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Revision 1.43 by root, Sat Jun 23 23:49:29 2007 UTC vs.
Revision 1.82 by root, Sun Dec 30 21:24:57 2007 UTC

1=head1 NAME 1=head1 NAME
2 2
3JSON::XS - JSON serialising/deserialising, done correctly and fast 3JSON::XS - JSON serialising/deserialising, done correctly and fast
4
5JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ
6 (http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html)
4 7
5=head1 SYNOPSIS 8=head1 SYNOPSIS
6 9
7 use JSON::XS; 10 use JSON::XS;
8 11
9 # exported functions, they croak on error 12 # exported functions, they croak on error
10 # and expect/generate UTF-8 13 # and expect/generate UTF-8
11 14
12 $utf8_encoded_json_text = to_json $perl_hash_or_arrayref; 15 $utf8_encoded_json_text = encode_json $perl_hash_or_arrayref;
13 $perl_hash_or_arrayref = from_json $utf8_encoded_json_text; 16 $perl_hash_or_arrayref = decode_json $utf8_encoded_json_text;
14
15 # objToJson and jsonToObj aliases to to_json and from_json
16 # are exported for compatibility to the JSON module,
17 # but should not be used in new code.
18 17
19 # OO-interface 18 # OO-interface
20 19
21 $coder = JSON::XS->new->ascii->pretty->allow_nonref; 20 $coder = JSON::XS->new->ascii->pretty->allow_nonref;
22 $pretty_printed_unencoded = $coder->encode ($perl_scalar); 21 $pretty_printed_unencoded = $coder->encode ($perl_scalar);
23 $perl_scalar = $coder->decode ($unicode_json_text); 22 $perl_scalar = $coder->decode ($unicode_json_text);
24 23
24 # Note that JSON version 2.0 and above will automatically use JSON::XS
25 # if available, at virtually no speed overhead either, so you should
26 # be able to just:
27
28 use JSON;
29
30 # and do the same things, except that you have a pure-perl fallback now.
31
25=head1 DESCRIPTION 32=head1 DESCRIPTION
26 33
27This module converts Perl data structures to JSON and vice versa. Its 34This module converts Perl data structures to JSON and vice versa. Its
28primary goal is to be I<correct> and its secondary goal is to be 35primary goal is to be I<correct> and its secondary goal is to be
29I<fast>. To reach the latter goal it was written in C. 36I<fast>. To reach the latter goal it was written in C.
37
38Beginning with version 2.0 of the JSON module, when both JSON and
39JSON::XS are installed, then JSON will fall back on JSON::XS (this can be
40overriden) with no overhead due to emulation (by inheritign constructor
41and methods). If JSON::XS is not available, it will fall back to the
42compatible JSON::PP module as backend, so using JSON instead of JSON::XS
43gives you a portable JSON API that can be fast when you need and doesn't
44require a C compiler when that is a problem.
30 45
31As this is the n-th-something JSON module on CPAN, what was the reason 46As this is the n-th-something JSON module on CPAN, what was the reason
32to write yet another JSON module? While it seems there are many JSON 47to write yet another JSON module? While it seems there are many JSON
33modules, none of them correctly handle all corner cases, and in most cases 48modules, none of them correctly handle all corner cases, and in most cases
34their maintainers are unresponsive, gone missing, or not listening to bug 49their maintainers are unresponsive, gone missing, or not listening to bug
… …
41 56
42=head2 FEATURES 57=head2 FEATURES
43 58
44=over 4 59=over 4
45 60
46=item * correct unicode handling 61=item * correct Unicode handling
47 62
48This module knows how to handle Unicode, and even documents how and when 63This module knows how to handle Unicode, and even documents how and when
49it does so. 64it does so.
50 65
51=item * round-trip integrity 66=item * round-trip integrity
… …
71This module has both a simple functional interface as well as an OO 86This module has both a simple functional interface as well as an OO
72interface. 87interface.
73 88
74=item * reasonably versatile output formats 89=item * reasonably versatile output formats
75 90
76You can choose between the most compact guarenteed single-line format 91You can choose between the most compact guaranteed single-line format
77possible (nice for simple line-based protocols), a pure-ascii format 92possible (nice for simple line-based protocols), a pure-ascii format
78(for when your transport is not 8-bit clean, still supports the whole 93(for when your transport is not 8-bit clean, still supports the whole
79unicode range), or a pretty-printed format (for when you want to read that 94Unicode range), or a pretty-printed format (for when you want to read that
80stuff). Or you can combine those features in whatever way you like. 95stuff). Or you can combine those features in whatever way you like.
81 96
82=back 97=back
83 98
84=cut 99=cut
85 100
86package JSON::XS; 101package JSON::XS;
87 102
88use strict; 103use strict;
89 104
90our $VERSION = '1.3'; 105our $VERSION = '2.01';
91our @ISA = qw(Exporter); 106our @ISA = qw(Exporter);
92 107
93our @EXPORT = qw(to_json from_json objToJson jsonToObj); 108our @EXPORT = qw(encode_json decode_json to_json from_json);
109
110sub to_json($) {
111 require Carp;
112 Carp::croak ("JSON::XS::to_json has been renamed to encode_json, either downgrade to pre-2.0 versions of JSON::XS or rename the call");
113}
114
115sub from_json($) {
116 require Carp;
117 Carp::croak ("JSON::XS::from_json has been renamed to decode_json, either downgrade to pre-2.0 versions of JSON::XS or rename the call");
118}
94 119
95use Exporter; 120use Exporter;
96use XSLoader; 121use XSLoader;
97 122
98=head1 FUNCTIONAL INTERFACE 123=head1 FUNCTIONAL INTERFACE
99 124
100The following convinience methods are provided by this module. They are 125The following convenience methods are provided by this module. They are
101exported by default: 126exported by default:
102 127
103=over 4 128=over 4
104 129
105=item $json_text = to_json $perl_scalar 130=item $json_text = encode_json $perl_scalar
106 131
107Converts the given Perl data structure (a simple scalar or a reference to 132Converts the given Perl data structure to a UTF-8 encoded, binary string
108a hash or array) to a UTF-8 encoded, binary string (that is, the string contains 133(that is, the string contains octets only). Croaks on error.
109octets only). Croaks on error.
110 134
111This function call is functionally identical to: 135This function call is functionally identical to:
112 136
113 $json_text = JSON::XS->new->utf8->encode ($perl_scalar) 137 $json_text = JSON::XS->new->utf8->encode ($perl_scalar)
114 138
115except being faster. 139except being faster.
116 140
117=item $perl_scalar = from_json $json_text 141=item $perl_scalar = decode_json $json_text
118 142
119The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to 143The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries
120parse that as an UTF-8 encoded JSON text, returning the resulting simple 144to parse that as an UTF-8 encoded JSON text, returning the resulting
121scalar or reference. Croaks on error. 145reference. Croaks on error.
122 146
123This function call is functionally identical to: 147This function call is functionally identical to:
124 148
125 $perl_scalar = JSON::XS->new->utf8->decode ($json_text) 149 $perl_scalar = JSON::XS->new->utf8->decode ($json_text)
126 150
… …
136Perl. 160Perl.
137 161
138=back 162=back
139 163
140 164
165=head1 A FEW NOTES ON UNICODE AND PERL
166
167Since this often leads to confusion, here are a few very clear words on
168how Unicode works in Perl, modulo bugs.
169
170=over 4
171
172=item 1. Perl strings can store characters with ordinal values > 255.
173
174This enables you to store Unicode characters as single characters in a
175Perl string - very natural.
176
177=item 2. Perl does I<not> associate an encoding with your strings.
178
179Unless you force it to, e.g. when matching it against a regex, or printing
180the scalar to a file, in which case Perl either interprets your string as
181locale-encoded text, octets/binary, or as Unicode, depending on various
182settings. In no case is an encoding stored together with your data, it is
183I<use> that decides encoding, not any magical metadata.
184
185=item 3. The internal utf-8 flag has no meaning with regards to the
186encoding of your string.
187
188Just ignore that flag unless you debug a Perl bug, a module written in
189XS or want to dive into the internals of perl. Otherwise it will only
190confuse you, as, despite the name, it says nothing about how your string
191is encoded. You can have Unicode strings with that flag set, with that
192flag clear, and you can have binary data with that flag set and that flag
193clear. Other possibilities exist, too.
194
195If you didn't know about that flag, just the better, pretend it doesn't
196exist.
197
198=item 4. A "Unicode String" is simply a string where each character can be
199validly interpreted as a Unicode codepoint.
200
201If you have UTF-8 encoded data, it is no longer a Unicode string, but a
202Unicode string encoded in UTF-8, giving you a binary string.
203
204=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.
205
206It's a fact. Learn to live with it.
207
208=back
209
210I hope this helps :)
211
212
141=head1 OBJECT-ORIENTED INTERFACE 213=head1 OBJECT-ORIENTED INTERFACE
142 214
143The object oriented interface lets you configure your own encoding or 215The object oriented interface lets you configure your own encoding or
144decoding style, within the limits of supported formats. 216decoding style, within the limits of supported formats.
145 217
… …
156 my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]}) 228 my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
157 => {"a": [1, 2]} 229 => {"a": [1, 2]}
158 230
159=item $json = $json->ascii ([$enable]) 231=item $json = $json->ascii ([$enable])
160 232
233=item $enabled = $json->get_ascii
234
161If C<$enable> is true (or missing), then the C<encode> method will not 235If C<$enable> is true (or missing), then the C<encode> method will not
162generate characters outside the code range C<0..127> (which is ASCII). Any 236generate characters outside the code range C<0..127> (which is ASCII). Any
163unicode characters outside that range will be escaped using either a 237Unicode characters outside that range will be escaped using either a
164single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, 238single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
165as per RFC4627. The resulting encoded JSON text can be treated as a native 239as per RFC4627. The resulting encoded JSON text can be treated as a native
166unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string, 240Unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
167or any other superset of ASCII. 241or any other superset of ASCII.
168 242
169If C<$enable> is false, then the C<encode> method will not escape Unicode 243If C<$enable> is false, then the C<encode> method will not escape Unicode
170characters unless required by the JSON syntax or other flags. This results 244characters unless required by the JSON syntax or other flags. This results
171in a faster and more compact format. 245in a faster and more compact format.
… …
177 JSON::XS->new->ascii (1)->encode ([chr 0x10401]) 251 JSON::XS->new->ascii (1)->encode ([chr 0x10401])
178 => ["\ud801\udc01"] 252 => ["\ud801\udc01"]
179 253
180=item $json = $json->latin1 ([$enable]) 254=item $json = $json->latin1 ([$enable])
181 255
256=item $enabled = $json->get_latin1
257
182If C<$enable> is true (or missing), then the C<encode> method will encode 258If C<$enable> is true (or missing), then the C<encode> method will encode
183the resulting JSON text as latin1 (or iso-8859-1), escaping any characters 259the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
184outside the code range C<0..255>. The resulting string can be treated as a 260outside the code range C<0..255>. The resulting string can be treated as a
185latin1-encoded JSON text or a native unicode string. The C<decode> method 261latin1-encoded JSON text or a native Unicode string. The C<decode> method
186will not be affected in any way by this flag, as C<decode> by default 262will not be affected in any way by this flag, as C<decode> by default
187expects unicode, which is a strict superset of latin1. 263expects Unicode, which is a strict superset of latin1.
188 264
189If C<$enable> is false, then the C<encode> method will not escape Unicode 265If C<$enable> is false, then the C<encode> method will not escape Unicode
190characters unless required by the JSON syntax or other flags. 266characters unless required by the JSON syntax or other flags.
191 267
192The main use for this flag is efficiently encoding binary data as JSON 268The main use for this flag is efficiently encoding binary data as JSON
193text, as most octets will not be escaped, resulting in a smaller encoded 269text, as most octets will not be escaped, resulting in a smaller encoded
194size. The disadvantage is that the resulting JSON text is encoded 270size. The disadvantage is that the resulting JSON text is encoded
195in latin1 (and must correctly be treated as such when storing and 271in latin1 (and must correctly be treated as such when storing and
196transfering), a rare encoding for JSON. It is therefore most useful when 272transferring), a rare encoding for JSON. It is therefore most useful when
197you want to store data structures known to contain binary data efficiently 273you want to store data structures known to contain binary data efficiently
198in files or databases, not when talking to other JSON encoders/decoders. 274in files or databases, not when talking to other JSON encoders/decoders.
199 275
200 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"] 276 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
201 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not) 277 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
202 278
203=item $json = $json->utf8 ([$enable]) 279=item $json = $json->utf8 ([$enable])
280
281=item $enabled = $json->get_utf8
204 282
205If C<$enable> is true (or missing), then the C<encode> method will encode 283If C<$enable> is true (or missing), then the C<encode> method will encode
206the JSON result into UTF-8, as required by many protocols, while the 284the JSON result into UTF-8, as required by many protocols, while the
207C<decode> method expects to be handled an UTF-8-encoded string. Please 285C<decode> method expects to be handled an UTF-8-encoded string. Please
208note that UTF-8-encoded strings do not contain any characters outside the 286note that UTF-8-encoded strings do not contain any characters outside the
209range C<0..255>, they are thus useful for bytewise/binary I/O. In future 287range C<0..255>, they are thus useful for bytewise/binary I/O. In future
210versions, enabling this option might enable autodetection of the UTF-16 288versions, enabling this option might enable autodetection of the UTF-16
211and UTF-32 encoding families, as described in RFC4627. 289and UTF-32 encoding families, as described in RFC4627.
212 290
213If C<$enable> is false, then the C<encode> method will return the JSON 291If C<$enable> is false, then the C<encode> method will return the JSON
214string as a (non-encoded) unicode string, while C<decode> expects thus a 292string as a (non-encoded) Unicode string, while C<decode> expects thus a
215unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs 293Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
216to be done yourself, e.g. using the Encode module. 294to be done yourself, e.g. using the Encode module.
217 295
218Example, output UTF-16BE-encoded JSON: 296Example, output UTF-16BE-encoded JSON:
219 297
220 use Encode; 298 use Encode;
… …
242 ] 320 ]
243 } 321 }
244 322
245=item $json = $json->indent ([$enable]) 323=item $json = $json->indent ([$enable])
246 324
325=item $enabled = $json->get_indent
326
247If C<$enable> is true (or missing), then the C<encode> method will use a multiline 327If C<$enable> is true (or missing), then the C<encode> method will use a multiline
248format as output, putting every array member or object/hash key-value pair 328format as output, putting every array member or object/hash key-value pair
249into its own line, identing them properly. 329into its own line, indenting them properly.
250 330
251If C<$enable> is false, no newlines or indenting will be produced, and the 331If C<$enable> is false, no newlines or indenting will be produced, and the
252resulting JSON text is guarenteed not to contain any C<newlines>. 332resulting JSON text is guaranteed not to contain any C<newlines>.
253 333
254This setting has no effect when decoding JSON texts. 334This setting has no effect when decoding JSON texts.
255 335
256=item $json = $json->space_before ([$enable]) 336=item $json = $json->space_before ([$enable])
337
338=item $enabled = $json->get_space_before
257 339
258If C<$enable> is true (or missing), then the C<encode> method will add an extra 340If C<$enable> is true (or missing), then the C<encode> method will add an extra
259optional space before the C<:> separating keys from values in JSON objects. 341optional space before the C<:> separating keys from values in JSON objects.
260 342
261If C<$enable> is false, then the C<encode> method will not add any extra 343If C<$enable> is false, then the C<encode> method will not add any extra
… …
267Example, space_before enabled, space_after and indent disabled: 349Example, space_before enabled, space_after and indent disabled:
268 350
269 {"key" :"value"} 351 {"key" :"value"}
270 352
271=item $json = $json->space_after ([$enable]) 353=item $json = $json->space_after ([$enable])
354
355=item $enabled = $json->get_space_after
272 356
273If C<$enable> is true (or missing), then the C<encode> method will add an extra 357If C<$enable> is true (or missing), then the C<encode> method will add an extra
274optional space after the C<:> separating keys from values in JSON objects 358optional space after the C<:> separating keys from values in JSON objects
275and extra whitespace after the C<,> separating key-value pairs and array 359and extra whitespace after the C<,> separating key-value pairs and array
276members. 360members.
… …
282 366
283Example, space_before and indent disabled, space_after enabled: 367Example, space_before and indent disabled, space_after enabled:
284 368
285 {"key": "value"} 369 {"key": "value"}
286 370
371=item $json = $json->relaxed ([$enable])
372
373=item $enabled = $json->get_relaxed
374
375If C<$enable> is true (or missing), then C<decode> will accept some
376extensions to normal JSON syntax (see below). C<encode> will not be
377affected in anyway. I<Be aware that this option makes you accept invalid
378JSON texts as if they were valid!>. I suggest only to use this option to
379parse application-specific files written by humans (configuration files,
380resource files etc.)
381
382If C<$enable> is false (the default), then C<decode> will only accept
383valid JSON texts.
384
385Currently accepted extensions are:
386
387=over 4
388
389=item * list items can have an end-comma
390
391JSON I<separates> array elements and key-value pairs with commas. This
392can be annoying if you write JSON texts manually and want to be able to
393quickly append elements, so this extension accepts comma at the end of
394such items not just between them:
395
396 [
397 1,
398 2, <- this comma not normally allowed
399 ]
400 {
401 "k1": "v1",
402 "k2": "v2", <- this comma not normally allowed
403 }
404
405=item * shell-style '#'-comments
406
407Whenever JSON allows whitespace, shell-style comments are additionally
408allowed. They are terminated by the first carriage-return or line-feed
409character, after which more white-space and comments are allowed.
410
411 [
412 1, # this comment not allowed in JSON
413 # neither this one...
414 ]
415
416=back
417
287=item $json = $json->canonical ([$enable]) 418=item $json = $json->canonical ([$enable])
419
420=item $enabled = $json->get_canonical
288 421
289If C<$enable> is true (or missing), then the C<encode> method will output JSON objects 422If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
290by sorting their keys. This is adding a comparatively high overhead. 423by sorting their keys. This is adding a comparatively high overhead.
291 424
292If C<$enable> is false, then the C<encode> method will output key-value 425If C<$enable> is false, then the C<encode> method will output key-value
293pairs in the order Perl stores them (which will likely change between runs 426pairs in the order Perl stores them (which will likely change between runs
294of the same script). 427of the same script).
295 428
296This option is useful if you want the same data structure to be encoded as 429This option is useful if you want the same data structure to be encoded as
297the same JSON text (given the same overall settings). If it is disabled, 430the same JSON text (given the same overall settings). If it is disabled,
298the same hash migh be encoded differently even if contains the same data, 431the same hash might be encoded differently even if contains the same data,
299as key-value pairs have no inherent ordering in Perl. 432as key-value pairs have no inherent ordering in Perl.
300 433
301This setting has no effect when decoding JSON texts. 434This setting has no effect when decoding JSON texts.
302 435
303=item $json = $json->allow_nonref ([$enable]) 436=item $json = $json->allow_nonref ([$enable])
437
438=item $enabled = $json->get_allow_nonref
304 439
305If C<$enable> is true (or missing), then the C<encode> method can convert a 440If C<$enable> is true (or missing), then the C<encode> method can convert a
306non-reference into its corresponding string, number or null JSON value, 441non-reference into its corresponding string, number or null JSON value,
307which is an extension to RFC4627. Likewise, C<decode> will accept those JSON 442which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
308values instead of croaking. 443values instead of croaking.
… …
316resulting in an invalid JSON text: 451resulting in an invalid JSON text:
317 452
318 JSON::XS->new->allow_nonref->encode ("Hello, World!") 453 JSON::XS->new->allow_nonref->encode ("Hello, World!")
319 => "Hello, World!" 454 => "Hello, World!"
320 455
456=item $json = $json->allow_blessed ([$enable])
457
458=item $enabled = $json->get_allow_blessed
459
460If C<$enable> is true (or missing), then the C<encode> method will not
461barf when it encounters a blessed reference. Instead, the value of the
462B<convert_blessed> option will decide whether C<null> (C<convert_blessed>
463disabled or no C<TO_JSON> method found) or a representation of the
464object (C<convert_blessed> enabled and C<TO_JSON> method found) is being
465encoded. Has no effect on C<decode>.
466
467If C<$enable> is false (the default), then C<encode> will throw an
468exception when it encounters a blessed object.
469
470=item $json = $json->convert_blessed ([$enable])
471
472=item $enabled = $json->get_convert_blessed
473
474If C<$enable> is true (or missing), then C<encode>, upon encountering a
475blessed object, will check for the availability of the C<TO_JSON> method
476on the object's class. If found, it will be called in scalar context
477and the resulting scalar will be encoded instead of the object. If no
478C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
479to do.
480
481The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
482returns other blessed objects, those will be handled in the same
483way. C<TO_JSON> must take care of not causing an endless recursion cycle
484(== crash) in this case. The name of C<TO_JSON> was chosen because other
485methods called by the Perl core (== not by the user of the object) are
486usually in upper case letters and to avoid collisions with any C<to_json>
487function or method.
488
489This setting does not yet influence C<decode> in any way, but in the
490future, global hooks might get installed that influence C<decode> and are
491enabled by this setting.
492
493If C<$enable> is false, then the C<allow_blessed> setting will decide what
494to do when a blessed object is found.
495
496=item $json = $json->filter_json_object ([$coderef->($hashref)])
497
498When C<$coderef> is specified, it will be called from C<decode> each
499time it decodes a JSON object. The only argument is a reference to the
500newly-created hash. If the code references returns a single scalar (which
501need not be a reference), this value (i.e. a copy of that scalar to avoid
502aliasing) is inserted into the deserialised data structure. If it returns
503an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the
504original deserialised hash will be inserted. This setting can slow down
505decoding considerably.
506
507When C<$coderef> is omitted or undefined, any existing callback will
508be removed and C<decode> will not change the deserialised hash in any
509way.
510
511Example, convert all JSON objects into the integer 5:
512
513 my $js = JSON::XS->new->filter_json_object (sub { 5 });
514 # returns [5]
515 $js->decode ('[{}]')
516 # throw an exception because allow_nonref is not enabled
517 # so a lone 5 is not allowed.
518 $js->decode ('{"a":1, "b":2}');
519
520=item $json = $json->filter_json_single_key_object ($key [=> $coderef->($value)])
521
522Works remotely similar to C<filter_json_object>, but is only called for
523JSON objects having a single key named C<$key>.
524
525This C<$coderef> is called before the one specified via
526C<filter_json_object>, if any. It gets passed the single value in the JSON
527object. If it returns a single value, it will be inserted into the data
528structure. If it returns nothing (not even C<undef> but the empty list),
529the callback from C<filter_json_object> will be called next, as if no
530single-key callback were specified.
531
532If C<$coderef> is omitted or undefined, the corresponding callback will be
533disabled. There can only ever be one callback for a given key.
534
535As this callback gets called less often then the C<filter_json_object>
536one, decoding speed will not usually suffer as much. Therefore, single-key
537objects make excellent targets to serialise Perl objects into, especially
538as single-key JSON objects are as close to the type-tagged value concept
539as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not
540support this in any way, so you need to make sure your data never looks
541like a serialised Perl hash.
542
543Typical names for the single object key are C<__class_whatever__>, or
544C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
545things like C<__class_md5sum(classname)__>, to reduce the risk of clashing
546with real hashes.
547
548Example, decode JSON objects of the form C<< { "__widget__" => <id> } >>
549into the corresponding C<< $WIDGET{<id>} >> object:
550
551 # return whatever is in $WIDGET{5}:
552 JSON::XS
553 ->new
554 ->filter_json_single_key_object (__widget__ => sub {
555 $WIDGET{ $_[0] }
556 })
557 ->decode ('{"__widget__": 5')
558
559 # this can be used with a TO_JSON method in some "widget" class
560 # for serialisation to json:
561 sub WidgetBase::TO_JSON {
562 my ($self) = @_;
563
564 unless ($self->{id}) {
565 $self->{id} = ..get..some..id..;
566 $WIDGET{$self->{id}} = $self;
567 }
568
569 { __widget__ => $self->{id} }
570 }
571
321=item $json = $json->shrink ([$enable]) 572=item $json = $json->shrink ([$enable])
573
574=item $enabled = $json->get_shrink
322 575
323Perl usually over-allocates memory a bit when allocating space for 576Perl usually over-allocates memory a bit when allocating space for
324strings. This flag optionally resizes strings generated by either 577strings. This flag optionally resizes strings generated by either
325C<encode> or C<decode> to their minimum size possible. This can save 578C<encode> or C<decode> to their minimum size possible. This can save
326memory when your JSON texts are either very very long or you have many 579memory when your JSON texts are either very very long or you have many
… …
344strings that look like integers or floats into integers or floats 597strings that look like integers or floats into integers or floats
345internally (there is no difference on the Perl level), saving space. 598internally (there is no difference on the Perl level), saving space.
346 599
347=item $json = $json->max_depth ([$maximum_nesting_depth]) 600=item $json = $json->max_depth ([$maximum_nesting_depth])
348 601
602=item $max_depth = $json->get_max_depth
603
349Sets the maximum nesting level (default C<512>) accepted while encoding 604Sets the maximum nesting level (default C<512>) accepted while encoding
350or decoding. If the JSON text or Perl data structure has an equal or 605or decoding. If the JSON text or Perl data structure has an equal or
351higher nesting level then this limit, then the encoder and decoder will 606higher nesting level then this limit, then the encoder and decoder will
352stop and croak at that point. 607stop and croak at that point.
353 608
… …
357given character in a string. 612given character in a string.
358 613
359Setting the maximum depth to one disallows any nesting, so that ensures 614Setting the maximum depth to one disallows any nesting, so that ensures
360that the object is only a single hash/object or array. 615that the object is only a single hash/object or array.
361 616
362The argument to C<max_depth> will be rounded up to the next nearest power 617The argument to C<max_depth> will be rounded up to the next highest power
363of two. 618of two. If no argument is given, the highest possible setting will be
619used, which is rarely useful.
620
621See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
622
623=item $json = $json->max_size ([$maximum_string_size])
624
625=item $max_size = $json->get_max_size
626
627Set the maximum length a JSON text may have (in bytes) where decoding is
628being attempted. The default is C<0>, meaning no limit. When C<decode>
629is called on a string longer then this number of characters it will not
630attempt to decode the string but throw an exception. This setting has no
631effect on C<encode> (yet).
632
633The argument to C<max_size> will be rounded up to the next B<highest>
634power of two (so may be more than requested). If no argument is given, the
635limit check will be deactivated (same as when C<0> is specified).
364 636
365See SECURITY CONSIDERATIONS, below, for more info on why this is useful. 637See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
366 638
367=item $json_text = $json->encode ($perl_scalar) 639=item $json_text = $json->encode ($perl_scalar)
368 640
… …
405vice versa. These mappings are designed to "do the right thing" in most 677vice versa. These mappings are designed to "do the right thing" in most
406circumstances automatically, preserving round-tripping characteristics 678circumstances automatically, preserving round-tripping characteristics
407(what you put in comes out as something equivalent). 679(what you put in comes out as something equivalent).
408 680
409For the more enlightened: note that in the following descriptions, 681For the more enlightened: note that in the following descriptions,
410lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> 682lowercase I<perl> refers to the Perl interpreter, while uppercase I<Perl>
411refers to the abstract Perl language itself. 683refers to the abstract Perl language itself.
412 684
413 685
414=head2 JSON -> PERL 686=head2 JSON -> PERL
415 687
416=over 4 688=over 4
417 689
418=item object 690=item object
419 691
420A JSON object becomes a reference to a hash in Perl. No ordering of object 692A JSON object becomes a reference to a hash in Perl. No ordering of object
421keys is preserved (JSON does not preserver object key ordering itself). 693keys is preserved (JSON does not preserve object key ordering itself).
422 694
423=item array 695=item array
424 696
425A JSON array becomes a reference to an array in Perl. 697A JSON array becomes a reference to an array in Perl.
426 698
… …
430are represented by the same codepoints in the Perl string, so no manual 702are represented by the same codepoints in the Perl string, so no manual
431decoding is necessary. 703decoding is necessary.
432 704
433=item number 705=item number
434 706
435A JSON number becomes either an integer or numeric (floating point) 707A JSON number becomes either an integer, numeric (floating point) or
436scalar in perl, depending on its range and any fractional parts. On the 708string scalar in perl, depending on its range and any fractional parts. On
437Perl level, there is no difference between those as Perl handles all the 709the Perl level, there is no difference between those as Perl handles all
438conversion details, but an integer may take slightly less memory and might 710the conversion details, but an integer may take slightly less memory and
439represent more values exactly than (floating point) numbers. 711might represent more values exactly than (floating point) numbers.
712
713If the number consists of digits only, JSON::XS will try to represent
714it as an integer value. If that fails, it will try to represent it as
715a numeric (floating point) value if that is possible without loss of
716precision. Otherwise it will preserve the number as a string value.
717
718Numbers containing a fractional or exponential part will always be
719represented as numeric (floating point) values, possibly at a loss of
720precision.
721
722This might create round-tripping problems as numbers might become strings,
723but as Perl is typeless there is no other way to do it.
440 724
441=item true, false 725=item true, false
442 726
443These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>, 727These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
444respectively. They are overloaded to act almost exactly like the numbers 728respectively. They are overloaded to act almost exactly like the numbers
445C<1> and C<0>. You can check wether a scalar is a JSON boolean by using 729C<1> and C<0>. You can check whether a scalar is a JSON boolean by using
446the C<JSON::XS::is_bool> function. 730the C<JSON::XS::is_bool> function.
447 731
448=item null 732=item null
449 733
450A JSON null atom becomes C<undef> in Perl. 734A JSON null atom becomes C<undef> in Perl.
… …
481Other unblessed references are generally not allowed and will cause an 765Other unblessed references are generally not allowed and will cause an
482exception to be thrown, except for references to the integers C<0> and 766exception to be thrown, except for references to the integers C<0> and
483C<1>, which get turned into C<false> and C<true> atoms in JSON. You can 767C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
484also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. 768also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
485 769
486 to_json [\0,JSON::XS::true] # yields [false,true] 770 encode_json [\0,JSON::XS::true] # yields [false,true]
487 771
488=item JSON::XS::true, JSON::XS::false 772=item JSON::XS::true, JSON::XS::false
489 773
490These special values become JSON true and JSON false values, 774These special values become JSON true and JSON false values,
491respectively. You cna alos use C<\1> and C<\0> directly if you want. 775respectively. You can also use C<\1> and C<\0> directly if you want.
492 776
493=item blessed objects 777=item blessed objects
494 778
495Blessed objects are not allowed. JSON::XS currently tries to encode their 779Blessed objects are not allowed. JSON::XS currently tries to encode their
496underlying representation (hash- or arrayref), but this behaviour might 780underlying representation (hash- or arrayref), but this behaviour might
… …
502difficult objects to encode: JSON::XS will encode undefined scalars as 786difficult objects to encode: JSON::XS will encode undefined scalars as
503JSON null value, scalars that have last been used in a string context 787JSON null value, scalars that have last been used in a string context
504before encoding as JSON strings and anything else as number value: 788before encoding as JSON strings and anything else as number value:
505 789
506 # dump as number 790 # dump as number
507 to_json [2] # yields [2] 791 encode_json [2] # yields [2]
508 to_json [-3.0e17] # yields [-3e+17] 792 encode_json [-3.0e17] # yields [-3e+17]
509 my $value = 5; to_json [$value] # yields [5] 793 my $value = 5; encode_json [$value] # yields [5]
510 794
511 # used as string, so dump as string 795 # used as string, so dump as string
512 print $value; 796 print $value;
513 to_json [$value] # yields ["5"] 797 encode_json [$value] # yields ["5"]
514 798
515 # undef becomes null 799 # undef becomes null
516 to_json [undef] # yields [null] 800 encode_json [undef] # yields [null]
517 801
518You can force the type to be a string by stringifying it: 802You can force the type to be a JSON string by stringifying it:
519 803
520 my $x = 3.1; # some variable containing a number 804 my $x = 3.1; # some variable containing a number
521 "$x"; # stringified 805 "$x"; # stringified
522 $x .= ""; # another, more awkward way to stringify 806 $x .= ""; # another, more awkward way to stringify
523 print $x; # perl does it for you, too, quite often 807 print $x; # perl does it for you, too, quite often
524 808
525You can force the type to be a number by numifying it: 809You can force the type to be a JSON number by numifying it:
526 810
527 my $x = "3"; # some variable containing a string 811 my $x = "3"; # some variable containing a string
528 $x += 0; # numify it, ensuring it will be dumped as a number 812 $x += 0; # numify it, ensuring it will be dumped as a number
529 $x *= 1; # same thing, the choise is yours. 813 $x *= 1; # same thing, the choice is yours.
530 814
531You can not currently output JSON booleans or force the type in other, 815You can not currently force the type in other, less obscure, ways. Tell me
532less obscure, ways. Tell me if you need this capability. 816if you need this capability.
533 817
534=back 818=back
535 819
536 820
537=head1 COMPARISON 821=head1 COMPARISON
… …
546 830
547=item JSON 1.07 831=item JSON 1.07
548 832
549Slow (but very portable, as it is written in pure Perl). 833Slow (but very portable, as it is written in pure Perl).
550 834
551Undocumented/buggy Unicode handling (how JSON handles unicode values is 835Undocumented/buggy Unicode handling (how JSON handles Unicode values is
552undocumented. One can get far by feeding it unicode strings and doing 836undocumented. One can get far by feeding it Unicode strings and doing
553en-/decoding oneself, but unicode escapes are not working properly). 837en-/decoding oneself, but Unicode escapes are not working properly).
554 838
555No roundtripping (strings get clobbered if they look like numbers, e.g. 839No round-tripping (strings get clobbered if they look like numbers, e.g.
556the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will 840the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will
557decode into the number 2. 841decode into the number 2.
558 842
559=item JSON::PC 0.01 843=item JSON::PC 0.01
560 844
561Very fast. 845Very fast.
562 846
563Undocumented/buggy Unicode handling. 847Undocumented/buggy Unicode handling.
564 848
565No roundtripping. 849No round-tripping.
566 850
567Has problems handling many Perl values (e.g. regex results and other magic 851Has problems handling many Perl values (e.g. regex results and other magic
568values will make it croak). 852values will make it croak).
569 853
570Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}> 854Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
… …
580Very inflexible (no human-readable format supported, format pretty much 864Very inflexible (no human-readable format supported, format pretty much
581undocumented. I need at least a format for easy reading by humans and a 865undocumented. I need at least a format for easy reading by humans and a
582single-line compact format for use in a protocol, and preferably a way to 866single-line compact format for use in a protocol, and preferably a way to
583generate ASCII-only JSON texts). 867generate ASCII-only JSON texts).
584 868
585Completely broken (and confusingly documented) Unicode handling (unicode 869Completely broken (and confusingly documented) Unicode handling (Unicode
586escapes are not working properly, you need to set ImplicitUnicode to 870escapes are not working properly, you need to set ImplicitUnicode to
587I<different> values on en- and decoding to get symmetric behaviour). 871I<different> values on en- and decoding to get symmetric behaviour).
588 872
589No roundtripping (simple cases work, but this depends on wether the scalar 873No round-tripping (simple cases work, but this depends on whether the scalar
590value was used in a numeric context or not). 874value was used in a numeric context or not).
591 875
592Dumping hashes may skip hash values depending on iterator state. 876Dumping hashes may skip hash values depending on iterator state.
593 877
594Unmaintained (maintainer unresponsive for many months, bugs are not 878Unmaintained (maintainer unresponsive for many months, bugs are not
595getting fixed). 879getting fixed).
596 880
597Does not check input for validity (i.e. will accept non-JSON input and 881Does not check input for validity (i.e. will accept non-JSON input and
598return "something" instead of raising an exception. This is a security 882return "something" instead of raising an exception. This is a security
599issue: imagine two banks transfering money between each other using 883issue: imagine two banks transferring money between each other using
600JSON. One bank might parse a given non-JSON request and deduct money, 884JSON. One bank might parse a given non-JSON request and deduct money,
601while the other might reject the transaction with a syntax error. While a 885while the other might reject the transaction with a syntax error. While a
602good protocol will at least recover, that is extra unnecessary work and 886good protocol will at least recover, that is extra unnecessary work and
603the transaction will still not succeed). 887the transaction will still not succeed).
604 888
605=item JSON::DWIW 0.04 889=item JSON::DWIW 0.04
606 890
607Very fast. Very natural. Very nice. 891Very fast. Very natural. Very nice.
608 892
609Undocumented unicode handling (but the best of the pack. Unicode escapes 893Undocumented Unicode handling (but the best of the pack. Unicode escapes
610still don't get parsed properly). 894still don't get parsed properly).
611 895
612Very inflexible. 896Very inflexible.
613 897
614No roundtripping. 898No round-tripping.
615 899
616Does not generate valid JSON texts (key strings are often unquoted, empty keys 900Does not generate valid JSON texts (key strings are often unquoted, empty keys
617result in nothing being output) 901result in nothing being output)
618 902
619Does not check input for validity. 903Does not check input for validity.
… …
621=back 905=back
622 906
623 907
624=head2 JSON and YAML 908=head2 JSON and YAML
625 909
626You often hear that JSON is a subset (or a close subset) of YAML. This is, 910You often hear that JSON is a subset of YAML. This is, however, a mass
627however, a mass hysteria and very far from the truth. In general, there is 911hysteria(*) and very far from the truth. In general, there is no way to
628no way to configure JSON::XS to output a data structure as valid YAML. 912configure JSON::XS to output a data structure as valid YAML that works for
913all cases.
629 914
630If you really must use JSON::XS to generate YAML, you should use this 915If you really must use JSON::XS to generate YAML, you should use this
631algorithm (subject to change in future versions): 916algorithm (subject to change in future versions):
632 917
633 my $to_yaml = JSON::XS->new->utf8->space_after (1); 918 my $to_yaml = JSON::XS->new->utf8->space_after (1);
634 my $yaml = $to_yaml->encode ($ref) . "\n"; 919 my $yaml = $to_yaml->encode ($ref) . "\n";
635 920
636This will usually generate JSON texts that also parse as valid 921This will usually generate JSON texts that also parse as valid
637YAML. Please note that YAML has hardcoded limits on (simple) object key 922YAML. Please note that YAML has hardcoded limits on (simple) object key
638lengths that JSON doesn't have, so you should make sure that your hash 923lengths that JSON doesn't have and also has different and incompatible
924unicode handling, so you should make sure that your hash keys are
639keys are noticably shorter than the 1024 characters YAML allows. 925noticeably shorter than the 1024 "stream characters" YAML allows and that
926you do not have codepoints with values outside the Unicode BMP (basic
927multilingual page). YAML also does not allow C<\/> sequences in strings
928(which JSON::XS does not I<currently> generate).
640 929
641There might be other incompatibilities that I am not aware of. In general 930There might be other incompatibilities that I am not aware of. In general
642you should not try to generate YAML with a JSON generator or vice versa, 931you should not try to generate YAML with a JSON generator or vice versa,
643or try to parse JSON with a YAML parser or vice versa: chances are high 932or try to parse JSON with a YAML parser or vice versa: chances are high
644that you will run into severe interoperability problems. 933that you will run into severe interoperability problems when you least
934expect it.
935
936=over 4
937
938=item (*)
939
940This is spread actively by the YAML team, however. For many years now they
941claim YAML were a superset of JSON, even when proven otherwise.
942
943Even the author of this manpage was at some point accused of providing
944"incorrect" information, despite the evidence presented (claims ranged
945from "your documentation contains inaccurate and negative statements about
946YAML" (the only negative comment is this footnote, and it didn't exist
947back then; the question on which claims were inaccurate was never answered
948etc.) to "the YAML spec is not up-to-date" (the *real* and suppsedly
949JSON-compatible spec is apparently not currently publicly available)
950to actual requests to replace this section by *incorrect* information,
951suppressing information about the real problem).
952
953So whenever you are told that YAML was a superset of JSON, first check
954wether it is really true (it might be when you check it, but it cetrainly
955is not true when this was written). I would much prefer if the YAML team
956would spent their time on actually making JSON compatibility a truth
957(JSON, after all, has a very small and simple specification) instead of
958trying to lobby/force people into reporting untruths.
959
960=back
645 961
646 962
647=head2 SPEED 963=head2 SPEED
648 964
649It seems that JSON::XS is surprisingly fast, as shown in the following 965It seems that JSON::XS is surprisingly fast, as shown in the following
… …
662with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables 978with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
663shrink). Higher is better: 979shrink). Higher is better:
664 980
665 module | encode | decode | 981 module | encode | decode |
666 -----------|------------|------------| 982 -----------|------------|------------|
667 JSON | 7645.468 | 4208.613 | 983 JSON 1.x | 4990.842 | 4088.813 |
668 JSON::DWIW | 40721.398 | 77101.176 | 984 JSON::DWIW | 51653.990 | 71575.154 |
669 JSON::PC | 65948.176 | 78251.940 | 985 JSON::PC | 65948.176 | 74631.744 |
670 JSON::Syck | 22844.793 | 26479.192 | 986 JSON::PP | 8931.652 | 3817.168 |
987 JSON::Syck | 24877.248 | 27776.848 |
671 JSON::XS | 388361.481 | 199728.762 | 988 JSON::XS | 388361.481 | 227951.304 |
672 JSON::XS/2 | 218453.333 | 192399.266 | 989 JSON::XS/2 | 227951.304 | 218453.333 |
673 JSON::XS/3 | 338250.323 | 192399.266 | 990 JSON::XS/3 | 338250.323 | 218453.333 |
674 Storable | 15779.925 | 14169.946 | 991 Storable | 16500.016 | 135300.129 |
675 -----------+------------+------------+ 992 -----------+------------+------------+
676 993
677That is, JSON::XS is about five times faster than JSON::DWIW on encoding, 994That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
678about three times faster on decoding, and over fourty times faster 995about three times faster on decoding, and over forty times faster
679than JSON, even with pretty-printing and key sorting. It also compares 996than JSON, even with pretty-printing and key sorting. It also compares
680favourably to Storable for small amounts of data. 997favourably to Storable for small amounts of data.
681 998
682Using a longer test string (roughly 18KB, generated from Yahoo! Locals 999Using a longer test string (roughly 18KB, generated from Yahoo! Locals
683search API (http://nanoref.com/yahooapis/mgPdGg): 1000search API (http://nanoref.com/yahooapis/mgPdGg):
684 1001
685 module | encode | decode | 1002 module | encode | decode |
686 -----------|------------|------------| 1003 -----------|------------|------------|
687 JSON | 254.685 | 37.665 | 1004 JSON 1.x | 55.260 | 34.971 |
688 JSON::DWIW | 843.343 | 1049.731 | 1005 JSON::DWIW | 825.228 | 1082.513 |
689 JSON::PC | 3602.116 | 2307.352 | 1006 JSON::PC | 3571.444 | 2394.829 |
1007 JSON::PP | 210.987 | 32.574 |
690 JSON::Syck | 505.107 | 787.899 | 1008 JSON::Syck | 552.551 | 787.544 |
691 JSON::XS | 5747.196 | 3690.220 | 1009 JSON::XS | 5780.463 | 4854.519 |
692 JSON::XS/2 | 3968.121 | 3676.634 | 1010 JSON::XS/2 | 3869.998 | 4798.975 |
693 JSON::XS/3 | 6105.246 | 3662.508 | 1011 JSON::XS/3 | 5862.880 | 4798.975 |
694 Storable | 4417.337 | 5285.161 | 1012 Storable | 4445.002 | 5235.027 |
695 -----------+------------+------------+ 1013 -----------+------------+------------+
696 1014
697Again, JSON::XS leads by far (except for Storable which non-surprisingly 1015Again, JSON::XS leads by far (except for Storable which non-surprisingly
698decodes faster). 1016decodes faster).
699 1017
700On large strings containing lots of high unicode characters, some modules 1018On large strings containing lots of high Unicode characters, some modules
701(such as JSON::PC) seem to decode faster than JSON::XS, but the result 1019(such as JSON::PC) seem to decode faster than JSON::XS, but the result
702will be broken due to missing (or wrong) unicode handling. Others refuse 1020will be broken due to missing (or wrong) Unicode handling. Others refuse
703to decode or encode properly, so it was impossible to prepare a fair 1021to decode or encode properly, so it was impossible to prepare a fair
704comparison table for that case. 1022comparison table for that case.
705 1023
706 1024
707=head1 SECURITY CONSIDERATIONS 1025=head1 SECURITY CONSIDERATIONS
… …
713any buffer overflows. Obviously, this module should ensure that and I am 1031any buffer overflows. Obviously, this module should ensure that and I am
714trying hard on making that true, but you never know. 1032trying hard on making that true, but you never know.
715 1033
716Second, you need to avoid resource-starving attacks. That means you should 1034Second, you need to avoid resource-starving attacks. That means you should
717limit the size of JSON texts you accept, or make sure then when your 1035limit the size of JSON texts you accept, or make sure then when your
718resources run out, thats just fine (e.g. by using a separate process that 1036resources run out, that's just fine (e.g. by using a separate process that
719can crash safely). The size of a JSON text in octets or characters is 1037can crash safely). The size of a JSON text in octets or characters is
720usually a good indication of the size of the resources required to decode 1038usually a good indication of the size of the resources required to decode
721it into a Perl structure. 1039it into a Perl structure. While JSON::XS can check the size of the JSON
1040text, it might be too late when you already have it in memory, so you
1041might want to check the size before you accept the string.
722 1042
723Third, JSON::XS recurses using the C stack when decoding objects and 1043Third, JSON::XS recurses using the C stack when decoding objects and
724arrays. The C stack is a limited resource: for instance, on my amd64 1044arrays. The C stack is a limited resource: for instance, on my amd64
725machine with 8MB of stack size I can decode around 180k nested arrays but 1045machine with 8MB of stack size I can decode around 180k nested arrays but
726only 14k nested JSON objects (due to perl itself recursing deeply on croak 1046only 14k nested JSON objects (due to perl itself recursing deeply on croak
727to free the temporary). If that is exceeded, the program crashes. to be 1047to free the temporary). If that is exceeded, the program crashes. To be
728conservative, the default nesting limit is set to 512. If your process 1048conservative, the default nesting limit is set to 512. If your process
729has a smaller stack, you should adjust this setting accordingly with the 1049has a smaller stack, you should adjust this setting accordingly with the
730C<max_depth> method. 1050C<max_depth> method.
731 1051
732And last but least, something else could bomb you that I forgot to think 1052And last but least, something else could bomb you that I forgot to think
733of. In that case, you get to keep the pieces. I am always open for hints, 1053of. In that case, you get to keep the pieces. I am always open for hints,
734though... 1054though...
735 1055
736If you are using JSON::XS to return packets to consumption 1056If you are using JSON::XS to return packets to consumption
737by javascript scripts in a browser you should have a look at 1057by JavaScript scripts in a browser you should have a look at
738L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether 1058L<http://jpsykes.com/47/practical-csrf-and-json-security> to see whether
739you are vulnerable to some common attack vectors (which really are browser 1059you are vulnerable to some common attack vectors (which really are browser
740design bugs, but it is still you who will have to deal with it, as major 1060design bugs, but it is still you who will have to deal with it, as major
741browser developers care only for features, not about doing security 1061browser developers care only for features, not about getting security
742right). 1062right).
1063
1064
1065=head1 THREADS
1066
1067This module is I<not> guaranteed to be thread safe and there are no
1068plans to change this until Perl gets thread support (as opposed to the
1069horribly slow so-called "threads" which are simply slow and bloated
1070process simulations - use fork, its I<much> faster, cheaper, better).
1071
1072(It might actually work, but you have been warned).
743 1073
744 1074
745=head1 BUGS 1075=head1 BUGS
746 1076
747While the goal of this module is to be correct, that unfortunately does 1077While the goal of this module is to be correct, that unfortunately does
748not mean its bug-free, only that I think its design is bug-free. It is 1078not mean its bug-free, only that I think its design is bug-free. It is
749still relatively early in its development. If you keep reporting bugs they 1079still relatively early in its development. If you keep reporting bugs they
750will be fixed swiftly, though. 1080will be fixed swiftly, though.
751 1081
1082Please refrain from using rt.cpan.org or any other bug reporting
1083service. I put the contact address into my modules for a reason.
1084
752=cut 1085=cut
753 1086
754our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" }; 1087our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
755our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" }; 1088our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
756 1089
757sub true() { $true } 1090sub true() { $true }
758sub false() { $false } 1091sub false() { $false }
759 1092
760sub is_bool($) { 1093sub is_bool($) {
761 UNIVERSAL::isa $_[0], "JSON::XS::Boolean" 1094 UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
762 or UNIVERSAL::isa $_[0], "JSON::Literal" 1095# or UNIVERSAL::isa $_[0], "JSON::Literal"
763} 1096}
764 1097
765XSLoader::load "JSON::XS", $VERSION; 1098XSLoader::load "JSON::XS", $VERSION;
766 1099
767package JSON::XS::Boolean; 1100package JSON::XS::Boolean;

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