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Comparing JSON-XS/XS.pm (file contents):
Revision 1.36 by root, Wed May 23 22:07:43 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 = '1.22'; 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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402 444
403For the more enlightened: note that in the following descriptions, 445For the more enlightened: note that in the following descriptions,
404lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> 446lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
405refers to the abstract Perl language itself. 447refers to the abstract Perl language itself.
406 448
449
407=head2 JSON -> PERL 450=head2 JSON -> PERL
408 451
409=over 4 452=over 4
410 453
411=item object 454=item object
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431conversion details, but an integer may take slightly less memory and might 474conversion details, but an integer may take slightly less memory and might
432represent more values exactly than (floating point) numbers. 475represent more values exactly than (floating point) numbers.
433 476
434=item true, false 477=item true, false
435 478
436These 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>,
437this process. Future versions might represent those values differently, 480respectively. They are overloaded to act almost exactly like the numbers
438but 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
439Perl. 482the C<JSON::XS::is_bool> function.
440 483
441=item null 484=item null
442 485
443A JSON null atom becomes C<undef> in Perl. 486A JSON null atom becomes C<undef> in Perl.
444 487
445=back 488=back
489
446 490
447=head2 PERL -> JSON 491=head2 PERL -> JSON
448 492
449The 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
450truly 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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475C<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
476also 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.
477 521
478 to_json [\0,JSON::XS::true] # yields [false,true] 522 to_json [\0,JSON::XS::true] # yields [false,true]
479 523
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
480=item blessed objects 529=item blessed objects
481 530
482Blessed objects are not allowed. JSON::XS currently tries to encode their 531Blessed objects are not allowed. JSON::XS currently tries to encode their
483underlying representation (hash- or arrayref), but this behaviour might 532underlying representation (hash- or arrayref), but this behaviour might
484change in future versions. 533change in future versions.
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605 654
606Does not check input for validity. 655Does not check input for validity.
607 656
608=back 657=back
609 658
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
610=head2 SPEED 683=head2 SPEED
611 684
612It 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
613tables. 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
614in 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
615system. 688system.
616 689
617First comes a comparison between various modules using a very short JSON 690First comes a comparison between various modules using a very short
618string: 691single-line JSON string:
619 692
620 {"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]}
621 695
622It shows the number of encodes/decodes per second (JSON::XS uses the 696It shows the number of encodes/decodes per second (JSON::XS uses
623functional interface, while JSON::XS/2 uses the OO interface with 697the functional interface, while JSON::XS/2 uses the OO interface
624pretty-printing and hashkey sorting enabled). Higher is better: 698with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
699shrink). Higher is better:
625 700
626 module | encode | decode | 701 module | encode | decode |
627 -----------|------------|------------| 702 -----------|------------|------------|
628 JSON | 11488.516 | 7823.035 | 703 JSON | 7645.468 | 4208.613 |
629 JSON::DWIW | 94708.054 | 129094.260 | 704 JSON::DWIW | 40721.398 | 77101.176 |
630 JSON::PC | 63884.157 | 128528.212 | 705 JSON::PC | 65948.176 | 78251.940 |
631 JSON::Syck | 34898.677 | 42096.911 | 706 JSON::Syck | 22844.793 | 26479.192 |
632 JSON::XS | 654027.064 | 396423.669 | 707 JSON::XS | 388361.481 | 199728.762 |
633 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 |
634 -----------+------------+------------+ 711 -----------+------------+------------+
635 712
636That 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,
637encoding, more than three times faster on decoding, and about thirty times 714about three times faster on decoding, and over fourty times faster
638faster 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.
639 717
640Using a longer test string (roughly 18KB, generated from Yahoo! Locals 718Using a longer test string (roughly 18KB, generated from Yahoo! Locals
641search API (http://nanoref.com/yahooapis/mgPdGg): 719search API (http://nanoref.com/yahooapis/mgPdGg):
642 720
643 module | encode | decode | 721 module | encode | decode |
644 -----------|------------|------------| 722 -----------|------------|------------|
645 JSON | 273.023 | 44.674 | 723 JSON | 254.685 | 37.665 |
646 JSON::DWIW | 1089.383 | 1145.704 | 724 JSON::DWIW | 843.343 | 1049.731 |
647 JSON::PC | 3097.419 | 2393.921 | 725 JSON::PC | 3602.116 | 2307.352 |
648 JSON::Syck | 514.060 | 843.053 | 726 JSON::Syck | 505.107 | 787.899 |
649 JSON::XS | 6479.668 | 3636.364 | 727 JSON::XS | 5747.196 | 3690.220 |
650 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 |
651 -----------+------------+------------+ 731 -----------+------------+------------+
652 732
653Again, JSON::XS leads by far. 733Again, JSON::XS leads by far (except for Storable which non-surprisingly
734decodes faster).
654 735
655On large strings containing lots of high unicode characters, some modules 736On large strings containing lots of high unicode characters, some modules
656(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
657will be broken due to missing (or wrong) unicode handling. Others refuse 738will be broken due to missing (or wrong) unicode handling. Others refuse
658to 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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686 767
687And 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
688of. 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,
689though... 770though...
690 771
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
691 780
692=head1 BUGS 781=head1 BUGS
693 782
694While 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
695not 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
696still relatively early in its development. If you keep reporting bugs they 785still relatively early in its development. If you keep reporting bugs they
697will be fixed swiftly, though. 786will be fixed swiftly, though.
698 787
699=cut 788=cut
700 789
790our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
791our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
792
701sub true() { \1 } 793sub true() { $true }
702sub 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;
703 810
7041; 8111;
705 812
706=head1 AUTHOR 813=head1 AUTHOR
707 814

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