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1 | package Encode::Unicode; |
2 | |
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3 | use strict; |
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4 | use warnings; |
5 | |
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6 | our $VERSION = do { my @r = (q$Revision: 1.37 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r }; |
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7 | |
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8 | use XSLoader; |
9 | XSLoader::load(__PACKAGE__,$VERSION); |
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10 | |
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11 | # |
12 | # Object Generator 8 transcoders all at once! |
13 | # |
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14 | |
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15 | require Encode; |
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16 | |
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17 | for my $name (qw(UTF-16 UTF-16BE UTF-16LE |
18 | UTF-32 UTF-32BE UTF-32LE |
19 | UCS-2BE UCS-2LE)) |
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20 | { |
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21 | my ($size, $endian, $ucs2, $mask); |
22 | $name =~ /^(\w+)-(\d+)(\w*)$/o; |
23 | if ($ucs2 = ($1 eq 'UCS')){ |
24 | $size = 2; |
25 | }else{ |
26 | $size = $2/8; |
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27 | } |
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28 | $endian = ($3 eq 'BE') ? 'n' : ($3 eq 'LE') ? 'v' : '' ; |
29 | $size == 4 and $endian = uc($endian); |
30 | |
31 | $Encode::Encoding{$name} = |
32 | bless { |
33 | Name => $name, |
34 | size => $size, |
35 | endian => $endian, |
36 | ucs2 => $ucs2, |
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37 | } => __PACKAGE__; |
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38 | |
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39 | } |
40 | |
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41 | use base qw(Encode::Encoding); |
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42 | |
43 | # |
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44 | # three implementations of (en|de)code exist. The XS version is the |
45 | # fastest. *_modern uses an array and *_classic sticks with substr. |
46 | # *_classic is much slower but more memory conservative. |
47 | # *_xs is the default. |
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48 | |
49 | sub set_transcoder{ |
50 | no warnings qw(redefine); |
51 | my $type = shift; |
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52 | if ($type eq "xs"){ |
53 | *decode = \&decode_xs; |
54 | *encode = \&encode_xs; |
55 | }elsif($type eq "modern"){ |
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56 | *decode = \&decode_modern; |
57 | *encode = \&encode_modern; |
58 | }elsif($type eq "classic"){ |
59 | *decode = \&decode_classic; |
60 | *encode = \&encode_classic; |
61 | }else{ |
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62 | require Carp; |
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63 | Carp::croak __PACKAGE__, "::set_transcoder(modern|classic|xs)"; |
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64 | } |
65 | } |
66 | |
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67 | set_transcoder("xs"); |
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68 | |
69 | # |
85982a32 |
70 | # Aux. subs & constants |
71 | # |
72 | |
73 | sub FBCHAR(){ 0xFFFd } |
74 | sub BOM_BE(){ 0xFeFF } |
75 | sub BOM16LE(){ 0xFFFe } |
76 | sub BOM32LE(){ 0xFFFe0000 } |
77 | |
78 | sub valid_ucs2($){ |
79 | return |
80 | (0 <= $_[0] && $_[0] < 0xD800) |
81 | || ( 0xDFFF < $_[0] && $_[0] <= 0xFFFF); |
82 | } |
83 | |
84 | sub issurrogate($){ 0xD800 <= $_[0] && $_[0] <= 0xDFFF } |
85 | sub isHiSurrogate($){ 0xD800 <= $_[0] && $_[0] < 0xDC00 } |
86 | sub isLoSurrogate($){ 0xDC00 <= $_[0] && $_[0] <= 0xDFFF } |
87 | |
88 | sub ensurrogate($){ |
89 | use integer; # we have divisions |
90 | my $uni = shift; |
91 | my $hi = ($uni - 0x10000) / 0x400 + 0xD800; |
92 | my $lo = ($uni - 0x10000) % 0x400 + 0xDC00; |
93 | return ($hi, $lo); |
94 | } |
95 | |
96 | sub desurrogate($$){ |
97 | my ($hi, $lo) = @_; |
98 | return 0x10000 + ($hi - 0xD800)*0x400 + ($lo - 0xDC00); |
99 | } |
100 | |
101 | sub Mask { {2 => 0xffff, 4 => 0xffffffff} } |
102 | |
103 | # |
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104 | # *_modern are much faster but guzzle more memory |
105 | # |
106 | |
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107 | sub decode_modern($$;$) |
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108 | { |
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109 | my ($obj, $str, $chk ) = @_; |
110 | my ($size, $endian, $ucs2) = @$obj{qw(size endian ucs2)}; |
111 | |
112 | # warn "$size, $endian, $ucs2"; |
113 | $endian ||= BOMB($size, substr($str, 0, $size, '')) |
114 | or poisoned2death($obj, "Where's the BOM?"); |
115 | my $mask = Mask->{$size}; |
116 | my $utf8 = ''; |
117 | my @ord = unpack("$endian*", $str); |
118 | undef $str; # to conserve memory |
119 | while (@ord){ |
120 | my $ord = shift @ord; |
121 | unless ($size == 4 or valid_ucs2($ord &= $mask)){ |
122 | if ($ucs2){ |
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123 | $chk and |
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124 | poisoned2death($obj, "no surrogates allowed", $ord); |
125 | shift @ord; # skip the next one as well |
126 | $ord = FBCHAR; |
127 | }else{ |
128 | unless (isHiSurrogate($ord)){ |
129 | poisoned2death($obj, "Malformed HI surrogate", $ord); |
130 | } |
131 | my $lo = shift @ord; |
132 | unless (isLoSurrogate($lo &= $mask)){ |
133 | poisoned2death($obj, "Malformed LO surrogate", $ord, $lo); |
134 | } |
135 | $ord = desurrogate($ord, $lo); |
136 | } |
137 | } |
138 | $utf8 .= chr($ord); |
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139 | } |
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140 | utf8::upgrade($utf8); |
141 | return $utf8; |
142 | } |
143 | |
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144 | sub encode_modern($$;$) |
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145 | { |
146 | my ($obj, $utf8, $chk) = @_; |
147 | my ($size, $endian, $ucs2) = @$obj{qw(size endian ucs2)}; |
148 | my @str = (); |
149 | unless ($endian){ |
150 | $endian = ($size == 4) ? 'N' : 'n'; |
151 | push @str, BOM_BE; |
152 | } |
153 | my @ord = unpack("U*", $utf8); |
154 | undef $utf8; # to conserve memory |
155 | for my $ord (@ord){ |
156 | unless ($size == 4 or valid_ucs2($ord)) { |
157 | unless(issurrogate($ord)){ |
158 | if ($ucs2){ |
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159 | $chk and |
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160 | poisoned2death($obj, "code point too high", $ord); |
161 | |
162 | push @str, FBCHAR; |
163 | }else{ |
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164 | |
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165 | push @str, ensurrogate($ord); |
166 | } |
167 | }else{ # not supposed to happen |
168 | push @str, FBCHAR; |
169 | } |
170 | }else{ |
171 | push @str, $ord; |
172 | } |
173 | } |
174 | return pack("$endian*", @str); |
175 | } |
176 | |
177 | # |
178 | # *_classic are slower but more memory conservative |
179 | # |
180 | |
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181 | sub decode_classic($$;$) |
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182 | { |
183 | my ($obj, $str, $chk ) = @_; |
184 | my ($size, $endian, $ucs2) = @$obj{qw(size endian ucs2)}; |
185 | |
186 | # warn "$size, $endian, $ucs2"; |
187 | $endian ||= BOMB($size, substr($str, 0, $size, '')) |
188 | or poisoned2death($obj, "Where's the BOM?"); |
189 | my $mask = Mask->{$size}; |
190 | my $utf8 = ''; |
191 | my @ord = unpack("$endian*", $str); |
192 | while (length($str)){ |
193 | my $ord = unpack($endian, substr($str, 0, $size, '')); |
194 | unless ($size == 4 or valid_ucs2($ord &= $mask)){ |
195 | if ($ucs2){ |
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196 | $chk and |
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197 | poisoned2death($obj, "no surrogates allowed", $ord); |
198 | substr($str,0,$size,''); # skip the next one as well |
199 | $ord = FBCHAR; |
200 | }else{ |
201 | unless (isHiSurrogate($ord)){ |
202 | poisoned2death($obj, "Malformed HI surrogate", $ord); |
203 | } |
204 | my $lo = unpack($endian ,substr($str,0,$size,'')); |
205 | unless (isLoSurrogate($lo &= $mask)){ |
206 | poisoned2death($obj, "Malformed LO surrogate", $ord, $lo); |
207 | } |
208 | $ord = desurrogate($ord, $lo); |
209 | } |
210 | } |
211 | $utf8 .= chr($ord); |
212 | } |
213 | utf8::upgrade($utf8); |
214 | return $utf8; |
215 | } |
216 | |
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217 | sub encode_classic($$;$) |
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218 | { |
219 | my ($obj, $utf8, $chk) = @_; |
220 | my ($size, $endian, $ucs2) = @$obj{qw(size endian ucs2)}; |
221 | # warn join ", ", $size, $ucs2, $endian, $mask; |
222 | my $str = ''; |
223 | unless ($endian){ |
224 | $endian = ($size == 4) ? 'N' : 'n'; |
225 | $str .= pack($endian, BOM_BE); |
226 | } |
227 | while (length($utf8)){ |
228 | my $ord = ord(substr($utf8,0,1,'')); |
229 | unless ($size == 4 or valid_ucs2($ord)) { |
230 | unless(issurrogate($ord)){ |
231 | if ($ucs2){ |
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232 | $chk and |
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233 | poisoned2death($obj, "code point too high", $ord); |
234 | $str .= pack($endian, FBCHAR); |
235 | }else{ |
236 | $str .= pack($endian.2, ensurrogate($ord)); |
237 | } |
238 | }else{ # not supposed to happen |
239 | $str .= pack($endian, FBCHAR); |
240 | } |
241 | }else{ |
242 | $str .= pack($endian, $ord); |
243 | } |
244 | } |
245 | return $str; |
246 | } |
247 | |
248 | sub BOMB { |
249 | my ($size, $bom) = @_; |
250 | my $N = $size == 2 ? 'n' : 'N'; |
251 | my $ord = unpack($N, $bom); |
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252 | return ($ord eq BOM_BE) ? $N : |
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253 | ($ord eq BOM16LE) ? 'v' : ($ord eq BOM32LE) ? 'V' : undef; |
254 | } |
255 | |
256 | sub poisoned2death{ |
257 | my $obj = shift; |
258 | my $msg = shift; |
259 | my $pair = join(", ", map {sprintf "\\x%x", $_} @_); |
260 | require Carp; |
261 | Carp::croak $obj->name, ":", $msg, "<$pair>.", caller; |
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262 | } |
263 | |
264 | 1; |
265 | __END__ |
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266 | |
267 | =head1 NAME |
268 | |
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269 | Encode::Unicode -- Various Unicode Transformation Formats |
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270 | |
271 | =cut |
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272 | |
273 | =head1 SYNOPSIS |
274 | |
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275 | use Encode qw/encode decode/; |
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276 | $ucs2 = encode("UCS-2BE", $utf8); |
277 | $utf8 = decode("UCS-2BE", $ucs2); |
278 | |
279 | =head1 ABSTRACT |
280 | |
281 | This module implements all Character Encoding Schemes of Unicode that |
282 | are officially documented by Unicode Consortium (except, of course, |
283 | for UTF-8, which is a native format in perl). |
284 | |
285 | =over 4 |
286 | |
287 | =item L<http://www.unicode.org/glossary/> says: |
288 | |
289 | I<Character Encoding Scheme> A character encoding form plus byte |
290 | serialization. There are seven character encoding schemes in Unicode: |
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291 | UTF-8, UTF-16, UTF-16BE, UTF-16LE, UTF-32 (UCS-4), UTF-32BE (UCS-4BE) and |
292 | UTF-32LE (UCS-4LE). |
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293 | |
294 | =item Quick Reference |
295 | |
296 | Decodes from ord(N) Encodes chr(N) to... |
297 | octet/char BOM S.P d800-dfff ord > 0xffff \x{1abcd} == |
298 | ---------------+-----------------+------------------------------ |
299 | UCS-2BE 2 N N is bogus Not Available |
300 | UCS-2LE 2 N N bogus Not Available |
301 | UTF-16 2/4 Y Y is S.P S.P BE/LE |
302 | UTF-16BE 2/4 N Y S.P S.P 0xd82a,0xdfcd |
303 | UTF-16LE 2 N Y S.P S.P 0x2ad8,0xcddf |
304 | UTF-32 4 Y - is bogus As is BE/LE |
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305 | UTF-32BE 4 N - bogus As is 0x0001abcd |
306 | UTF-32LE 4 N - bogus As is 0xcdab0100 |
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307 | UTF-8 1-4 - - bogus >= 4 octets \xf0\x9a\af\8d |
308 | ---------------+-----------------+------------------------------ |
309 | |
310 | =back |
311 | |
312 | =head1 Size, Endianness, and BOM |
313 | |
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314 | You can categorize these CES by 3 criteria: size of each character, |
315 | endianness, and Byte Order Mark. |
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316 | |
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317 | =head2 by size |
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318 | |
319 | UCS-2 is a fixed-length encoding with each character taking 16 bits. |
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320 | It B<does not> support I<surrogate pairs>. When a surrogate pair |
321 | is encountered during decode(), its place is filled with \x{FFFD} |
322 | if I<CHECK> is 0, or the routine croaks if I<CHECK> is 1. When a |
323 | character whose ord value is larger than 0xFFFF is encountered, |
324 | its place is filled with \x{FFFD} if I<CHECK> is 0, or the routine |
325 | croaks if I<CHECK> is 1. |
326 | |
327 | UTF-16 is almost the same as UCS-2 but it supports I<surrogate pairs>. |
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328 | When it encounters a high surrogate (0xD800-0xDBFF), it fetches the |
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329 | following low surrogate (0xDC00-0xDFFF) and C<desurrogate>s them to |
330 | form a character. Bogus surrogates result in death. When \x{10000} |
331 | or above is encountered during encode(), it C<ensurrogate>s them and |
332 | pushes the surrogate pair to the output stream. |
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333 | |
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334 | UTF-32 (UCS-4) is a fixed-length encoding with each character taking 32 bits. |
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335 | Since it is 32-bit, there is no need for I<surrogate pairs>. |
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336 | |
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337 | =head2 by endianness |
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338 | |
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339 | The first (and now failed) goal of Unicode was to map all character |
340 | repertoires into a fixed-length integer so that programmers are happy. |
341 | Since each character is either a I<short> or I<long> in C, you have to |
342 | pay attention to the endianness of each platform when you pass data |
343 | to one another. |
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344 | |
345 | Anything marked as BE is Big Endian (or network byte order) and LE is |
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346 | Little Endian (aka VAX byte order). For anything not marked either |
347 | BE or LE, a character called Byte Order Mark (BOM) indicating the |
348 | endianness is prepended to the string. |
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349 | |
350 | =over 4 |
351 | |
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352 | =item BOM as integer when fetched in network byte order |
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353 | |
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354 | 16 32 bits/char |
355 | ------------------------- |
356 | BE 0xFeFF 0x0000FeFF |
357 | LE 0xFFeF 0xFFFe0000 |
358 | ------------------------- |
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359 | |
360 | =back |
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361 | |
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362 | This modules handles the BOM as follows. |
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363 | |
364 | =over 4 |
365 | |
366 | =item * |
367 | |
368 | When BE or LE is explicitly stated as the name of encoding, BOM is |
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369 | simply treated as a normal character (ZERO WIDTH NO-BREAK SPACE). |
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370 | |
371 | =item * |
372 | |
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373 | When BE or LE is omitted during decode(), it checks if BOM is at the |
374 | beginning of the string; if one is found, the endianness is set to |
375 | what the BOM says. If no BOM is found, the routine dies. |
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376 | |
377 | =item * |
378 | |
379 | When BE or LE is omitted during encode(), it returns a BE-encoded |
380 | string with BOM prepended. So when you want to encode a whole text |
0ab8f81e |
381 | file, make sure you encode() the whole text at once, not line by line |
382 | or each line, not file, will have a BOM prepended. |
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383 | |
384 | =item * |
385 | |
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386 | C<UCS-2> is an exception. Unlike others, this is an alias of UCS-2BE. |
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387 | UCS-2 is already registered by IANA and others that way. |
388 | |
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389 | =back |
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390 | |
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391 | =head1 Surrogate Pairs |
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392 | |
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393 | To say the least, surrogate pairs were the biggest mistake of the |
394 | Unicode Consortium. But according to the late Douglas Adams in I<The |
395 | Hitchhiker's Guide to the Galaxy> Trilogy, C<In the beginning the |
396 | Universe was created. This has made a lot of people very angry and |
397 | been widely regarded as a bad move>. Their mistake was not of this |
398 | magnitude so let's forgive them. |
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399 | |
400 | (I don't dare make any comparison with Unicode Consortium and the |
c731e18e |
401 | Vogons here ;) Or, comparing Encode to Babel Fish is completely |
402 | appropriate -- if you can only stick this into your ear :) |
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403 | |
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404 | Surrogate pairs were born when the Unicode Consortium finally |
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405 | admitted that 16 bits were not big enough to hold all the world's |
0ab8f81e |
406 | character repertoires. But they already made UCS-2 16-bit. What |
f2a2953c |
407 | do we do? |
408 | |
0ab8f81e |
409 | Back then, the range 0xD800-0xDFFF was not allocated. Let's split |
410 | that range in half and use the first half to represent the C<upper |
411 | half of a character> and the second half to represent the C<lower |
412 | half of a character>. That way, you can represent 1024 * 1024 = |
413 | 1048576 more characters. Now we can store character ranges up to |
414 | \x{10ffff} even with 16-bit encodings. This pair of half-character is |
415 | now called a I<surrogate pair> and UTF-16 is the name of the encoding |
416 | that embraces them. |
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417 | |
448e90bb |
418 | Here is a formula to ensurrogate a Unicode character \x{10000} and |
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419 | above; |
420 | |
421 | $hi = ($uni - 0x10000) / 0x400 + 0xD800; |
422 | $lo = ($uni - 0x10000) % 0x400 + 0xDC00; |
423 | |
424 | And to desurrogate; |
425 | |
426 | $uni = 0x10000 + ($hi - 0xD800) * 0x400 + ($lo - 0xDC00); |
427 | |
fcb875d4 |
428 | Note this move has made \x{D800}-\x{DFFF} into a forbidden zone but |
429 | perl does not prohibit the use of characters within this range. To perl, |
430 | every one of \x{0000_0000} up to \x{ffff_ffff} (*) is I<a character>. |
431 | |
432 | (*) or \x{ffff_ffff_ffff_ffff} if your perl is compiled with 64-bit |
0ab8f81e |
433 | integer support! |
f2a2953c |
434 | |
435 | =head1 SEE ALSO |
436 | |
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437 | L<Encode>, L<http://www.unicode.org/glossary/>, |
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438 | L<http://www.unicode.org/unicode/faq/utf_bom.html>, |
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439 | |
fdd579e2 |
440 | RFC 2781 L<http://rfc.net/rfc2781.html>, |
441 | |
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442 | The whole Unicode standard L<http://www.unicode.org/unicode/uni2book/u2.html> |
fdd579e2 |
443 | |
fcb875d4 |
444 | Ch. 15, pp. 403 of C<Programming Perl (3rd Edition)> |
445 | by Larry Wall, Tom Christiansen, Jon Orwant; |
446 | O'Reilly & Associates; ISBN 0-596-00027-8 |
447 | |
fdd579e2 |
448 | =cut |