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Revision 1.30 by root, Mon Apr 9 06:37:40 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
90BEGIN {
91 our $VERSION = '1.11'; 105our $VERSION = '2.01';
92 our @ISA = qw(Exporter); 106our @ISA = qw(Exporter);
93 107
94 our @EXPORT = qw(to_json from_json objToJson jsonToObj); 108our @EXPORT = qw(encode_json decode_json to_json from_json);
95 require Exporter;
96 109
110sub to_json($) {
97 require XSLoader; 111 require Carp;
98 XSLoader::load JSON::XS::, $VERSION; 112 Carp::croak ("JSON::XS::to_json has been renamed to encode_json, either downgrade to pre-2.0 versions of JSON::XS or rename the call");
99} 113}
100 114
115sub from_json($) {
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}
119
120use Exporter;
121use XSLoader;
122
101=head1 FUNCTIONAL INTERFACE 123=head1 FUNCTIONAL INTERFACE
102 124
103The following convinience methods are provided by this module. They are 125The following convenience methods are provided by this module. They are
104exported by default: 126exported by default:
105 127
106=over 4 128=over 4
107 129
108=item $json_text = to_json $perl_scalar 130=item $json_text = encode_json $perl_scalar
109 131
110Converts 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
111a 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.
112octets only). Croaks on error.
113 134
114This function call is functionally identical to: 135This function call is functionally identical to:
115 136
116 $json_text = JSON::XS->new->utf8->encode ($perl_scalar) 137 $json_text = JSON::XS->new->utf8->encode ($perl_scalar)
117 138
118except being faster. 139except being faster.
119 140
120=item $perl_scalar = from_json $json_text 141=item $perl_scalar = decode_json $json_text
121 142
122The 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
123parse 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
124scalar or reference. Croaks on error. 145reference. Croaks on error.
125 146
126This function call is functionally identical to: 147This function call is functionally identical to:
127 148
128 $perl_scalar = JSON::XS->new->utf8->decode ($json_text) 149 $perl_scalar = JSON::XS->new->utf8->decode ($json_text)
129 150
130except being faster. 151except being faster.
131 152
153=item $is_boolean = JSON::XS::is_bool $scalar
154
155Returns true if the passed scalar represents either JSON::XS::true or
156JSON::XS::false, two constants that act like C<1> and C<0>, respectively
157and are used to represent JSON C<true> and C<false> values in Perl.
158
159See MAPPING, below, for more information on how JSON values are mapped to
160Perl.
161
132=back 162=back
163
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 :)
133 211
134 212
135=head1 OBJECT-ORIENTED INTERFACE 213=head1 OBJECT-ORIENTED INTERFACE
136 214
137The object oriented interface lets you configure your own encoding or 215The object oriented interface lets you configure your own encoding or
… …
150 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]})
151 => {"a": [1, 2]} 229 => {"a": [1, 2]}
152 230
153=item $json = $json->ascii ([$enable]) 231=item $json = $json->ascii ([$enable])
154 232
233=item $enabled = $json->get_ascii
234
155If C<$enable> is true (or missing), then the C<encode> method will not 235If C<$enable> is true (or missing), then the C<encode> method will not
156generate characters outside the code range C<0..127> (which is ASCII). Any 236generate characters outside the code range C<0..127> (which is ASCII). Any
157unicode characters outside that range will be escaped using either a 237Unicode characters outside that range will be escaped using either a
158single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, 238single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
159as per RFC4627. 239as per RFC4627. The resulting encoded JSON text can be treated as a native
240Unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
241or any other superset of ASCII.
160 242
161If C<$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
162characters unless required by the JSON syntax. This results in a faster 244characters unless required by the JSON syntax or other flags. This results
163and more compact format. 245in a faster and more compact format.
246
247The main use for this flag is to produce JSON texts that can be
248transmitted over a 7-bit channel, as the encoded JSON texts will not
249contain any 8 bit characters.
164 250
165 JSON::XS->new->ascii (1)->encode ([chr 0x10401]) 251 JSON::XS->new->ascii (1)->encode ([chr 0x10401])
166 => ["\ud801\udc01"] 252 => ["\ud801\udc01"]
167 253
254=item $json = $json->latin1 ([$enable])
255
256=item $enabled = $json->get_latin1
257
258If C<$enable> is true (or missing), then the C<encode> method will encode
259the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
260outside the code range C<0..255>. The resulting string can be treated as a
261latin1-encoded JSON text or a native Unicode string. The C<decode> method
262will not be affected in any way by this flag, as C<decode> by default
263expects Unicode, which is a strict superset of latin1.
264
265If C<$enable> is false, then the C<encode> method will not escape Unicode
266characters unless required by the JSON syntax or other flags.
267
268The main use for this flag is efficiently encoding binary data as JSON
269text, as most octets will not be escaped, resulting in a smaller encoded
270size. The disadvantage is that the resulting JSON text is encoded
271in latin1 (and must correctly be treated as such when storing and
272transferring), a rare encoding for JSON. It is therefore most useful when
273you want to store data structures known to contain binary data efficiently
274in files or databases, not when talking to other JSON encoders/decoders.
275
276 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
277 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
278
168=item $json = $json->utf8 ([$enable]) 279=item $json = $json->utf8 ([$enable])
280
281=item $enabled = $json->get_utf8
169 282
170If C<$enable> is true (or missing), then the C<encode> method will encode 283If C<$enable> is true (or missing), then the C<encode> method will encode
171the JSON result into UTF-8, as required by many protocols, while the 284the JSON result into UTF-8, as required by many protocols, while the
172C<decode> method expects to be handled an UTF-8-encoded string. Please 285C<decode> method expects to be handled an UTF-8-encoded string. Please
173note that UTF-8-encoded strings do not contain any characters outside the 286note that UTF-8-encoded strings do not contain any characters outside the
174range C<0..255>, they are thus useful for bytewise/binary I/O. In future 287range C<0..255>, they are thus useful for bytewise/binary I/O. In future
175versions, enabling this option might enable autodetection of the UTF-16 288versions, enabling this option might enable autodetection of the UTF-16
176and UTF-32 encoding families, as described in RFC4627. 289and UTF-32 encoding families, as described in RFC4627.
177 290
178If C<$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
179string 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
180unicode 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
181to be done yourself, e.g. using the Encode module. 294to be done yourself, e.g. using the Encode module.
182 295
183Example, output UTF-16BE-encoded JSON: 296Example, output UTF-16BE-encoded JSON:
184 297
185 use Encode; 298 use Encode;
… …
207 ] 320 ]
208 } 321 }
209 322
210=item $json = $json->indent ([$enable]) 323=item $json = $json->indent ([$enable])
211 324
325=item $enabled = $json->get_indent
326
212If C<$enable> is true (or missing), then the C<encode> method will use a multiline 327If C<$enable> is true (or missing), then the C<encode> method will use a multiline
213format as output, putting every array member or object/hash key-value pair 328format as output, putting every array member or object/hash key-value pair
214into its own line, identing them properly. 329into its own line, indenting them properly.
215 330
216If C<$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
217resulting JSON text is guarenteed not to contain any C<newlines>. 332resulting JSON text is guaranteed not to contain any C<newlines>.
218 333
219This setting has no effect when decoding JSON texts. 334This setting has no effect when decoding JSON texts.
220 335
221=item $json = $json->space_before ([$enable]) 336=item $json = $json->space_before ([$enable])
337
338=item $enabled = $json->get_space_before
222 339
223If C<$enable> is true (or missing), then the C<encode> method will add an extra 340If C<$enable> is true (or missing), then the C<encode> method will add an extra
224optional space before the C<:> separating keys from values in JSON objects. 341optional space before the C<:> separating keys from values in JSON objects.
225 342
226If C<$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
… …
232Example, space_before enabled, space_after and indent disabled: 349Example, space_before enabled, space_after and indent disabled:
233 350
234 {"key" :"value"} 351 {"key" :"value"}
235 352
236=item $json = $json->space_after ([$enable]) 353=item $json = $json->space_after ([$enable])
354
355=item $enabled = $json->get_space_after
237 356
238If C<$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
239optional space after the C<:> separating keys from values in JSON objects 358optional space after the C<:> separating keys from values in JSON objects
240and extra whitespace after the C<,> separating key-value pairs and array 359and extra whitespace after the C<,> separating key-value pairs and array
241members. 360members.
… …
247 366
248Example, space_before and indent disabled, space_after enabled: 367Example, space_before and indent disabled, space_after enabled:
249 368
250 {"key": "value"} 369 {"key": "value"}
251 370
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
252=item $json = $json->canonical ([$enable]) 418=item $json = $json->canonical ([$enable])
419
420=item $enabled = $json->get_canonical
253 421
254If C<$enable> is true (or missing), then the C<encode> method will output JSON objects 422If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
255by sorting their keys. This is adding a comparatively high overhead. 423by sorting their keys. This is adding a comparatively high overhead.
256 424
257If C<$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
258pairs 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
259of the same script). 427of the same script).
260 428
261This 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
262the 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,
263the 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,
264as key-value pairs have no inherent ordering in Perl. 432as key-value pairs have no inherent ordering in Perl.
265 433
266This setting has no effect when decoding JSON texts. 434This setting has no effect when decoding JSON texts.
267 435
268=item $json = $json->allow_nonref ([$enable]) 436=item $json = $json->allow_nonref ([$enable])
437
438=item $enabled = $json->get_allow_nonref
269 439
270If C<$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
271non-reference into its corresponding string, number or null JSON value, 441non-reference into its corresponding string, number or null JSON value,
272which 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
273values instead of croaking. 443values instead of croaking.
… …
281resulting in an invalid JSON text: 451resulting in an invalid JSON text:
282 452
283 JSON::XS->new->allow_nonref->encode ("Hello, World!") 453 JSON::XS->new->allow_nonref->encode ("Hello, World!")
284 => "Hello, World!" 454 => "Hello, World!"
285 455
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
286=item $json = $json->shrink ([$enable]) 572=item $json = $json->shrink ([$enable])
573
574=item $enabled = $json->get_shrink
287 575
288Perl usually over-allocates memory a bit when allocating space for 576Perl usually over-allocates memory a bit when allocating space for
289strings. This flag optionally resizes strings generated by either 577strings. This flag optionally resizes strings generated by either
290C<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
291memory 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
… …
309strings that look like integers or floats into integers or floats 597strings that look like integers or floats into integers or floats
310internally (there is no difference on the Perl level), saving space. 598internally (there is no difference on the Perl level), saving space.
311 599
312=item $json = $json->max_depth ([$maximum_nesting_depth]) 600=item $json = $json->max_depth ([$maximum_nesting_depth])
313 601
602=item $max_depth = $json->get_max_depth
603
314Sets the maximum nesting level (default C<512>) accepted while encoding 604Sets the maximum nesting level (default C<512>) accepted while encoding
315or 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
316higher nesting level then this limit, then the encoder and decoder will 606higher nesting level then this limit, then the encoder and decoder will
317stop and croak at that point. 607stop and croak at that point.
318 608
… …
322given character in a string. 612given character in a string.
323 613
324Setting the maximum depth to one disallows any nesting, so that ensures 614Setting the maximum depth to one disallows any nesting, so that ensures
325that the object is only a single hash/object or array. 615that the object is only a single hash/object or array.
326 616
327The 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
328of 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).
329 636
330See SECURITY CONSIDERATIONS, below, for more info on why this is useful. 637See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
331 638
332=item $json_text = $json->encode ($perl_scalar) 639=item $json_text = $json->encode ($perl_scalar)
333 640
… …
345 652
346JSON numbers and strings become simple Perl scalars. JSON arrays become 653JSON numbers and strings become simple Perl scalars. JSON arrays become
347Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes 654Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
348C<1>, C<false> becomes C<0> and C<null> becomes C<undef>. 655C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
349 656
657=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
658
659This works like the C<decode> method, but instead of raising an exception
660when there is trailing garbage after the first JSON object, it will
661silently stop parsing there and return the number of characters consumed
662so far.
663
664This is useful if your JSON texts are not delimited by an outer protocol
665(which is not the brightest thing to do in the first place) and you need
666to know where the JSON text ends.
667
668 JSON::XS->new->decode_prefix ("[1] the tail")
669 => ([], 3)
670
350=back 671=back
351 672
352 673
353=head1 MAPPING 674=head1 MAPPING
354 675
… …
356vice 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
357circumstances automatically, preserving round-tripping characteristics 678circumstances automatically, preserving round-tripping characteristics
358(what you put in comes out as something equivalent). 679(what you put in comes out as something equivalent).
359 680
360For the more enlightened: note that in the following descriptions, 681For the more enlightened: note that in the following descriptions,
361lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> 682lowercase I<perl> refers to the Perl interpreter, while uppercase I<Perl>
362refers to the abstract Perl language itself. 683refers to the abstract Perl language itself.
363 684
685
364=head2 JSON -> PERL 686=head2 JSON -> PERL
365 687
366=over 4 688=over 4
367 689
368=item object 690=item object
369 691
370A 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
371keys is preserved (JSON does not preserver object key ordering itself). 693keys is preserved (JSON does not preserve object key ordering itself).
372 694
373=item array 695=item array
374 696
375A JSON array becomes a reference to an array in Perl. 697A JSON array becomes a reference to an array in Perl.
376 698
… …
380are 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
381decoding is necessary. 703decoding is necessary.
382 704
383=item number 705=item number
384 706
385A JSON number becomes either an integer or numeric (floating point) 707A JSON number becomes either an integer, numeric (floating point) or
386scalar 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
387Perl 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
388conversion details, but an integer may take slightly less memory and might 710the conversion details, but an integer may take slightly less memory and
389represent 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.
390 724
391=item true, false 725=item true, false
392 726
393These JSON atoms become C<0>, C<1>, respectively. Information is lost in 727These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
394this process. Future versions might represent those values differently, 728respectively. They are overloaded to act almost exactly like the numbers
395but they will be guarenteed to act like these integers would normally in 729C<1> and C<0>. You can check whether a scalar is a JSON boolean by using
396Perl. 730the C<JSON::XS::is_bool> function.
397 731
398=item null 732=item null
399 733
400A JSON null atom becomes C<undef> in Perl. 734A JSON null atom becomes C<undef> in Perl.
401 735
402=back 736=back
737
403 738
404=head2 PERL -> JSON 739=head2 PERL -> JSON
405 740
406The mapping from Perl to JSON is slightly more difficult, as Perl is a 741The mapping from Perl to JSON is slightly more difficult, as Perl is a
407truly typeless language, so we can only guess which JSON type is meant by 742truly typeless language, so we can only guess which JSON type is meant by
… …
430Other unblessed references are generally not allowed and will cause an 765Other unblessed references are generally not allowed and will cause an
431exception 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
432C<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
433also 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.
434 769
435 to_json [\0,JSON::XS::true] # yields [false,true] 770 encode_json [\0,JSON::XS::true] # yields [false,true]
771
772=item JSON::XS::true, JSON::XS::false
773
774These special values become JSON true and JSON false values,
775respectively. You can also use C<\1> and C<\0> directly if you want.
436 776
437=item blessed objects 777=item blessed objects
438 778
439Blessed objects are not allowed. JSON::XS currently tries to encode their 779Blessed objects are not allowed. JSON::XS currently tries to encode their
440underlying representation (hash- or arrayref), but this behaviour might 780underlying representation (hash- or arrayref), but this behaviour might
… …
446difficult objects to encode: JSON::XS will encode undefined scalars as 786difficult objects to encode: JSON::XS will encode undefined scalars as
447JSON 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
448before encoding as JSON strings and anything else as number value: 788before encoding as JSON strings and anything else as number value:
449 789
450 # dump as number 790 # dump as number
451 to_json [2] # yields [2] 791 encode_json [2] # yields [2]
452 to_json [-3.0e17] # yields [-3e+17] 792 encode_json [-3.0e17] # yields [-3e+17]
453 my $value = 5; to_json [$value] # yields [5] 793 my $value = 5; encode_json [$value] # yields [5]
454 794
455 # used as string, so dump as string 795 # used as string, so dump as string
456 print $value; 796 print $value;
457 to_json [$value] # yields ["5"] 797 encode_json [$value] # yields ["5"]
458 798
459 # undef becomes null 799 # undef becomes null
460 to_json [undef] # yields [null] 800 encode_json [undef] # yields [null]
461 801
462You can force the type to be a string by stringifying it: 802You can force the type to be a JSON string by stringifying it:
463 803
464 my $x = 3.1; # some variable containing a number 804 my $x = 3.1; # some variable containing a number
465 "$x"; # stringified 805 "$x"; # stringified
466 $x .= ""; # another, more awkward way to stringify 806 $x .= ""; # another, more awkward way to stringify
467 print $x; # perl does it for you, too, quite often 807 print $x; # perl does it for you, too, quite often
468 808
469You can force the type to be a number by numifying it: 809You can force the type to be a JSON number by numifying it:
470 810
471 my $x = "3"; # some variable containing a string 811 my $x = "3"; # some variable containing a string
472 $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
473 $x *= 1; # same thing, the choise is yours. 813 $x *= 1; # same thing, the choice is yours.
474 814
475You 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
476less obscure, ways. Tell me if you need this capability. 816if you need this capability.
477 817
478=back 818=back
479 819
480 820
481=head1 COMPARISON 821=head1 COMPARISON
… …
490 830
491=item JSON 1.07 831=item JSON 1.07
492 832
493Slow (but very portable, as it is written in pure Perl). 833Slow (but very portable, as it is written in pure Perl).
494 834
495Undocumented/buggy Unicode handling (how JSON handles unicode values is 835Undocumented/buggy Unicode handling (how JSON handles Unicode values is
496undocumented. One can get far by feeding it unicode strings and doing 836undocumented. One can get far by feeding it Unicode strings and doing
497en-/decoding oneself, but unicode escapes are not working properly). 837en-/decoding oneself, but Unicode escapes are not working properly).
498 838
499No roundtripping (strings get clobbered if they look like numbers, e.g. 839No round-tripping (strings get clobbered if they look like numbers, e.g.
500the 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
501decode into the number 2. 841decode into the number 2.
502 842
503=item JSON::PC 0.01 843=item JSON::PC 0.01
504 844
505Very fast. 845Very fast.
506 846
507Undocumented/buggy Unicode handling. 847Undocumented/buggy Unicode handling.
508 848
509No roundtripping. 849No round-tripping.
510 850
511Has 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
512values will make it croak). 852values will make it croak).
513 853
514Does 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}>
… …
524Very inflexible (no human-readable format supported, format pretty much 864Very inflexible (no human-readable format supported, format pretty much
525undocumented. 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
526single-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
527generate ASCII-only JSON texts). 867generate ASCII-only JSON texts).
528 868
529Completely broken (and confusingly documented) Unicode handling (unicode 869Completely broken (and confusingly documented) Unicode handling (Unicode
530escapes are not working properly, you need to set ImplicitUnicode to 870escapes are not working properly, you need to set ImplicitUnicode to
531I<different> values on en- and decoding to get symmetric behaviour). 871I<different> values on en- and decoding to get symmetric behaviour).
532 872
533No roundtripping (simple cases work, but this depends on wether the scalar 873No round-tripping (simple cases work, but this depends on whether the scalar
534value was used in a numeric context or not). 874value was used in a numeric context or not).
535 875
536Dumping hashes may skip hash values depending on iterator state. 876Dumping hashes may skip hash values depending on iterator state.
537 877
538Unmaintained (maintainer unresponsive for many months, bugs are not 878Unmaintained (maintainer unresponsive for many months, bugs are not
539getting fixed). 879getting fixed).
540 880
541Does 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
542return "something" instead of raising an exception. This is a security 882return "something" instead of raising an exception. This is a security
543issue: imagine two banks transfering money between each other using 883issue: imagine two banks transferring money between each other using
544JSON. 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,
545while 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
546good protocol will at least recover, that is extra unnecessary work and 886good protocol will at least recover, that is extra unnecessary work and
547the transaction will still not succeed). 887the transaction will still not succeed).
548 888
549=item JSON::DWIW 0.04 889=item JSON::DWIW 0.04
550 890
551Very fast. Very natural. Very nice. 891Very fast. Very natural. Very nice.
552 892
553Undocumented unicode handling (but the best of the pack. Unicode escapes 893Undocumented Unicode handling (but the best of the pack. Unicode escapes
554still don't get parsed properly). 894still don't get parsed properly).
555 895
556Very inflexible. 896Very inflexible.
557 897
558No roundtripping. 898No round-tripping.
559 899
560Does 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
561result in nothing being output) 901result in nothing being output)
562 902
563Does not check input for validity. 903Does not check input for validity.
564 904
565=back 905=back
906
907
908=head2 JSON and YAML
909
910You often hear that JSON is a subset of YAML. This is, however, a mass
911hysteria(*) and very far from the truth. In general, there is no way to
912configure JSON::XS to output a data structure as valid YAML that works for
913all cases.
914
915If you really must use JSON::XS to generate YAML, you should use this
916algorithm (subject to change in future versions):
917
918 my $to_yaml = JSON::XS->new->utf8->space_after (1);
919 my $yaml = $to_yaml->encode ($ref) . "\n";
920
921This will usually generate JSON texts that also parse as valid
922YAML. Please note that YAML has hardcoded limits on (simple) object key
923lengths that JSON doesn't have and also has different and incompatible
924unicode handling, so you should make sure that your hash keys are
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).
929
930There might be other incompatibilities that I am not aware of. In general
931you should not try to generate YAML with a JSON generator or vice versa,
932or try to parse JSON with a YAML parser or vice versa: chances are high
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
961
566 962
567=head2 SPEED 963=head2 SPEED
568 964
569It 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
570tables. They have been generated with the help of the C<eg/bench> program 966tables. They have been generated with the help of the C<eg/bench> program
571in the JSON::XS distribution, to make it easy to compare on your own 967in the JSON::XS distribution, to make it easy to compare on your own
572system. 968system.
573 969
574First comes a comparison between various modules using a very short JSON 970First comes a comparison between various modules using a very short
575string: 971single-line JSON string:
576 972
577 {"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null} 973 {"method": "handleMessage", "params": ["user1", "we were just talking"], \
974 "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
578 975
579It shows the number of encodes/decodes per second (JSON::XS uses the 976It shows the number of encodes/decodes per second (JSON::XS uses
580functional interface, while JSON::XS/2 uses the OO interface with 977the functional interface, while JSON::XS/2 uses the OO interface
581pretty-printing and hashkey sorting enabled). Higher is better: 978with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
979shrink). Higher is better:
582 980
583 module | encode | decode | 981 module | encode | decode |
584 -----------|------------|------------| 982 -----------|------------|------------|
585 JSON | 11488.516 | 7823.035 | 983 JSON 1.x | 4990.842 | 4088.813 |
586 JSON::DWIW | 94708.054 | 129094.260 | 984 JSON::DWIW | 51653.990 | 71575.154 |
587 JSON::PC | 63884.157 | 128528.212 | 985 JSON::PC | 65948.176 | 74631.744 |
588 JSON::Syck | 34898.677 | 42096.911 | 986 JSON::PP | 8931.652 | 3817.168 |
589 JSON::XS | 654027.064 | 396423.669 | 987 JSON::Syck | 24877.248 | 27776.848 |
590 JSON::XS/2 | 371564.190 | 371725.613 | 988 JSON::XS | 388361.481 | 227951.304 |
989 JSON::XS/2 | 227951.304 | 218453.333 |
990 JSON::XS/3 | 338250.323 | 218453.333 |
991 Storable | 16500.016 | 135300.129 |
591 -----------+------------+------------+ 992 -----------+------------+------------+
592 993
593That is, JSON::XS is more than six times faster than JSON::DWIW on 994That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
594encoding, more than three times faster on decoding, and about thirty times 995about three times faster on decoding, and over forty times faster
595faster than JSON, even with pretty-printing and key sorting. 996than JSON, even with pretty-printing and key sorting. It also compares
997favourably to Storable for small amounts of data.
596 998
597Using a longer test string (roughly 18KB, generated from Yahoo! Locals 999Using a longer test string (roughly 18KB, generated from Yahoo! Locals
598search API (http://nanoref.com/yahooapis/mgPdGg): 1000search API (http://nanoref.com/yahooapis/mgPdGg):
599 1001
600 module | encode | decode | 1002 module | encode | decode |
601 -----------|------------|------------| 1003 -----------|------------|------------|
602 JSON | 273.023 | 44.674 | 1004 JSON 1.x | 55.260 | 34.971 |
603 JSON::DWIW | 1089.383 | 1145.704 | 1005 JSON::DWIW | 825.228 | 1082.513 |
604 JSON::PC | 3097.419 | 2393.921 | 1006 JSON::PC | 3571.444 | 2394.829 |
605 JSON::Syck | 514.060 | 843.053 | 1007 JSON::PP | 210.987 | 32.574 |
606 JSON::XS | 6479.668 | 3636.364 | 1008 JSON::Syck | 552.551 | 787.544 |
607 JSON::XS/2 | 3774.221 | 3599.124 | 1009 JSON::XS | 5780.463 | 4854.519 |
1010 JSON::XS/2 | 3869.998 | 4798.975 |
1011 JSON::XS/3 | 5862.880 | 4798.975 |
1012 Storable | 4445.002 | 5235.027 |
608 -----------+------------+------------+ 1013 -----------+------------+------------+
609 1014
610Again, JSON::XS leads by far. 1015Again, JSON::XS leads by far (except for Storable which non-surprisingly
1016decodes faster).
611 1017
612On large strings containing lots of high unicode characters, some modules 1018On large strings containing lots of high Unicode characters, some modules
613(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
614will be broken due to missing (or wrong) unicode handling. Others refuse 1020will be broken due to missing (or wrong) Unicode handling. Others refuse
615to 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
616comparison table for that case. 1022comparison table for that case.
617 1023
618 1024
619=head1 SECURITY CONSIDERATIONS 1025=head1 SECURITY CONSIDERATIONS
… …
625any buffer overflows. Obviously, this module should ensure that and I am 1031any buffer overflows. Obviously, this module should ensure that and I am
626trying hard on making that true, but you never know. 1032trying hard on making that true, but you never know.
627 1033
628Second, you need to avoid resource-starving attacks. That means you should 1034Second, you need to avoid resource-starving attacks. That means you should
629limit 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
630resources 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
631can 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
632usually 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
633it 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.
634 1042
635Third, JSON::XS recurses using the C stack when decoding objects and 1043Third, JSON::XS recurses using the C stack when decoding objects and
636arrays. 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
637machine 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
638only 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
639to 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
640conservative, the default nesting limit is set to 512. If your process 1048conservative, the default nesting limit is set to 512. If your process
641has a smaller stack, you should adjust this setting accordingly with the 1049has a smaller stack, you should adjust this setting accordingly with the
642C<max_depth> method. 1050C<max_depth> method.
643 1051
644And 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
645of. 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,
646though... 1054though...
1055
1056If you are using JSON::XS to return packets to consumption
1057by JavaScript scripts in a browser you should have a look at
1058L<http://jpsykes.com/47/practical-csrf-and-json-security> to see whether
1059you are vulnerable to some common attack vectors (which really are browser
1060design bugs, but it is still you who will have to deal with it, as major
1061browser developers care only for features, not about getting security
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).
647 1073
648 1074
649=head1 BUGS 1075=head1 BUGS
650 1076
651While 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
652not 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
653still relatively early in its development. If you keep reporting bugs they 1079still relatively early in its development. If you keep reporting bugs they
654will be fixed swiftly, though. 1080will be fixed swiftly, though.
655 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
656=cut 1085=cut
657 1086
1087our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
1088our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
1089
658sub true() { \1 } 1090sub true() { $true }
659sub false() { \0 } 1091sub false() { $false }
1092
1093sub is_bool($) {
1094 UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
1095# or UNIVERSAL::isa $_[0], "JSON::Literal"
1096}
1097
1098XSLoader::load "JSON::XS", $VERSION;
1099
1100package JSON::XS::Boolean;
1101
1102use overload
1103 "0+" => sub { ${$_[0]} },
1104 "++" => sub { $_[0] = ${$_[0]} + 1 },
1105 "--" => sub { $_[0] = ${$_[0]} - 1 },
1106 fallback => 1;
660 1107
6611; 11081;
662 1109
663=head1 AUTHOR 1110=head1 AUTHOR
664 1111

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