ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/JSON-XS/XS.pm
(Generate patch)

Comparing JSON-XS/XS.pm (file contents):
Revision 1.35 by root, Wed May 9 16:41:12 2007 UTC vs.
Revision 1.44 by root, Mon Jun 25 04:08:17 2007 UTC

… …
85 85
86package JSON::XS; 86package JSON::XS;
87 87
88use strict; 88use strict;
89 89
90BEGIN {
91 our $VERSION = '1.21'; 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:
… …
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
… …
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<$enable> is true (or missing), then C<encode>, upon encountering a
336blessed object, will check for the availability of the C<TO_JSON> method
337on the object's class. If found, it will be called in scalar context
338and the resulting scalar will be encoded instead of the object. If no
339C<TO_JSON> method is found, the value of C<allow_blessed> will decide what
340to do.
341
342The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
343returns other blessed objects, those will be handled in the same
344way. C<TO_JSON> must take care of not causing an endless recursion cycle
345(== crash) in this case. The name of C<TO_JSON> was chosen because other
346methods called by the Perl core (== not the user of the object) are
347usually in upper case letters and to avoid collisions with the C<to_json>
348function.
349
350If C<$enable> is false, then the C<allow_blessed> setting will decide what
351to do when a blessed object is found.
314 352
315=item $json = $json->shrink ([$enable]) 353=item $json = $json->shrink ([$enable])
316 354
317Perl usually over-allocates memory a bit when allocating space for 355Perl usually over-allocates memory a bit when allocating space for
318strings. This flag optionally resizes strings generated by either 356strings. This flag optionally resizes strings generated by either
… …
402 440
403For the more enlightened: note that in the following descriptions, 441For the more enlightened: note that in the following descriptions,
404lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> 442lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
405refers to the abstract Perl language itself. 443refers to the abstract Perl language itself.
406 444
445
407=head2 JSON -> PERL 446=head2 JSON -> PERL
408 447
409=over 4 448=over 4
410 449
411=item object 450=item object
… …
431conversion details, but an integer may take slightly less memory and might 470conversion details, but an integer may take slightly less memory and might
432represent more values exactly than (floating point) numbers. 471represent more values exactly than (floating point) numbers.
433 472
434=item true, false 473=item true, false
435 474
436These JSON atoms become C<0>, C<1>, respectively. Information is lost in 475These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
437this process. Future versions might represent those values differently, 476respectively. They are overloaded to act almost exactly like the numbers
438but they will be guarenteed to act like these integers would normally in 477C<1> and C<0>. You can check wether a scalar is a JSON boolean by using
439Perl. 478the C<JSON::XS::is_bool> function.
440 479
441=item null 480=item null
442 481
443A JSON null atom becomes C<undef> in Perl. 482A JSON null atom becomes C<undef> in Perl.
444 483
445=back 484=back
485
446 486
447=head2 PERL -> JSON 487=head2 PERL -> JSON
448 488
449The mapping from Perl to JSON is slightly more difficult, as Perl is a 489The 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 490truly typeless language, so we can only guess which JSON type is meant by
… …
475C<1>, which get turned into C<false> and C<true> atoms in JSON. You can 515C<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. 516also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
477 517
478 to_json [\0,JSON::XS::true] # yields [false,true] 518 to_json [\0,JSON::XS::true] # yields [false,true]
479 519
520=item JSON::XS::true, JSON::XS::false
521
522These special values become JSON true and JSON false values,
523respectively. You cna alos use C<\1> and C<\0> directly if you want.
524
480=item blessed objects 525=item blessed objects
481 526
482Blessed objects are not allowed. JSON::XS currently tries to encode their 527Blessed objects are not allowed. JSON::XS currently tries to encode their
483underlying representation (hash- or arrayref), but this behaviour might 528underlying representation (hash- or arrayref), but this behaviour might
484change in future versions. 529change in future versions.
… …
605 650
606Does not check input for validity. 651Does not check input for validity.
607 652
608=back 653=back
609 654
655
656=head2 JSON and YAML
657
658You often hear that JSON is a subset (or a close subset) of YAML. This is,
659however, a mass hysteria and very far from the truth. In general, there is
660no way to configure JSON::XS to output a data structure as valid YAML.
661
662If you really must use JSON::XS to generate YAML, you should use this
663algorithm (subject to change in future versions):
664
665 my $to_yaml = JSON::XS->new->utf8->space_after (1);
666 my $yaml = $to_yaml->encode ($ref) . "\n";
667
668This will usually generate JSON texts that also parse as valid
669YAML. Please note that YAML has hardcoded limits on (simple) object key
670lengths that JSON doesn't have, so you should make sure that your hash
671keys are noticably shorter than the 1024 characters YAML allows.
672
673There might be other incompatibilities that I am not aware of. In general
674you should not try to generate YAML with a JSON generator or vice versa,
675or try to parse JSON with a YAML parser or vice versa: chances are high
676that you will run into severe interoperability problems.
677
678
610=head2 SPEED 679=head2 SPEED
611 680
612It seems that JSON::XS is surprisingly fast, as shown in the following 681It 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 682tables. 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 683in the JSON::XS distribution, to make it easy to compare on your own
615system. 684system.
616 685
617First comes a comparison between various modules using a very short JSON 686First comes a comparison between various modules using a very short
618string: 687single-line JSON string:
619 688
620 {"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null} 689 {"method": "handleMessage", "params": ["user1", "we were just talking"], \
690 "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
621 691
622It shows the number of encodes/decodes per second (JSON::XS uses the 692It shows the number of encodes/decodes per second (JSON::XS uses
623functional interface, while JSON::XS/2 uses the OO interface with 693the functional interface, while JSON::XS/2 uses the OO interface
624pretty-printing and hashkey sorting enabled). Higher is better: 694with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
695shrink). Higher is better:
625 696
626 module | encode | decode | 697 module | encode | decode |
627 -----------|------------|------------| 698 -----------|------------|------------|
628 JSON | 11488.516 | 7823.035 | 699 JSON | 7645.468 | 4208.613 |
629 JSON::DWIW | 94708.054 | 129094.260 | 700 JSON::DWIW | 40721.398 | 77101.176 |
630 JSON::PC | 63884.157 | 128528.212 | 701 JSON::PC | 65948.176 | 78251.940 |
631 JSON::Syck | 34898.677 | 42096.911 | 702 JSON::Syck | 22844.793 | 26479.192 |
632 JSON::XS | 654027.064 | 396423.669 | 703 JSON::XS | 388361.481 | 199728.762 |
633 JSON::XS/2 | 371564.190 | 371725.613 | 704 JSON::XS/2 | 218453.333 | 192399.266 |
705 JSON::XS/3 | 338250.323 | 192399.266 |
706 Storable | 15779.925 | 14169.946 |
634 -----------+------------+------------+ 707 -----------+------------+------------+
635 708
636That is, JSON::XS is more than six times faster than JSON::DWIW on 709That 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 710about three times faster on decoding, and over fourty times faster
638faster than JSON, even with pretty-printing and key sorting. 711than JSON, even with pretty-printing and key sorting. It also compares
712favourably to Storable for small amounts of data.
639 713
640Using a longer test string (roughly 18KB, generated from Yahoo! Locals 714Using a longer test string (roughly 18KB, generated from Yahoo! Locals
641search API (http://nanoref.com/yahooapis/mgPdGg): 715search API (http://nanoref.com/yahooapis/mgPdGg):
642 716
643 module | encode | decode | 717 module | encode | decode |
644 -----------|------------|------------| 718 -----------|------------|------------|
645 JSON | 273.023 | 44.674 | 719 JSON | 254.685 | 37.665 |
646 JSON::DWIW | 1089.383 | 1145.704 | 720 JSON::DWIW | 843.343 | 1049.731 |
647 JSON::PC | 3097.419 | 2393.921 | 721 JSON::PC | 3602.116 | 2307.352 |
648 JSON::Syck | 514.060 | 843.053 | 722 JSON::Syck | 505.107 | 787.899 |
649 JSON::XS | 6479.668 | 3636.364 | 723 JSON::XS | 5747.196 | 3690.220 |
650 JSON::XS/2 | 3774.221 | 3599.124 | 724 JSON::XS/2 | 3968.121 | 3676.634 |
725 JSON::XS/3 | 6105.246 | 3662.508 |
726 Storable | 4417.337 | 5285.161 |
651 -----------+------------+------------+ 727 -----------+------------+------------+
652 728
653Again, JSON::XS leads by far. 729Again, JSON::XS leads by far (except for Storable which non-surprisingly
730decodes faster).
654 731
655On large strings containing lots of high unicode characters, some modules 732On 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 733(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 734will be broken due to missing (or wrong) unicode handling. Others refuse
658to decode or encode properly, so it was impossible to prepare a fair 735to decode or encode properly, so it was impossible to prepare a fair
… …
686 763
687And last but least, something else could bomb you that I forgot to think 764And 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, 765of. In that case, you get to keep the pieces. I am always open for hints,
689though... 766though...
690 767
768If you are using JSON::XS to return packets to consumption
769by javascript scripts in a browser you should have a look at
770L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether
771you are vulnerable to some common attack vectors (which really are browser
772design bugs, but it is still you who will have to deal with it, as major
773browser developers care only for features, not about doing security
774right).
775
691 776
692=head1 BUGS 777=head1 BUGS
693 778
694While the goal of this module is to be correct, that unfortunately does 779While 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 780not 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 781still relatively early in its development. If you keep reporting bugs they
697will be fixed swiftly, though. 782will be fixed swiftly, though.
698 783
699=cut 784=cut
700 785
786our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
787our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
788
701sub true() { \1 } 789sub true() { $true }
702sub false() { \0 } 790sub false() { $false }
791
792sub is_bool($) {
793 UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
794# or UNIVERSAL::isa $_[0], "JSON::Literal"
795}
796
797XSLoader::load "JSON::XS", $VERSION;
798
799package JSON::XS::Boolean;
800
801use overload
802 "0+" => sub { ${$_[0]} },
803 "++" => sub { $_[0] = ${$_[0]} + 1 },
804 "--" => sub { $_[0] = ${$_[0]} - 1 },
805 fallback => 1;
703 806
7041; 8071;
705 808
706=head1 AUTHOR 809=head1 AUTHOR
707 810

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines