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Revision 1.60 by root, Mon Aug 27 02:03:23 2007 UTC vs.
Revision 1.72 by root, Sun Nov 25 19:11:07 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
37 40
38=head2 FEATURES 41=head2 FEATURES
39 42
40=over 4 43=over 4
41 44
42=item * correct unicode handling 45=item * correct Unicode handling
43 46
44This module knows how to handle Unicode, and even documents how and when 47This module knows how to handle Unicode, and even documents how and when
45it does so. 48it does so.
46 49
47=item * round-trip integrity 50=item * round-trip integrity
67This module has both a simple functional interface as well as an OO 70This module has both a simple functional interface as well as an OO
68interface. 71interface.
69 72
70=item * reasonably versatile output formats 73=item * reasonably versatile output formats
71 74
72You can choose between the most compact guarenteed single-line format 75You can choose between the most compact guaranteed single-line format
73possible (nice for simple line-based protocols), a pure-ascii format 76possible (nice for simple line-based protocols), a pure-ascii format
74(for when your transport is not 8-bit clean, still supports the whole 77(for when your transport is not 8-bit clean, still supports the whole
75unicode range), or a pretty-printed format (for when you want to read that 78Unicode range), or a pretty-printed format (for when you want to read that
76stuff). Or you can combine those features in whatever way you like. 79stuff). Or you can combine those features in whatever way you like.
77 80
78=back 81=back
79 82
80=cut 83=cut
81 84
82package JSON::XS; 85package JSON::XS;
83 86
84use strict; 87use strict;
85 88
86our $VERSION = '1.5'; 89our $VERSION = '1.53';
87our @ISA = qw(Exporter); 90our @ISA = qw(Exporter);
88 91
89our @EXPORT = qw(to_json from_json); 92our @EXPORT = qw(to_json from_json);
90 93
91use Exporter; 94use Exporter;
92use XSLoader; 95use XSLoader;
93 96
94=head1 FUNCTIONAL INTERFACE 97=head1 FUNCTIONAL INTERFACE
95 98
96The following convinience methods are provided by this module. They are 99The following convenience methods are provided by this module. They are
97exported by default: 100exported by default:
98 101
99=over 4 102=over 4
100 103
101=item $json_text = to_json $perl_scalar 104=item $json_text = to_json $perl_scalar
102 105
103Converts the given Perl data structure (a simple scalar or a reference to 106Converts the given Perl data structure to a UTF-8 encoded, binary string
104a hash or array) to a UTF-8 encoded, binary string (that is, the string contains 107(that is, the string contains octets only). Croaks on error.
105octets only). Croaks on error.
106 108
107This function call is functionally identical to: 109This function call is functionally identical to:
108 110
109 $json_text = JSON::XS->new->utf8->encode ($perl_scalar) 111 $json_text = JSON::XS->new->utf8->encode ($perl_scalar)
110 112
111except being faster. 113except being faster.
112 114
113=item $perl_scalar = from_json $json_text 115=item $perl_scalar = from_json $json_text
114 116
115The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to 117The opposite of C<to_json>: expects an UTF-8 (binary) string and tries
116parse that as an UTF-8 encoded JSON text, returning the resulting simple 118to parse that as an UTF-8 encoded JSON text, returning the resulting
117scalar or reference. Croaks on error. 119reference. Croaks on error.
118 120
119This function call is functionally identical to: 121This function call is functionally identical to:
120 122
121 $perl_scalar = JSON::XS->new->utf8->decode ($json_text) 123 $perl_scalar = JSON::XS->new->utf8->decode ($json_text)
122 124
132Perl. 134Perl.
133 135
134=back 136=back
135 137
136 138
139=head1 A FEW NOTES ON UNICODE AND PERL
140
141Since this often leads to confusion, here are a few very clear words on
142how Unicode works in Perl, modulo bugs.
143
144=over 4
145
146=item 1. Perl strings can store characters with ordinal values > 255.
147
148This enables you to store Unicode characters as single characters in a
149Perl string - very natural.
150
151=item 2. Perl does I<not> associate an encoding with your strings.
152
153Unless you force it to, e.g. when matching it against a regex, or printing
154the scalar to a file, in which case Perl either interprets your string as
155locale-encoded text, octets/binary, or as Unicode, depending on various
156settings. In no case is an encoding stored together with your data, it is
157I<use> that decides encoding, not any magical metadata.
158
159=item 3. The internal utf-8 flag has no meaning with regards to the
160encoding of your string.
161
162Just ignore that flag unless you debug a Perl bug, a module written in
163XS or want to dive into the internals of perl. Otherwise it will only
164confuse you, as, despite the name, it says nothing about how your string
165is encoded. You can have Unicode strings with that flag set, with that
166flag clear, and you can have binary data with that flag set and that flag
167clear. Other possibilities exist, too.
168
169If you didn't know about that flag, just the better, pretend it doesn't
170exist.
171
172=item 4. A "Unicode String" is simply a string where each character can be
173validly interpreted as a Unicode codepoint.
174
175If you have UTF-8 encoded data, it is no longer a Unicode string, but a
176Unicode string encoded in UTF-8, giving you a binary string.
177
178=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.
179
180It's a fact. Learn to live with it.
181
182=back
183
184I hope this helps :)
185
186
137=head1 OBJECT-ORIENTED INTERFACE 187=head1 OBJECT-ORIENTED INTERFACE
138 188
139The object oriented interface lets you configure your own encoding or 189The object oriented interface lets you configure your own encoding or
140decoding style, within the limits of supported formats. 190decoding style, within the limits of supported formats.
141 191
152 my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]}) 202 my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
153 => {"a": [1, 2]} 203 => {"a": [1, 2]}
154 204
155=item $json = $json->ascii ([$enable]) 205=item $json = $json->ascii ([$enable])
156 206
207=item $enabled = $json->get_ascii
208
157If C<$enable> is true (or missing), then the C<encode> method will not 209If C<$enable> is true (or missing), then the C<encode> method will not
158generate characters outside the code range C<0..127> (which is ASCII). Any 210generate characters outside the code range C<0..127> (which is ASCII). Any
159unicode characters outside that range will be escaped using either a 211Unicode characters outside that range will be escaped using either a
160single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, 212single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
161as per RFC4627. The resulting encoded JSON text can be treated as a native 213as per RFC4627. The resulting encoded JSON text can be treated as a native
162unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string, 214Unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
163or any other superset of ASCII. 215or any other superset of ASCII.
164 216
165If C<$enable> is false, then the C<encode> method will not escape Unicode 217If C<$enable> is false, then the C<encode> method will not escape Unicode
166characters unless required by the JSON syntax or other flags. This results 218characters unless required by the JSON syntax or other flags. This results
167in a faster and more compact format. 219in a faster and more compact format.
173 JSON::XS->new->ascii (1)->encode ([chr 0x10401]) 225 JSON::XS->new->ascii (1)->encode ([chr 0x10401])
174 => ["\ud801\udc01"] 226 => ["\ud801\udc01"]
175 227
176=item $json = $json->latin1 ([$enable]) 228=item $json = $json->latin1 ([$enable])
177 229
230=item $enabled = $json->get_latin1
231
178If C<$enable> is true (or missing), then the C<encode> method will encode 232If C<$enable> is true (or missing), then the C<encode> method will encode
179the resulting JSON text as latin1 (or iso-8859-1), escaping any characters 233the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
180outside the code range C<0..255>. The resulting string can be treated as a 234outside the code range C<0..255>. The resulting string can be treated as a
181latin1-encoded JSON text or a native unicode string. The C<decode> method 235latin1-encoded JSON text or a native Unicode string. The C<decode> method
182will not be affected in any way by this flag, as C<decode> by default 236will not be affected in any way by this flag, as C<decode> by default
183expects unicode, which is a strict superset of latin1. 237expects Unicode, which is a strict superset of latin1.
184 238
185If C<$enable> is false, then the C<encode> method will not escape Unicode 239If C<$enable> is false, then the C<encode> method will not escape Unicode
186characters unless required by the JSON syntax or other flags. 240characters unless required by the JSON syntax or other flags.
187 241
188The main use for this flag is efficiently encoding binary data as JSON 242The main use for this flag is efficiently encoding binary data as JSON
189text, as most octets will not be escaped, resulting in a smaller encoded 243text, as most octets will not be escaped, resulting in a smaller encoded
190size. The disadvantage is that the resulting JSON text is encoded 244size. The disadvantage is that the resulting JSON text is encoded
191in latin1 (and must correctly be treated as such when storing and 245in latin1 (and must correctly be treated as such when storing and
192transfering), a rare encoding for JSON. It is therefore most useful when 246transferring), a rare encoding for JSON. It is therefore most useful when
193you want to store data structures known to contain binary data efficiently 247you want to store data structures known to contain binary data efficiently
194in files or databases, not when talking to other JSON encoders/decoders. 248in files or databases, not when talking to other JSON encoders/decoders.
195 249
196 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"] 250 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
197 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not) 251 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
198 252
199=item $json = $json->utf8 ([$enable]) 253=item $json = $json->utf8 ([$enable])
254
255=item $enabled = $json->get_utf8
200 256
201If C<$enable> is true (or missing), then the C<encode> method will encode 257If C<$enable> is true (or missing), then the C<encode> method will encode
202the JSON result into UTF-8, as required by many protocols, while the 258the JSON result into UTF-8, as required by many protocols, while the
203C<decode> method expects to be handled an UTF-8-encoded string. Please 259C<decode> method expects to be handled an UTF-8-encoded string. Please
204note that UTF-8-encoded strings do not contain any characters outside the 260note that UTF-8-encoded strings do not contain any characters outside the
205range C<0..255>, they are thus useful for bytewise/binary I/O. In future 261range C<0..255>, they are thus useful for bytewise/binary I/O. In future
206versions, enabling this option might enable autodetection of the UTF-16 262versions, enabling this option might enable autodetection of the UTF-16
207and UTF-32 encoding families, as described in RFC4627. 263and UTF-32 encoding families, as described in RFC4627.
208 264
209If C<$enable> is false, then the C<encode> method will return the JSON 265If C<$enable> is false, then the C<encode> method will return the JSON
210string as a (non-encoded) unicode string, while C<decode> expects thus a 266string as a (non-encoded) Unicode string, while C<decode> expects thus a
211unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs 267Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
212to be done yourself, e.g. using the Encode module. 268to be done yourself, e.g. using the Encode module.
213 269
214Example, output UTF-16BE-encoded JSON: 270Example, output UTF-16BE-encoded JSON:
215 271
216 use Encode; 272 use Encode;
220 276
221 use Encode; 277 use Encode;
222 $object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext); 278 $object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext);
223 279
224=item $json = $json->pretty ([$enable]) 280=item $json = $json->pretty ([$enable])
281
282=item $enabled = $json->get_pretty
225 283
226This enables (or disables) all of the C<indent>, C<space_before> and 284This enables (or disables) all of the C<indent>, C<space_before> and
227C<space_after> (and in the future possibly more) flags in one call to 285C<space_after> (and in the future possibly more) flags in one call to
228generate the most readable (or most compact) form possible. 286generate the most readable (or most compact) form possible.
229 287
238 ] 296 ]
239 } 297 }
240 298
241=item $json = $json->indent ([$enable]) 299=item $json = $json->indent ([$enable])
242 300
301=item $enabled = $json->get_indent
302
243If C<$enable> is true (or missing), then the C<encode> method will use a multiline 303If C<$enable> is true (or missing), then the C<encode> method will use a multiline
244format as output, putting every array member or object/hash key-value pair 304format as output, putting every array member or object/hash key-value pair
245into its own line, identing them properly. 305into its own line, indenting them properly.
246 306
247If C<$enable> is false, no newlines or indenting will be produced, and the 307If C<$enable> is false, no newlines or indenting will be produced, and the
248resulting JSON text is guarenteed not to contain any C<newlines>. 308resulting JSON text is guaranteed not to contain any C<newlines>.
249 309
250This setting has no effect when decoding JSON texts. 310This setting has no effect when decoding JSON texts.
251 311
252=item $json = $json->space_before ([$enable]) 312=item $json = $json->space_before ([$enable])
313
314=item $enabled = $json->get_space_before
253 315
254If C<$enable> is true (or missing), then the C<encode> method will add an extra 316If C<$enable> is true (or missing), then the C<encode> method will add an extra
255optional space before the C<:> separating keys from values in JSON objects. 317optional space before the C<:> separating keys from values in JSON objects.
256 318
257If C<$enable> is false, then the C<encode> method will not add any extra 319If C<$enable> is false, then the C<encode> method will not add any extra
263Example, space_before enabled, space_after and indent disabled: 325Example, space_before enabled, space_after and indent disabled:
264 326
265 {"key" :"value"} 327 {"key" :"value"}
266 328
267=item $json = $json->space_after ([$enable]) 329=item $json = $json->space_after ([$enable])
330
331=item $enabled = $json->get_space_after
268 332
269If C<$enable> is true (or missing), then the C<encode> method will add an extra 333If C<$enable> is true (or missing), then the C<encode> method will add an extra
270optional space after the C<:> separating keys from values in JSON objects 334optional space after the C<:> separating keys from values in JSON objects
271and extra whitespace after the C<,> separating key-value pairs and array 335and extra whitespace after the C<,> separating key-value pairs and array
272members. 336members.
279Example, space_before and indent disabled, space_after enabled: 343Example, space_before and indent disabled, space_after enabled:
280 344
281 {"key": "value"} 345 {"key": "value"}
282 346
283=item $json = $json->relaxed ([$enable]) 347=item $json = $json->relaxed ([$enable])
348
349=item $enabled = $json->get_relaxed
284 350
285If C<$enable> is true (or missing), then C<decode> will accept some 351If C<$enable> is true (or missing), then C<decode> will accept some
286extensions to normal JSON syntax (see below). C<encode> will not be 352extensions to normal JSON syntax (see below). C<encode> will not be
287affected in anyway. I<Be aware that this option makes you accept invalid 353affected in anyway. I<Be aware that this option makes you accept invalid
288JSON texts as if they were valid!>. I suggest only to use this option to 354JSON texts as if they were valid!>. I suggest only to use this option to
325 391
326=back 392=back
327 393
328=item $json = $json->canonical ([$enable]) 394=item $json = $json->canonical ([$enable])
329 395
396=item $enabled = $json->get_canonical
397
330If C<$enable> is true (or missing), then the C<encode> method will output JSON objects 398If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
331by sorting their keys. This is adding a comparatively high overhead. 399by sorting their keys. This is adding a comparatively high overhead.
332 400
333If C<$enable> is false, then the C<encode> method will output key-value 401If C<$enable> is false, then the C<encode> method will output key-value
334pairs in the order Perl stores them (which will likely change between runs 402pairs in the order Perl stores them (which will likely change between runs
335of the same script). 403of the same script).
336 404
337This option is useful if you want the same data structure to be encoded as 405This option is useful if you want the same data structure to be encoded as
338the same JSON text (given the same overall settings). If it is disabled, 406the same JSON text (given the same overall settings). If it is disabled,
339the same hash migh be encoded differently even if contains the same data, 407the same hash might be encoded differently even if contains the same data,
340as key-value pairs have no inherent ordering in Perl. 408as key-value pairs have no inherent ordering in Perl.
341 409
342This setting has no effect when decoding JSON texts. 410This setting has no effect when decoding JSON texts.
343 411
344=item $json = $json->allow_nonref ([$enable]) 412=item $json = $json->allow_nonref ([$enable])
413
414=item $enabled = $json->get_allow_nonref
345 415
346If C<$enable> is true (or missing), then the C<encode> method can convert a 416If C<$enable> is true (or missing), then the C<encode> method can convert a
347non-reference into its corresponding string, number or null JSON value, 417non-reference into its corresponding string, number or null JSON value,
348which is an extension to RFC4627. Likewise, C<decode> will accept those JSON 418which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
349values instead of croaking. 419values instead of croaking.
359 JSON::XS->new->allow_nonref->encode ("Hello, World!") 429 JSON::XS->new->allow_nonref->encode ("Hello, World!")
360 => "Hello, World!" 430 => "Hello, World!"
361 431
362=item $json = $json->allow_blessed ([$enable]) 432=item $json = $json->allow_blessed ([$enable])
363 433
434=item $enabled = $json->get_allow_bless
435
364If C<$enable> is true (or missing), then the C<encode> method will not 436If C<$enable> is true (or missing), then the C<encode> method will not
365barf when it encounters a blessed reference. Instead, the value of the 437barf when it encounters a blessed reference. Instead, the value of the
366B<convert_blessed> option will decide wether C<null> (C<convert_blessed> 438B<convert_blessed> option will decide whether C<null> (C<convert_blessed>
367disabled or no C<to_json> method found) or a representation of the 439disabled or no C<to_json> method found) or a representation of the
368object (C<convert_blessed> enabled and C<to_json> method found) is being 440object (C<convert_blessed> enabled and C<to_json> method found) is being
369encoded. Has no effect on C<decode>. 441encoded. Has no effect on C<decode>.
370 442
371If C<$enable> is false (the default), then C<encode> will throw an 443If C<$enable> is false (the default), then C<encode> will throw an
372exception when it encounters a blessed object. 444exception when it encounters a blessed object.
373 445
374=item $json = $json->convert_blessed ([$enable]) 446=item $json = $json->convert_blessed ([$enable])
447
448=item $enabled = $json->get_convert_blessed
375 449
376If C<$enable> is true (or missing), then C<encode>, upon encountering a 450If C<$enable> is true (or missing), then C<encode>, upon encountering a
377blessed object, will check for the availability of the C<TO_JSON> method 451blessed object, will check for the availability of the C<TO_JSON> method
378on the object's class. If found, it will be called in scalar context 452on the object's class. If found, it will be called in scalar context
379and the resulting scalar will be encoded instead of the object. If no 453and the resulting scalar will be encoded instead of the object. If no
436 510
437As this callback gets called less often then the C<filter_json_object> 511As this callback gets called less often then the C<filter_json_object>
438one, decoding speed will not usually suffer as much. Therefore, single-key 512one, decoding speed will not usually suffer as much. Therefore, single-key
439objects make excellent targets to serialise Perl objects into, especially 513objects make excellent targets to serialise Perl objects into, especially
440as single-key JSON objects are as close to the type-tagged value concept 514as single-key JSON objects are as close to the type-tagged value concept
441as JSON gets (its basically an ID/VALUE tuple). Of course, JSON does not 515as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not
442support this in any way, so you need to make sure your data never looks 516support this in any way, so you need to make sure your data never looks
443like a serialised Perl hash. 517like a serialised Perl hash.
444 518
445Typical names for the single object key are C<__class_whatever__>, or 519Typical names for the single object key are C<__class_whatever__>, or
446C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even 520C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
470 544
471 { __widget__ => $self->{id} } 545 { __widget__ => $self->{id} }
472 } 546 }
473 547
474=item $json = $json->shrink ([$enable]) 548=item $json = $json->shrink ([$enable])
549
550=item $enabled = $json->get_shrink
475 551
476Perl usually over-allocates memory a bit when allocating space for 552Perl usually over-allocates memory a bit when allocating space for
477strings. This flag optionally resizes strings generated by either 553strings. This flag optionally resizes strings generated by either
478C<encode> or C<decode> to their minimum size possible. This can save 554C<encode> or C<decode> to their minimum size possible. This can save
479memory when your JSON texts are either very very long or you have many 555memory when your JSON texts are either very very long or you have many
497strings that look like integers or floats into integers or floats 573strings that look like integers or floats into integers or floats
498internally (there is no difference on the Perl level), saving space. 574internally (there is no difference on the Perl level), saving space.
499 575
500=item $json = $json->max_depth ([$maximum_nesting_depth]) 576=item $json = $json->max_depth ([$maximum_nesting_depth])
501 577
578=item $max_depth = $json->get_max_depth
579
502Sets the maximum nesting level (default C<512>) accepted while encoding 580Sets the maximum nesting level (default C<512>) accepted while encoding
503or decoding. If the JSON text or Perl data structure has an equal or 581or decoding. If the JSON text or Perl data structure has an equal or
504higher nesting level then this limit, then the encoder and decoder will 582higher nesting level then this limit, then the encoder and decoder will
505stop and croak at that point. 583stop and croak at that point.
506 584
517used, which is rarely useful. 595used, which is rarely useful.
518 596
519See SECURITY CONSIDERATIONS, below, for more info on why this is useful. 597See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
520 598
521=item $json = $json->max_size ([$maximum_string_size]) 599=item $json = $json->max_size ([$maximum_string_size])
600
601=item $max_size = $json->get_max_size
522 602
523Set the maximum length a JSON text may have (in bytes) where decoding is 603Set the maximum length a JSON text may have (in bytes) where decoding is
524being attempted. The default is C<0>, meaning no limit. When C<decode> 604being attempted. The default is C<0>, meaning no limit. When C<decode>
525is called on a string longer then this number of characters it will not 605is called on a string longer then this number of characters it will not
526attempt to decode the string but throw an exception. This setting has no 606attempt to decode the string but throw an exception. This setting has no
573vice versa. These mappings are designed to "do the right thing" in most 653vice versa. These mappings are designed to "do the right thing" in most
574circumstances automatically, preserving round-tripping characteristics 654circumstances automatically, preserving round-tripping characteristics
575(what you put in comes out as something equivalent). 655(what you put in comes out as something equivalent).
576 656
577For the more enlightened: note that in the following descriptions, 657For the more enlightened: note that in the following descriptions,
578lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> 658lowercase I<perl> refers to the Perl interpreter, while uppercase I<Perl>
579refers to the abstract Perl language itself. 659refers to the abstract Perl language itself.
580 660
581 661
582=head2 JSON -> PERL 662=head2 JSON -> PERL
583 663
584=over 4 664=over 4
585 665
586=item object 666=item object
587 667
588A JSON object becomes a reference to a hash in Perl. No ordering of object 668A JSON object becomes a reference to a hash in Perl. No ordering of object
589keys is preserved (JSON does not preserver object key ordering itself). 669keys is preserved (JSON does not preserve object key ordering itself).
590 670
591=item array 671=item array
592 672
593A JSON array becomes a reference to an array in Perl. 673A JSON array becomes a reference to an array in Perl.
594 674
620 700
621=item true, false 701=item true, false
622 702
623These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>, 703These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
624respectively. They are overloaded to act almost exactly like the numbers 704respectively. They are overloaded to act almost exactly like the numbers
625C<1> and C<0>. You can check wether a scalar is a JSON boolean by using 705C<1> and C<0>. You can check whether a scalar is a JSON boolean by using
626the C<JSON::XS::is_bool> function. 706the C<JSON::XS::is_bool> function.
627 707
628=item null 708=item null
629 709
630A JSON null atom becomes C<undef> in Perl. 710A JSON null atom becomes C<undef> in Perl.
666 to_json [\0,JSON::XS::true] # yields [false,true] 746 to_json [\0,JSON::XS::true] # yields [false,true]
667 747
668=item JSON::XS::true, JSON::XS::false 748=item JSON::XS::true, JSON::XS::false
669 749
670These special values become JSON true and JSON false values, 750These special values become JSON true and JSON false values,
671respectively. You cna alos use C<\1> and C<\0> directly if you want. 751respectively. You can also use C<\1> and C<\0> directly if you want.
672 752
673=item blessed objects 753=item blessed objects
674 754
675Blessed objects are not allowed. JSON::XS currently tries to encode their 755Blessed objects are not allowed. JSON::XS currently tries to encode their
676underlying representation (hash- or arrayref), but this behaviour might 756underlying representation (hash- or arrayref), but this behaviour might
693 to_json [$value] # yields ["5"] 773 to_json [$value] # yields ["5"]
694 774
695 # undef becomes null 775 # undef becomes null
696 to_json [undef] # yields [null] 776 to_json [undef] # yields [null]
697 777
698You can force the type to be a string by stringifying it: 778You can force the type to be a JSON string by stringifying it:
699 779
700 my $x = 3.1; # some variable containing a number 780 my $x = 3.1; # some variable containing a number
701 "$x"; # stringified 781 "$x"; # stringified
702 $x .= ""; # another, more awkward way to stringify 782 $x .= ""; # another, more awkward way to stringify
703 print $x; # perl does it for you, too, quite often 783 print $x; # perl does it for you, too, quite often
704 784
705You can force the type to be a number by numifying it: 785You can force the type to be a JSON number by numifying it:
706 786
707 my $x = "3"; # some variable containing a string 787 my $x = "3"; # some variable containing a string
708 $x += 0; # numify it, ensuring it will be dumped as a number 788 $x += 0; # numify it, ensuring it will be dumped as a number
709 $x *= 1; # same thing, the choise is yours. 789 $x *= 1; # same thing, the choice is yours.
710 790
711You can not currently output JSON booleans or force the type in other, 791You can not currently force the type in other, less obscure, ways. Tell me
712less obscure, ways. Tell me if you need this capability. 792if you need this capability.
713 793
714=back 794=back
715 795
716 796
717=head1 COMPARISON 797=head1 COMPARISON
726 806
727=item JSON 1.07 807=item JSON 1.07
728 808
729Slow (but very portable, as it is written in pure Perl). 809Slow (but very portable, as it is written in pure Perl).
730 810
731Undocumented/buggy Unicode handling (how JSON handles unicode values is 811Undocumented/buggy Unicode handling (how JSON handles Unicode values is
732undocumented. One can get far by feeding it unicode strings and doing 812undocumented. One can get far by feeding it Unicode strings and doing
733en-/decoding oneself, but unicode escapes are not working properly). 813en-/decoding oneself, but Unicode escapes are not working properly).
734 814
735No roundtripping (strings get clobbered if they look like numbers, e.g. 815No round-tripping (strings get clobbered if they look like numbers, e.g.
736the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will 816the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will
737decode into the number 2. 817decode into the number 2.
738 818
739=item JSON::PC 0.01 819=item JSON::PC 0.01
740 820
741Very fast. 821Very fast.
742 822
743Undocumented/buggy Unicode handling. 823Undocumented/buggy Unicode handling.
744 824
745No roundtripping. 825No round-tripping.
746 826
747Has problems handling many Perl values (e.g. regex results and other magic 827Has problems handling many Perl values (e.g. regex results and other magic
748values will make it croak). 828values will make it croak).
749 829
750Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}> 830Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
760Very inflexible (no human-readable format supported, format pretty much 840Very inflexible (no human-readable format supported, format pretty much
761undocumented. I need at least a format for easy reading by humans and a 841undocumented. I need at least a format for easy reading by humans and a
762single-line compact format for use in a protocol, and preferably a way to 842single-line compact format for use in a protocol, and preferably a way to
763generate ASCII-only JSON texts). 843generate ASCII-only JSON texts).
764 844
765Completely broken (and confusingly documented) Unicode handling (unicode 845Completely broken (and confusingly documented) Unicode handling (Unicode
766escapes are not working properly, you need to set ImplicitUnicode to 846escapes are not working properly, you need to set ImplicitUnicode to
767I<different> values on en- and decoding to get symmetric behaviour). 847I<different> values on en- and decoding to get symmetric behaviour).
768 848
769No roundtripping (simple cases work, but this depends on wether the scalar 849No round-tripping (simple cases work, but this depends on whether the scalar
770value was used in a numeric context or not). 850value was used in a numeric context or not).
771 851
772Dumping hashes may skip hash values depending on iterator state. 852Dumping hashes may skip hash values depending on iterator state.
773 853
774Unmaintained (maintainer unresponsive for many months, bugs are not 854Unmaintained (maintainer unresponsive for many months, bugs are not
775getting fixed). 855getting fixed).
776 856
777Does not check input for validity (i.e. will accept non-JSON input and 857Does not check input for validity (i.e. will accept non-JSON input and
778return "something" instead of raising an exception. This is a security 858return "something" instead of raising an exception. This is a security
779issue: imagine two banks transfering money between each other using 859issue: imagine two banks transferring money between each other using
780JSON. One bank might parse a given non-JSON request and deduct money, 860JSON. One bank might parse a given non-JSON request and deduct money,
781while the other might reject the transaction with a syntax error. While a 861while the other might reject the transaction with a syntax error. While a
782good protocol will at least recover, that is extra unnecessary work and 862good protocol will at least recover, that is extra unnecessary work and
783the transaction will still not succeed). 863the transaction will still not succeed).
784 864
785=item JSON::DWIW 0.04 865=item JSON::DWIW 0.04
786 866
787Very fast. Very natural. Very nice. 867Very fast. Very natural. Very nice.
788 868
789Undocumented unicode handling (but the best of the pack. Unicode escapes 869Undocumented Unicode handling (but the best of the pack. Unicode escapes
790still don't get parsed properly). 870still don't get parsed properly).
791 871
792Very inflexible. 872Very inflexible.
793 873
794No roundtripping. 874No round-tripping.
795 875
796Does not generate valid JSON texts (key strings are often unquoted, empty keys 876Does not generate valid JSON texts (key strings are often unquoted, empty keys
797result in nothing being output) 877result in nothing being output)
798 878
799Does not check input for validity. 879Does not check input for validity.
814 my $yaml = $to_yaml->encode ($ref) . "\n"; 894 my $yaml = $to_yaml->encode ($ref) . "\n";
815 895
816This will usually generate JSON texts that also parse as valid 896This will usually generate JSON texts that also parse as valid
817YAML. Please note that YAML has hardcoded limits on (simple) object key 897YAML. Please note that YAML has hardcoded limits on (simple) object key
818lengths that JSON doesn't have, so you should make sure that your hash 898lengths that JSON doesn't have, so you should make sure that your hash
819keys are noticably shorter than the 1024 characters YAML allows. 899keys are noticeably shorter than the 1024 characters YAML allows.
820 900
821There might be other incompatibilities that I am not aware of. In general 901There might be other incompatibilities that I am not aware of. In general
822you should not try to generate YAML with a JSON generator or vice versa, 902you should not try to generate YAML with a JSON generator or vice versa,
823or try to parse JSON with a YAML parser or vice versa: chances are high 903or try to parse JSON with a YAML parser or vice versa: chances are high
824that you will run into severe interoperability problems. 904that you will run into severe interoperability problems.
840It shows the number of encodes/decodes per second (JSON::XS uses 920It shows the number of encodes/decodes per second (JSON::XS uses
841the functional interface, while JSON::XS/2 uses the OO interface 921the functional interface, while JSON::XS/2 uses the OO interface
842with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables 922with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
843shrink). Higher is better: 923shrink). Higher is better:
844 924
845 Storable | 15779.925 | 14169.946 |
846 -----------+------------+------------+
847 module | encode | decode | 925 module | encode | decode |
848 -----------|------------|------------| 926 -----------|------------|------------|
849 JSON | 4990.842 | 4088.813 | 927 JSON 1.x | 4990.842 | 4088.813 |
850 JSON::DWIW | 51653.990 | 71575.154 | 928 JSON::DWIW | 51653.990 | 71575.154 |
851 JSON::PC | 65948.176 | 74631.744 | 929 JSON::PC | 65948.176 | 74631.744 |
852 JSON::PP | 8931.652 | 3817.168 | 930 JSON::PP | 8931.652 | 3817.168 |
853 JSON::Syck | 24877.248 | 27776.848 | 931 JSON::Syck | 24877.248 | 27776.848 |
854 JSON::XS | 388361.481 | 227951.304 | 932 JSON::XS | 388361.481 | 227951.304 |
856 JSON::XS/3 | 338250.323 | 218453.333 | 934 JSON::XS/3 | 338250.323 | 218453.333 |
857 Storable | 16500.016 | 135300.129 | 935 Storable | 16500.016 | 135300.129 |
858 -----------+------------+------------+ 936 -----------+------------+------------+
859 937
860That is, JSON::XS is about five times faster than JSON::DWIW on encoding, 938That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
861about three times faster on decoding, and over fourty times faster 939about three times faster on decoding, and over forty times faster
862than JSON, even with pretty-printing and key sorting. It also compares 940than JSON, even with pretty-printing and key sorting. It also compares
863favourably to Storable for small amounts of data. 941favourably to Storable for small amounts of data.
864 942
865Using a longer test string (roughly 18KB, generated from Yahoo! Locals 943Using a longer test string (roughly 18KB, generated from Yahoo! Locals
866search API (http://nanoref.com/yahooapis/mgPdGg): 944search API (http://nanoref.com/yahooapis/mgPdGg):
867 945
868 module | encode | decode | 946 module | encode | decode |
869 -----------|------------|------------| 947 -----------|------------|------------|
870 JSON | 55.260 | 34.971 | 948 JSON 1.x | 55.260 | 34.971 |
871 JSON::DWIW | 825.228 | 1082.513 | 949 JSON::DWIW | 825.228 | 1082.513 |
872 JSON::PC | 3571.444 | 2394.829 | 950 JSON::PC | 3571.444 | 2394.829 |
873 JSON::PP | 210.987 | 32.574 | 951 JSON::PP | 210.987 | 32.574 |
874 JSON::Syck | 552.551 | 787.544 | 952 JSON::Syck | 552.551 | 787.544 |
875 JSON::XS | 5780.463 | 4854.519 | 953 JSON::XS | 5780.463 | 4854.519 |
879 -----------+------------+------------+ 957 -----------+------------+------------+
880 958
881Again, JSON::XS leads by far (except for Storable which non-surprisingly 959Again, JSON::XS leads by far (except for Storable which non-surprisingly
882decodes faster). 960decodes faster).
883 961
884On large strings containing lots of high unicode characters, some modules 962On large strings containing lots of high Unicode characters, some modules
885(such as JSON::PC) seem to decode faster than JSON::XS, but the result 963(such as JSON::PC) seem to decode faster than JSON::XS, but the result
886will be broken due to missing (or wrong) unicode handling. Others refuse 964will be broken due to missing (or wrong) Unicode handling. Others refuse
887to decode or encode properly, so it was impossible to prepare a fair 965to decode or encode properly, so it was impossible to prepare a fair
888comparison table for that case. 966comparison table for that case.
889 967
890 968
891=head1 SECURITY CONSIDERATIONS 969=head1 SECURITY CONSIDERATIONS
897any buffer overflows. Obviously, this module should ensure that and I am 975any buffer overflows. Obviously, this module should ensure that and I am
898trying hard on making that true, but you never know. 976trying hard on making that true, but you never know.
899 977
900Second, you need to avoid resource-starving attacks. That means you should 978Second, you need to avoid resource-starving attacks. That means you should
901limit the size of JSON texts you accept, or make sure then when your 979limit the size of JSON texts you accept, or make sure then when your
902resources run out, thats just fine (e.g. by using a separate process that 980resources run out, that's just fine (e.g. by using a separate process that
903can crash safely). The size of a JSON text in octets or characters is 981can crash safely). The size of a JSON text in octets or characters is
904usually a good indication of the size of the resources required to decode 982usually a good indication of the size of the resources required to decode
905it into a Perl structure. While JSON::XS can check the size of the JSON 983it into a Perl structure. While JSON::XS can check the size of the JSON
906text, it might be too late when you already have it in memory, so you 984text, it might be too late when you already have it in memory, so you
907might want to check the size before you accept the string. 985might want to check the size before you accept the string.
918And last but least, something else could bomb you that I forgot to think 996And last but least, something else could bomb you that I forgot to think
919of. In that case, you get to keep the pieces. I am always open for hints, 997of. In that case, you get to keep the pieces. I am always open for hints,
920though... 998though...
921 999
922If you are using JSON::XS to return packets to consumption 1000If you are using JSON::XS to return packets to consumption
923by javascript scripts in a browser you should have a look at 1001by JavaScript scripts in a browser you should have a look at
924L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether 1002L<http://jpsykes.com/47/practical-csrf-and-json-security> to see whether
925you are vulnerable to some common attack vectors (which really are browser 1003you are vulnerable to some common attack vectors (which really are browser
926design bugs, but it is still you who will have to deal with it, as major 1004design bugs, but it is still you who will have to deal with it, as major
927browser developers care only for features, not about doing security 1005browser developers care only for features, not about doing security
928right). 1006right).
929 1007
930 1008
1009=head1 THREADS
1010
1011This module is I<not> guaranteed to be thread safe and there are no
1012plans to change this until Perl gets thread support (as opposed to the
1013horribly slow so-called "threads" which are simply slow and bloated
1014process simulations - use fork, its I<much> faster, cheaper, better).
1015
1016(It might actually work, but you have been warned).
1017
1018
931=head1 BUGS 1019=head1 BUGS
932 1020
933While the goal of this module is to be correct, that unfortunately does 1021While the goal of this module is to be correct, that unfortunately does
934not mean its bug-free, only that I think its design is bug-free. It is 1022not mean its bug-free, only that I think its design is bug-free. It is
935still relatively early in its development. If you keep reporting bugs they 1023still relatively early in its development. If you keep reporting bugs they
936will be fixed swiftly, though. 1024will be fixed swiftly, though.
1025
1026Please refrain from using rt.cpan.org or any other bug reporting
1027service. I put the contact address into my modules for a reason.
937 1028
938=cut 1029=cut
939 1030
940our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" }; 1031our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
941our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" }; 1032our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };

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