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1 | package open; |
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2 | use Carp; |
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3 | $open::hint_bits = 0x20000; |
4 | |
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5 | our $VERSION = '1.01'; |
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6 | |
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7 | my $locale_encoding; |
8 | |
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9 | sub in_locale { $^H & ($locale::hint_bits || 0)} |
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10 | |
11 | sub _get_locale_encoding { |
12 | unless (defined $locale_encoding) { |
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13 | # I18N::Langinfo isn't available everywhere |
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14 | eval { |
15 | require I18N::Langinfo; |
16 | I18N::Langinfo->import(qw(langinfo CODESET)); |
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17 | $locale_encoding = langinfo(CODESET()); |
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18 | }; |
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19 | my $country_language; |
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20 | |
21 | no warnings 'uninitialized'; |
22 | |
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23 | if (not $locale_encoding && in_locale()) { |
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24 | if ($ENV{LC_ALL} =~ /^([^.]+)\.([^.]+)$/) { |
25 | ($country_language, $locale_encoding) = ($1, $2); |
26 | } elsif ($ENV{LANG} =~ /^([^.]+)\.([^.]+)$/) { |
27 | ($country_language, $locale_encoding) = ($1, $2); |
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28 | } |
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29 | } elsif (not $locale_encoding) { |
30 | if ($ENV{LC_ALL} =~ /\butf-?8\b/i || |
31 | $ENV{LANG} =~ /\butf-?8\b/i) { |
32 | $locale_encoding = 'utf8'; |
33 | } |
34 | # Could do more heuristics based on the country and language |
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35 | # parts of LC_ALL and LANG (the parts before the dot (if any)), |
36 | # since we have Locale::Country and Locale::Language available. |
37 | # TODO: get a database of Language -> Encoding mappings |
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38 | # (the Estonian database at http://www.eki.ee/letter/ |
39 | # would be excellent!) --jhi |
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40 | } |
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41 | if (defined $locale_encoding && |
42 | $locale_encoding eq 'euc' && |
43 | defined $country_language) { |
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44 | if ($country_language =~ /^ja_JP|japan(?:ese)?$/i) { |
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45 | $locale_encoding = 'euc-jp'; |
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46 | } elsif ($country_language =~ /^ko_KR|korean?$/i) { |
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47 | $locale_encoding = 'euc-kr'; |
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48 | } elsif ($country_language =~ /^zh_CN|chin(?:a|ese)?$/i) { |
49 | $locale_encoding = 'euc-cn'; |
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50 | } elsif ($country_language =~ /^zh_TW|taiwan(?:ese)?$/i) { |
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51 | $locale_encoding = 'big5'; |
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52 | } |
53 | croak "Locale encoding 'euc' too ambiguous" |
54 | if $locale_encoding eq 'euc'; |
55 | } |
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56 | } |
57 | } |
58 | |
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59 | sub import { |
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60 | my ($class,@args) = @_; |
61 | croak("`use open' needs explicit list of disciplines") unless @args; |
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62 | my $std; |
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63 | $^H |= $open::hint_bits; |
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64 | my ($in,$out) = split(/\0/,(${^OPEN} || "\0"), -1); |
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65 | while (@args) { |
66 | my $type = shift(@args); |
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67 | my $dscp; |
68 | if ($type =~ /^:?(utf8|locale|encoding\(.+\))$/) { |
69 | $type = 'IO'; |
70 | $dscp = ":$1"; |
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71 | } elsif ($type eq ':std') { |
72 | $std = 1; |
73 | next; |
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74 | } else { |
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75 | $dscp = shift(@args) || ''; |
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76 | } |
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77 | my @val; |
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78 | foreach my $layer (split(/\s+/,$dscp)) { |
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79 | $layer =~ s/^://; |
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80 | if ($layer eq 'locale') { |
81 | use Encode; |
82 | _get_locale_encoding() |
83 | unless defined $locale_encoding; |
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84 | (carp("Cannot figure out an encoding to use"), last) |
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85 | unless defined $locale_encoding; |
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86 | if ($locale_encoding =~ /^utf-?8$/i) { |
87 | $layer = "utf8"; |
88 | } else { |
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89 | $layer = "encoding($locale_encoding)"; |
11fc5dc3 |
90 | } |
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91 | $std = 1; |
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92 | } else { |
93 | unless(PerlIO::Layer::->find($layer)) { |
94 | carp("Unknown discipline layer '$layer'"); |
95 | } |
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96 | } |
97 | push(@val,":$layer"); |
98 | if ($layer =~ /^(crlf|raw)$/) { |
99 | $^H{"open_$type"} = $layer; |
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100 | } |
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101 | } |
102 | if ($type eq 'IN') { |
103 | $in = join(' ',@val); |
104 | } |
105 | elsif ($type eq 'OUT') { |
106 | $out = join(' ',@val); |
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107 | } |
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108 | elsif ($type eq 'IO') { |
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109 | $in = $out = join(' ',@val); |
110 | } |
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111 | else { |
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112 | croak "Unknown discipline class '$type'"; |
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113 | } |
114 | } |
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115 | ${^OPEN} = join("\0",$in,$out) if $in or $out; |
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116 | if ($std) { |
117 | if ($in) { |
118 | if ($in =~ /:utf8\b/) { |
119 | binmode(STDIN, ":utf8"); |
120 | } elsif ($in =~ /(\w+\(.+\))/) { |
121 | binmode(STDIN, ":$1"); |
122 | } |
123 | } |
124 | if ($out) { |
125 | if ($out =~ /:utf8\b/) { |
126 | binmode(STDOUT, ":utf8"); |
127 | binmode(STDERR, ":utf8"); |
128 | } elsif ($out =~ /(\w+\(.+\))/) { |
129 | binmode(STDOUT, ":$1"); |
130 | binmode(STDERR, ":$1"); |
131 | } |
132 | } |
133 | } |
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134 | } |
135 | |
136 | 1; |
137 | __END__ |
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138 | |
139 | =head1 NAME |
140 | |
141 | open - perl pragma to set default disciplines for input and output |
142 | |
143 | =head1 SYNOPSIS |
144 | |
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145 | use open IN => ":crlf", OUT => ":raw"; |
146 | use open OUT => ':utf8'; |
147 | use open IO => ":encoding(iso-8859-7)"; |
148 | |
149 | use open IO => ':locale'; |
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150 | |
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151 | use open ':utf8'; |
152 | use open ':locale'; |
153 | use open ':encoding(iso-8859-7)'; |
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154 | |
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155 | use open ':std'; |
156 | |
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157 | =head1 DESCRIPTION |
158 | |
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159 | Full-fledged support for I/O disciplines is now implemented provided |
160 | Perl is configured to use PerlIO as its IO system (which is now the |
161 | default). |
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162 | |
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163 | The C<open> pragma serves as one of the interfaces to declare default |
164 | "layers" (aka disciplines) for all I/O. |
165 | |
166 | The C<open> pragma is used to declare one or more default layers for |
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167 | I/O operations. Any open(), readpipe() (aka qx//) and similar |
168 | operators found within the lexical scope of this pragma will use the |
169 | declared defaults. |
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170 | |
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171 | With the C<IN> subpragma you can declare the default layers |
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172 | of input streams, and with the C<OUT> subpragma you can declare |
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173 | the default layers of output streams. With the C<IO> subpragma |
174 | you can control both input and output streams simultaneously. |
175 | |
176 | If you have a legacy encoding, you can use the C<:encoding(...)> tag. |
177 | |
178 | if you want to set your encoding disciplines based on your |
179 | locale environment variables, you can use the C<:locale> tag. |
180 | For example: |
181 | |
182 | $ENV{LANG} = 'ru_RU.KOI8-R'; |
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183 | # the :locale will probe the locale environment variables like LANG |
184 | use open OUT => ':locale'; |
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185 | open(O, ">koi8"); |
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186 | print O chr(0x430); # Unicode CYRILLIC SMALL LETTER A = KOI8-R 0xc1 |
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187 | close O; |
188 | open(I, "<koi8"); |
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189 | printf "%#x\n", ord(<I>), "\n"; # this should print 0xc1 |
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190 | close I; |
191 | |
192 | These are equivalent |
193 | |
194 | use open ':utf8'; |
195 | use open IO => ':utf8'; |
196 | |
197 | as are these |
198 | |
199 | use open ':locale'; |
200 | use open IO => ':locale'; |
201 | |
202 | and these |
203 | |
204 | use open ':encoding(iso-8859-7)'; |
205 | use open IO => ':encoding(iso-8859-7)'; |
206 | |
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207 | When open() is given an explicit list of layers they are appended to |
208 | the list declared using this pragma. |
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209 | |
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210 | The C<:std> subpragma on its own has no effect, but if combined with |
211 | the C<:utf8> or C<:encoding> subpragmas, it converts the standard |
212 | filehandles (STDIN, STDOUT, STDERR) to comply with encoding selected |
213 | for input/output handles. For example, if both input and out are |
214 | chosen to be C<:utf8>, a C<:std> will mean that STDIN, STDOUT, and |
215 | STDERR are also in C<:utf8>. On the other hand, if only output is |
216 | chosen to be in C<:encoding(koi8r)', a C<:std> will cause only the |
217 | STDOUT and STDERR to be in C<koi8r>. The C<:locale> subpragma |
218 | implicitly turns on C<:std>. |
219 | |
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220 | The logic of C<:locale> is as follows: |
221 | |
222 | =over 4 |
223 | |
224 | =item 1. |
225 | |
226 | If the platform supports the langinfo(CODESET) interface, the codeset |
227 | returned is used as the default encoding for the open pragma. |
228 | |
229 | =item 2. |
230 | |
231 | If 1. didn't work but we are under the locale pragma, the environment |
232 | variables LC_ALL and LANG (in that order) are matched for encodings |
233 | (the part after C<.>, if any), and if any found, that is used |
234 | as the default encoding for the open pragma. |
235 | |
236 | =item 3. |
237 | |
238 | If 1. and 2. didn't work, the environment variables LC_ALL and LANG |
239 | (in that order) are matched for anything looking like UTF-8, and if |
240 | any found, C<:utf8> is used as the default encoding for the open |
241 | pragma. |
242 | |
243 | =back |
244 | |
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245 | Directory handles may also support disciplines in future. |
246 | |
247 | =head1 NONPERLIO FUNCTIONALITY |
248 | |
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249 | If Perl is not built to use PerlIO as its IO system then only the two |
250 | pseudo-disciplines ":raw" and ":crlf" are available. |
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251 | |
252 | The ":raw" discipline corresponds to "binary mode" and the ":crlf" |
253 | discipline corresponds to "text mode" on platforms that distinguish |
254 | between the two modes when opening files (which is many DOS-like |
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255 | platforms, including Windows). These two disciplines are no-ops on |
256 | platforms where binmode() is a no-op, but perform their functions |
257 | everywhere if PerlIO is enabled. |
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258 | |
259 | =head1 IMPLEMENTATION DETAILS |
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260 | |
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261 | There is a class method in C<PerlIO::Layer> C<find> which is |
262 | implemented as XS code. It is called by C<import> to validate the |
263 | layers: |
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264 | |
265 | PerlIO::Layer::->find("perlio") |
266 | |
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267 | The return value (if defined) is a Perl object, of class |
268 | C<PerlIO::Layer> which is created by the C code in F<perlio.c>. As |
269 | yet there is nothing useful you can do with the object at the perl |
270 | level. |
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271 | |
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272 | =head1 SEE ALSO |
273 | |
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274 | L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>, L<PerlIO>, |
275 | L<encoding> |
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276 | |
277 | =cut |