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Comparing JSON-XS/XS.pm (file contents):
Revision 1.26 by root, Sat Mar 31 14:20:06 2007 UTC vs.
Revision 1.38 by root, Wed Jun 6 18:16:52 2007 UTC

86package JSON::XS; 86package JSON::XS;
87 87
88use strict; 88use strict;
89 89
90BEGIN { 90BEGIN {
91 our $VERSION = '1.01'; 91 our $VERSION = '1.23';
92 our @ISA = qw(Exporter); 92 our @ISA = qw(Exporter);
93 93
94 our @EXPORT = qw(to_json from_json objToJson jsonToObj); 94 our @EXPORT = qw(to_json from_json objToJson jsonToObj);
95 require Exporter; 95 require Exporter;
96 96
154 154
155If C<$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
309strings that look like integers or floats into integers or floats 338strings that look like integers or floats into integers or floats
310internally (there is no difference on the Perl level), saving space. 339internally (there is no difference on the Perl level), saving space.
311 340
312=item $json = $json->max_depth ([$maximum_nesting_depth]) 341=item $json = $json->max_depth ([$maximum_nesting_depth])
313 342
314Sets the maximum nesting level (default C<4096>) accepted while encoding 343Sets the maximum nesting level (default C<512>) accepted while encoding
315or decoding. If the JSON text or Perl data structure has an equal or 344or decoding. If the JSON text or Perl data structure has an equal or
316higher nesting level then this limit, then the encoder and decoder will 345higher nesting level then this limit, then the encoder and decoder will
317stop and croak at that point. 346stop and croak at that point.
318 347
319Nesting level is defined by number of hash- or arrayrefs that the encoder 348Nesting level is defined by number of hash- or arrayrefs that the encoder
344returning the resulting simple scalar or reference. Croaks on error. 373returning the resulting simple scalar or reference. Croaks on error.
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>.
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)
349 392
350=back 393=back
351 394
352 395
353=head1 MAPPING 396=head1 MAPPING
473 $x *= 1; # same thing, the choise is yours. 516 $x *= 1; # same thing, the choise is yours.
474 517
475You can not currently output JSON booleans or force the type in other, 518You can not currently output JSON booleans or force the type in other,
476less obscure, ways. Tell me if you need this capability. 519less obscure, ways. Tell me if you need this capability.
477 520
478=item circular data structures
479
480Those will be encoded until memory or stackspace runs out.
481
482=back 521=back
483 522
484 523
485=head1 COMPARISON 524=head1 COMPARISON
486 525
573It seems that JSON::XS is surprisingly fast, as shown in the following 612It seems that JSON::XS is surprisingly fast, as shown in the following
574tables. They have been generated with the help of the C<eg/bench> program 613tables. They have been generated with the help of the C<eg/bench> program
575in the JSON::XS distribution, to make it easy to compare on your own 614in the JSON::XS distribution, to make it easy to compare on your own
576system. 615system.
577 616
578First comes a comparison between various modules using a very short JSON 617First comes a comparison between various modules using a very short
579string: 618single-line JSON string:
580 619
581 {"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null} 620 {"method": "handleMessage", "params": ["user1", "we were just talking"], \
621 "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
582 622
583It shows the number of encodes/decodes per second (JSON::XS uses the 623It shows the number of encodes/decodes per second (JSON::XS uses the
584functional interface, while JSON::XS/2 uses the OO interface with 624functional interface, while JSON::XS/2 uses the OO interface with
585pretty-printing and hashkey sorting enabled). Higher is better: 625pretty-printing and hashkey sorting enabled). Higher is better:
586 626
587 module | encode | decode | 627 module | encode | decode |
588 -----------|------------|------------| 628 -----------|------------|------------|
589 JSON | 11488.516 | 7823.035 | 629 JSON | 7645.468 | 4208.613 |
590 JSON::DWIW | 94708.054 | 129094.260 | 630 JSON::DWIW | 68534.379 | 79437.576 |
591 JSON::PC | 63884.157 | 128528.212 | 631 JSON::PC | 65948.176 | 78251.940 |
592 JSON::Syck | 34898.677 | 42096.911 | 632 JSON::Syck | 23379.621 | 28416.694 |
593 JSON::XS | 654027.064 | 396423.669 | 633 JSON::XS | 388361.481 | 199728.762 |
594 JSON::XS/2 | 371564.190 | 371725.613 | 634 JSON::XS/2 | 218453.333 | 192399.266 |
635 JSON::XS/3 | 338250.323 | 192399.266 |
636 Storable | 15732.573 | 28571.553 |
595 -----------+------------+------------+ 637 -----------+------------+------------+
596 638
597That is, JSON::XS is more than six times faster than JSON::DWIW on 639That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
598encoding, more than three times faster on decoding, and about thirty times 640about three times faster on decoding, and over fourty times faster
599faster than JSON, even with pretty-printing and key sorting. 641than JSON, even with pretty-printing and key sorting. It also compares
642favourably to Storable for small amounts of data.
600 643
601Using a longer test string (roughly 18KB, generated from Yahoo! Locals 644Using a longer test string (roughly 18KB, generated from Yahoo! Locals
602search API (http://nanoref.com/yahooapis/mgPdGg): 645search API (http://nanoref.com/yahooapis/mgPdGg):
603 646
604 module | encode | decode | 647 module | encode | decode |
605 -----------|------------|------------| 648 -----------|------------|------------|
606 JSON | 273.023 | 44.674 | 649 JSON | 254.685 | 37.665 |
607 JSON::DWIW | 1089.383 | 1145.704 | 650 JSON::DWIW | 1014.244 | 1087.678 |
608 JSON::PC | 3097.419 | 2393.921 | 651 JSON::PC | 3602.116 | 2307.352 |
609 JSON::Syck | 514.060 | 843.053 | 652 JSON::Syck | 558.035 | 776.263 |
610 JSON::XS | 6479.668 | 3636.364 | 653 JSON::XS | 5747.196 | 3543.684 |
611 JSON::XS/2 | 3774.221 | 3599.124 | 654 JSON::XS/2 | 3968.121 | 3589.170 |
655 JSON::XS/3 | 6105.246 | 3561.134 |
656 Storable | 4456.337 | 5320.020 |
612 -----------+------------+------------+ 657 -----------+------------+------------+
613 658
614Again, JSON::XS leads by far. 659Again, JSON::XS leads by far.
615 660
616On large strings containing lots of high unicode characters, some modules 661On large strings containing lots of high unicode characters, some modules
636usually a good indication of the size of the resources required to decode 681usually a good indication of the size of the resources required to decode
637it into a Perl structure. 682it into a Perl structure.
638 683
639Third, JSON::XS recurses using the C stack when decoding objects and 684Third, JSON::XS recurses using the C stack when decoding objects and
640arrays. The C stack is a limited resource: for instance, on my amd64 685arrays. The C stack is a limited resource: for instance, on my amd64
641machine with 8MB of stack size I can decode around 180k nested arrays 686machine with 8MB of stack size I can decode around 180k nested arrays but
642but only 14k nested JSON objects. If that is exceeded, the program 687only 14k nested JSON objects (due to perl itself recursing deeply on croak
643crashes. Thats why the default nesting limit is set to 4096. If your 688to free the temporary). If that is exceeded, the program crashes. to be
689conservative, the default nesting limit is set to 512. If your process
644process has a smaller stack, you should adjust this setting accordingly 690has a smaller stack, you should adjust this setting accordingly with the
645with the C<max_depth> method. 691C<max_depth> method.
646 692
647And last but least, something else could bomb you that I forgot to think 693And last but least, something else could bomb you that I forgot to think
648of. In that case, you get to keep the pieces. I am alway sopen for hints, 694of. In that case, you get to keep the pieces. I am always open for hints,
649though... 695though...
650 696
651 697
652=head1 BUGS 698=head1 BUGS
653 699

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