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Comparing JSON-XS/XS.pm (file contents):
Revision 1.31 by root, Wed Apr 11 12:23:02 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 $VERSION = '1.24';
92 our @ISA = qw(Exporter); 92 our @ISA = qw(Exporter);
93 93
94 our @EXPORT = qw(to_json from_json objToJson jsonToObj); 94 our @EXPORT = qw(to_json from_json objToJson jsonToObj);
95 require Exporter; 95 require Exporter;
96 96
… …
154 154
155If C<$enable> is true (or missing), then the C<encode> method will not 155If C<$enable> is true (or missing), then the C<encode> method will not
156generate characters outside the code range C<0..127> (which is ASCII). Any 156generate characters outside the code range C<0..127> (which is ASCII). Any
157unicode characters outside that range will be escaped using either a 157unicode characters outside that range will be escaped using either a
158single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, 158single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
159as per RFC4627. 159as per RFC4627. The resulting encoded JSON text can be treated as a native
160unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
161or any other superset of ASCII.
160 162
161If C<$enable> is false, then the C<encode> method will not escape Unicode 163If C<$enable> is false, then the C<encode> method will not escape Unicode
162characters unless required by the JSON syntax. This results in a faster 164characters unless required by the JSON syntax or other flags. This results
163and more compact format. 165in a faster and more compact format.
166
167The main use for this flag is to produce JSON texts that can be
168transmitted over a 7-bit channel, as the encoded JSON texts will not
169contain any 8 bit characters.
164 170
165 JSON::XS->new->ascii (1)->encode ([chr 0x10401]) 171 JSON::XS->new->ascii (1)->encode ([chr 0x10401])
166 => ["\ud801\udc01"] 172 => ["\ud801\udc01"]
173
174=item $json = $json->latin1 ([$enable])
175
176If C<$enable> is true (or missing), then the C<encode> method will encode
177the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
178outside the code range C<0..255>. The resulting string can be treated as a
179latin1-encoded JSON text or a native unicode string. The C<decode> method
180will not be affected in any way by this flag, as C<decode> by default
181expects unicode, which is a strict superset of latin1.
182
183If C<$enable> is false, then the C<encode> method will not escape Unicode
184characters unless required by the JSON syntax or other flags.
185
186The main use for this flag is efficiently encoding binary data as JSON
187text, as most octets will not be escaped, resulting in a smaller encoded
188size. The disadvantage is that the resulting JSON text is encoded
189in latin1 (and must correctly be treated as such when storing and
190transfering), a rare encoding for JSON. It is therefore most useful when
191you want to store data structures known to contain binary data efficiently
192in files or databases, not when talking to other JSON encoders/decoders.
193
194 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
195 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
167 196
168=item $json = $json->utf8 ([$enable]) 197=item $json = $json->utf8 ([$enable])
169 198
170If C<$enable> is true (or missing), then the C<encode> method will encode 199If C<$enable> is true (or missing), then the C<encode> method will encode
171the JSON result into UTF-8, as required by many protocols, while the 200the JSON result into UTF-8, as required by many protocols, while the
… …
345 374
346JSON numbers and strings become simple Perl scalars. JSON arrays become 375JSON numbers and strings become simple Perl scalars. JSON arrays become
347Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes 376Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
348C<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>.
349 378
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
350=back 393=back
351 394
352 395
353=head1 MAPPING 396=head1 MAPPING
354 397
… …
358(what you put in comes out as something equivalent). 401(what you put in comes out as something equivalent).
359 402
360For the more enlightened: note that in the following descriptions, 403For the more enlightened: note that in the following descriptions,
361lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> 404lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
362refers to the abstract Perl language itself. 405refers to the abstract Perl language itself.
406
363 407
364=head2 JSON -> PERL 408=head2 JSON -> PERL
365 409
366=over 4 410=over 4
367 411
… …
398=item null 442=item null
399 443
400A JSON null atom becomes C<undef> in Perl. 444A JSON null atom becomes C<undef> in Perl.
401 445
402=back 446=back
447
403 448
404=head2 PERL -> JSON 449=head2 PERL -> JSON
405 450
406The 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
407truly 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
… …
562 607
563Does not check input for validity. 608Does not check input for validity.
564 609
565=back 610=back
566 611
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
567=head2 SPEED 636=head2 SPEED
568 637
569It 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
570tables. 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
571in 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
572system. 641system.
573 642
574First comes a comparison between various modules using a very short JSON 643First comes a comparison between various modules using a very short
575string: 644single-line JSON string:
576 645
577 {"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]}
578 648
579It shows the number of encodes/decodes per second (JSON::XS uses the 649It shows the number of encodes/decodes per second (JSON::XS uses
580functional interface, while JSON::XS/2 uses the OO interface with 650the functional interface, while JSON::XS/2 uses the OO interface
581pretty-printing and hashkey sorting enabled). Higher is better: 651with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
652shrink). Higher is better:
582 653
583 module | encode | decode | 654 module | encode | decode |
584 -----------|------------|------------| 655 -----------|------------|------------|
585 JSON | 11488.516 | 7823.035 | 656 JSON | 7645.468 | 4208.613 |
586 JSON::DWIW | 94708.054 | 129094.260 | 657 JSON::DWIW | 40721.398 | 77101.176 |
587 JSON::PC | 63884.157 | 128528.212 | 658 JSON::PC | 65948.176 | 78251.940 |
588 JSON::Syck | 34898.677 | 42096.911 | 659 JSON::Syck | 22844.793 | 26479.192 |
589 JSON::XS | 654027.064 | 396423.669 | 660 JSON::XS | 388361.481 | 199728.762 |
590 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 |
591 -----------+------------+------------+ 664 -----------+------------+------------+
592 665
593That 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,
594encoding, more than three times faster on decoding, and about thirty times 667about three times faster on decoding, and over fourty times faster
595faster 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.
596 670
597Using a longer test string (roughly 18KB, generated from Yahoo! Locals 671Using a longer test string (roughly 18KB, generated from Yahoo! Locals
598search API (http://nanoref.com/yahooapis/mgPdGg): 672search API (http://nanoref.com/yahooapis/mgPdGg):
599 673
600 module | encode | decode | 674 module | encode | decode |
601 -----------|------------|------------| 675 -----------|------------|------------|
602 JSON | 273.023 | 44.674 | 676 JSON | 254.685 | 37.665 |
603 JSON::DWIW | 1089.383 | 1145.704 | 677 JSON::DWIW | 843.343 | 1049.731 |
604 JSON::PC | 3097.419 | 2393.921 | 678 JSON::PC | 3602.116 | 2307.352 |
605 JSON::Syck | 514.060 | 843.053 | 679 JSON::Syck | 505.107 | 787.899 |
606 JSON::XS | 6479.668 | 3636.364 | 680 JSON::XS | 5747.196 | 3690.220 |
607 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 |
608 -----------+------------+------------+ 684 -----------+------------+------------+
609 685
610Again, JSON::XS leads by far. 686Again, JSON::XS leads by far (except for Storable which non-surprisingly
687decodes faster).
611 688
612On large strings containing lots of high unicode characters, some modules 689On large strings containing lots of high unicode characters, some modules
613(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
614will be broken due to missing (or wrong) unicode handling. Others refuse 691will be broken due to missing (or wrong) unicode handling. Others refuse
615to 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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