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Comparing JSON-XS/XS.pm (file contents):
Revision 1.33 by root, Wed May 9 16:10:37 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 = '1.12'; 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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309Example, 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>,
310resulting in an invalid JSON text: 316resulting in an invalid JSON text:
311 317
312 JSON::XS->new->allow_nonref->encode ("Hello, World!") 318 JSON::XS->new->allow_nonref->encode ("Hello, World!")
313 => "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.
314 356
315=item $json = $json->shrink ([$enable]) 357=item $json = $json->shrink ([$enable])
316 358
317Perl usually over-allocates memory a bit when allocating space for 359Perl usually over-allocates memory a bit when allocating space for
318strings. This flag optionally resizes strings generated by either 360strings. This flag optionally resizes strings generated by either
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374 416
375JSON numbers and strings become simple Perl scalars. JSON arrays become 417JSON numbers and strings become simple Perl scalars. JSON arrays become
376Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes 418Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
377C<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>.
378 420
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
379=back 435=back
380 436
381 437
382=head1 MAPPING 438=head1 MAPPING
383 439
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387(what you put in comes out as something equivalent). 443(what you put in comes out as something equivalent).
388 444
389For the more enlightened: note that in the following descriptions, 445For the more enlightened: note that in the following descriptions,
390lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> 446lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
391refers to the abstract Perl language itself. 447refers to the abstract Perl language itself.
448
392 449
393=head2 JSON -> PERL 450=head2 JSON -> PERL
394 451
395=over 4 452=over 4
396 453
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417conversion details, but an integer may take slightly less memory and might 474conversion details, but an integer may take slightly less memory and might
418represent more values exactly than (floating point) numbers. 475represent more values exactly than (floating point) numbers.
419 476
420=item true, false 477=item true, false
421 478
422These 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>,
423this process. Future versions might represent those values differently, 480respectively. They are overloaded to act almost exactly like the numbers
424but 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
425Perl. 482the C<JSON::XS::is_bool> function.
426 483
427=item null 484=item null
428 485
429A JSON null atom becomes C<undef> in Perl. 486A JSON null atom becomes C<undef> in Perl.
430 487
431=back 488=back
489
432 490
433=head2 PERL -> JSON 491=head2 PERL -> JSON
434 492
435The 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
436truly 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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461C<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
462also 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.
463 521
464 to_json [\0,JSON::XS::true] # yields [false,true] 522 to_json [\0,JSON::XS::true] # yields [false,true]
465 523
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
466=item blessed objects 529=item blessed objects
467 530
468Blessed objects are not allowed. JSON::XS currently tries to encode their 531Blessed objects are not allowed. JSON::XS currently tries to encode their
469underlying representation (hash- or arrayref), but this behaviour might 532underlying representation (hash- or arrayref), but this behaviour might
470change in future versions. 533change in future versions.
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591 654
592Does not check input for validity. 655Does not check input for validity.
593 656
594=back 657=back
595 658
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
596=head2 SPEED 683=head2 SPEED
597 684
598It 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
599tables. 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
600in 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
601system. 688system.
602 689
603First comes a comparison between various modules using a very short JSON 690First comes a comparison between various modules using a very short
604string: 691single-line JSON string:
605 692
606 {"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]}
607 695
608It shows the number of encodes/decodes per second (JSON::XS uses the 696It shows the number of encodes/decodes per second (JSON::XS uses
609functional interface, while JSON::XS/2 uses the OO interface with 697the functional interface, while JSON::XS/2 uses the OO interface
610pretty-printing and hashkey sorting enabled). Higher is better: 698with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
699shrink). Higher is better:
611 700
612 module | encode | decode | 701 module | encode | decode |
613 -----------|------------|------------| 702 -----------|------------|------------|
614 JSON | 11488.516 | 7823.035 | 703 JSON | 7645.468 | 4208.613 |
615 JSON::DWIW | 94708.054 | 129094.260 | 704 JSON::DWIW | 40721.398 | 77101.176 |
616 JSON::PC | 63884.157 | 128528.212 | 705 JSON::PC | 65948.176 | 78251.940 |
617 JSON::Syck | 34898.677 | 42096.911 | 706 JSON::Syck | 22844.793 | 26479.192 |
618 JSON::XS | 654027.064 | 396423.669 | 707 JSON::XS | 388361.481 | 199728.762 |
619 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 |
620 -----------+------------+------------+ 711 -----------+------------+------------+
621 712
622That 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,
623encoding, more than three times faster on decoding, and about thirty times 714about three times faster on decoding, and over fourty times faster
624faster 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.
625 717
626Using a longer test string (roughly 18KB, generated from Yahoo! Locals 718Using a longer test string (roughly 18KB, generated from Yahoo! Locals
627search API (http://nanoref.com/yahooapis/mgPdGg): 719search API (http://nanoref.com/yahooapis/mgPdGg):
628 720
629 module | encode | decode | 721 module | encode | decode |
630 -----------|------------|------------| 722 -----------|------------|------------|
631 JSON | 273.023 | 44.674 | 723 JSON | 254.685 | 37.665 |
632 JSON::DWIW | 1089.383 | 1145.704 | 724 JSON::DWIW | 843.343 | 1049.731 |
633 JSON::PC | 3097.419 | 2393.921 | 725 JSON::PC | 3602.116 | 2307.352 |
634 JSON::Syck | 514.060 | 843.053 | 726 JSON::Syck | 505.107 | 787.899 |
635 JSON::XS | 6479.668 | 3636.364 | 727 JSON::XS | 5747.196 | 3690.220 |
636 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 |
637 -----------+------------+------------+ 731 -----------+------------+------------+
638 732
639Again, JSON::XS leads by far. 733Again, JSON::XS leads by far (except for Storable which non-surprisingly
734decodes faster).
640 735
641On large strings containing lots of high unicode characters, some modules 736On large strings containing lots of high unicode characters, some modules
642(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
643will be broken due to missing (or wrong) unicode handling. Others refuse 738will be broken due to missing (or wrong) unicode handling. Others refuse
644to 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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672 767
673And 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
674of. 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,
675though... 770though...
676 771
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
677 780
678=head1 BUGS 781=head1 BUGS
679 782
680While 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
681not 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
682still relatively early in its development. If you keep reporting bugs they 785still relatively early in its development. If you keep reporting bugs they
683will be fixed swiftly, though. 786will be fixed swiftly, though.
684 787
685=cut 788=cut
686 789
790our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
791our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
792
687sub true() { \1 } 793sub true() { $true }
688sub 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;
689 810
6901; 8111;
691 812
692=head1 AUTHOR 813=head1 AUTHOR
693 814

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