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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 1.41 by root, Mon Jun 11 03:45:26 2007 UTC

… …
86package JSON::XS; 86package JSON::XS;
87 87
88use strict; 88use strict;
89 89
90BEGIN { 90BEGIN {
91 our $VERSION = '1.12'; 91 our $VERSION = '1.24';
92 our @ISA = qw(Exporter); 92 our @ISA = qw(Exporter);
93 93
94 our @EXPORT = qw(to_json from_json objToJson jsonToObj); 94 our @EXPORT = qw(to_json from_json objToJson jsonToObj);
95 require Exporter; 95 require Exporter;
96 96
… …
374 374
375JSON numbers and strings become simple Perl scalars. JSON arrays become 375JSON numbers and strings become simple Perl scalars. JSON arrays become
376Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes 376Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
377C<1>, C<false> becomes C<0> and C<null> becomes C<undef>. 377C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
378 378
379=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
380
381This works like the C<decode> method, but instead of raising an exception
382when there is trailing garbage after the first JSON object, it will
383silently stop parsing there and return the number of characters consumed
384so far.
385
386This is useful if your JSON texts are not delimited by an outer protocol
387(which is not the brightest thing to do in the first place) and you need
388to know where the JSON text ends.
389
390 JSON::XS->new->decode_prefix ("[1] the tail")
391 => ([], 3)
392
379=back 393=back
380 394
381 395
382=head1 MAPPING 396=head1 MAPPING
383 397
… …
387(what you put in comes out as something equivalent). 401(what you put in comes out as something equivalent).
388 402
389For the more enlightened: note that in the following descriptions, 403For the more enlightened: note that in the following descriptions,
390lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> 404lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
391refers to the abstract Perl language itself. 405refers to the abstract Perl language itself.
406
392 407
393=head2 JSON -> PERL 408=head2 JSON -> PERL
394 409
395=over 4 410=over 4
396 411
… …
427=item null 442=item null
428 443
429A JSON null atom becomes C<undef> in Perl. 444A JSON null atom becomes C<undef> in Perl.
430 445
431=back 446=back
447
432 448
433=head2 PERL -> JSON 449=head2 PERL -> JSON
434 450
435The mapping from Perl to JSON is slightly more difficult, as Perl is a 451The 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 452truly typeless language, so we can only guess which JSON type is meant by
… …
591 607
592Does not check input for validity. 608Does not check input for validity.
593 609
594=back 610=back
595 611
612
613=head2 JSON and YAML
614
615You often hear that JSON is a subset (or a close subset) of YAML. This is,
616however, a mass hysteria and very far from the truth. In general, there is
617no way to configure JSON::XS to output a data structure as valid YAML.
618
619If you really must use JSON::XS to generate YAML, you should use this
620algorithm (subject to change in future versions):
621
622 my $to_yaml = JSON::XS->new->utf8->space_after (1);
623 my $yaml = $to_yaml->encode ($ref) . "\n";
624
625This will usually generate JSON texts that also parse as valid
626YAML. Please note that YAML has hardcoded limits on (simple) object key
627lengths that JSON doesn't have, so you should make sure that your hash
628keys are noticably shorter than the 1024 characters YAML allows.
629
630There might be other incompatibilities that I am not aware of. In general
631you should not try to generate YAML with a JSON generator or vice versa,
632or try to parse JSON with a YAML parser or vice versa: chances are high
633that you will run into severe interoperability problems.
634
635
596=head2 SPEED 636=head2 SPEED
597 637
598It seems that JSON::XS is surprisingly fast, as shown in the following 638It 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 639tables. 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 640in the JSON::XS distribution, to make it easy to compare on your own
601system. 641system.
602 642
603First comes a comparison between various modules using a very short JSON 643First comes a comparison between various modules using a very short
604string: 644single-line JSON string:
605 645
606 {"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null} 646 {"method": "handleMessage", "params": ["user1", "we were just talking"], \
647 "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
607 648
608It shows the number of encodes/decodes per second (JSON::XS uses the 649It shows the number of encodes/decodes per second (JSON::XS uses
609functional interface, while JSON::XS/2 uses the OO interface with 650the functional interface, while JSON::XS/2 uses the OO interface
610pretty-printing and hashkey sorting enabled). Higher is better: 651with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
652shrink). Higher is better:
611 653
612 module | encode | decode | 654 module | encode | decode |
613 -----------|------------|------------| 655 -----------|------------|------------|
614 JSON | 11488.516 | 7823.035 | 656 JSON | 7645.468 | 4208.613 |
615 JSON::DWIW | 94708.054 | 129094.260 | 657 JSON::DWIW | 40721.398 | 77101.176 |
616 JSON::PC | 63884.157 | 128528.212 | 658 JSON::PC | 65948.176 | 78251.940 |
617 JSON::Syck | 34898.677 | 42096.911 | 659 JSON::Syck | 22844.793 | 26479.192 |
618 JSON::XS | 654027.064 | 396423.669 | 660 JSON::XS | 388361.481 | 199728.762 |
619 JSON::XS/2 | 371564.190 | 371725.613 | 661 JSON::XS/2 | 218453.333 | 192399.266 |
662 JSON::XS/3 | 338250.323 | 192399.266 |
663 Storable | 15779.925 | 14169.946 |
620 -----------+------------+------------+ 664 -----------+------------+------------+
621 665
622That is, JSON::XS is more than six times faster than JSON::DWIW on 666That 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 667about three times faster on decoding, and over fourty times faster
624faster than JSON, even with pretty-printing and key sorting. 668than JSON, even with pretty-printing and key sorting. It also compares
669favourably to Storable for small amounts of data.
625 670
626Using a longer test string (roughly 18KB, generated from Yahoo! Locals 671Using a longer test string (roughly 18KB, generated from Yahoo! Locals
627search API (http://nanoref.com/yahooapis/mgPdGg): 672search API (http://nanoref.com/yahooapis/mgPdGg):
628 673
629 module | encode | decode | 674 module | encode | decode |
630 -----------|------------|------------| 675 -----------|------------|------------|
631 JSON | 273.023 | 44.674 | 676 JSON | 254.685 | 37.665 |
632 JSON::DWIW | 1089.383 | 1145.704 | 677 JSON::DWIW | 843.343 | 1049.731 |
633 JSON::PC | 3097.419 | 2393.921 | 678 JSON::PC | 3602.116 | 2307.352 |
634 JSON::Syck | 514.060 | 843.053 | 679 JSON::Syck | 505.107 | 787.899 |
635 JSON::XS | 6479.668 | 3636.364 | 680 JSON::XS | 5747.196 | 3690.220 |
636 JSON::XS/2 | 3774.221 | 3599.124 | 681 JSON::XS/2 | 3968.121 | 3676.634 |
682 JSON::XS/3 | 6105.246 | 3662.508 |
683 Storable | 4417.337 | 5285.161 |
637 -----------+------------+------------+ 684 -----------+------------+------------+
638 685
639Again, JSON::XS leads by far. 686Again, JSON::XS leads by far (except for Storable which non-surprisingly
687decodes faster).
640 688
641On large strings containing lots of high unicode characters, some modules 689On 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 690(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 691will be broken due to missing (or wrong) unicode handling. Others refuse
644to decode or encode properly, so it was impossible to prepare a fair 692to decode or encode properly, so it was impossible to prepare a fair

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