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86530b38 AT |
1 | package open; |
2 | use warnings; | |
3 | use Carp; | |
4 | $open::hint_bits = 0x20000; | |
5 | ||
6 | our $VERSION = '1.01'; | |
7 | ||
8 | my $locale_encoding; | |
9 | ||
10 | sub in_locale { $^H & ($locale::hint_bits || 0)} | |
11 | ||
12 | sub _get_locale_encoding { | |
13 | unless (defined $locale_encoding) { | |
14 | # I18N::Langinfo isn't available everywhere | |
15 | eval { | |
16 | require I18N::Langinfo; | |
17 | I18N::Langinfo->import(qw(langinfo CODESET)); | |
18 | $locale_encoding = langinfo(CODESET()); | |
19 | }; | |
20 | my $country_language; | |
21 | ||
22 | no warnings 'uninitialized'; | |
23 | ||
24 | if (not $locale_encoding && in_locale()) { | |
25 | if ($ENV{LC_ALL} =~ /^([^.]+)\.([^.]+)$/) { | |
26 | ($country_language, $locale_encoding) = ($1, $2); | |
27 | } elsif ($ENV{LANG} =~ /^([^.]+)\.([^.]+)$/) { | |
28 | ($country_language, $locale_encoding) = ($1, $2); | |
29 | } | |
30 | } elsif (not $locale_encoding) { | |
31 | if ($ENV{LC_ALL} =~ /\butf-?8\b/i || | |
32 | $ENV{LANG} =~ /\butf-?8\b/i) { | |
33 | $locale_encoding = 'utf8'; | |
34 | } | |
35 | # Could do more heuristics based on the country and language | |
36 | # parts of LC_ALL and LANG (the parts before the dot (if any)), | |
37 | # since we have Locale::Country and Locale::Language available. | |
38 | # TODO: get a database of Language -> Encoding mappings | |
39 | # (the Estonian database at http://www.eki.ee/letter/ | |
40 | # would be excellent!) --jhi | |
41 | } | |
42 | if (defined $locale_encoding && | |
43 | $locale_encoding eq 'euc' && | |
44 | defined $country_language) { | |
45 | if ($country_language =~ /^ja_JP|japan(?:ese)?$/i) { | |
46 | $locale_encoding = 'euc-jp'; | |
47 | } elsif ($country_language =~ /^ko_KR|korean?$/i) { | |
48 | $locale_encoding = 'euc-kr'; | |
49 | } elsif ($country_language =~ /^zh_CN|chin(?:a|ese)?$/i) { | |
50 | $locale_encoding = 'euc-cn'; | |
51 | } elsif ($country_language =~ /^zh_TW|taiwan(?:ese)?$/i) { | |
52 | $locale_encoding = 'euc-tw'; | |
53 | } | |
54 | croak "Locale encoding 'euc' too ambiguous" | |
55 | if $locale_encoding eq 'euc'; | |
56 | } | |
57 | } | |
58 | } | |
59 | ||
60 | sub import { | |
61 | my ($class,@args) = @_; | |
62 | croak("`use open' needs explicit list of PerlIO layers") unless @args; | |
63 | my $std; | |
64 | $^H |= $open::hint_bits; | |
65 | my ($in,$out) = split(/\0/,(${^OPEN} || "\0"), -1); | |
66 | while (@args) { | |
67 | my $type = shift(@args); | |
68 | my $dscp; | |
69 | if ($type =~ /^:?(utf8|locale|encoding\(.+\))$/) { | |
70 | $type = 'IO'; | |
71 | $dscp = ":$1"; | |
72 | } elsif ($type eq ':std') { | |
73 | $std = 1; | |
74 | next; | |
75 | } else { | |
76 | $dscp = shift(@args) || ''; | |
77 | } | |
78 | my @val; | |
79 | foreach my $layer (split(/\s+/,$dscp)) { | |
80 | $layer =~ s/^://; | |
81 | if ($layer eq 'locale') { | |
82 | use Encode; | |
83 | _get_locale_encoding() | |
84 | unless defined $locale_encoding; | |
85 | (warnings::warnif("layer", "Cannot figure out an encoding to use"), last) | |
86 | unless defined $locale_encoding; | |
87 | if ($locale_encoding =~ /^utf-?8$/i) { | |
88 | $layer = "utf8"; | |
89 | } else { | |
90 | $layer = "encoding($locale_encoding)"; | |
91 | } | |
92 | $std = 1; | |
93 | } else { | |
94 | my $target = $layer; # the layer name itself | |
95 | $target =~ s/^(\w+)\(.+\)$/$1/; # strip parameters | |
96 | ||
97 | unless(PerlIO::Layer::->find($target)) { | |
98 | warnings::warnif("layer", "Unknown PerlIO layer '$layer'"); | |
99 | } | |
100 | } | |
101 | push(@val,":$layer"); | |
102 | if ($layer =~ /^(crlf|raw)$/) { | |
103 | $^H{"open_$type"} = $layer; | |
104 | } | |
105 | } | |
106 | if ($type eq 'IN') { | |
107 | $in = join(' ',@val); | |
108 | } | |
109 | elsif ($type eq 'OUT') { | |
110 | $out = join(' ',@val); | |
111 | } | |
112 | elsif ($type eq 'IO') { | |
113 | $in = $out = join(' ',@val); | |
114 | } | |
115 | else { | |
116 | croak "Unknown PerlIO layer class '$type'"; | |
117 | } | |
118 | } | |
119 | ${^OPEN} = join("\0",$in,$out) if $in or $out; | |
120 | if ($std) { | |
121 | if ($in) { | |
122 | if ($in =~ /:utf8\b/) { | |
123 | binmode(STDIN, ":utf8"); | |
124 | } elsif ($in =~ /(\w+\(.+\))/) { | |
125 | binmode(STDIN, ":$1"); | |
126 | } | |
127 | } | |
128 | if ($out) { | |
129 | if ($out =~ /:utf8\b/) { | |
130 | binmode(STDOUT, ":utf8"); | |
131 | binmode(STDERR, ":utf8"); | |
132 | } elsif ($out =~ /(\w+\(.+\))/) { | |
133 | binmode(STDOUT, ":$1"); | |
134 | binmode(STDERR, ":$1"); | |
135 | } | |
136 | } | |
137 | } | |
138 | } | |
139 | ||
140 | 1; | |
141 | __END__ | |
142 | ||
143 | =head1 NAME | |
144 | ||
145 | open - perl pragma to set default PerlIO layers for input and output | |
146 | ||
147 | =head1 SYNOPSIS | |
148 | ||
149 | use open IN => ":crlf", OUT => ":bytes"; | |
150 | use open OUT => ':utf8'; | |
151 | use open IO => ":encoding(iso-8859-7)"; | |
152 | ||
153 | use open IO => ':locale'; | |
154 | ||
155 | use open ':utf8'; | |
156 | use open ':locale'; | |
157 | use open ':encoding(iso-8859-7)'; | |
158 | ||
159 | use open ':std'; | |
160 | ||
161 | =head1 DESCRIPTION | |
162 | ||
163 | Full-fledged support for I/O layers is now implemented provided | |
164 | Perl is configured to use PerlIO as its IO system (which is now the | |
165 | default). | |
166 | ||
167 | The C<open> pragma serves as one of the interfaces to declare default | |
168 | "layers" (also known as "disciplines") for all I/O. Any open(), | |
169 | readpipe() (aka qx//) and similar operators found within the lexical | |
170 | scope of this pragma will use the declared defaults. | |
171 | ||
172 | With the C<IN> subpragma you can declare the default layers | |
173 | of input streams, and with the C<OUT> subpragma you can declare | |
174 | the default layers of output streams. With the C<IO> subpragma | |
175 | you can control both input and output streams simultaneously. | |
176 | ||
177 | If you have a legacy encoding, you can use the C<:encoding(...)> tag. | |
178 | ||
179 | if you want to set your encoding layers based on your | |
180 | locale environment variables, you can use the C<:locale> tag. | |
181 | For example: | |
182 | ||
183 | $ENV{LANG} = 'ru_RU.KOI8-R'; | |
184 | # the :locale will probe the locale environment variables like LANG | |
185 | use open OUT => ':locale'; | |
186 | open(O, ">koi8"); | |
187 | print O chr(0x430); # Unicode CYRILLIC SMALL LETTER A = KOI8-R 0xc1 | |
188 | close O; | |
189 | open(I, "<koi8"); | |
190 | printf "%#x\n", ord(<I>), "\n"; # this should print 0xc1 | |
191 | close I; | |
192 | ||
193 | These are equivalent | |
194 | ||
195 | use open ':utf8'; | |
196 | use open IO => ':utf8'; | |
197 | ||
198 | as are these | |
199 | ||
200 | use open ':locale'; | |
201 | use open IO => ':locale'; | |
202 | ||
203 | and these | |
204 | ||
205 | use open ':encoding(iso-8859-7)'; | |
206 | use open IO => ':encoding(iso-8859-7)'; | |
207 | ||
208 | The matching of encoding names is loose: case does not matter, and | |
209 | many encodings have several aliases. See L<Encode::Supported> for | |
210 | details and the list of supported locales. | |
211 | ||
212 | Note that C<:utf8> PerlIO layer must always be specified exactly like | |
213 | that, it is not subject to the loose matching of encoding names. | |
214 | ||
215 | When open() is given an explicit list of layers they are appended to | |
216 | the list declared using this pragma. | |
217 | ||
218 | The C<:std> subpragma on its own has no effect, but if combined with | |
219 | the C<:utf8> or C<:encoding> subpragmas, it converts the standard | |
220 | filehandles (STDIN, STDOUT, STDERR) to comply with encoding selected | |
221 | for input/output handles. For example, if both input and out are | |
222 | chosen to be C<:utf8>, a C<:std> will mean that STDIN, STDOUT, and | |
223 | STDERR are also in C<:utf8>. On the other hand, if only output is | |
224 | chosen to be in C<< :encoding(koi8r) >>, a C<:std> will cause only the | |
225 | STDOUT and STDERR to be in C<koi8r>. The C<:locale> subpragma | |
226 | implicitly turns on C<:std>. | |
227 | ||
228 | The logic of C<:locale> is as follows: | |
229 | ||
230 | =over 4 | |
231 | ||
232 | =item 1. | |
233 | ||
234 | If the platform supports the langinfo(CODESET) interface, the codeset | |
235 | returned is used as the default encoding for the open pragma. | |
236 | ||
237 | =item 2. | |
238 | ||
239 | If 1. didn't work but we are under the locale pragma, the environment | |
240 | variables LC_ALL and LANG (in that order) are matched for encodings | |
241 | (the part after C<.>, if any), and if any found, that is used | |
242 | as the default encoding for the open pragma. | |
243 | ||
244 | =item 3. | |
245 | ||
246 | If 1. and 2. didn't work, the environment variables LC_ALL and LANG | |
247 | (in that order) are matched for anything looking like UTF-8, and if | |
248 | any found, C<:utf8> is used as the default encoding for the open | |
249 | pragma. | |
250 | ||
251 | =back | |
252 | ||
253 | If your locale environment variables (LANGUAGE, LC_ALL, LC_CTYPE, LANG) | |
254 | contain the strings 'UTF-8' or 'UTF8' (case-insensitive matching), | |
255 | the default encoding of your STDIN, STDOUT, and STDERR, and of | |
256 | B<any subsequent file open>, is UTF-8. | |
257 | ||
258 | Directory handles may also support PerlIO layers in the future. | |
259 | ||
260 | =head1 NONPERLIO FUNCTIONALITY | |
261 | ||
262 | If Perl is not built to use PerlIO as its IO system then only the two | |
263 | pseudo-layers C<:bytes> and C<:crlf> are available. | |
264 | ||
265 | The C<:bytes> layer corresponds to "binary mode" and the C<:crlf> | |
266 | layer corresponds to "text mode" on platforms that distinguish | |
267 | between the two modes when opening files (which is many DOS-like | |
268 | platforms, including Windows). These two layers are no-ops on | |
269 | platforms where binmode() is a no-op, but perform their functions | |
270 | everywhere if PerlIO is enabled. | |
271 | ||
272 | =head1 IMPLEMENTATION DETAILS | |
273 | ||
274 | There is a class method in C<PerlIO::Layer> C<find> which is | |
275 | implemented as XS code. It is called by C<import> to validate the | |
276 | layers: | |
277 | ||
278 | PerlIO::Layer::->find("perlio") | |
279 | ||
280 | The return value (if defined) is a Perl object, of class | |
281 | C<PerlIO::Layer> which is created by the C code in F<perlio.c>. As | |
282 | yet there is nothing useful you can do with the object at the perl | |
283 | level. | |
284 | ||
285 | =head1 SEE ALSO | |
286 | ||
287 | L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>, L<PerlIO>, | |
288 | L<encoding> | |
289 | ||
290 | =cut |