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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 | |
9 | sub in_locale { $^H & $locale::hint_bits } |
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 | $locale_encoding = langinfo(CODESET()); |
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18 | }; |
19 | unless ($@) { |
20 | print "# locale_encoding = $locale_encoding\n"; |
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21 | } |
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22 | my $country_language; |
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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_TW|taiwan(?:ese)?$/i) { |
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49 | $locale_encoding = 'euc-tw'; |
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50 | } |
51 | croak "Locale encoding 'euc' too ambiguous" |
52 | if $locale_encoding eq 'euc'; |
53 | } |
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54 | } |
55 | } |
56 | |
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57 | sub import { |
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58 | my ($class,@args) = @_; |
59 | croak("`use open' needs explicit list of disciplines") unless @args; |
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60 | $^H |= $open::hint_bits; |
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61 | my ($in,$out) = split(/\0/,(${^OPEN} || "\0"), -1); |
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62 | while (@args) { |
63 | my $type = shift(@args); |
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64 | my $dscp; |
65 | if ($type =~ /^:?(utf8|locale|encoding\(.+\))$/) { |
66 | $type = 'IO'; |
67 | $dscp = ":$1"; |
68 | } else { |
69 | $dscp = shift(@args); |
70 | } |
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71 | my @val; |
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72 | foreach my $layer (split(/\s+/,$dscp)) { |
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73 | $layer =~ s/^://; |
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74 | if ($layer eq 'locale') { |
75 | use Encode; |
76 | _get_locale_encoding() |
77 | unless defined $locale_encoding; |
78 | croak "Cannot figure out an encoding to use" |
79 | unless defined $locale_encoding; |
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80 | if ($locale_encoding =~ /^utf-?8$/i) { |
81 | $layer = "utf8"; |
82 | } else { |
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83 | $layer = "encoding($locale_encoding)"; |
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84 | } |
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85 | } else { |
86 | unless(PerlIO::Layer::->find($layer)) { |
87 | carp("Unknown discipline layer '$layer'"); |
88 | } |
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89 | } |
90 | push(@val,":$layer"); |
91 | if ($layer =~ /^(crlf|raw)$/) { |
92 | $^H{"open_$type"} = $layer; |
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93 | } |
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94 | } |
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95 | # print "# type = $type, val = @val\n"; |
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96 | if ($type eq 'IN') { |
97 | $in = join(' ',@val); |
98 | } |
99 | elsif ($type eq 'OUT') { |
100 | $out = join(' ',@val); |
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101 | } |
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102 | elsif ($type eq 'IO') { |
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103 | $in = $out = join(' ',@val); |
104 | } |
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105 | else { |
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106 | croak "Unknown discipline class '$type'"; |
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107 | } |
108 | } |
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109 | ${^OPEN} = join("\0",$in,$out); |
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110 | } |
111 | |
112 | 1; |
113 | __END__ |
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114 | |
115 | =head1 NAME |
116 | |
117 | open - perl pragma to set default disciplines for input and output |
118 | |
119 | =head1 SYNOPSIS |
120 | |
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121 | use open IN => ":crlf", OUT => ":raw"; |
122 | use open OUT => ':utf8'; |
123 | use open IO => ":encoding(iso-8859-7)"; |
124 | |
125 | use open IO => ':locale'; |
126 | |
127 | use open ':utf8'; |
128 | use open ':locale'; |
129 | use open ':encoding(iso-8859-7)'; |
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130 | |
131 | =head1 DESCRIPTION |
132 | |
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133 | Full-fledged support for I/O disciplines is now implemented provided |
134 | Perl is configured to use PerlIO as its IO system (which is now the |
135 | default). |
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136 | |
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137 | The C<open> pragma serves as one of the interfaces to declare default |
138 | "layers" (aka disciplines) for all I/O. |
139 | |
140 | The C<open> pragma is used to declare one or more default layers for |
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141 | I/O operations. Any open(), readpipe() (aka qx//) and similar |
142 | operators found within the lexical scope of this pragma will use the |
143 | declared defaults. |
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144 | |
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145 | With the C<IN> subpragma you can declare the default layers |
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146 | of input streams, and with the C<OUT> subpragma you can declare |
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147 | the default layers of output streams. With the C<IO> subpragma |
148 | you can control both input and output streams simultaneously. |
149 | |
150 | If you have a legacy encoding, you can use the C<:encoding(...)> tag. |
151 | |
152 | if you want to set your encoding disciplines based on your |
153 | locale environment variables, you can use the C<:locale> tag. |
154 | For example: |
155 | |
156 | $ENV{LANG} = 'ru_RU.KOI8-R'; |
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157 | # the :locale will probe the locale environment variables like LANG |
158 | use open OUT => ':locale'; |
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159 | open(O, ">koi8"); |
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160 | print O chr(0x430); # Unicode CYRILLIC SMALL LETTER A = KOI8-R 0xc1 |
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161 | close O; |
162 | open(I, "<koi8"); |
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163 | printf "%#x\n", ord(<I>), "\n"; # this should print 0xc1 |
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164 | close I; |
165 | |
166 | These are equivalent |
167 | |
168 | use open ':utf8'; |
169 | use open IO => ':utf8'; |
170 | |
171 | as are these |
172 | |
173 | use open ':locale'; |
174 | use open IO => ':locale'; |
175 | |
176 | and these |
177 | |
178 | use open ':encoding(iso-8859-7)'; |
179 | use open IO => ':encoding(iso-8859-7)'; |
180 | |
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181 | When open() is given an explicit list of layers they are appended to |
182 | the list declared using this pragma. |
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183 | |
184 | Directory handles may also support disciplines in future. |
185 | |
186 | =head1 NONPERLIO FUNCTIONALITY |
187 | |
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188 | If Perl is not built to use PerlIO as its IO system then only the two |
189 | pseudo-disciplines ":raw" and ":crlf" are available. |
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190 | |
191 | The ":raw" discipline corresponds to "binary mode" and the ":crlf" |
192 | discipline corresponds to "text mode" on platforms that distinguish |
193 | between the two modes when opening files (which is many DOS-like |
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194 | platforms, including Windows). These two disciplines are no-ops on |
195 | platforms where binmode() is a no-op, but perform their functions |
196 | everywhere if PerlIO is enabled. |
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197 | |
198 | =head1 IMPLEMENTATION DETAILS |
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199 | |
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200 | There is a class method in C<PerlIO::Layer> C<find> which is |
201 | implemented as XS code. It is called by C<import> to validate the |
202 | layers: |
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203 | |
204 | PerlIO::Layer::->find("perlio") |
205 | |
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206 | The return value (if defined) is a Perl object, of class |
207 | C<PerlIO::Layer> which is created by the C code in F<perlio.c>. As |
208 | yet there is nothing useful you can do with the object at the perl |
209 | level. |
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210 | |
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211 | =head1 SEE ALSO |
212 | |
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213 | L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>, L<PerlIO>, |
214 | L<encoding> |
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215 | |
216 | =cut |