("encoding: Unknown encoding '$name'"); | |
122 | } | |
123 | $name = $enc->name; # canonize | |
124 | unless ( $arg{Filter} ) { | |
125 | DEBUG and warn "_exception($name) = ", _exception($name); | |
126 | _exception($name) or ${^ENCODING} = $enc; | |
127 | $HAS_PERLIO or return 1; | |
3ef515df | 128 | } |
d1256cb1 RGS |
129 | else { |
130 | defined( ${^ENCODING} ) and undef ${^ENCODING}; | |
131 | ||
132 | # implicitly 'use utf8' | |
133 | require utf8; # to fetch $utf8::hint_bits; | |
134 | $^H |= $utf8::hint_bits; | |
135 | eval { | |
136 | require Filter::Util::Call; | |
137 | Filter::Util::Call->import; | |
138 | filter_add( | |
139 | sub { | |
140 | my $status = filter_read(); | |
141 | if ( $status > 0 ) { | |
142 | $_ = $enc->decode( $_, 1 ); | |
143 | DEBUG and warn $_; | |
144 | } | |
145 | $status; | |
146 | } | |
147 | ); | |
148 | }; | |
d7fe8a7a | 149 | $@ eq '' and DEBUG and warn "Filter installed"; |
b1aeb384 | 150 | } |
05ef2f67 | 151 | defined ${^UNICODE} and ${^UNICODE} != 0 and return 1; |
d1256cb1 RGS |
152 | for my $h (qw(STDIN STDOUT)) { |
153 | if ( $arg{$h} ) { | |
154 | unless ( defined find_encoding( $arg{$h} ) ) { | |
155 | require Carp; | |
156 | Carp::croak( | |
157 | "encoding: Unknown encoding for $h, '$arg{$h}'"); | |
158 | } | |
159 | eval { binmode( $h, ":raw :encoding($arg{$h})" ) }; | |
160 | } | |
161 | else { | |
162 | unless ( exists $arg{$h} ) { | |
163 | eval { | |
164 | no warnings 'uninitialized'; | |
165 | binmode( $h, ":raw :encoding($name)" ); | |
166 | }; | |
167 | } | |
168 | } | |
169 | if ($@) { | |
170 | require Carp; | |
171 | Carp::croak($@); | |
172 | } | |
3ef515df | 173 | } |
d1256cb1 | 174 | return 1; # I doubt if we need it, though |
3ef515df JH |
175 | } |
176 | ||
d1256cb1 | 177 | sub unimport { |
3ef515df JH |
178 | no warnings; |
179 | undef ${^ENCODING}; | |
d1256cb1 RGS |
180 | if ($HAS_PERLIO) { |
181 | binmode( STDIN, ":raw" ); | |
182 | binmode( STDOUT, ":raw" ); | |
183 | } | |
184 | else { | |
185 | binmode(STDIN); | |
186 | binmode(STDOUT); | |
621b0f8d | 187 | } |
d1256cb1 RGS |
188 | if ( $INC{"Filter/Util/Call.pm"} ) { |
189 | eval { filter_del() }; | |
aae85ceb | 190 | } |
3ef515df JH |
191 | } |
192 | ||
193 | 1; | |
194 | __END__ | |
85982a32 | 195 | |
3ef515df JH |
196 | =pod |
197 | ||
198 | =head1 NAME | |
199 | ||
0ab8f81e | 200 | encoding - allows you to write your script in non-ascii or non-utf8 |
3ef515df JH |
201 | |
202 | =head1 SYNOPSIS | |
203 | ||
962111ca | 204 | use encoding "greek"; # Perl like Greek to you? |
3ef515df JH |
205 | use encoding "euc-jp"; # Jperl! |
206 | ||
962111ca | 207 | # or you can even do this if your shell supports your native encoding |
3ef515df | 208 | |
962111ca | 209 | perl -Mencoding=latin2 -e '...' # Feeling centrally European? |
0ab8f81e | 210 | perl -Mencoding=euc-kr -e '...' # Or Korean? |
3ef515df | 211 | |
3ef515df JH |
212 | # more control |
213 | ||
962111ca | 214 | # A simple euc-cn => utf-8 converter |
6d1c0808 | 215 | use encoding "euc-cn", STDOUT => "utf8"; while(<>){print}; |
3ef515df JH |
216 | |
217 | # "no encoding;" supported (but not scoped!) | |
218 | no encoding; | |
219 | ||
aae85ceb DK |
220 | # an alternate way, Filter |
221 | use encoding "euc-jp", Filter=>1; | |
aae85ceb DK |
222 | # now you can use kanji identifiers -- in euc-jp! |
223 | ||
b1aeb384 JH |
224 | # switch on locale - |
225 | # note that this probably means that unless you have a complete control | |
226 | # over the environments the application is ever going to be run, you should | |
227 | # NOT use the feature of encoding pragma allowing you to write your script | |
228 | # in any recognized encoding because changing locale settings will wreck | |
229 | # the script; you can of course still use the other features of the pragma. | |
230 | use encoding ':locale'; | |
231 | ||
3ef515df JH |
232 | =head1 ABSTRACT |
233 | ||
962111ca JH |
234 | Let's start with a bit of history: Perl 5.6.0 introduced Unicode |
235 | support. You could apply C<substr()> and regexes even to complex CJK | |
236 | characters -- so long as the script was written in UTF-8. But back | |
0ab8f81e JH |
237 | then, text editors that supported UTF-8 were still rare and many users |
238 | instead chose to write scripts in legacy encodings, giving up a whole | |
239 | new feature of Perl 5.6. | |
3ef515df | 240 | |
0ab8f81e | 241 | Rewind to the future: starting from perl 5.8.0 with the B<encoding> |
962111ca JH |
242 | pragma, you can write your script in any encoding you like (so long |
243 | as the C<Encode> module supports it) and still enjoy Unicode support. | |
0f29a567 | 244 | This pragma achieves that by doing the following: |
05ef2f67 JH |
245 | |
246 | =over | |
247 | ||
248 | =item * | |
249 | ||
250 | Internally converts all literals (C<q//,qq//,qr//,qw///, qx//>) from | |
251 | the encoding specified to utf8. In Perl 5.8.1 and later, literals in | |
252 | C<tr///> and C<DATA> pseudo-filehandle are also converted. | |
253 | ||
254 | =item * | |
255 | ||
256 | Changing PerlIO layers of C<STDIN> and C<STDOUT> to the encoding | |
257 | specified. | |
258 | ||
259 | =back | |
260 | ||
261 | =head2 Literal Conversions | |
262 | ||
0ab8f81e | 263 | You can write code in EUC-JP as follows: |
3ef515df JH |
264 | |
265 | my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji | |
266 | #<-char-><-char-> # 4 octets | |
267 | s/\bCamel\b/$Rakuda/; | |
268 | ||
269 | And with C<use encoding "euc-jp"> in effect, it is the same thing as | |
962111ca | 270 | the code in UTF-8: |
3ef515df | 271 | |
32b9ed1f | 272 | my $Rakuda = "\x{99F1}\x{99DD}"; # two Unicode Characters |
3ef515df JH |
273 | s/\bCamel\b/$Rakuda/; |
274 | ||
05ef2f67 JH |
275 | =head2 PerlIO layers for C<STD(IN|OUT)> |
276 | ||
277 | The B<encoding> pragma also modifies the filehandle layers of | |
4b291ae6 | 278 | STDIN and STDOUT to the specified encoding. Therefore, |
3ef515df JH |
279 | |
280 | use encoding "euc-jp"; | |
281 | my $message = "Camel is the symbol of perl.\n"; | |
282 | my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji | |
283 | $message =~ s/\bCamel\b/$Rakuda/; | |
284 | print $message; | |
285 | ||
962111ca JH |
286 | Will print "\xF1\xD1\xF1\xCC is the symbol of perl.\n", |
287 | not "\x{99F1}\x{99DD} is the symbol of perl.\n". | |
3ef515df | 288 | |
0ab8f81e | 289 | You can override this by giving extra arguments; see below. |
3ef515df | 290 | |
990e18f7 AT |
291 | =head2 Implicit upgrading for byte strings |
292 | ||
293 | By default, if strings operating under byte semantics and strings | |
294 | with Unicode character data are concatenated, the new string will | |
295 | be created by decoding the byte strings as I<ISO 8859-1 (Latin-1)>. | |
296 | ||
297 | The B<encoding> pragma changes this to use the specified encoding | |
298 | instead. For example: | |
299 | ||
300 | use encoding 'utf8'; | |
301 | my $string = chr(20000); # a Unicode string | |
302 | utf8::encode($string); # now it's a UTF-8 encoded byte string | |
303 | # concatenate with another Unicode string | |
304 | print length($string . chr(20000)); | |
305 | ||
306 | Will print C<2>, because C<$string> is upgraded as UTF-8. Without | |
307 | C<use encoding 'utf8';>, it will print C<4> instead, since C<$string> | |
308 | is three octets when interpreted as Latin-1. | |
309 | ||
2575c402 JW |
310 | =head2 Side effects |
311 | ||
312 | If the C<encoding> pragma is in scope then the lengths returned are | |
313 | calculated from the length of C<$/> in Unicode characters, which is not | |
314 | always the same as the length of C<$/> in the native encoding. | |
315 | ||
316 | This pragma affects utf8::upgrade, but not utf8::downgrade. | |
317 | ||
51e4e64d NC |
318 | =head2 Side effects |
319 | ||
320 | If the C<encoding> pragma is in scope then the lengths returned are | |
321 | calculated from the length of C<$/> in Unicode characters, which is not | |
322 | always the same as the length of C<$/> in the native encoding. | |
323 | ||
324 | This pragma affects utf8::upgrade, but not utf8::downgrade. | |
325 | ||
44b3b9c7 SP |
326 | =head2 Side effects |
327 | ||
328 | If the C<encoding> pragma is in scope then the lengths returned are | |
329 | calculated from the length of C<$/> in Unicode characters, which is not | |
330 | always the same as the length of C<$/> in the native encoding. | |
331 | ||
332 | This pragma affects utf8::upgrade, but not utf8::downgrade. | |
333 | ||
05ef2f67 JH |
334 | =head1 FEATURES THAT REQUIRE 5.8.1 |
335 | ||
336 | Some of the features offered by this pragma requires perl 5.8.1. Most | |
0f29a567 | 337 | of these are done by Inaba Hiroto. Any other features and changes |
05ef2f67 JH |
338 | are good for 5.8.0. |
339 | ||
340 | =over | |
341 | ||
342 | =item "NON-EUC" doublebyte encodings | |
343 | ||
0f29a567 | 344 | Because perl needs to parse script before applying this pragma, such |
05ef2f67 JH |
345 | encodings as Shift_JIS and Big-5 that may contain '\' (BACKSLASH; |
346 | \x5c) in the second byte fails because the second byte may | |
0f29a567 | 347 | accidentally escape the quoting character that follows. Perl 5.8.1 |
05ef2f67 JH |
348 | or later fixes this problem. |
349 | ||
350 | =item tr// | |
351 | ||
352 | C<tr//> was overlooked by Perl 5 porters when they released perl 5.8.0 | |
353 | See the section below for details. | |
354 | ||
355 | =item DATA pseudo-filehandle | |
356 | ||
357 | Another feature that was overlooked was C<DATA>. | |
358 | ||
359 | =back | |
360 | ||
3ef515df JH |
361 | =head1 USAGE |
362 | ||
363 | =over 4 | |
364 | ||
365 | =item use encoding [I<ENCNAME>] ; | |
366 | ||
05ef2f67 JH |
367 | Sets the script encoding to I<ENCNAME>. And unless ${^UNICODE} |
368 | exists and non-zero, PerlIO layers of STDIN and STDOUT are set to | |
369 | ":encoding(I<ENCNAME>)". | |
370 | ||
371 | Note that STDERR WILL NOT be changed. | |
372 | ||
373 | Also note that non-STD file handles remain unaffected. Use C<use | |
374 | open> or C<binmode> to change layers of those. | |
3ef515df JH |
375 | |
376 | If no encoding is specified, the environment variable L<PERL_ENCODING> | |
962111ca JH |
377 | is consulted. If no encoding can be found, the error C<Unknown encoding |
378 | 'I<ENCNAME>'> will be thrown. | |
3ef515df | 379 | |
aae85ceb | 380 | =item use encoding I<ENCNAME> [ STDIN =E<gt> I<ENCNAME_IN> ...] ; |
3ef515df | 381 | |
0ab8f81e | 382 | You can also individually set encodings of STDIN and STDOUT via the |
32b9ed1f A |
383 | C<< STDIN => I<ENCNAME> >> form. In this case, you cannot omit the |
384 | first I<ENCNAME>. C<< STDIN => undef >> turns the IO transcoding | |
aae85ceb | 385 | completely off. |
3ef515df | 386 | |
05ef2f67 JH |
387 | When ${^UNICODE} exists and non-zero, these options will completely |
388 | ignored. ${^UNICODE} is a variable introduced in perl 5.8.1. See | |
389 | L<perlrun> see L<perlvar/"${^UNICODE}"> and L<perlrun/"-C"> for | |
390 | details (perl 5.8.1 and later). | |
391 | ||
151b5d36 JH |
392 | =item use encoding I<ENCNAME> Filter=E<gt>1; |
393 | ||
394 | This turns the encoding pragma into a source filter. While the | |
395 | default approach just decodes interpolated literals (in qq() and | |
396 | qr()), this will apply a source filter to the entire source code. See | |
05ef2f67 | 397 | L</"The Filter Option"> below for details. |
151b5d36 | 398 | |
3ef515df JH |
399 | =item no encoding; |
400 | ||
05ef2f67 | 401 | Unsets the script encoding. The layers of STDIN, STDOUT are |
962111ca | 402 | reset to ":raw" (the default unprocessed raw stream of bytes). |
3ef515df JH |
403 | |
404 | =back | |
405 | ||
151b5d36 JH |
406 | =head1 The Filter Option |
407 | ||
408 | The magic of C<use encoding> is not applied to the names of | |
409 | identifiers. In order to make C<${"\x{4eba}"}++> ($human++, where human | |
410 | is a single Han ideograph) work, you still need to write your script | |
411 | in UTF-8 -- or use a source filter. That's what 'Filter=>1' does. | |
412 | ||
151b5d36 JH |
413 | What does this mean? Your source code behaves as if it is written in |
414 | UTF-8 with 'use utf8' in effect. So even if your editor only supports | |
415 | Shift_JIS, for example, you can still try examples in Chapter 15 of | |
416 | C<Programming Perl, 3rd Ed.>. For instance, you can use UTF-8 | |
417 | identifiers. | |
418 | ||
419 | This option is significantly slower and (as of this writing) non-ASCII | |
420 | identifiers are not very stable WITHOUT this option and with the | |
421 | source code written in UTF-8. | |
422 | ||
423 | =head2 Filter-related changes at Encode version 1.87 | |
424 | ||
425 | =over | |
426 | ||
427 | =item * | |
428 | ||
429 | The Filter option now sets STDIN and STDOUT like non-filter options. | |
430 | And C<< STDIN=>I<ENCODING> >> and C<< STDOUT=>I<ENCODING> >> work like | |
431 | non-filter version. | |
432 | ||
433 | =item * | |
434 | ||
435 | C<use utf8> is implicitly declared so you no longer have to C<use | |
436 | utf8> to C<${"\x{4eba}"}++>. | |
437 | ||
438 | =back | |
439 | ||
3ef515df JH |
440 | =head1 CAVEATS |
441 | ||
442 | =head2 NOT SCOPED | |
443 | ||
444 | The pragma is a per script, not a per block lexical. Only the last | |
621b0f8d DK |
445 | C<use encoding> or C<no encoding> matters, and it affects |
446 | B<the whole script>. However, the <no encoding> pragma is supported and | |
447 | B<use encoding> can appear as many times as you want in a given script. | |
448 | The multiple use of this pragma is discouraged. | |
449 | ||
0f29a567 | 450 | By the same reason, the use this pragma inside modules is also |
3c4b39be | 451 | discouraged (though not as strongly discouraged as the case above. |
0f29a567 | 452 | See below). |
05ef2f67 JH |
453 | |
454 | If you still have to write a module with this pragma, be very careful | |
455 | of the load order. See the codes below; | |
456 | ||
457 | # called module | |
458 | package Module_IN_BAR; | |
459 | use encoding "bar"; | |
460 | # stuff in "bar" encoding here | |
461 | 1; | |
462 | ||
463 | # caller script | |
464 | use encoding "foo" | |
465 | use Module_IN_BAR; | |
466 | # surprise! use encoding "bar" is in effect. | |
467 | ||
468 | The best way to avoid this oddity is to use this pragma RIGHT AFTER | |
469 | other modules are loaded. i.e. | |
470 | ||
471 | use Module_IN_BAR; | |
472 | use encoding "foo"; | |
3ef515df JH |
473 | |
474 | =head2 DO NOT MIX MULTIPLE ENCODINGS | |
475 | ||
476 | Notice that only literals (string or regular expression) having only | |
477 | legacy code points are affected: if you mix data like this | |
478 | ||
d1256cb1 | 479 | \xDF\x{100} |
3ef515df JH |
480 | |
481 | the data is assumed to be in (Latin 1 and) Unicode, not in your native | |
482 | encoding. In other words, this will match in "greek": | |
483 | ||
d1256cb1 | 484 | "\xDF" =~ /\x{3af}/ |
3ef515df JH |
485 | |
486 | but this will not | |
487 | ||
d1256cb1 | 488 | "\xDF\x{100}" =~ /\x{3af}\x{100}/ |
3ef515df | 489 | |
962111ca JH |
490 | since the C<\xDF> (ISO 8859-7 GREEK SMALL LETTER IOTA WITH TONOS) on |
491 | the left will B<not> be upgraded to C<\x{3af}> (Unicode GREEK SMALL | |
492 | LETTER IOTA WITH TONOS) because of the C<\x{100}> on the left. You | |
493 | should not be mixing your legacy data and Unicode in the same string. | |
3ef515df JH |
494 | |
495 | This pragma also affects encoding of the 0x80..0xFF code point range: | |
496 | normally characters in that range are left as eight-bit bytes (unless | |
497 | they are combined with characters with code points 0x100 or larger, | |
498 | in which case all characters need to become UTF-8 encoded), but if | |
499 | the C<encoding> pragma is present, even the 0x80..0xFF range always | |
500 | gets UTF-8 encoded. | |
501 | ||
502 | After all, the best thing about this pragma is that you don't have to | |
0ab8f81e JH |
503 | resort to \x{....} just to spell your name in a native encoding. |
504 | So feel free to put your strings in your encoding in quotes and | |
505 | regexes. | |
3ef515df | 506 | |
151b5d36 | 507 | =head2 tr/// with ranges |
4b291ae6 DK |
508 | |
509 | The B<encoding> pragma works by decoding string literals in | |
151b5d36 | 510 | C<q//,qq//,qr//,qw///, qx//> and so forth. In perl 5.8.0, this |
4b291ae6 DK |
511 | does not apply to C<tr///>. Therefore, |
512 | ||
513 | use encoding 'euc-jp'; | |
514 | #.... | |
515 | $kana =~ tr/\xA4\xA1-\xA4\xF3/\xA5\xA1-\xA5\xF3/; | |
516 | # -------- -------- -------- -------- | |
517 | ||
518 | Does not work as | |
519 | ||
520 | $kana =~ tr/\x{3041}-\x{3093}/\x{30a1}-\x{30f3}/; | |
521 | ||
522 | =over | |
523 | ||
524 | =item Legend of characters above | |
525 | ||
526 | utf8 euc-jp charnames::viacode() | |
527 | ----------------------------------------- | |
528 | \x{3041} \xA4\xA1 HIRAGANA LETTER SMALL A | |
529 | \x{3093} \xA4\xF3 HIRAGANA LETTER N | |
530 | \x{30a1} \xA5\xA1 KATAKANA LETTER SMALL A | |
531 | \x{30f3} \xA5\xF3 KATAKANA LETTER N | |
532 | ||
533 | =back | |
534 | ||
05ef2f67 | 535 | This counterintuitive behavior has been fixed in perl 5.8.1. |
151b5d36 | 536 | |
4b291ae6 DK |
537 | =head3 workaround to tr///; |
538 | ||
ce16148b | 539 | In perl 5.8.0, you can work around as follows; |
4b291ae6 DK |
540 | |
541 | use encoding 'euc-jp'; | |
151b5d36 | 542 | # .... |
4b291ae6 DK |
543 | eval qq{ \$kana =~ tr/\xA4\xA1-\xA4\xF3/\xA5\xA1-\xA5\xF3/ }; |
544 | ||
ce16148b | 545 | Note the C<tr//> expression is surrounded by C<qq{}>. The idea behind |
4b291ae6 DK |
546 | is the same as classic idiom that makes C<tr///> 'interpolate'. |
547 | ||
548 | tr/$from/$to/; # wrong! | |
549 | eval qq{ tr/$from/$to/ }; # workaround. | |
550 | ||
551 | Nevertheless, in case of B<encoding> pragma even C<q//> is affected so | |
552 | C<tr///> not being decoded was obviously against the will of Perl5 | |
05ef2f67 | 553 | Porters so it has been fixed in Perl 5.8.1 or later. |
aae85ceb | 554 | |
3ef515df JH |
555 | =head1 EXAMPLE - Greekperl |
556 | ||
557 | use encoding "iso 8859-7"; | |
558 | ||
0ab8f81e | 559 | # \xDF in ISO 8859-7 (Greek) is \x{3af} in Unicode. |
3ef515df JH |
560 | |
561 | $a = "\xDF"; | |
562 | $b = "\x{100}"; | |
563 | ||
564 | printf "%#x\n", ord($a); # will print 0x3af, not 0xdf | |
565 | ||
566 | $c = $a . $b; | |
567 | ||
568 | # $c will be "\x{3af}\x{100}", not "\x{df}\x{100}". | |
569 | ||
570 | # chr() is affected, and ... | |
571 | ||
572 | print "mega\n" if ord(chr(0xdf)) == 0x3af; | |
573 | ||
574 | # ... ord() is affected by the encoding pragma ... | |
575 | ||
576 | print "tera\n" if ord(pack("C", 0xdf)) == 0x3af; | |
577 | ||
578 | # ... as are eq and cmp ... | |
579 | ||
580 | print "peta\n" if "\x{3af}" eq pack("C", 0xdf); | |
581 | print "exa\n" if "\x{3af}" cmp pack("C", 0xdf) == 0; | |
582 | ||
583 | # ... but pack/unpack C are not affected, in case you still | |
0ab8f81e | 584 | # want to go back to your native encoding |
3ef515df JH |
585 | |
586 | print "zetta\n" if unpack("C", (pack("C", 0xdf))) == 0xdf; | |
587 | ||
588 | =head1 KNOWN PROBLEMS | |
589 | ||
151b5d36 JH |
590 | =over |
591 | ||
0f29a567 | 592 | =item literals in regex that are longer than 127 bytes |
151b5d36 | 593 | |
0ab8f81e | 594 | For native multibyte encodings (either fixed or variable length), |
3ef515df | 595 | the current implementation of the regular expressions may introduce |
0ab8f81e | 596 | recoding errors for regular expression literals longer than 127 bytes. |
3ef515df | 597 | |
05ef2f67 | 598 | =item EBCDIC |
151b5d36 | 599 | |
3ef515df | 600 | The encoding pragma is not supported on EBCDIC platforms. |
0ab8f81e JH |
601 | (Porters who are willing and able to remove this limitation are |
602 | welcome.) | |
3ef515df | 603 | |
05ef2f67 JH |
604 | =item format |
605 | ||
606 | This pragma doesn't work well with format because PerlIO does not | |
607 | get along very well with it. When format contains non-ascii | |
608 | characters it prints funny or gets "wide character warnings". | |
609 | To understand it, try the code below. | |
610 | ||
611 | # Save this one in utf8 | |
612 | # replace *non-ascii* with a non-ascii string | |
613 | my $camel; | |
614 | format STDOUT = | |
615 | *non-ascii*@>>>>>>> | |
616 | $camel | |
617 | . | |
618 | $camel = "*non-ascii*"; | |
619 | binmode(STDOUT=>':encoding(utf8)'); # bang! | |
620 | write; # funny | |
621 | print $camel, "\n"; # fine | |
622 | ||
623 | Without binmode this happens to work but without binmode, print() | |
624 | fails instead of write(). | |
625 | ||
626 | At any rate, the very use of format is questionable when it comes to | |
627 | unicode characters since you have to consider such things as character | |
628 | width (i.e. double-width for ideographs) and directions (i.e. BIDI for | |
629 | Arabic and Hebrew). | |
630 | ||
7303322e RGS |
631 | =item Thread safety |
632 | ||
633 | C<use encoding ...> is not thread-safe (i.e., do not use in threaded | |
634 | applications). | |
635 | ||
151b5d36 JH |
636 | =back |
637 | ||
b1aeb384 JH |
638 | =head2 The Logic of :locale |
639 | ||
640 | The logic of C<:locale> is as follows: | |
641 | ||
642 | =over 4 | |
643 | ||
644 | =item 1. | |
645 | ||
646 | If the platform supports the langinfo(CODESET) interface, the codeset | |
647 | returned is used as the default encoding for the open pragma. | |
648 | ||
649 | =item 2. | |
650 | ||
651 | If 1. didn't work but we are under the locale pragma, the environment | |
652 | variables LC_ALL and LANG (in that order) are matched for encodings | |
653 | (the part after C<.>, if any), and if any found, that is used | |
654 | as the default encoding for the open pragma. | |
655 | ||
656 | =item 3. | |
657 | ||
658 | If 1. and 2. didn't work, the environment variables LC_ALL and LANG | |
659 | (in that order) are matched for anything looking like UTF-8, and if | |
660 | any found, C<:utf8> is used as the default encoding for the open | |
661 | pragma. | |
662 | ||
663 | =back | |
664 | ||
665 | If your locale environment variables (LC_ALL, LC_CTYPE, LANG) | |
666 | contain the strings 'UTF-8' or 'UTF8' (case-insensitive matching), | |
667 | the default encoding of your STDIN, STDOUT, and STDERR, and of | |
668 | B<any subsequent file open>, is UTF-8. | |
669 | ||
05ef2f67 JH |
670 | =head1 HISTORY |
671 | ||
672 | This pragma first appeared in Perl 5.8.0. For features that require | |
673 | 5.8.1 and better, see above. | |
674 | ||
b1aeb384 JH |
675 | The C<:locale> subpragma was implemented in 2.01, or Perl 5.8.6. |
676 | ||
3ef515df JH |
677 | =head1 SEE ALSO |
678 | ||
aae85ceb DK |
679 | L<perlunicode>, L<Encode>, L<open>, L<Filter::Util::Call>, |
680 | ||
681 | Ch. 15 of C<Programming Perl (3rd Edition)> | |
682 | by Larry Wall, Tom Christiansen, Jon Orwant; | |
683 | O'Reilly & Associates; ISBN 0-596-00027-8 | |
3ef515df JH |
684 | |
685 | =cut |