… | |
… | |
9 | # exported functions, they croak on error |
9 | # exported functions, they croak on error |
10 | # and expect/generate UTF-8 |
10 | # and expect/generate UTF-8 |
11 | |
11 | |
12 | $utf8_encoded_json_text = to_json $perl_hash_or_arrayref; |
12 | $utf8_encoded_json_text = to_json $perl_hash_or_arrayref; |
13 | $perl_hash_or_arrayref = from_json $utf8_encoded_json_text; |
13 | $perl_hash_or_arrayref = from_json $utf8_encoded_json_text; |
14 | |
|
|
15 | # objToJson and jsonToObj aliases to to_json and from_json |
|
|
16 | # are exported for compatibility to the JSON module, |
|
|
17 | # but should not be used in new code. |
|
|
18 | |
14 | |
19 | # OO-interface |
15 | # OO-interface |
20 | |
16 | |
21 | $coder = JSON::XS->new->ascii->pretty->allow_nonref; |
17 | $coder = JSON::XS->new->ascii->pretty->allow_nonref; |
22 | $pretty_printed_unencoded = $coder->encode ($perl_scalar); |
18 | $pretty_printed_unencoded = $coder->encode ($perl_scalar); |
… | |
… | |
85 | |
81 | |
86 | package JSON::XS; |
82 | package JSON::XS; |
87 | |
83 | |
88 | use strict; |
84 | use strict; |
89 | |
85 | |
90 | BEGIN { |
|
|
91 | our $VERSION = '1.2'; |
86 | our $VERSION = '1.4'; |
92 | our @ISA = qw(Exporter); |
87 | our @ISA = qw(Exporter); |
93 | |
88 | |
94 | our @EXPORT = qw(to_json from_json objToJson jsonToObj); |
89 | our @EXPORT = qw(to_json from_json); |
95 | require Exporter; |
|
|
96 | |
90 | |
97 | require XSLoader; |
91 | use Exporter; |
98 | XSLoader::load JSON::XS::, $VERSION; |
92 | use XSLoader; |
99 | } |
|
|
100 | |
93 | |
101 | =head1 FUNCTIONAL INTERFACE |
94 | =head1 FUNCTIONAL INTERFACE |
102 | |
95 | |
103 | The following convinience methods are provided by this module. They are |
96 | The following convinience methods are provided by this module. They are |
104 | exported by default: |
97 | exported by default: |
… | |
… | |
126 | This function call is functionally identical to: |
119 | This function call is functionally identical to: |
127 | |
120 | |
128 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
121 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
129 | |
122 | |
130 | except being faster. |
123 | except being faster. |
|
|
124 | |
|
|
125 | =item $is_boolean = JSON::XS::is_bool $scalar |
|
|
126 | |
|
|
127 | Returns true if the passed scalar represents either JSON::XS::true or |
|
|
128 | JSON::XS::false, two constants that act like C<1> and C<0>, respectively |
|
|
129 | and are used to represent JSON C<true> and C<false> values in Perl. |
|
|
130 | |
|
|
131 | See MAPPING, below, for more information on how JSON values are mapped to |
|
|
132 | Perl. |
131 | |
133 | |
132 | =back |
134 | =back |
133 | |
135 | |
134 | |
136 | |
135 | =head1 OBJECT-ORIENTED INTERFACE |
137 | =head1 OBJECT-ORIENTED INTERFACE |
… | |
… | |
309 | Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>, |
311 | Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>, |
310 | resulting in an invalid JSON text: |
312 | resulting in an invalid JSON text: |
311 | |
313 | |
312 | JSON::XS->new->allow_nonref->encode ("Hello, World!") |
314 | JSON::XS->new->allow_nonref->encode ("Hello, World!") |
313 | => "Hello, World!" |
315 | => "Hello, World!" |
|
|
316 | |
|
|
317 | =item $json = $json->allow_blessed ([$enable]) |
|
|
318 | |
|
|
319 | If C<$enable> is true (or missing), then the C<encode> method will not |
|
|
320 | barf when it encounters a blessed reference. Instead, the value of the |
|
|
321 | B<convert_blessed> option will decide wether C<null> (C<convert_blessed> |
|
|
322 | disabled or no C<to_json> method found) or a representation of the |
|
|
323 | object (C<convert_blessed> enabled and C<to_json> method found) is being |
|
|
324 | encoded. Has no effect on C<decode>. |
|
|
325 | |
|
|
326 | If C<$enable> is false (the default), then C<encode> will throw an |
|
|
327 | exception when it encounters a blessed object. |
|
|
328 | |
|
|
329 | =item $json = $json->convert_blessed ([$enable]) |
|
|
330 | |
|
|
331 | If C<$enable> is true (or missing), then C<encode>, upon encountering a |
|
|
332 | blessed object, will check for the availability of the C<TO_JSON> method |
|
|
333 | on the object's class. If found, it will be called in scalar context |
|
|
334 | and the resulting scalar will be encoded instead of the object. If no |
|
|
335 | C<TO_JSON> method is found, the value of C<allow_blessed> will decide what |
|
|
336 | to do. |
|
|
337 | |
|
|
338 | The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON> |
|
|
339 | returns other blessed objects, those will be handled in the same |
|
|
340 | way. C<TO_JSON> must take care of not causing an endless recursion cycle |
|
|
341 | (== crash) in this case. The name of C<TO_JSON> was chosen because other |
|
|
342 | methods called by the Perl core (== not by the user of the object) are |
|
|
343 | usually in upper case letters and to avoid collisions with the C<to_json> |
|
|
344 | function. |
|
|
345 | |
|
|
346 | This setting does not yet influence C<decode> in any way, but in the |
|
|
347 | future, global hooks might get installed that influence C<decode> and are |
|
|
348 | enabled by this setting. |
|
|
349 | |
|
|
350 | If C<$enable> is false, then the C<allow_blessed> setting will decide what |
|
|
351 | to do when a blessed object is found. |
314 | |
352 | |
315 | =item $json = $json->shrink ([$enable]) |
353 | =item $json = $json->shrink ([$enable]) |
316 | |
354 | |
317 | Perl usually over-allocates memory a bit when allocating space for |
355 | Perl usually over-allocates memory a bit when allocating space for |
318 | strings. This flag optionally resizes strings generated by either |
356 | strings. This flag optionally resizes strings generated by either |
… | |
… | |
351 | given character in a string. |
389 | given character in a string. |
352 | |
390 | |
353 | Setting the maximum depth to one disallows any nesting, so that ensures |
391 | Setting the maximum depth to one disallows any nesting, so that ensures |
354 | that the object is only a single hash/object or array. |
392 | that the object is only a single hash/object or array. |
355 | |
393 | |
356 | The argument to C<max_depth> will be rounded up to the next nearest power |
394 | The argument to C<max_depth> will be rounded up to the next highest power |
357 | of two. |
395 | of two. If no argument is given, the highest possible setting will be |
|
|
396 | used, which is rarely useful. |
|
|
397 | |
|
|
398 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
|
|
399 | |
|
|
400 | =item $json = $json->max_size ([$maximum_string_size]) |
|
|
401 | |
|
|
402 | Set the maximum length a JSON text may have (in bytes) where decoding is |
|
|
403 | being attempted. The default is C<0>, meaning no limit. When C<decode> |
|
|
404 | is called on a string longer then this number of characters it will not |
|
|
405 | attempt to decode the string but throw an exception. This setting has no |
|
|
406 | effect on C<encode> (yet). |
|
|
407 | |
|
|
408 | The argument to C<max_size> will be rounded up to the next B<highest> |
|
|
409 | power of two (so may be more than requested). If no argument is given, the |
|
|
410 | limit check will be deactivated (same as when C<0> is specified). |
358 | |
411 | |
359 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
412 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
360 | |
413 | |
361 | =item $json_text = $json->encode ($perl_scalar) |
414 | =item $json_text = $json->encode ($perl_scalar) |
362 | |
415 | |
… | |
… | |
402 | |
455 | |
403 | For the more enlightened: note that in the following descriptions, |
456 | For the more enlightened: note that in the following descriptions, |
404 | lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> |
457 | lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> |
405 | refers to the abstract Perl language itself. |
458 | refers to the abstract Perl language itself. |
406 | |
459 | |
|
|
460 | |
407 | =head2 JSON -> PERL |
461 | =head2 JSON -> PERL |
408 | |
462 | |
409 | =over 4 |
463 | =over 4 |
410 | |
464 | |
411 | =item object |
465 | =item object |
… | |
… | |
431 | conversion details, but an integer may take slightly less memory and might |
485 | conversion details, but an integer may take slightly less memory and might |
432 | represent more values exactly than (floating point) numbers. |
486 | represent more values exactly than (floating point) numbers. |
433 | |
487 | |
434 | =item true, false |
488 | =item true, false |
435 | |
489 | |
436 | These JSON atoms become C<0>, C<1>, respectively. Information is lost in |
490 | These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>, |
437 | this process. Future versions might represent those values differently, |
491 | respectively. They are overloaded to act almost exactly like the numbers |
438 | but they will be guarenteed to act like these integers would normally in |
492 | C<1> and C<0>. You can check wether a scalar is a JSON boolean by using |
439 | Perl. |
493 | the C<JSON::XS::is_bool> function. |
440 | |
494 | |
441 | =item null |
495 | =item null |
442 | |
496 | |
443 | A JSON null atom becomes C<undef> in Perl. |
497 | A JSON null atom becomes C<undef> in Perl. |
444 | |
498 | |
445 | =back |
499 | =back |
|
|
500 | |
446 | |
501 | |
447 | =head2 PERL -> JSON |
502 | =head2 PERL -> JSON |
448 | |
503 | |
449 | The mapping from Perl to JSON is slightly more difficult, as Perl is a |
504 | The mapping from Perl to JSON is slightly more difficult, as Perl is a |
450 | truly typeless language, so we can only guess which JSON type is meant by |
505 | truly typeless language, so we can only guess which JSON type is meant by |
… | |
… | |
475 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
530 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can |
476 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
531 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. |
477 | |
532 | |
478 | to_json [\0,JSON::XS::true] # yields [false,true] |
533 | to_json [\0,JSON::XS::true] # yields [false,true] |
479 | |
534 | |
|
|
535 | =item JSON::XS::true, JSON::XS::false |
|
|
536 | |
|
|
537 | These special values become JSON true and JSON false values, |
|
|
538 | respectively. You cna alos use C<\1> and C<\0> directly if you want. |
|
|
539 | |
480 | =item blessed objects |
540 | =item blessed objects |
481 | |
541 | |
482 | Blessed objects are not allowed. JSON::XS currently tries to encode their |
542 | Blessed objects are not allowed. JSON::XS currently tries to encode their |
483 | underlying representation (hash- or arrayref), but this behaviour might |
543 | underlying representation (hash- or arrayref), but this behaviour might |
484 | change in future versions. |
544 | change in future versions. |
… | |
… | |
605 | |
665 | |
606 | Does not check input for validity. |
666 | Does not check input for validity. |
607 | |
667 | |
608 | =back |
668 | =back |
609 | |
669 | |
|
|
670 | |
|
|
671 | =head2 JSON and YAML |
|
|
672 | |
|
|
673 | You often hear that JSON is a subset (or a close subset) of YAML. This is, |
|
|
674 | however, a mass hysteria and very far from the truth. In general, there is |
|
|
675 | no way to configure JSON::XS to output a data structure as valid YAML. |
|
|
676 | |
|
|
677 | If you really must use JSON::XS to generate YAML, you should use this |
|
|
678 | algorithm (subject to change in future versions): |
|
|
679 | |
|
|
680 | my $to_yaml = JSON::XS->new->utf8->space_after (1); |
|
|
681 | my $yaml = $to_yaml->encode ($ref) . "\n"; |
|
|
682 | |
|
|
683 | This will usually generate JSON texts that also parse as valid |
|
|
684 | YAML. Please note that YAML has hardcoded limits on (simple) object key |
|
|
685 | lengths that JSON doesn't have, so you should make sure that your hash |
|
|
686 | keys are noticably shorter than the 1024 characters YAML allows. |
|
|
687 | |
|
|
688 | There might be other incompatibilities that I am not aware of. In general |
|
|
689 | you should not try to generate YAML with a JSON generator or vice versa, |
|
|
690 | or try to parse JSON with a YAML parser or vice versa: chances are high |
|
|
691 | that you will run into severe interoperability problems. |
|
|
692 | |
|
|
693 | |
610 | =head2 SPEED |
694 | =head2 SPEED |
611 | |
695 | |
612 | It seems that JSON::XS is surprisingly fast, as shown in the following |
696 | It seems that JSON::XS is surprisingly fast, as shown in the following |
613 | tables. They have been generated with the help of the C<eg/bench> program |
697 | tables. They have been generated with the help of the C<eg/bench> program |
614 | in the JSON::XS distribution, to make it easy to compare on your own |
698 | in the JSON::XS distribution, to make it easy to compare on your own |
615 | system. |
699 | system. |
616 | |
700 | |
617 | First comes a comparison between various modules using a very short JSON |
701 | First comes a comparison between various modules using a very short |
618 | string: |
702 | single-line JSON string: |
619 | |
703 | |
620 | {"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null} |
704 | {"method": "handleMessage", "params": ["user1", "we were just talking"], \ |
|
|
705 | "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]} |
621 | |
706 | |
622 | It shows the number of encodes/decodes per second (JSON::XS uses the |
707 | It shows the number of encodes/decodes per second (JSON::XS uses |
623 | functional interface, while JSON::XS/2 uses the OO interface with |
708 | the functional interface, while JSON::XS/2 uses the OO interface |
624 | pretty-printing and hashkey sorting enabled). Higher is better: |
709 | with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables |
|
|
710 | shrink). Higher is better: |
625 | |
711 | |
|
|
712 | Storable | 15779.925 | 14169.946 | |
|
|
713 | -----------+------------+------------+ |
626 | module | encode | decode | |
714 | module | encode | decode | |
627 | -----------|------------|------------| |
715 | -----------|------------|------------| |
628 | JSON | 11488.516 | 7823.035 | |
716 | JSON | 4990.842 | 4088.813 | |
629 | JSON::DWIW | 94708.054 | 129094.260 | |
717 | JSON::DWIW | 51653.990 | 71575.154 | |
630 | JSON::PC | 63884.157 | 128528.212 | |
718 | JSON::PC | 65948.176 | 74631.744 | |
631 | JSON::Syck | 34898.677 | 42096.911 | |
719 | JSON::PP | 8931.652 | 3817.168 | |
632 | JSON::XS | 654027.064 | 396423.669 | |
720 | JSON::Syck | 24877.248 | 27776.848 | |
633 | JSON::XS/2 | 371564.190 | 371725.613 | |
721 | JSON::XS | 388361.481 | 227951.304 | |
|
|
722 | JSON::XS/2 | 227951.304 | 218453.333 | |
|
|
723 | JSON::XS/3 | 338250.323 | 218453.333 | |
|
|
724 | Storable | 16500.016 | 135300.129 | |
634 | -----------+------------+------------+ |
725 | -----------+------------+------------+ |
635 | |
726 | |
636 | That is, JSON::XS is more than six times faster than JSON::DWIW on |
727 | That is, JSON::XS is about five times faster than JSON::DWIW on encoding, |
637 | encoding, more than three times faster on decoding, and about thirty times |
728 | about three times faster on decoding, and over fourty times faster |
638 | faster than JSON, even with pretty-printing and key sorting. |
729 | than JSON, even with pretty-printing and key sorting. It also compares |
|
|
730 | favourably to Storable for small amounts of data. |
639 | |
731 | |
640 | Using a longer test string (roughly 18KB, generated from Yahoo! Locals |
732 | Using a longer test string (roughly 18KB, generated from Yahoo! Locals |
641 | search API (http://nanoref.com/yahooapis/mgPdGg): |
733 | search API (http://nanoref.com/yahooapis/mgPdGg): |
642 | |
734 | |
643 | module | encode | decode | |
735 | module | encode | decode | |
644 | -----------|------------|------------| |
736 | -----------|------------|------------| |
645 | JSON | 273.023 | 44.674 | |
737 | JSON | 55.260 | 34.971 | |
646 | JSON::DWIW | 1089.383 | 1145.704 | |
738 | JSON::DWIW | 825.228 | 1082.513 | |
647 | JSON::PC | 3097.419 | 2393.921 | |
739 | JSON::PC | 3571.444 | 2394.829 | |
648 | JSON::Syck | 514.060 | 843.053 | |
740 | JSON::PP | 210.987 | 32.574 | |
649 | JSON::XS | 6479.668 | 3636.364 | |
741 | JSON::Syck | 552.551 | 787.544 | |
650 | JSON::XS/2 | 3774.221 | 3599.124 | |
742 | JSON::XS | 5780.463 | 4854.519 | |
|
|
743 | JSON::XS/2 | 3869.998 | 4798.975 | |
|
|
744 | JSON::XS/3 | 5862.880 | 4798.975 | |
|
|
745 | Storable | 4445.002 | 5235.027 | |
651 | -----------+------------+------------+ |
746 | -----------+------------+------------+ |
652 | |
747 | |
653 | Again, JSON::XS leads by far. |
748 | Again, JSON::XS leads by far (except for Storable which non-surprisingly |
|
|
749 | decodes faster). |
654 | |
750 | |
655 | On large strings containing lots of high unicode characters, some modules |
751 | On 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 |
752 | (such as JSON::PC) seem to decode faster than JSON::XS, but the result |
657 | will be broken due to missing (or wrong) unicode handling. Others refuse |
753 | will be broken due to missing (or wrong) unicode handling. Others refuse |
658 | to decode or encode properly, so it was impossible to prepare a fair |
754 | to decode or encode properly, so it was impossible to prepare a fair |
… | |
… | |
671 | Second, you need to avoid resource-starving attacks. That means you should |
767 | Second, you need to avoid resource-starving attacks. That means you should |
672 | limit the size of JSON texts you accept, or make sure then when your |
768 | limit the size of JSON texts you accept, or make sure then when your |
673 | resources run out, thats just fine (e.g. by using a separate process that |
769 | resources run out, thats just fine (e.g. by using a separate process that |
674 | can crash safely). The size of a JSON text in octets or characters is |
770 | can crash safely). The size of a JSON text in octets or characters is |
675 | usually a good indication of the size of the resources required to decode |
771 | usually a good indication of the size of the resources required to decode |
676 | it into a Perl structure. |
772 | it into a Perl structure. While JSON::XS can check the size of the JSON |
|
|
773 | text, it might be too late when you already have it in memory, so you |
|
|
774 | might want to check the size before you accept the string. |
677 | |
775 | |
678 | Third, JSON::XS recurses using the C stack when decoding objects and |
776 | Third, JSON::XS recurses using the C stack when decoding objects and |
679 | arrays. The C stack is a limited resource: for instance, on my amd64 |
777 | arrays. The C stack is a limited resource: for instance, on my amd64 |
680 | machine with 8MB of stack size I can decode around 180k nested arrays but |
778 | machine with 8MB of stack size I can decode around 180k nested arrays but |
681 | only 14k nested JSON objects (due to perl itself recursing deeply on croak |
779 | only 14k nested JSON objects (due to perl itself recursing deeply on croak |
… | |
… | |
686 | |
784 | |
687 | And last but least, something else could bomb you that I forgot to think |
785 | And last but least, something else could bomb you that I forgot to think |
688 | of. In that case, you get to keep the pieces. I am always open for hints, |
786 | of. In that case, you get to keep the pieces. I am always open for hints, |
689 | though... |
787 | though... |
690 | |
788 | |
|
|
789 | If you are using JSON::XS to return packets to consumption |
|
|
790 | by javascript scripts in a browser you should have a look at |
|
|
791 | L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether |
|
|
792 | you are vulnerable to some common attack vectors (which really are browser |
|
|
793 | design bugs, but it is still you who will have to deal with it, as major |
|
|
794 | browser developers care only for features, not about doing security |
|
|
795 | right). |
|
|
796 | |
691 | |
797 | |
692 | =head1 BUGS |
798 | =head1 BUGS |
693 | |
799 | |
694 | While the goal of this module is to be correct, that unfortunately does |
800 | While the goal of this module is to be correct, that unfortunately does |
695 | not mean its bug-free, only that I think its design is bug-free. It is |
801 | not mean its bug-free, only that I think its design is bug-free. It is |
696 | still relatively early in its development. If you keep reporting bugs they |
802 | still relatively early in its development. If you keep reporting bugs they |
697 | will be fixed swiftly, though. |
803 | will be fixed swiftly, though. |
698 | |
804 | |
699 | =cut |
805 | =cut |
700 | |
806 | |
|
|
807 | our $true = do { bless \(my $dummy = "1"), "JSON::XS::Boolean" }; |
|
|
808 | our $false = do { bless \(my $dummy = "0"), "JSON::XS::Boolean" }; |
|
|
809 | |
701 | sub true() { \1 } |
810 | sub true() { $true } |
702 | sub false() { \0 } |
811 | sub false() { $false } |
|
|
812 | |
|
|
813 | sub is_bool($) { |
|
|
814 | UNIVERSAL::isa $_[0], "JSON::XS::Boolean" |
|
|
815 | # or UNIVERSAL::isa $_[0], "JSON::Literal" |
|
|
816 | } |
|
|
817 | |
|
|
818 | XSLoader::load "JSON::XS", $VERSION; |
|
|
819 | |
|
|
820 | package JSON::XS::Boolean; |
|
|
821 | |
|
|
822 | use overload |
|
|
823 | "0+" => sub { ${$_[0]} }, |
|
|
824 | "++" => sub { $_[0] = ${$_[0]} + 1 }, |
|
|
825 | "--" => sub { $_[0] = ${$_[0]} - 1 }, |
|
|
826 | fallback => 1; |
703 | |
827 | |
704 | 1; |
828 | 1; |
705 | |
829 | |
706 | =head1 AUTHOR |
830 | =head1 AUTHOR |
707 | |
831 | |