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Revision 1.66 by root, Sun Oct 14 20:02:57 2007 UTC vs.
Revision 1.73 by root, Sun Nov 25 19:36:54 2007 UTC

40 40
41=head2 FEATURES 41=head2 FEATURES
42 42
43=over 4 43=over 4
44 44
45=item * correct unicode handling 45=item * correct Unicode handling
46 46
47This 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
48it does so. 48it does so.
49 49
50=item * round-trip integrity 50=item * round-trip integrity
70This 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
71interface. 71interface.
72 72
73=item * reasonably versatile output formats 73=item * reasonably versatile output formats
74 74
75You can choose between the most compact guarenteed single-line format 75You can choose between the most compact guaranteed single-line format
76possible (nice for simple line-based protocols), a pure-ascii format 76possible (nice for simple line-based protocols), a pure-ascii format
77(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
78unicode 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
79stuff). Or you can combine those features in whatever way you like. 79stuff). Or you can combine those features in whatever way you like.
80 80
81=back 81=back
82 82
83=cut 83=cut
84 84
85package JSON::XS; 85package JSON::XS;
86 86
87use strict; 87use strict;
88 88
89our $VERSION = '1.51'; 89our $VERSION = '1.6';
90our @ISA = qw(Exporter); 90our @ISA = qw(Exporter);
91 91
92our @EXPORT = qw(to_json from_json); 92our @EXPORT = qw(to_json from_json);
93 93
94use Exporter; 94use Exporter;
95use XSLoader; 95use XSLoader;
96 96
97=head1 FUNCTIONAL INTERFACE 97=head1 FUNCTIONAL INTERFACE
98 98
99The following convinience methods are provided by this module. They are 99The following convenience methods are provided by this module. They are
100exported by default: 100exported by default:
101 101
102=over 4 102=over 4
103 103
104=item $json_text = to_json $perl_scalar 104=item $json_text = to_json $perl_scalar
143 143
144=over 4 144=over 4
145 145
146=item 1. Perl strings can store characters with ordinal values > 255. 146=item 1. Perl strings can store characters with ordinal values > 255.
147 147
148This enables you to store unicode characters as single characters in a 148This enables you to store Unicode characters as single characters in a
149Perl string - very natural. 149Perl string - very natural.
150 150
151=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.
152 152
153Unless 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
160encoding of your string. 160encoding of your string.
161 161
162Just 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
163XS 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
164confuse 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
165is 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
166flag 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
167clear. Other possibilities exist, too. 167clear. Other possibilities exist, too.
168 168
169If 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
170exist. 170exist.
175If 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
176Unicode string encoded in UTF-8, giving you a binary string. 176Unicode string encoded in UTF-8, giving you a binary string.
177 177
178=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.
179 179
180Its a fact. Learn to live with it. 180It's a fact. Learn to live with it.
181 181
182=back 182=back
183 183
184I hope this helps :) 184I hope this helps :)
185 185
202 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]})
203 => {"a": [1, 2]} 203 => {"a": [1, 2]}
204 204
205=item $json = $json->ascii ([$enable]) 205=item $json = $json->ascii ([$enable])
206 206
207=item $enabled = $json->get_ascii
208
207If C<$enable> is true (or missing), then the C<encode> method will not 209If C<$enable> is true (or missing), then the C<encode> method will not
208generate characters outside the code range C<0..127> (which is ASCII). Any 210generate characters outside the code range C<0..127> (which is ASCII). Any
209unicode characters outside that range will be escaped using either a 211Unicode characters outside that range will be escaped using either a
210single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, 212single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
211as per RFC4627. The resulting encoded JSON text can be treated as a native 213as per RFC4627. The resulting encoded JSON text can be treated as a native
212unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string, 214Unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
213or any other superset of ASCII. 215or any other superset of ASCII.
214 216
215If C<$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
216characters unless required by the JSON syntax or other flags. This results 218characters unless required by the JSON syntax or other flags. This results
217in a faster and more compact format. 219in a faster and more compact format.
223 JSON::XS->new->ascii (1)->encode ([chr 0x10401]) 225 JSON::XS->new->ascii (1)->encode ([chr 0x10401])
224 => ["\ud801\udc01"] 226 => ["\ud801\udc01"]
225 227
226=item $json = $json->latin1 ([$enable]) 228=item $json = $json->latin1 ([$enable])
227 229
230=item $enabled = $json->get_latin1
231
228If C<$enable> is true (or missing), then the C<encode> method will encode 232If C<$enable> is true (or missing), then the C<encode> method will encode
229the resulting JSON text as latin1 (or iso-8859-1), escaping any characters 233the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
230outside the code range C<0..255>. The resulting string can be treated as a 234outside the code range C<0..255>. The resulting string can be treated as a
231latin1-encoded JSON text or a native unicode string. The C<decode> method 235latin1-encoded JSON text or a native Unicode string. The C<decode> method
232will not be affected in any way by this flag, as C<decode> by default 236will not be affected in any way by this flag, as C<decode> by default
233expects unicode, which is a strict superset of latin1. 237expects Unicode, which is a strict superset of latin1.
234 238
235If C<$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
236characters unless required by the JSON syntax or other flags. 240characters unless required by the JSON syntax or other flags.
237 241
238The 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
239text, 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
240size. The disadvantage is that the resulting JSON text is encoded 244size. The disadvantage is that the resulting JSON text is encoded
241in latin1 (and must correctly be treated as such when storing and 245in latin1 (and must correctly be treated as such when storing and
242transfering), a rare encoding for JSON. It is therefore most useful when 246transferring), a rare encoding for JSON. It is therefore most useful when
243you want to store data structures known to contain binary data efficiently 247you want to store data structures known to contain binary data efficiently
244in files or databases, not when talking to other JSON encoders/decoders. 248in files or databases, not when talking to other JSON encoders/decoders.
245 249
246 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"] 250 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
247 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not) 251 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
248 252
249=item $json = $json->utf8 ([$enable]) 253=item $json = $json->utf8 ([$enable])
254
255=item $enabled = $json->get_utf8
250 256
251If C<$enable> is true (or missing), then the C<encode> method will encode 257If C<$enable> is true (or missing), then the C<encode> method will encode
252the JSON result into UTF-8, as required by many protocols, while the 258the JSON result into UTF-8, as required by many protocols, while the
253C<decode> method expects to be handled an UTF-8-encoded string. Please 259C<decode> method expects to be handled an UTF-8-encoded string. Please
254note that UTF-8-encoded strings do not contain any characters outside the 260note that UTF-8-encoded strings do not contain any characters outside the
255range C<0..255>, they are thus useful for bytewise/binary I/O. In future 261range C<0..255>, they are thus useful for bytewise/binary I/O. In future
256versions, enabling this option might enable autodetection of the UTF-16 262versions, enabling this option might enable autodetection of the UTF-16
257and UTF-32 encoding families, as described in RFC4627. 263and UTF-32 encoding families, as described in RFC4627.
258 264
259If C<$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
260string 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
261unicode 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
262to be done yourself, e.g. using the Encode module. 268to be done yourself, e.g. using the Encode module.
263 269
264Example, output UTF-16BE-encoded JSON: 270Example, output UTF-16BE-encoded JSON:
265 271
266 use Encode; 272 use Encode;
270 276
271 use Encode; 277 use Encode;
272 $object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext); 278 $object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext);
273 279
274=item $json = $json->pretty ([$enable]) 280=item $json = $json->pretty ([$enable])
281
282=item $enabled = $json->get_pretty
275 283
276This 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
277C<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
278generate the most readable (or most compact) form possible. 286generate the most readable (or most compact) form possible.
279 287
288 ] 296 ]
289 } 297 }
290 298
291=item $json = $json->indent ([$enable]) 299=item $json = $json->indent ([$enable])
292 300
301=item $enabled = $json->get_indent
302
293If C<$enable> is true (or missing), then the C<encode> method will use a multiline 303If C<$enable> is true (or missing), then the C<encode> method will use a multiline
294format as output, putting every array member or object/hash key-value pair 304format as output, putting every array member or object/hash key-value pair
295into its own line, identing them properly. 305into its own line, indenting them properly.
296 306
297If C<$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
298resulting JSON text is guarenteed not to contain any C<newlines>. 308resulting JSON text is guaranteed not to contain any C<newlines>.
299 309
300This setting has no effect when decoding JSON texts. 310This setting has no effect when decoding JSON texts.
301 311
302=item $json = $json->space_before ([$enable]) 312=item $json = $json->space_before ([$enable])
313
314=item $enabled = $json->get_space_before
303 315
304If C<$enable> is true (or missing), then the C<encode> method will add an extra 316If C<$enable> is true (or missing), then the C<encode> method will add an extra
305optional space before the C<:> separating keys from values in JSON objects. 317optional space before the C<:> separating keys from values in JSON objects.
306 318
307If C<$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
313Example, space_before enabled, space_after and indent disabled: 325Example, space_before enabled, space_after and indent disabled:
314 326
315 {"key" :"value"} 327 {"key" :"value"}
316 328
317=item $json = $json->space_after ([$enable]) 329=item $json = $json->space_after ([$enable])
330
331=item $enabled = $json->get_space_after
318 332
319If C<$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
320optional space after the C<:> separating keys from values in JSON objects 334optional space after the C<:> separating keys from values in JSON objects
321and extra whitespace after the C<,> separating key-value pairs and array 335and extra whitespace after the C<,> separating key-value pairs and array
322members. 336members.
329Example, space_before and indent disabled, space_after enabled: 343Example, space_before and indent disabled, space_after enabled:
330 344
331 {"key": "value"} 345 {"key": "value"}
332 346
333=item $json = $json->relaxed ([$enable]) 347=item $json = $json->relaxed ([$enable])
348
349=item $enabled = $json->get_relaxed
334 350
335If C<$enable> is true (or missing), then C<decode> will accept some 351If C<$enable> is true (or missing), then C<decode> will accept some
336extensions to normal JSON syntax (see below). C<encode> will not be 352extensions to normal JSON syntax (see below). C<encode> will not be
337affected 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
338JSON 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
375 391
376=back 392=back
377 393
378=item $json = $json->canonical ([$enable]) 394=item $json = $json->canonical ([$enable])
379 395
396=item $enabled = $json->get_canonical
397
380If C<$enable> is true (or missing), then the C<encode> method will output JSON objects 398If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
381by sorting their keys. This is adding a comparatively high overhead. 399by sorting their keys. This is adding a comparatively high overhead.
382 400
383If C<$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
384pairs 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
385of the same script). 403of the same script).
386 404
387This 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
388the 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,
389the 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,
390as key-value pairs have no inherent ordering in Perl. 408as key-value pairs have no inherent ordering in Perl.
391 409
392This setting has no effect when decoding JSON texts. 410This setting has no effect when decoding JSON texts.
393 411
394=item $json = $json->allow_nonref ([$enable]) 412=item $json = $json->allow_nonref ([$enable])
413
414=item $enabled = $json->get_allow_nonref
395 415
396If C<$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
397non-reference into its corresponding string, number or null JSON value, 417non-reference into its corresponding string, number or null JSON value,
398which 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
399values instead of croaking. 419values instead of croaking.
409 JSON::XS->new->allow_nonref->encode ("Hello, World!") 429 JSON::XS->new->allow_nonref->encode ("Hello, World!")
410 => "Hello, World!" 430 => "Hello, World!"
411 431
412=item $json = $json->allow_blessed ([$enable]) 432=item $json = $json->allow_blessed ([$enable])
413 433
434=item $enabled = $json->get_allow_bless
435
414If C<$enable> is true (or missing), then the C<encode> method will not 436If C<$enable> is true (or missing), then the C<encode> method will not
415barf when it encounters a blessed reference. Instead, the value of the 437barf when it encounters a blessed reference. Instead, the value of the
416B<convert_blessed> option will decide wether C<null> (C<convert_blessed> 438B<convert_blessed> option will decide whether C<null> (C<convert_blessed>
417disabled or no C<to_json> method found) or a representation of the 439disabled or no C<to_json> method found) or a representation of the
418object (C<convert_blessed> enabled and C<to_json> method found) is being 440object (C<convert_blessed> enabled and C<to_json> method found) is being
419encoded. Has no effect on C<decode>. 441encoded. Has no effect on C<decode>.
420 442
421If C<$enable> is false (the default), then C<encode> will throw an 443If C<$enable> is false (the default), then C<encode> will throw an
422exception when it encounters a blessed object. 444exception when it encounters a blessed object.
423 445
424=item $json = $json->convert_blessed ([$enable]) 446=item $json = $json->convert_blessed ([$enable])
447
448=item $enabled = $json->get_convert_blessed
425 449
426If C<$enable> is true (or missing), then C<encode>, upon encountering a 450If C<$enable> is true (or missing), then C<encode>, upon encountering a
427blessed object, will check for the availability of the C<TO_JSON> method 451blessed object, will check for the availability of the C<TO_JSON> method
428on the object's class. If found, it will be called in scalar context 452on the object's class. If found, it will be called in scalar context
429and the resulting scalar will be encoded instead of the object. If no 453and the resulting scalar will be encoded instead of the object. If no
486 510
487As this callback gets called less often then the C<filter_json_object> 511As this callback gets called less often then the C<filter_json_object>
488one, decoding speed will not usually suffer as much. Therefore, single-key 512one, decoding speed will not usually suffer as much. Therefore, single-key
489objects make excellent targets to serialise Perl objects into, especially 513objects make excellent targets to serialise Perl objects into, especially
490as single-key JSON objects are as close to the type-tagged value concept 514as single-key JSON objects are as close to the type-tagged value concept
491as JSON gets (its basically an ID/VALUE tuple). Of course, JSON does not 515as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not
492support this in any way, so you need to make sure your data never looks 516support this in any way, so you need to make sure your data never looks
493like a serialised Perl hash. 517like a serialised Perl hash.
494 518
495Typical names for the single object key are C<__class_whatever__>, or 519Typical names for the single object key are C<__class_whatever__>, or
496C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even 520C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
520 544
521 { __widget__ => $self->{id} } 545 { __widget__ => $self->{id} }
522 } 546 }
523 547
524=item $json = $json->shrink ([$enable]) 548=item $json = $json->shrink ([$enable])
549
550=item $enabled = $json->get_shrink
525 551
526Perl usually over-allocates memory a bit when allocating space for 552Perl usually over-allocates memory a bit when allocating space for
527strings. This flag optionally resizes strings generated by either 553strings. This flag optionally resizes strings generated by either
528C<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
529memory 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
547strings that look like integers or floats into integers or floats 573strings that look like integers or floats into integers or floats
548internally (there is no difference on the Perl level), saving space. 574internally (there is no difference on the Perl level), saving space.
549 575
550=item $json = $json->max_depth ([$maximum_nesting_depth]) 576=item $json = $json->max_depth ([$maximum_nesting_depth])
551 577
578=item $max_depth = $json->get_max_depth
579
552Sets the maximum nesting level (default C<512>) accepted while encoding 580Sets the maximum nesting level (default C<512>) accepted while encoding
553or 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
554higher nesting level then this limit, then the encoder and decoder will 582higher nesting level then this limit, then the encoder and decoder will
555stop and croak at that point. 583stop and croak at that point.
556 584
567used, which is rarely useful. 595used, which is rarely useful.
568 596
569See SECURITY CONSIDERATIONS, below, for more info on why this is useful. 597See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
570 598
571=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
572 602
573Set 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
574being 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>
575is 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
576attempt 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
623vice 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
624circumstances automatically, preserving round-tripping characteristics 654circumstances automatically, preserving round-tripping characteristics
625(what you put in comes out as something equivalent). 655(what you put in comes out as something equivalent).
626 656
627For the more enlightened: note that in the following descriptions, 657For the more enlightened: note that in the following descriptions,
628lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> 658lowercase I<perl> refers to the Perl interpreter, while uppercase I<Perl>
629refers to the abstract Perl language itself. 659refers to the abstract Perl language itself.
630 660
631 661
632=head2 JSON -> PERL 662=head2 JSON -> PERL
633 663
634=over 4 664=over 4
635 665
636=item object 666=item object
637 667
638A 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
639keys is preserved (JSON does not preserver object key ordering itself). 669keys is preserved (JSON does not preserve object key ordering itself).
640 670
641=item array 671=item array
642 672
643A JSON array becomes a reference to an array in Perl. 673A JSON array becomes a reference to an array in Perl.
644 674
670 700
671=item true, false 701=item true, false
672 702
673These 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>,
674respectively. They are overloaded to act almost exactly like the numbers 704respectively. They are overloaded to act almost exactly like the numbers
675C<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
676the C<JSON::XS::is_bool> function. 706the C<JSON::XS::is_bool> function.
677 707
678=item null 708=item null
679 709
680A JSON null atom becomes C<undef> in Perl. 710A JSON null atom becomes C<undef> in Perl.
743 to_json [$value] # yields ["5"] 773 to_json [$value] # yields ["5"]
744 774
745 # undef becomes null 775 # undef becomes null
746 to_json [undef] # yields [null] 776 to_json [undef] # yields [null]
747 777
748You can force the type to be a string by stringifying it: 778You can force the type to be a JSON string by stringifying it:
749 779
750 my $x = 3.1; # some variable containing a number 780 my $x = 3.1; # some variable containing a number
751 "$x"; # stringified 781 "$x"; # stringified
752 $x .= ""; # another, more awkward way to stringify 782 $x .= ""; # another, more awkward way to stringify
753 print $x; # perl does it for you, too, quite often 783 print $x; # perl does it for you, too, quite often
754 784
755You can force the type to be a number by numifying it: 785You can force the type to be a JSON number by numifying it:
756 786
757 my $x = "3"; # some variable containing a string 787 my $x = "3"; # some variable containing a string
758 $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
759 $x *= 1; # same thing, the choise is yours. 789 $x *= 1; # same thing, the choice is yours.
760 790
761You 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
762less obscure, ways. Tell me if you need this capability. 792if you need this capability.
763 793
764=back 794=back
765 795
766 796
767=head1 COMPARISON 797=head1 COMPARISON
776 806
777=item JSON 1.07 807=item JSON 1.07
778 808
779Slow (but very portable, as it is written in pure Perl). 809Slow (but very portable, as it is written in pure Perl).
780 810
781Undocumented/buggy Unicode handling (how JSON handles unicode values is 811Undocumented/buggy Unicode handling (how JSON handles Unicode values is
782undocumented. One can get far by feeding it unicode strings and doing 812undocumented. One can get far by feeding it Unicode strings and doing
783en-/decoding oneself, but unicode escapes are not working properly). 813en-/decoding oneself, but Unicode escapes are not working properly).
784 814
785No roundtripping (strings get clobbered if they look like numbers, e.g. 815No round-tripping (strings get clobbered if they look like numbers, e.g.
786the 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
787decode into the number 2. 817decode into the number 2.
788 818
789=item JSON::PC 0.01 819=item JSON::PC 0.01
790 820
791Very fast. 821Very fast.
792 822
793Undocumented/buggy Unicode handling. 823Undocumented/buggy Unicode handling.
794 824
795No roundtripping. 825No round-tripping.
796 826
797Has 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
798values will make it croak). 828values will make it croak).
799 829
800Does 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}>
810Very inflexible (no human-readable format supported, format pretty much 840Very inflexible (no human-readable format supported, format pretty much
811undocumented. 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
812single-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
813generate ASCII-only JSON texts). 843generate ASCII-only JSON texts).
814 844
815Completely broken (and confusingly documented) Unicode handling (unicode 845Completely broken (and confusingly documented) Unicode handling (Unicode
816escapes are not working properly, you need to set ImplicitUnicode to 846escapes are not working properly, you need to set ImplicitUnicode to
817I<different> values on en- and decoding to get symmetric behaviour). 847I<different> values on en- and decoding to get symmetric behaviour).
818 848
819No roundtripping (simple cases work, but this depends on wether the scalar 849No round-tripping (simple cases work, but this depends on whether the scalar
820value was used in a numeric context or not). 850value was used in a numeric context or not).
821 851
822Dumping hashes may skip hash values depending on iterator state. 852Dumping hashes may skip hash values depending on iterator state.
823 853
824Unmaintained (maintainer unresponsive for many months, bugs are not 854Unmaintained (maintainer unresponsive for many months, bugs are not
825getting fixed). 855getting fixed).
826 856
827Does 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
828return "something" instead of raising an exception. This is a security 858return "something" instead of raising an exception. This is a security
829issue: imagine two banks transfering money between each other using 859issue: imagine two banks transferring money between each other using
830JSON. 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,
831while 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
832good protocol will at least recover, that is extra unnecessary work and 862good protocol will at least recover, that is extra unnecessary work and
833the transaction will still not succeed). 863the transaction will still not succeed).
834 864
835=item JSON::DWIW 0.04 865=item JSON::DWIW 0.04
836 866
837Very fast. Very natural. Very nice. 867Very fast. Very natural. Very nice.
838 868
839Undocumented unicode handling (but the best of the pack. Unicode escapes 869Undocumented Unicode handling (but the best of the pack. Unicode escapes
840still don't get parsed properly). 870still don't get parsed properly).
841 871
842Very inflexible. 872Very inflexible.
843 873
844No roundtripping. 874No round-tripping.
845 875
846Does 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
847result in nothing being output) 877result in nothing being output)
848 878
849Does not check input for validity. 879Does not check input for validity.
864 my $yaml = $to_yaml->encode ($ref) . "\n"; 894 my $yaml = $to_yaml->encode ($ref) . "\n";
865 895
866This will usually generate JSON texts that also parse as valid 896This will usually generate JSON texts that also parse as valid
867YAML. Please note that YAML has hardcoded limits on (simple) object key 897YAML. Please note that YAML has hardcoded limits on (simple) object key
868lengths 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
869keys are noticably shorter than the 1024 characters YAML allows. 899keys are noticeably shorter than the 1024 characters YAML allows.
870 900
871There 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
872you 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,
873or 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
874that you will run into severe interoperability problems. 904that you will run into severe interoperability problems.
890It shows the number of encodes/decodes per second (JSON::XS uses 920It shows the number of encodes/decodes per second (JSON::XS uses
891the functional interface, while JSON::XS/2 uses the OO interface 921the functional interface, while JSON::XS/2 uses the OO interface
892with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables 922with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
893shrink). Higher is better: 923shrink). Higher is better:
894 924
895 Storable | 15779.925 | 14169.946 |
896 -----------+------------+------------+
897 module | encode | decode | 925 module | encode | decode |
898 -----------|------------|------------| 926 -----------|------------|------------|
899 JSON | 4990.842 | 4088.813 | 927 JSON 1.x | 4990.842 | 4088.813 |
900 JSON::DWIW | 51653.990 | 71575.154 | 928 JSON::DWIW | 51653.990 | 71575.154 |
901 JSON::PC | 65948.176 | 74631.744 | 929 JSON::PC | 65948.176 | 74631.744 |
902 JSON::PP | 8931.652 | 3817.168 | 930 JSON::PP | 8931.652 | 3817.168 |
903 JSON::Syck | 24877.248 | 27776.848 | 931 JSON::Syck | 24877.248 | 27776.848 |
904 JSON::XS | 388361.481 | 227951.304 | 932 JSON::XS | 388361.481 | 227951.304 |
906 JSON::XS/3 | 338250.323 | 218453.333 | 934 JSON::XS/3 | 338250.323 | 218453.333 |
907 Storable | 16500.016 | 135300.129 | 935 Storable | 16500.016 | 135300.129 |
908 -----------+------------+------------+ 936 -----------+------------+------------+
909 937
910That 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,
911about three times faster on decoding, and over fourty times faster 939about three times faster on decoding, and over forty times faster
912than JSON, even with pretty-printing and key sorting. It also compares 940than JSON, even with pretty-printing and key sorting. It also compares
913favourably to Storable for small amounts of data. 941favourably to Storable for small amounts of data.
914 942
915Using a longer test string (roughly 18KB, generated from Yahoo! Locals 943Using a longer test string (roughly 18KB, generated from Yahoo! Locals
916search API (http://nanoref.com/yahooapis/mgPdGg): 944search API (http://nanoref.com/yahooapis/mgPdGg):
917 945
918 module | encode | decode | 946 module | encode | decode |
919 -----------|------------|------------| 947 -----------|------------|------------|
920 JSON | 55.260 | 34.971 | 948 JSON 1.x | 55.260 | 34.971 |
921 JSON::DWIW | 825.228 | 1082.513 | 949 JSON::DWIW | 825.228 | 1082.513 |
922 JSON::PC | 3571.444 | 2394.829 | 950 JSON::PC | 3571.444 | 2394.829 |
923 JSON::PP | 210.987 | 32.574 | 951 JSON::PP | 210.987 | 32.574 |
924 JSON::Syck | 552.551 | 787.544 | 952 JSON::Syck | 552.551 | 787.544 |
925 JSON::XS | 5780.463 | 4854.519 | 953 JSON::XS | 5780.463 | 4854.519 |
929 -----------+------------+------------+ 957 -----------+------------+------------+
930 958
931Again, JSON::XS leads by far (except for Storable which non-surprisingly 959Again, JSON::XS leads by far (except for Storable which non-surprisingly
932decodes faster). 960decodes faster).
933 961
934On large strings containing lots of high unicode characters, some modules 962On large strings containing lots of high Unicode characters, some modules
935(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
936will be broken due to missing (or wrong) unicode handling. Others refuse 964will be broken due to missing (or wrong) Unicode handling. Others refuse
937to 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
938comparison table for that case. 966comparison table for that case.
939 967
940 968
941=head1 SECURITY CONSIDERATIONS 969=head1 SECURITY CONSIDERATIONS
947any buffer overflows. Obviously, this module should ensure that and I am 975any buffer overflows. Obviously, this module should ensure that and I am
948trying hard on making that true, but you never know. 976trying hard on making that true, but you never know.
949 977
950Second, you need to avoid resource-starving attacks. That means you should 978Second, you need to avoid resource-starving attacks. That means you should
951limit 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
952resources 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
953can 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
954usually 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
955it 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
956text, 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
957might want to check the size before you accept the string. 985might want to check the size before you accept the string.
968And 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
969of. 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,
970though... 998though...
971 999
972If you are using JSON::XS to return packets to consumption 1000If you are using JSON::XS to return packets to consumption
973by javascript scripts in a browser you should have a look at 1001by JavaScript scripts in a browser you should have a look at
974L<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
975you are vulnerable to some common attack vectors (which really are browser 1003you are vulnerable to some common attack vectors (which really are browser
976design 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
977browser developers care only for features, not about doing security 1005browser developers care only for features, not about doing security
978right). 1006right).
979 1007
980 1008
981=head1 THREADS 1009=head1 THREADS
982 1010
983This module is I<not> guarenteed to be thread safe and there are no 1011This module is I<not> guaranteed to be thread safe and there are no
984plans to change this until Perl gets thread support (as opposed to the 1012plans to change this until Perl gets thread support (as opposed to the
985horribly slow so-called "threads" which are simply slow and bloated 1013horribly slow so-called "threads" which are simply slow and bloated
986process simulations - use fork, its I<much> faster, cheaper, better). 1014process simulations - use fork, its I<much> faster, cheaper, better).
987 1015
988(It might actually work, but you ahve ben warned). 1016(It might actually work, but you have been warned).
989 1017
990 1018
991=head1 BUGS 1019=head1 BUGS
992 1020
993While 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

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