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Revision 1.65 by root, Sat Oct 13 01:55:31 2007 UTC vs.
Revision 1.76 by root, Sun Dec 2 15:34:13 2007 UTC

1=encoding utf-8
2
3=head1 NAME 1=head1 NAME
4 2
5JSON::XS - JSON serialising/deserialising, done correctly and fast 3JSON::XS - JSON serialising/deserialising, done correctly and fast
6 4
7JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ 5JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ
42 40
43=head2 FEATURES 41=head2 FEATURES
44 42
45=over 4 43=over 4
46 44
47=item * correct unicode handling 45=item * correct Unicode handling
48 46
49This 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
50it does so. 48it does so.
51 49
52=item * round-trip integrity 50=item * round-trip integrity
72This 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
73interface. 71interface.
74 72
75=item * reasonably versatile output formats 73=item * reasonably versatile output formats
76 74
77You can choose between the most compact guarenteed single-line format 75You can choose between the most compact guaranteed single-line format
78possible (nice for simple line-based protocols), a pure-ascii format 76possible (nice for simple line-based protocols), a pure-ascii format
79(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
80unicode 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
81stuff). Or you can combine those features in whatever way you like. 79stuff). Or you can combine those features in whatever way you like.
82 80
83=back 81=back
84 82
85=cut 83=cut
86 84
87package JSON::XS; 85package JSON::XS;
88 86
89use strict; 87use strict;
90 88
91our $VERSION = '1.51'; 89our $VERSION = '2.0';
92our @ISA = qw(Exporter); 90our @ISA = qw(Exporter);
93 91
94our @EXPORT = qw(to_json from_json); 92our @EXPORT = qw(to_json from_json);
95 93
96use Exporter; 94use Exporter;
97use XSLoader; 95use XSLoader;
98 96
99=head1 FUNCTIONAL INTERFACE 97=head1 FUNCTIONAL INTERFACE
100 98
101The following convinience methods are provided by this module. They are 99The following convenience methods are provided by this module. They are
102exported by default: 100exported by default:
103 101
104=over 4 102=over 4
105 103
106=item $json_text = to_json $perl_scalar 104=item $json_text = to_json $perl_scalar
145 143
146=over 4 144=over 4
147 145
148=item 1. Perl strings can store characters with ordinal values > 255. 146=item 1. Perl strings can store characters with ordinal values > 255.
149 147
150This enables you to store unicode characters as single characters in a 148This enables you to store Unicode characters as single characters in a
151Perl string - very natural. 149Perl string - very natural.
152 150
153=item 2. Perl does I<not> associate an encoding with your strings. 151=item 2. Perl does I<not> associate an encoding with your strings.
154 152
155Unless you force it to, e.g. when matching it against a regex, or printing 153Unless you force it to, e.g. when matching it against a regex, or printing
162encoding of your string. 160encoding of your string.
163 161
164Just ignore that flag unless you debug a Perl bug, a module written in 162Just ignore that flag unless you debug a Perl bug, a module written in
165XS or want to dive into the internals of perl. Otherwise it will only 163XS or want to dive into the internals of perl. Otherwise it will only
166confuse you, as, despite the name, it says nothing about how your string 164confuse you, as, despite the name, it says nothing about how your string
167is encoded. You can have unicode strings with that flag set, with that 165is encoded. You can have Unicode strings with that flag set, with that
168flag clear, and you can have binary data with that flag set and that flag 166flag clear, and you can have binary data with that flag set and that flag
169clear. Other possibilities exist, too. 167clear. Other possibilities exist, too.
170 168
171If you didn't know about that flag, just the better, pretend it doesn't 169If you didn't know about that flag, just the better, pretend it doesn't
172exist. 170exist.
177If you have UTF-8 encoded data, it is no longer a Unicode string, but a 175If you have UTF-8 encoded data, it is no longer a Unicode string, but a
178Unicode string encoded in UTF-8, giving you a binary string. 176Unicode string encoded in UTF-8, giving you a binary string.
179 177
180=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string. 178=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.
181 179
182Its a fact. Learn to live with it. 180It's a fact. Learn to live with it.
183 181
184=back 182=back
185 183
186I hope this helps :) 184I hope this helps :)
187 185
204 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]})
205 => {"a": [1, 2]} 203 => {"a": [1, 2]}
206 204
207=item $json = $json->ascii ([$enable]) 205=item $json = $json->ascii ([$enable])
208 206
207=item $enabled = $json->get_ascii
208
209If C<$enable> is true (or missing), then the C<encode> method will not 209If C<$enable> is true (or missing), then the C<encode> method will not
210generate characters outside the code range C<0..127> (which is ASCII). Any 210generate characters outside the code range C<0..127> (which is ASCII). Any
211unicode characters outside that range will be escaped using either a 211Unicode characters outside that range will be escaped using either a
212single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, 212single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
213as per RFC4627. The resulting encoded JSON text can be treated as a native 213as per RFC4627. The resulting encoded JSON text can be treated as a native
214unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string, 214Unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
215or any other superset of ASCII. 215or any other superset of ASCII.
216 216
217If C<$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
218characters unless required by the JSON syntax or other flags. This results 218characters unless required by the JSON syntax or other flags. This results
219in a faster and more compact format. 219in a faster and more compact format.
225 JSON::XS->new->ascii (1)->encode ([chr 0x10401]) 225 JSON::XS->new->ascii (1)->encode ([chr 0x10401])
226 => ["\ud801\udc01"] 226 => ["\ud801\udc01"]
227 227
228=item $json = $json->latin1 ([$enable]) 228=item $json = $json->latin1 ([$enable])
229 229
230=item $enabled = $json->get_latin1
231
230If C<$enable> is true (or missing), then the C<encode> method will encode 232If C<$enable> is true (or missing), then the C<encode> method will encode
231the resulting JSON text as latin1 (or iso-8859-1), escaping any characters 233the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
232outside the code range C<0..255>. The resulting string can be treated as a 234outside the code range C<0..255>. The resulting string can be treated as a
233latin1-encoded JSON text or a native unicode string. The C<decode> method 235latin1-encoded JSON text or a native Unicode string. The C<decode> method
234will not be affected in any way by this flag, as C<decode> by default 236will not be affected in any way by this flag, as C<decode> by default
235expects unicode, which is a strict superset of latin1. 237expects Unicode, which is a strict superset of latin1.
236 238
237If C<$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
238characters unless required by the JSON syntax or other flags. 240characters unless required by the JSON syntax or other flags.
239 241
240The 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
241text, 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
242size. The disadvantage is that the resulting JSON text is encoded 244size. The disadvantage is that the resulting JSON text is encoded
243in latin1 (and must correctly be treated as such when storing and 245in latin1 (and must correctly be treated as such when storing and
244transfering), a rare encoding for JSON. It is therefore most useful when 246transferring), a rare encoding for JSON. It is therefore most useful when
245you want to store data structures known to contain binary data efficiently 247you want to store data structures known to contain binary data efficiently
246in files or databases, not when talking to other JSON encoders/decoders. 248in files or databases, not when talking to other JSON encoders/decoders.
247 249
248 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"] 250 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
249 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not) 251 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
250 252
251=item $json = $json->utf8 ([$enable]) 253=item $json = $json->utf8 ([$enable])
254
255=item $enabled = $json->get_utf8
252 256
253If C<$enable> is true (or missing), then the C<encode> method will encode 257If C<$enable> is true (or missing), then the C<encode> method will encode
254the JSON result into UTF-8, as required by many protocols, while the 258the JSON result into UTF-8, as required by many protocols, while the
255C<decode> method expects to be handled an UTF-8-encoded string. Please 259C<decode> method expects to be handled an UTF-8-encoded string. Please
256note that UTF-8-encoded strings do not contain any characters outside the 260note that UTF-8-encoded strings do not contain any characters outside the
257range C<0..255>, they are thus useful for bytewise/binary I/O. In future 261range C<0..255>, they are thus useful for bytewise/binary I/O. In future
258versions, enabling this option might enable autodetection of the UTF-16 262versions, enabling this option might enable autodetection of the UTF-16
259and UTF-32 encoding families, as described in RFC4627. 263and UTF-32 encoding families, as described in RFC4627.
260 264
261If C<$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
262string 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
263unicode 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
264to be done yourself, e.g. using the Encode module. 268to be done yourself, e.g. using the Encode module.
265 269
266Example, output UTF-16BE-encoded JSON: 270Example, output UTF-16BE-encoded JSON:
267 271
268 use Encode; 272 use Encode;
290 ] 294 ]
291 } 295 }
292 296
293=item $json = $json->indent ([$enable]) 297=item $json = $json->indent ([$enable])
294 298
299=item $enabled = $json->get_indent
300
295If C<$enable> is true (or missing), then the C<encode> method will use a multiline 301If C<$enable> is true (or missing), then the C<encode> method will use a multiline
296format as output, putting every array member or object/hash key-value pair 302format as output, putting every array member or object/hash key-value pair
297into its own line, identing them properly. 303into its own line, indenting them properly.
298 304
299If C<$enable> is false, no newlines or indenting will be produced, and the 305If C<$enable> is false, no newlines or indenting will be produced, and the
300resulting JSON text is guarenteed not to contain any C<newlines>. 306resulting JSON text is guaranteed not to contain any C<newlines>.
301 307
302This setting has no effect when decoding JSON texts. 308This setting has no effect when decoding JSON texts.
303 309
304=item $json = $json->space_before ([$enable]) 310=item $json = $json->space_before ([$enable])
311
312=item $enabled = $json->get_space_before
305 313
306If C<$enable> is true (or missing), then the C<encode> method will add an extra 314If C<$enable> is true (or missing), then the C<encode> method will add an extra
307optional space before the C<:> separating keys from values in JSON objects. 315optional space before the C<:> separating keys from values in JSON objects.
308 316
309If C<$enable> is false, then the C<encode> method will not add any extra 317If C<$enable> is false, then the C<encode> method will not add any extra
315Example, space_before enabled, space_after and indent disabled: 323Example, space_before enabled, space_after and indent disabled:
316 324
317 {"key" :"value"} 325 {"key" :"value"}
318 326
319=item $json = $json->space_after ([$enable]) 327=item $json = $json->space_after ([$enable])
328
329=item $enabled = $json->get_space_after
320 330
321If C<$enable> is true (or missing), then the C<encode> method will add an extra 331If C<$enable> is true (or missing), then the C<encode> method will add an extra
322optional space after the C<:> separating keys from values in JSON objects 332optional space after the C<:> separating keys from values in JSON objects
323and extra whitespace after the C<,> separating key-value pairs and array 333and extra whitespace after the C<,> separating key-value pairs and array
324members. 334members.
331Example, space_before and indent disabled, space_after enabled: 341Example, space_before and indent disabled, space_after enabled:
332 342
333 {"key": "value"} 343 {"key": "value"}
334 344
335=item $json = $json->relaxed ([$enable]) 345=item $json = $json->relaxed ([$enable])
346
347=item $enabled = $json->get_relaxed
336 348
337If C<$enable> is true (or missing), then C<decode> will accept some 349If C<$enable> is true (or missing), then C<decode> will accept some
338extensions to normal JSON syntax (see below). C<encode> will not be 350extensions to normal JSON syntax (see below). C<encode> will not be
339affected in anyway. I<Be aware that this option makes you accept invalid 351affected in anyway. I<Be aware that this option makes you accept invalid
340JSON texts as if they were valid!>. I suggest only to use this option to 352JSON texts as if they were valid!>. I suggest only to use this option to
377 389
378=back 390=back
379 391
380=item $json = $json->canonical ([$enable]) 392=item $json = $json->canonical ([$enable])
381 393
394=item $enabled = $json->get_canonical
395
382If C<$enable> is true (or missing), then the C<encode> method will output JSON objects 396If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
383by sorting their keys. This is adding a comparatively high overhead. 397by sorting their keys. This is adding a comparatively high overhead.
384 398
385If C<$enable> is false, then the C<encode> method will output key-value 399If C<$enable> is false, then the C<encode> method will output key-value
386pairs in the order Perl stores them (which will likely change between runs 400pairs in the order Perl stores them (which will likely change between runs
387of the same script). 401of the same script).
388 402
389This option is useful if you want the same data structure to be encoded as 403This option is useful if you want the same data structure to be encoded as
390the same JSON text (given the same overall settings). If it is disabled, 404the same JSON text (given the same overall settings). If it is disabled,
391the same hash migh be encoded differently even if contains the same data, 405the same hash might be encoded differently even if contains the same data,
392as key-value pairs have no inherent ordering in Perl. 406as key-value pairs have no inherent ordering in Perl.
393 407
394This setting has no effect when decoding JSON texts. 408This setting has no effect when decoding JSON texts.
395 409
396=item $json = $json->allow_nonref ([$enable]) 410=item $json = $json->allow_nonref ([$enable])
411
412=item $enabled = $json->get_allow_nonref
397 413
398If C<$enable> is true (or missing), then the C<encode> method can convert a 414If C<$enable> is true (or missing), then the C<encode> method can convert a
399non-reference into its corresponding string, number or null JSON value, 415non-reference into its corresponding string, number or null JSON value,
400which is an extension to RFC4627. Likewise, C<decode> will accept those JSON 416which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
401values instead of croaking. 417values instead of croaking.
411 JSON::XS->new->allow_nonref->encode ("Hello, World!") 427 JSON::XS->new->allow_nonref->encode ("Hello, World!")
412 => "Hello, World!" 428 => "Hello, World!"
413 429
414=item $json = $json->allow_blessed ([$enable]) 430=item $json = $json->allow_blessed ([$enable])
415 431
432=item $enabled = $json->get_allow_blessed
433
416If C<$enable> is true (or missing), then the C<encode> method will not 434If C<$enable> is true (or missing), then the C<encode> method will not
417barf when it encounters a blessed reference. Instead, the value of the 435barf when it encounters a blessed reference. Instead, the value of the
418B<convert_blessed> option will decide wether C<null> (C<convert_blessed> 436B<convert_blessed> option will decide whether C<null> (C<convert_blessed>
419disabled or no C<to_json> method found) or a representation of the 437disabled or no C<TO_JSON> method found) or a representation of the
420object (C<convert_blessed> enabled and C<to_json> method found) is being 438object (C<convert_blessed> enabled and C<TO_JSON> method found) is being
421encoded. Has no effect on C<decode>. 439encoded. Has no effect on C<decode>.
422 440
423If C<$enable> is false (the default), then C<encode> will throw an 441If C<$enable> is false (the default), then C<encode> will throw an
424exception when it encounters a blessed object. 442exception when it encounters a blessed object.
425 443
426=item $json = $json->convert_blessed ([$enable]) 444=item $json = $json->convert_blessed ([$enable])
445
446=item $enabled = $json->get_convert_blessed
427 447
428If C<$enable> is true (or missing), then C<encode>, upon encountering a 448If C<$enable> is true (or missing), then C<encode>, upon encountering a
429blessed object, will check for the availability of the C<TO_JSON> method 449blessed object, will check for the availability of the C<TO_JSON> method
430on the object's class. If found, it will be called in scalar context 450on the object's class. If found, it will be called in scalar context
431and the resulting scalar will be encoded instead of the object. If no 451and the resulting scalar will be encoded instead of the object. If no
488 508
489As this callback gets called less often then the C<filter_json_object> 509As this callback gets called less often then the C<filter_json_object>
490one, decoding speed will not usually suffer as much. Therefore, single-key 510one, decoding speed will not usually suffer as much. Therefore, single-key
491objects make excellent targets to serialise Perl objects into, especially 511objects make excellent targets to serialise Perl objects into, especially
492as single-key JSON objects are as close to the type-tagged value concept 512as single-key JSON objects are as close to the type-tagged value concept
493as JSON gets (its basically an ID/VALUE tuple). Of course, JSON does not 513as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not
494support this in any way, so you need to make sure your data never looks 514support this in any way, so you need to make sure your data never looks
495like a serialised Perl hash. 515like a serialised Perl hash.
496 516
497Typical names for the single object key are C<__class_whatever__>, or 517Typical names for the single object key are C<__class_whatever__>, or
498C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even 518C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
522 542
523 { __widget__ => $self->{id} } 543 { __widget__ => $self->{id} }
524 } 544 }
525 545
526=item $json = $json->shrink ([$enable]) 546=item $json = $json->shrink ([$enable])
547
548=item $enabled = $json->get_shrink
527 549
528Perl usually over-allocates memory a bit when allocating space for 550Perl usually over-allocates memory a bit when allocating space for
529strings. This flag optionally resizes strings generated by either 551strings. This flag optionally resizes strings generated by either
530C<encode> or C<decode> to their minimum size possible. This can save 552C<encode> or C<decode> to their minimum size possible. This can save
531memory when your JSON texts are either very very long or you have many 553memory when your JSON texts are either very very long or you have many
549strings that look like integers or floats into integers or floats 571strings that look like integers or floats into integers or floats
550internally (there is no difference on the Perl level), saving space. 572internally (there is no difference on the Perl level), saving space.
551 573
552=item $json = $json->max_depth ([$maximum_nesting_depth]) 574=item $json = $json->max_depth ([$maximum_nesting_depth])
553 575
576=item $max_depth = $json->get_max_depth
577
554Sets the maximum nesting level (default C<512>) accepted while encoding 578Sets the maximum nesting level (default C<512>) accepted while encoding
555or decoding. If the JSON text or Perl data structure has an equal or 579or decoding. If the JSON text or Perl data structure has an equal or
556higher nesting level then this limit, then the encoder and decoder will 580higher nesting level then this limit, then the encoder and decoder will
557stop and croak at that point. 581stop and croak at that point.
558 582
569used, which is rarely useful. 593used, which is rarely useful.
570 594
571See SECURITY CONSIDERATIONS, below, for more info on why this is useful. 595See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
572 596
573=item $json = $json->max_size ([$maximum_string_size]) 597=item $json = $json->max_size ([$maximum_string_size])
598
599=item $max_size = $json->get_max_size
574 600
575Set the maximum length a JSON text may have (in bytes) where decoding is 601Set the maximum length a JSON text may have (in bytes) where decoding is
576being attempted. The default is C<0>, meaning no limit. When C<decode> 602being attempted. The default is C<0>, meaning no limit. When C<decode>
577is called on a string longer then this number of characters it will not 603is called on a string longer then this number of characters it will not
578attempt to decode the string but throw an exception. This setting has no 604attempt to decode the string but throw an exception. This setting has no
625vice versa. These mappings are designed to "do the right thing" in most 651vice versa. These mappings are designed to "do the right thing" in most
626circumstances automatically, preserving round-tripping characteristics 652circumstances automatically, preserving round-tripping characteristics
627(what you put in comes out as something equivalent). 653(what you put in comes out as something equivalent).
628 654
629For the more enlightened: note that in the following descriptions, 655For the more enlightened: note that in the following descriptions,
630lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> 656lowercase I<perl> refers to the Perl interpreter, while uppercase I<Perl>
631refers to the abstract Perl language itself. 657refers to the abstract Perl language itself.
632 658
633 659
634=head2 JSON -> PERL 660=head2 JSON -> PERL
635 661
636=over 4 662=over 4
637 663
638=item object 664=item object
639 665
640A JSON object becomes a reference to a hash in Perl. No ordering of object 666A JSON object becomes a reference to a hash in Perl. No ordering of object
641keys is preserved (JSON does not preserver object key ordering itself). 667keys is preserved (JSON does not preserve object key ordering itself).
642 668
643=item array 669=item array
644 670
645A JSON array becomes a reference to an array in Perl. 671A JSON array becomes a reference to an array in Perl.
646 672
672 698
673=item true, false 699=item true, false
674 700
675These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>, 701These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
676respectively. They are overloaded to act almost exactly like the numbers 702respectively. They are overloaded to act almost exactly like the numbers
677C<1> and C<0>. You can check wether a scalar is a JSON boolean by using 703C<1> and C<0>. You can check whether a scalar is a JSON boolean by using
678the C<JSON::XS::is_bool> function. 704the C<JSON::XS::is_bool> function.
679 705
680=item null 706=item null
681 707
682A JSON null atom becomes C<undef> in Perl. 708A JSON null atom becomes C<undef> in Perl.
745 to_json [$value] # yields ["5"] 771 to_json [$value] # yields ["5"]
746 772
747 # undef becomes null 773 # undef becomes null
748 to_json [undef] # yields [null] 774 to_json [undef] # yields [null]
749 775
750You can force the type to be a string by stringifying it: 776You can force the type to be a JSON string by stringifying it:
751 777
752 my $x = 3.1; # some variable containing a number 778 my $x = 3.1; # some variable containing a number
753 "$x"; # stringified 779 "$x"; # stringified
754 $x .= ""; # another, more awkward way to stringify 780 $x .= ""; # another, more awkward way to stringify
755 print $x; # perl does it for you, too, quite often 781 print $x; # perl does it for you, too, quite often
756 782
757You can force the type to be a number by numifying it: 783You can force the type to be a JSON number by numifying it:
758 784
759 my $x = "3"; # some variable containing a string 785 my $x = "3"; # some variable containing a string
760 $x += 0; # numify it, ensuring it will be dumped as a number 786 $x += 0; # numify it, ensuring it will be dumped as a number
761 $x *= 1; # same thing, the choise is yours. 787 $x *= 1; # same thing, the choice is yours.
762 788
763You can not currently output JSON booleans or force the type in other, 789You can not currently force the type in other, less obscure, ways. Tell me
764less obscure, ways. Tell me if you need this capability. 790if you need this capability.
765 791
766=back 792=back
767 793
768 794
769=head1 COMPARISON 795=head1 COMPARISON
778 804
779=item JSON 1.07 805=item JSON 1.07
780 806
781Slow (but very portable, as it is written in pure Perl). 807Slow (but very portable, as it is written in pure Perl).
782 808
783Undocumented/buggy Unicode handling (how JSON handles unicode values is 809Undocumented/buggy Unicode handling (how JSON handles Unicode values is
784undocumented. One can get far by feeding it unicode strings and doing 810undocumented. One can get far by feeding it Unicode strings and doing
785en-/decoding oneself, but unicode escapes are not working properly). 811en-/decoding oneself, but Unicode escapes are not working properly).
786 812
787No roundtripping (strings get clobbered if they look like numbers, e.g. 813No round-tripping (strings get clobbered if they look like numbers, e.g.
788the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will 814the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will
789decode into the number 2. 815decode into the number 2.
790 816
791=item JSON::PC 0.01 817=item JSON::PC 0.01
792 818
793Very fast. 819Very fast.
794 820
795Undocumented/buggy Unicode handling. 821Undocumented/buggy Unicode handling.
796 822
797No roundtripping. 823No round-tripping.
798 824
799Has problems handling many Perl values (e.g. regex results and other magic 825Has problems handling many Perl values (e.g. regex results and other magic
800values will make it croak). 826values will make it croak).
801 827
802Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}> 828Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
812Very inflexible (no human-readable format supported, format pretty much 838Very inflexible (no human-readable format supported, format pretty much
813undocumented. I need at least a format for easy reading by humans and a 839undocumented. I need at least a format for easy reading by humans and a
814single-line compact format for use in a protocol, and preferably a way to 840single-line compact format for use in a protocol, and preferably a way to
815generate ASCII-only JSON texts). 841generate ASCII-only JSON texts).
816 842
817Completely broken (and confusingly documented) Unicode handling (unicode 843Completely broken (and confusingly documented) Unicode handling (Unicode
818escapes are not working properly, you need to set ImplicitUnicode to 844escapes are not working properly, you need to set ImplicitUnicode to
819I<different> values on en- and decoding to get symmetric behaviour). 845I<different> values on en- and decoding to get symmetric behaviour).
820 846
821No roundtripping (simple cases work, but this depends on wether the scalar 847No round-tripping (simple cases work, but this depends on whether the scalar
822value was used in a numeric context or not). 848value was used in a numeric context or not).
823 849
824Dumping hashes may skip hash values depending on iterator state. 850Dumping hashes may skip hash values depending on iterator state.
825 851
826Unmaintained (maintainer unresponsive for many months, bugs are not 852Unmaintained (maintainer unresponsive for many months, bugs are not
827getting fixed). 853getting fixed).
828 854
829Does not check input for validity (i.e. will accept non-JSON input and 855Does not check input for validity (i.e. will accept non-JSON input and
830return "something" instead of raising an exception. This is a security 856return "something" instead of raising an exception. This is a security
831issue: imagine two banks transfering money between each other using 857issue: imagine two banks transferring money between each other using
832JSON. One bank might parse a given non-JSON request and deduct money, 858JSON. One bank might parse a given non-JSON request and deduct money,
833while the other might reject the transaction with a syntax error. While a 859while the other might reject the transaction with a syntax error. While a
834good protocol will at least recover, that is extra unnecessary work and 860good protocol will at least recover, that is extra unnecessary work and
835the transaction will still not succeed). 861the transaction will still not succeed).
836 862
837=item JSON::DWIW 0.04 863=item JSON::DWIW 0.04
838 864
839Very fast. Very natural. Very nice. 865Very fast. Very natural. Very nice.
840 866
841Undocumented unicode handling (but the best of the pack. Unicode escapes 867Undocumented Unicode handling (but the best of the pack. Unicode escapes
842still don't get parsed properly). 868still don't get parsed properly).
843 869
844Very inflexible. 870Very inflexible.
845 871
846No roundtripping. 872No round-tripping.
847 873
848Does not generate valid JSON texts (key strings are often unquoted, empty keys 874Does not generate valid JSON texts (key strings are often unquoted, empty keys
849result in nothing being output) 875result in nothing being output)
850 876
851Does not check input for validity. 877Does not check input for validity.
866 my $yaml = $to_yaml->encode ($ref) . "\n"; 892 my $yaml = $to_yaml->encode ($ref) . "\n";
867 893
868This will usually generate JSON texts that also parse as valid 894This will usually generate JSON texts that also parse as valid
869YAML. Please note that YAML has hardcoded limits on (simple) object key 895YAML. Please note that YAML has hardcoded limits on (simple) object key
870lengths that JSON doesn't have, so you should make sure that your hash 896lengths that JSON doesn't have, so you should make sure that your hash
871keys are noticably shorter than the 1024 characters YAML allows. 897keys are noticeably shorter than the 1024 characters YAML allows.
872 898
873There might be other incompatibilities that I am not aware of. In general 899There might be other incompatibilities that I am not aware of. In general
874you should not try to generate YAML with a JSON generator or vice versa, 900you should not try to generate YAML with a JSON generator or vice versa,
875or try to parse JSON with a YAML parser or vice versa: chances are high 901or try to parse JSON with a YAML parser or vice versa: chances are high
876that you will run into severe interoperability problems. 902that you will run into severe interoperability problems.
892It shows the number of encodes/decodes per second (JSON::XS uses 918It shows the number of encodes/decodes per second (JSON::XS uses
893the functional interface, while JSON::XS/2 uses the OO interface 919the functional interface, while JSON::XS/2 uses the OO interface
894with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables 920with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
895shrink). Higher is better: 921shrink). Higher is better:
896 922
897 Storable | 15779.925 | 14169.946 |
898 -----------+------------+------------+
899 module | encode | decode | 923 module | encode | decode |
900 -----------|------------|------------| 924 -----------|------------|------------|
901 JSON | 4990.842 | 4088.813 | 925 JSON 1.x | 4990.842 | 4088.813 |
902 JSON::DWIW | 51653.990 | 71575.154 | 926 JSON::DWIW | 51653.990 | 71575.154 |
903 JSON::PC | 65948.176 | 74631.744 | 927 JSON::PC | 65948.176 | 74631.744 |
904 JSON::PP | 8931.652 | 3817.168 | 928 JSON::PP | 8931.652 | 3817.168 |
905 JSON::Syck | 24877.248 | 27776.848 | 929 JSON::Syck | 24877.248 | 27776.848 |
906 JSON::XS | 388361.481 | 227951.304 | 930 JSON::XS | 388361.481 | 227951.304 |
908 JSON::XS/3 | 338250.323 | 218453.333 | 932 JSON::XS/3 | 338250.323 | 218453.333 |
909 Storable | 16500.016 | 135300.129 | 933 Storable | 16500.016 | 135300.129 |
910 -----------+------------+------------+ 934 -----------+------------+------------+
911 935
912That is, JSON::XS is about five times faster than JSON::DWIW on encoding, 936That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
913about three times faster on decoding, and over fourty times faster 937about three times faster on decoding, and over forty times faster
914than JSON, even with pretty-printing and key sorting. It also compares 938than JSON, even with pretty-printing and key sorting. It also compares
915favourably to Storable for small amounts of data. 939favourably to Storable for small amounts of data.
916 940
917Using a longer test string (roughly 18KB, generated from Yahoo! Locals 941Using a longer test string (roughly 18KB, generated from Yahoo! Locals
918search API (http://nanoref.com/yahooapis/mgPdGg): 942search API (http://nanoref.com/yahooapis/mgPdGg):
919 943
920 module | encode | decode | 944 module | encode | decode |
921 -----------|------------|------------| 945 -----------|------------|------------|
922 JSON | 55.260 | 34.971 | 946 JSON 1.x | 55.260 | 34.971 |
923 JSON::DWIW | 825.228 | 1082.513 | 947 JSON::DWIW | 825.228 | 1082.513 |
924 JSON::PC | 3571.444 | 2394.829 | 948 JSON::PC | 3571.444 | 2394.829 |
925 JSON::PP | 210.987 | 32.574 | 949 JSON::PP | 210.987 | 32.574 |
926 JSON::Syck | 552.551 | 787.544 | 950 JSON::Syck | 552.551 | 787.544 |
927 JSON::XS | 5780.463 | 4854.519 | 951 JSON::XS | 5780.463 | 4854.519 |
931 -----------+------------+------------+ 955 -----------+------------+------------+
932 956
933Again, JSON::XS leads by far (except for Storable which non-surprisingly 957Again, JSON::XS leads by far (except for Storable which non-surprisingly
934decodes faster). 958decodes faster).
935 959
936On large strings containing lots of high unicode characters, some modules 960On large strings containing lots of high Unicode characters, some modules
937(such as JSON::PC) seem to decode faster than JSON::XS, but the result 961(such as JSON::PC) seem to decode faster than JSON::XS, but the result
938will be broken due to missing (or wrong) unicode handling. Others refuse 962will be broken due to missing (or wrong) Unicode handling. Others refuse
939to decode or encode properly, so it was impossible to prepare a fair 963to decode or encode properly, so it was impossible to prepare a fair
940comparison table for that case. 964comparison table for that case.
941 965
942 966
943=head1 SECURITY CONSIDERATIONS 967=head1 SECURITY CONSIDERATIONS
949any buffer overflows. Obviously, this module should ensure that and I am 973any buffer overflows. Obviously, this module should ensure that and I am
950trying hard on making that true, but you never know. 974trying hard on making that true, but you never know.
951 975
952Second, you need to avoid resource-starving attacks. That means you should 976Second, you need to avoid resource-starving attacks. That means you should
953limit the size of JSON texts you accept, or make sure then when your 977limit the size of JSON texts you accept, or make sure then when your
954resources run out, thats just fine (e.g. by using a separate process that 978resources run out, that's just fine (e.g. by using a separate process that
955can crash safely). The size of a JSON text in octets or characters is 979can crash safely). The size of a JSON text in octets or characters is
956usually a good indication of the size of the resources required to decode 980usually a good indication of the size of the resources required to decode
957it into a Perl structure. While JSON::XS can check the size of the JSON 981it into a Perl structure. While JSON::XS can check the size of the JSON
958text, it might be too late when you already have it in memory, so you 982text, it might be too late when you already have it in memory, so you
959might want to check the size before you accept the string. 983might want to check the size before you accept the string.
970And last but least, something else could bomb you that I forgot to think 994And last but least, something else could bomb you that I forgot to think
971of. In that case, you get to keep the pieces. I am always open for hints, 995of. In that case, you get to keep the pieces. I am always open for hints,
972though... 996though...
973 997
974If you are using JSON::XS to return packets to consumption 998If you are using JSON::XS to return packets to consumption
975by javascript scripts in a browser you should have a look at 999by JavaScript scripts in a browser you should have a look at
976L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether 1000L<http://jpsykes.com/47/practical-csrf-and-json-security> to see whether
977you are vulnerable to some common attack vectors (which really are browser 1001you are vulnerable to some common attack vectors (which really are browser
978design bugs, but it is still you who will have to deal with it, as major 1002design bugs, but it is still you who will have to deal with it, as major
979browser developers care only for features, not about doing security 1003browser developers care only for features, not about doing security
980right). 1004right).
981 1005
982 1006
983=head1 THREADS 1007=head1 THREADS
984 1008
985This module is I<not> guarenteed to be thread safe and there are no 1009This module is I<not> guaranteed to be thread safe and there are no
986plans to change this until Perl gets thread support (as opposed to the 1010plans to change this until Perl gets thread support (as opposed to the
987horribly slow so-called "threads" which are simply slow and bloated 1011horribly slow so-called "threads" which are simply slow and bloated
988process simulations - use fork, its I<much> faster, cheaper, better). 1012process simulations - use fork, its I<much> faster, cheaper, better).
989 1013
990(It might actually work, but you ahve ben warned). 1014(It might actually work, but you have been warned).
991 1015
992 1016
993=head1 BUGS 1017=head1 BUGS
994 1018
995While the goal of this module is to be correct, that unfortunately does 1019While the goal of this module is to be correct, that unfortunately does

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