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Comparing JSON-XS/XS.pm (file contents):
Revision 1.30 by root, Mon Apr 9 06:37:40 2007 UTC vs.
Revision 1.46 by root, Mon Jun 25 04:21:14 2007 UTC

… …
85 85
86package JSON::XS; 86package JSON::XS;
87 87
88use strict; 88use strict;
89 89
90BEGIN {
91 our $VERSION = '1.11'; 90our $VERSION = '1.4';
92 our @ISA = qw(Exporter); 91our @ISA = qw(Exporter);
93 92
94 our @EXPORT = qw(to_json from_json objToJson jsonToObj); 93our @EXPORT = qw(to_json from_json objToJson jsonToObj);
95 require Exporter;
96 94
97 require XSLoader; 95use Exporter;
98 XSLoader::load JSON::XS::, $VERSION; 96use XSLoader;
99}
100 97
101=head1 FUNCTIONAL INTERFACE 98=head1 FUNCTIONAL INTERFACE
102 99
103The following convinience methods are provided by this module. They are 100The following convinience methods are provided by this module. They are
104exported by default: 101exported by default:
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126This function call is functionally identical to: 123This function call is functionally identical to:
127 124
128 $perl_scalar = JSON::XS->new->utf8->decode ($json_text) 125 $perl_scalar = JSON::XS->new->utf8->decode ($json_text)
129 126
130except being faster. 127except being faster.
128
129=item $is_boolean = JSON::XS::is_bool $scalar
130
131Returns true if the passed scalar represents either JSON::XS::true or
132JSON::XS::false, two constants that act like C<1> and C<0>, respectively
133and are used to represent JSON C<true> and C<false> values in Perl.
134
135See MAPPING, below, for more information on how JSON values are mapped to
136Perl.
131 137
132=back 138=back
133 139
134 140
135=head1 OBJECT-ORIENTED INTERFACE 141=head1 OBJECT-ORIENTED INTERFACE
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154 160
155If C<$enable> is true (or missing), then the C<encode> method will not 161If C<$enable> is true (or missing), then the C<encode> method will not
156generate characters outside the code range C<0..127> (which is ASCII). Any 162generate characters outside the code range C<0..127> (which is ASCII). Any
157unicode characters outside that range will be escaped using either a 163unicode characters outside that range will be escaped using either a
158single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, 164single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
159as per RFC4627. 165as per RFC4627. The resulting encoded JSON text can be treated as a native
166unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
167or any other superset of ASCII.
160 168
161If C<$enable> is false, then the C<encode> method will not escape Unicode 169If C<$enable> is false, then the C<encode> method will not escape Unicode
162characters unless required by the JSON syntax. This results in a faster 170characters unless required by the JSON syntax or other flags. This results
163and more compact format. 171in a faster and more compact format.
172
173The main use for this flag is to produce JSON texts that can be
174transmitted over a 7-bit channel, as the encoded JSON texts will not
175contain any 8 bit characters.
164 176
165 JSON::XS->new->ascii (1)->encode ([chr 0x10401]) 177 JSON::XS->new->ascii (1)->encode ([chr 0x10401])
166 => ["\ud801\udc01"] 178 => ["\ud801\udc01"]
179
180=item $json = $json->latin1 ([$enable])
181
182If C<$enable> is true (or missing), then the C<encode> method will encode
183the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
184outside the code range C<0..255>. The resulting string can be treated as a
185latin1-encoded JSON text or a native unicode string. The C<decode> method
186will not be affected in any way by this flag, as C<decode> by default
187expects unicode, which is a strict superset of latin1.
188
189If C<$enable> is false, then the C<encode> method will not escape Unicode
190characters unless required by the JSON syntax or other flags.
191
192The main use for this flag is efficiently encoding binary data as JSON
193text, as most octets will not be escaped, resulting in a smaller encoded
194size. The disadvantage is that the resulting JSON text is encoded
195in latin1 (and must correctly be treated as such when storing and
196transfering), a rare encoding for JSON. It is therefore most useful when
197you want to store data structures known to contain binary data efficiently
198in files or databases, not when talking to other JSON encoders/decoders.
199
200 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
201 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
167 202
168=item $json = $json->utf8 ([$enable]) 203=item $json = $json->utf8 ([$enable])
169 204
170If C<$enable> is true (or missing), then the C<encode> method will encode 205If C<$enable> is true (or missing), then the C<encode> method will encode
171the JSON result into UTF-8, as required by many protocols, while the 206the JSON result into UTF-8, as required by many protocols, while the
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280Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>, 315Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
281resulting in an invalid JSON text: 316resulting in an invalid JSON text:
282 317
283 JSON::XS->new->allow_nonref->encode ("Hello, World!") 318 JSON::XS->new->allow_nonref->encode ("Hello, World!")
284 => "Hello, World!" 319 => "Hello, World!"
320
321=item $json = $json->allow_blessed ([$enable])
322
323If C<$enable> is true (or missing), then the C<encode> method will not
324barf when it encounters a blessed reference. Instead, the value of the
325B<convert_blessed> option will decide wether C<null> (C<convert_blessed>
326disabled or no C<to_json> method found) or a representation of the
327object (C<convert_blessed> enabled and C<to_json> method found) is being
328encoded. Has no effect on C<decode>.
329
330If C<$enable> is false (the default), then C<encode> will throw an
331exception when it encounters a blessed object.
332
333=item $json = $json->convert_blessed ([$enable])
334
335If C<$enable> is true (or missing), then C<encode>, upon encountering a
336blessed object, will check for the availability of the C<TO_JSON> method
337on the object's class. If found, it will be called in scalar context
338and the resulting scalar will be encoded instead of the object. If no
339C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
340to do.
341
342The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
343returns other blessed objects, those will be handled in the same
344way. C<TO_JSON> must take care of not causing an endless recursion cycle
345(== crash) in this case. The name of C<TO_JSON> was chosen because other
346methods called by the Perl core (== not by the user of the object) are
347usually in upper case letters and to avoid collisions with the C<to_json>
348function.
349
350This setting does not yet influence C<decode> in any way, but in the
351future, global hooks might get installed that influence C<decode> and are
352enabled by this setting.
353
354If C<$enable> is false, then the C<allow_blessed> setting will decide what
355to do when a blessed object is found.
285 356
286=item $json = $json->shrink ([$enable]) 357=item $json = $json->shrink ([$enable])
287 358
288Perl usually over-allocates memory a bit when allocating space for 359Perl usually over-allocates memory a bit when allocating space for
289strings. This flag optionally resizes strings generated by either 360strings. This flag optionally resizes strings generated by either
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345 416
346JSON numbers and strings become simple Perl scalars. JSON arrays become 417JSON numbers and strings become simple Perl scalars. JSON arrays become
347Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes 418Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
348C<1>, C<false> becomes C<0> and C<null> becomes C<undef>. 419C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
349 420
421=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
422
423This works like the C<decode> method, but instead of raising an exception
424when there is trailing garbage after the first JSON object, it will
425silently stop parsing there and return the number of characters consumed
426so far.
427
428This is useful if your JSON texts are not delimited by an outer protocol
429(which is not the brightest thing to do in the first place) and you need
430to know where the JSON text ends.
431
432 JSON::XS->new->decode_prefix ("[1] the tail")
433 => ([], 3)
434
350=back 435=back
351 436
352 437
353=head1 MAPPING 438=head1 MAPPING
354 439
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358(what you put in comes out as something equivalent). 443(what you put in comes out as something equivalent).
359 444
360For the more enlightened: note that in the following descriptions, 445For the more enlightened: note that in the following descriptions,
361lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> 446lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
362refers to the abstract Perl language itself. 447refers to the abstract Perl language itself.
448
363 449
364=head2 JSON -> PERL 450=head2 JSON -> PERL
365 451
366=over 4 452=over 4
367 453
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388conversion details, but an integer may take slightly less memory and might 474conversion details, but an integer may take slightly less memory and might
389represent more values exactly than (floating point) numbers. 475represent more values exactly than (floating point) numbers.
390 476
391=item true, false 477=item true, false
392 478
393These JSON atoms become C<0>, C<1>, respectively. Information is lost in 479These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
394this process. Future versions might represent those values differently, 480respectively. They are overloaded to act almost exactly like the numbers
395but they will be guarenteed to act like these integers would normally in 481C<1> and C<0>. You can check wether a scalar is a JSON boolean by using
396Perl. 482the C<JSON::XS::is_bool> function.
397 483
398=item null 484=item null
399 485
400A JSON null atom becomes C<undef> in Perl. 486A JSON null atom becomes C<undef> in Perl.
401 487
402=back 488=back
489
403 490
404=head2 PERL -> JSON 491=head2 PERL -> JSON
405 492
406The mapping from Perl to JSON is slightly more difficult, as Perl is a 493The mapping from Perl to JSON is slightly more difficult, as Perl is a
407truly typeless language, so we can only guess which JSON type is meant by 494truly typeless language, so we can only guess which JSON type is meant by
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432C<1>, which get turned into C<false> and C<true> atoms in JSON. You can 519C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
433also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. 520also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
434 521
435 to_json [\0,JSON::XS::true] # yields [false,true] 522 to_json [\0,JSON::XS::true] # yields [false,true]
436 523
524=item JSON::XS::true, JSON::XS::false
525
526These special values become JSON true and JSON false values,
527respectively. You cna alos use C<\1> and C<\0> directly if you want.
528
437=item blessed objects 529=item blessed objects
438 530
439Blessed objects are not allowed. JSON::XS currently tries to encode their 531Blessed objects are not allowed. JSON::XS currently tries to encode their
440underlying representation (hash- or arrayref), but this behaviour might 532underlying representation (hash- or arrayref), but this behaviour might
441change in future versions. 533change in future versions.
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562 654
563Does not check input for validity. 655Does not check input for validity.
564 656
565=back 657=back
566 658
659
660=head2 JSON and YAML
661
662You often hear that JSON is a subset (or a close subset) of YAML. This is,
663however, a mass hysteria and very far from the truth. In general, there is
664no way to configure JSON::XS to output a data structure as valid YAML.
665
666If you really must use JSON::XS to generate YAML, you should use this
667algorithm (subject to change in future versions):
668
669 my $to_yaml = JSON::XS->new->utf8->space_after (1);
670 my $yaml = $to_yaml->encode ($ref) . "\n";
671
672This will usually generate JSON texts that also parse as valid
673YAML. Please note that YAML has hardcoded limits on (simple) object key
674lengths that JSON doesn't have, so you should make sure that your hash
675keys are noticably shorter than the 1024 characters YAML allows.
676
677There might be other incompatibilities that I am not aware of. In general
678you should not try to generate YAML with a JSON generator or vice versa,
679or try to parse JSON with a YAML parser or vice versa: chances are high
680that you will run into severe interoperability problems.
681
682
567=head2 SPEED 683=head2 SPEED
568 684
569It seems that JSON::XS is surprisingly fast, as shown in the following 685It seems that JSON::XS is surprisingly fast, as shown in the following
570tables. They have been generated with the help of the C<eg/bench> program 686tables. They have been generated with the help of the C<eg/bench> program
571in the JSON::XS distribution, to make it easy to compare on your own 687in the JSON::XS distribution, to make it easy to compare on your own
572system. 688system.
573 689
574First comes a comparison between various modules using a very short JSON 690First comes a comparison between various modules using a very short
575string: 691single-line JSON string:
576 692
577 {"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null} 693 {"method": "handleMessage", "params": ["user1", "we were just talking"], \
694 "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
578 695
579It shows the number of encodes/decodes per second (JSON::XS uses the 696It shows the number of encodes/decodes per second (JSON::XS uses
580functional interface, while JSON::XS/2 uses the OO interface with 697the functional interface, while JSON::XS/2 uses the OO interface
581pretty-printing and hashkey sorting enabled). Higher is better: 698with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
699shrink). Higher is better:
582 700
583 module | encode | decode | 701 module | encode | decode |
584 -----------|------------|------------| 702 -----------|------------|------------|
585 JSON | 11488.516 | 7823.035 | 703 JSON | 7645.468 | 4208.613 |
586 JSON::DWIW | 94708.054 | 129094.260 | 704 JSON::DWIW | 40721.398 | 77101.176 |
587 JSON::PC | 63884.157 | 128528.212 | 705 JSON::PC | 65948.176 | 78251.940 |
588 JSON::Syck | 34898.677 | 42096.911 | 706 JSON::Syck | 22844.793 | 26479.192 |
589 JSON::XS | 654027.064 | 396423.669 | 707 JSON::XS | 388361.481 | 199728.762 |
590 JSON::XS/2 | 371564.190 | 371725.613 | 708 JSON::XS/2 | 218453.333 | 192399.266 |
709 JSON::XS/3 | 338250.323 | 192399.266 |
710 Storable | 15779.925 | 14169.946 |
591 -----------+------------+------------+ 711 -----------+------------+------------+
592 712
593That is, JSON::XS is more than six times faster than JSON::DWIW on 713That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
594encoding, more than three times faster on decoding, and about thirty times 714about three times faster on decoding, and over fourty times faster
595faster than JSON, even with pretty-printing and key sorting. 715than JSON, even with pretty-printing and key sorting. It also compares
716favourably to Storable for small amounts of data.
596 717
597Using a longer test string (roughly 18KB, generated from Yahoo! Locals 718Using a longer test string (roughly 18KB, generated from Yahoo! Locals
598search API (http://nanoref.com/yahooapis/mgPdGg): 719search API (http://nanoref.com/yahooapis/mgPdGg):
599 720
600 module | encode | decode | 721 module | encode | decode |
601 -----------|------------|------------| 722 -----------|------------|------------|
602 JSON | 273.023 | 44.674 | 723 JSON | 254.685 | 37.665 |
603 JSON::DWIW | 1089.383 | 1145.704 | 724 JSON::DWIW | 843.343 | 1049.731 |
604 JSON::PC | 3097.419 | 2393.921 | 725 JSON::PC | 3602.116 | 2307.352 |
605 JSON::Syck | 514.060 | 843.053 | 726 JSON::Syck | 505.107 | 787.899 |
606 JSON::XS | 6479.668 | 3636.364 | 727 JSON::XS | 5747.196 | 3690.220 |
607 JSON::XS/2 | 3774.221 | 3599.124 | 728 JSON::XS/2 | 3968.121 | 3676.634 |
729 JSON::XS/3 | 6105.246 | 3662.508 |
730 Storable | 4417.337 | 5285.161 |
608 -----------+------------+------------+ 731 -----------+------------+------------+
609 732
610Again, JSON::XS leads by far. 733Again, JSON::XS leads by far (except for Storable which non-surprisingly
734decodes faster).
611 735
612On large strings containing lots of high unicode characters, some modules 736On large strings containing lots of high unicode characters, some modules
613(such as JSON::PC) seem to decode faster than JSON::XS, but the result 737(such as JSON::PC) seem to decode faster than JSON::XS, but the result
614will be broken due to missing (or wrong) unicode handling. Others refuse 738will be broken due to missing (or wrong) unicode handling. Others refuse
615to decode or encode properly, so it was impossible to prepare a fair 739to decode or encode properly, so it was impossible to prepare a fair
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643 767
644And last but least, something else could bomb you that I forgot to think 768And last but least, something else could bomb you that I forgot to think
645of. In that case, you get to keep the pieces. I am always open for hints, 769of. In that case, you get to keep the pieces. I am always open for hints,
646though... 770though...
647 771
772If you are using JSON::XS to return packets to consumption
773by javascript scripts in a browser you should have a look at
774L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether
775you are vulnerable to some common attack vectors (which really are browser
776design bugs, but it is still you who will have to deal with it, as major
777browser developers care only for features, not about doing security
778right).
779
648 780
649=head1 BUGS 781=head1 BUGS
650 782
651While the goal of this module is to be correct, that unfortunately does 783While the goal of this module is to be correct, that unfortunately does
652not mean its bug-free, only that I think its design is bug-free. It is 784not mean its bug-free, only that I think its design is bug-free. It is
653still relatively early in its development. If you keep reporting bugs they 785still relatively early in its development. If you keep reporting bugs they
654will be fixed swiftly, though. 786will be fixed swiftly, though.
655 787
656=cut 788=cut
657 789
790our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
791our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
792
658sub true() { \1 } 793sub true() { $true }
659sub false() { \0 } 794sub false() { $false }
795
796sub is_bool($) {
797 UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
798# or UNIVERSAL::isa $_[0], "JSON::Literal"
799}
800
801XSLoader::load "JSON::XS", $VERSION;
802
803package JSON::XS::Boolean;
804
805use overload
806 "0+" => sub { ${$_[0]} },
807 "++" => sub { $_[0] = ${$_[0]} + 1 },
808 "--" => sub { $_[0] = ${$_[0]} - 1 },
809 fallback => 1;
660 810
6611; 8111;
662 812
663=head1 AUTHOR 813=head1 AUTHOR
664 814

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