| … | |
… | |
| 86 | package JSON::XS; |
86 | package JSON::XS; |
| 87 | |
87 | |
| 88 | use strict; |
88 | use strict; |
| 89 | |
89 | |
| 90 | BEGIN { |
90 | BEGIN { |
| 91 | our $VERSION = '0.8'; |
91 | our $VERSION = '1.22'; |
| 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 | |
| … | |
… | |
| 128 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
128 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
| 129 | |
129 | |
| 130 | except being faster. |
130 | except being faster. |
| 131 | |
131 | |
| 132 | =back |
132 | =back |
|
|
133 | |
| 133 | |
134 | |
| 134 | =head1 OBJECT-ORIENTED INTERFACE |
135 | =head1 OBJECT-ORIENTED INTERFACE |
| 135 | |
136 | |
| 136 | The object oriented interface lets you configure your own encoding or |
137 | The object oriented interface lets you configure your own encoding or |
| 137 | decoding style, within the limits of supported formats. |
138 | decoding style, within the limits of supported formats. |
| … | |
… | |
| 153 | |
154 | |
| 154 | If C<$enable> is true (or missing), then the C<encode> method will not |
155 | If C<$enable> is true (or missing), then the C<encode> method will not |
| 155 | generate characters outside the code range C<0..127> (which is ASCII). Any |
156 | generate characters outside the code range C<0..127> (which is ASCII). Any |
| 156 | unicode characters outside that range will be escaped using either a |
157 | unicode characters outside that range will be escaped using either a |
| 157 | single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, |
158 | single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, |
| 158 | as per RFC4627. |
159 | as per RFC4627. The resulting encoded JSON text can be treated as a native |
|
|
160 | unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string, |
|
|
161 | or any other superset of ASCII. |
| 159 | |
162 | |
| 160 | If C<$enable> is false, then the C<encode> method will not escape Unicode |
163 | If C<$enable> is false, then the C<encode> method will not escape Unicode |
| 161 | characters unless required by the JSON syntax. This results in a faster |
164 | characters unless required by the JSON syntax or other flags. This results |
| 162 | and more compact format. |
165 | in a faster and more compact format. |
|
|
166 | |
|
|
167 | The main use for this flag is to produce JSON texts that can be |
|
|
168 | transmitted over a 7-bit channel, as the encoded JSON texts will not |
|
|
169 | contain any 8 bit characters. |
| 163 | |
170 | |
| 164 | JSON::XS->new->ascii (1)->encode ([chr 0x10401]) |
171 | JSON::XS->new->ascii (1)->encode ([chr 0x10401]) |
| 165 | => ["\ud801\udc01"] |
172 | => ["\ud801\udc01"] |
|
|
173 | |
|
|
174 | =item $json = $json->latin1 ([$enable]) |
|
|
175 | |
|
|
176 | If C<$enable> is true (or missing), then the C<encode> method will encode |
|
|
177 | the resulting JSON text as latin1 (or iso-8859-1), escaping any characters |
|
|
178 | outside the code range C<0..255>. The resulting string can be treated as a |
|
|
179 | latin1-encoded JSON text or a native unicode string. The C<decode> method |
|
|
180 | will not be affected in any way by this flag, as C<decode> by default |
|
|
181 | expects unicode, which is a strict superset of latin1. |
|
|
182 | |
|
|
183 | If C<$enable> is false, then the C<encode> method will not escape Unicode |
|
|
184 | characters unless required by the JSON syntax or other flags. |
|
|
185 | |
|
|
186 | The main use for this flag is efficiently encoding binary data as JSON |
|
|
187 | text, as most octets will not be escaped, resulting in a smaller encoded |
|
|
188 | size. The disadvantage is that the resulting JSON text is encoded |
|
|
189 | in latin1 (and must correctly be treated as such when storing and |
|
|
190 | transfering), a rare encoding for JSON. It is therefore most useful when |
|
|
191 | you want to store data structures known to contain binary data efficiently |
|
|
192 | in 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) |
| 166 | |
196 | |
| 167 | =item $json = $json->utf8 ([$enable]) |
197 | =item $json = $json->utf8 ([$enable]) |
| 168 | |
198 | |
| 169 | If C<$enable> is true (or missing), then the C<encode> method will encode |
199 | If C<$enable> is true (or missing), then the C<encode> method will encode |
| 170 | the JSON result into UTF-8, as required by many protocols, while the |
200 | the JSON result into UTF-8, as required by many protocols, while the |
| … | |
… | |
| 283 | => "Hello, World!" |
313 | => "Hello, World!" |
| 284 | |
314 | |
| 285 | =item $json = $json->shrink ([$enable]) |
315 | =item $json = $json->shrink ([$enable]) |
| 286 | |
316 | |
| 287 | Perl usually over-allocates memory a bit when allocating space for |
317 | Perl usually over-allocates memory a bit when allocating space for |
| 288 | strings. This flag optionally resizes strings generated by either |
318 | strings. This flag optionally resizes strings generated by either |
| 289 | C<encode> or C<decode> to their minimum size possible. This can save |
319 | C<encode> or C<decode> to their minimum size possible. This can save |
| 290 | memory when your JSON texts are either very very long or you have many |
320 | memory when your JSON texts are either very very long or you have many |
| 291 | short strings. It will also try to downgrade any strings to octet-form |
321 | short strings. It will also try to downgrade any strings to octet-form |
| 292 | if possible: perl stores strings internally either in an encoding called |
322 | if possible: perl stores strings internally either in an encoding called |
| 293 | UTF-X or in octet-form. The latter cannot store everything but uses less |
323 | UTF-X or in octet-form. The latter cannot store everything but uses less |
| 294 | space in general. |
324 | space in general (and some buggy Perl or C code might even rely on that |
|
|
325 | internal representation being used). |
| 295 | |
326 | |
|
|
327 | The actual definition of what shrink does might change in future versions, |
|
|
328 | but it will always try to save space at the expense of time. |
|
|
329 | |
| 296 | If C<$enable> is true (or missing), the string returned by C<encode> will be shrunk-to-fit, |
330 | If C<$enable> is true (or missing), the string returned by C<encode> will |
| 297 | while all strings generated by C<decode> will also be shrunk-to-fit. |
331 | be shrunk-to-fit, while all strings generated by C<decode> will also be |
|
|
332 | shrunk-to-fit. |
| 298 | |
333 | |
| 299 | If C<$enable> is false, then the normal perl allocation algorithms are used. |
334 | If C<$enable> is false, then the normal perl allocation algorithms are used. |
| 300 | If you work with your data, then this is likely to be faster. |
335 | If you work with your data, then this is likely to be faster. |
| 301 | |
336 | |
| 302 | In the future, this setting might control other things, such as converting |
337 | In the future, this setting might control other things, such as converting |
| 303 | strings that look like integers or floats into integers or floats |
338 | strings that look like integers or floats into integers or floats |
| 304 | internally (there is no difference on the Perl level), saving space. |
339 | internally (there is no difference on the Perl level), saving space. |
|
|
340 | |
|
|
341 | =item $json = $json->max_depth ([$maximum_nesting_depth]) |
|
|
342 | |
|
|
343 | Sets the maximum nesting level (default C<512>) accepted while encoding |
|
|
344 | or decoding. If the JSON text or Perl data structure has an equal or |
|
|
345 | higher nesting level then this limit, then the encoder and decoder will |
|
|
346 | stop and croak at that point. |
|
|
347 | |
|
|
348 | Nesting level is defined by number of hash- or arrayrefs that the encoder |
|
|
349 | needs to traverse to reach a given point or the number of C<{> or C<[> |
|
|
350 | characters without their matching closing parenthesis crossed to reach a |
|
|
351 | given character in a string. |
|
|
352 | |
|
|
353 | Setting the maximum depth to one disallows any nesting, so that ensures |
|
|
354 | that the object is only a single hash/object or array. |
|
|
355 | |
|
|
356 | The argument to C<max_depth> will be rounded up to the next nearest power |
|
|
357 | of two. |
|
|
358 | |
|
|
359 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. |
| 305 | |
360 | |
| 306 | =item $json_text = $json->encode ($perl_scalar) |
361 | =item $json_text = $json->encode ($perl_scalar) |
| 307 | |
362 | |
| 308 | Converts the given Perl data structure (a simple scalar or a reference |
363 | Converts the given Perl data structure (a simple scalar or a reference |
| 309 | to a hash or array) to its JSON representation. Simple scalars will be |
364 | to a hash or array) to its JSON representation. Simple scalars will be |
| … | |
… | |
| 319 | |
374 | |
| 320 | JSON numbers and strings become simple Perl scalars. JSON arrays become |
375 | JSON numbers and strings become simple Perl scalars. JSON arrays become |
| 321 | Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes |
376 | Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes |
| 322 | C<1>, C<false> becomes C<0> and C<null> becomes C<undef>. |
377 | C<1>, C<false> becomes C<0> and C<null> becomes C<undef>. |
| 323 | |
378 | |
|
|
379 | =item ($perl_scalar, $characters) = $json->decode_prefix ($json_text) |
|
|
380 | |
|
|
381 | This works like the C<decode> method, but instead of raising an exception |
|
|
382 | when there is trailing garbage after the first JSON object, it will |
|
|
383 | silently stop parsing there and return the number of characters consumed |
|
|
384 | so far. |
|
|
385 | |
|
|
386 | This 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 |
|
|
388 | to know where the JSON text ends. |
|
|
389 | |
|
|
390 | JSON::XS->new->decode_prefix ("[1] the tail") |
|
|
391 | => ([], 3) |
|
|
392 | |
| 324 | =back |
393 | =back |
|
|
394 | |
| 325 | |
395 | |
| 326 | =head1 MAPPING |
396 | =head1 MAPPING |
| 327 | |
397 | |
| 328 | This section describes how JSON::XS maps Perl values to JSON values and |
398 | This section describes how JSON::XS maps Perl values to JSON values and |
| 329 | vice versa. These mappings are designed to "do the right thing" in most |
399 | vice versa. These mappings are designed to "do the right thing" in most |
| … | |
… | |
| 383 | =over 4 |
453 | =over 4 |
| 384 | |
454 | |
| 385 | =item hash references |
455 | =item hash references |
| 386 | |
456 | |
| 387 | Perl hash references become JSON objects. As there is no inherent ordering |
457 | Perl hash references become JSON objects. As there is no inherent ordering |
| 388 | in hash keys, they will usually be encoded in a pseudo-random order that |
458 | in hash keys (or JSON objects), they will usually be encoded in a |
| 389 | can change between runs of the same program but stays generally the same |
459 | pseudo-random order that can change between runs of the same program but |
| 390 | within a single run of a program. JSON::XS can optionally sort the hash |
460 | stays generally the same within a single run of a program. JSON::XS can |
| 391 | keys (determined by the I<canonical> flag), so the same datastructure |
461 | optionally sort the hash keys (determined by the I<canonical> flag), so |
| 392 | will serialise to the same JSON text (given same settings and version of |
462 | the same datastructure will serialise to the same JSON text (given same |
| 393 | JSON::XS), but this incurs a runtime overhead. |
463 | settings and version of JSON::XS), but this incurs a runtime overhead |
|
|
464 | and is only rarely useful, e.g. when you want to compare some JSON text |
|
|
465 | against another for equality. |
| 394 | |
466 | |
| 395 | =item array references |
467 | =item array references |
| 396 | |
468 | |
| 397 | Perl array references become JSON arrays. |
469 | Perl array references become JSON arrays. |
|
|
470 | |
|
|
471 | =item other references |
|
|
472 | |
|
|
473 | Other unblessed references are generally not allowed and will cause an |
|
|
474 | exception to be thrown, except for references to the integers C<0> and |
|
|
475 | 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. |
|
|
477 | |
|
|
478 | to_json [\0,JSON::XS::true] # yields [false,true] |
| 398 | |
479 | |
| 399 | =item blessed objects |
480 | =item blessed objects |
| 400 | |
481 | |
| 401 | Blessed objects are not allowed. JSON::XS currently tries to encode their |
482 | Blessed objects are not allowed. JSON::XS currently tries to encode their |
| 402 | underlying representation (hash- or arrayref), but this behaviour might |
483 | underlying representation (hash- or arrayref), but this behaviour might |
| … | |
… | |
| 435 | $x *= 1; # same thing, the choise is yours. |
516 | $x *= 1; # same thing, the choise is yours. |
| 436 | |
517 | |
| 437 | You can not currently output JSON booleans or force the type in other, |
518 | You can not currently output JSON booleans or force the type in other, |
| 438 | less obscure, ways. Tell me if you need this capability. |
519 | less obscure, ways. Tell me if you need this capability. |
| 439 | |
520 | |
| 440 | =item circular data structures |
|
|
| 441 | |
|
|
| 442 | Those will be encoded until memory or stackspace runs out. |
|
|
| 443 | |
|
|
| 444 | =back |
521 | =back |
|
|
522 | |
| 445 | |
523 | |
| 446 | =head1 COMPARISON |
524 | =head1 COMPARISON |
| 447 | |
525 | |
| 448 | As already mentioned, this module was created because none of the existing |
526 | As already mentioned, this module was created because none of the existing |
| 449 | JSON modules could be made to work correctly. First I will describe the |
527 | JSON modules could be made to work correctly. First I will describe the |
| … | |
… | |
| 534 | It seems that JSON::XS is surprisingly fast, as shown in the following |
612 | It seems that JSON::XS is surprisingly fast, as shown in the following |
| 535 | tables. They have been generated with the help of the C<eg/bench> program |
613 | tables. They have been generated with the help of the C<eg/bench> program |
| 536 | in the JSON::XS distribution, to make it easy to compare on your own |
614 | in the JSON::XS distribution, to make it easy to compare on your own |
| 537 | system. |
615 | system. |
| 538 | |
616 | |
| 539 | First comes a comparison between various modules using a very short JSON |
617 | First comes a comparison between various modules using a very short |
| 540 | string: |
618 | single-line JSON string: |
| 541 | |
619 | |
| 542 | {"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null} |
620 | {"method": "handleMessage", "params": ["user1", "we were just talking"], \ |
|
|
621 | "id": null, [1,11,234,-5,1e5,1e7, true, false]} |
| 543 | |
622 | |
| 544 | It shows the number of encodes/decodes per second (JSON::XS uses the |
623 | It shows the number of encodes/decodes per second (JSON::XS uses the |
| 545 | functional interface, while JSON::XS/2 uses the OO interface with |
624 | functional interface, while JSON::XS/2 uses the OO interface with |
| 546 | pretty-printing and hashkey sorting enabled). Higher is better: |
625 | pretty-printing and hashkey sorting enabled). Higher is better: |
| 547 | |
626 | |
|
|
627 | -----------+------------+------------+ |
| 548 | module | encode | decode | |
628 | module | encode | decode | |
| 549 | -----------|------------|------------| |
629 | -----------|------------|------------| |
| 550 | JSON | 11488.516 | 7823.035 | |
630 | JSON | 10597.029 | 5740.903 | |
| 551 | JSON::DWIW | 94708.054 | 129094.260 | |
631 | JSON::DWIW | 78251.940 | 98457.840 | |
| 552 | JSON::PC | 63884.157 | 128528.212 | |
632 | JSON::PC | 70611.178 | 92794.336 | |
| 553 | JSON::Syck | 34898.677 | 42096.911 | |
633 | JSON::Syck | 28767.517 | 38199.490 | |
| 554 | JSON::XS | 654027.064 | 396423.669 | |
634 | JSON::XS | 419430.400 | 265462.278 | |
| 555 | JSON::XS/2 | 371564.190 | 371725.613 | |
635 | JSON::XS/2 | 279620.267 | 265462.278 | |
|
|
636 | JSON::XS/3 | 388361.481 | 265462.278 | |
|
|
637 | Storable | 16294.887 | 16844.594 | |
| 556 | -----------+------------+------------+ |
638 | -----------+------------+------------+ |
| 557 | |
639 | |
| 558 | That is, JSON::XS is more than six times faster than JSON::DWIW on |
640 | That is, JSON::XS is about five times faster than JSON::DWIW on encoding, |
| 559 | encoding, more than three times faster on decoding, and about thirty times |
641 | about three times faster on decoding, and about fourty times faster |
| 560 | faster than JSON, even with pretty-printing and key sorting. |
642 | than JSON, even with pretty-printing and key sorting. It also compares |
|
|
643 | favourably to Storable for small amounts of data. |
| 561 | |
644 | |
| 562 | Using a longer test string (roughly 18KB, generated from Yahoo! Locals |
645 | Using a longer test string (roughly 18KB, generated from Yahoo! Locals |
| 563 | search API (http://nanoref.com/yahooapis/mgPdGg): |
646 | search API (http://nanoref.com/yahooapis/mgPdGg): |
| 564 | |
647 | |
| 565 | module | encode | decode | |
648 | module | encode | decode | |
| 566 | -----------|------------|------------| |
649 | -----------|------------|------------| |
| 567 | JSON | 273.023 | 44.674 | |
650 | JSON | 254.685 | 37.665 | |
| 568 | JSON::DWIW | 1089.383 | 1145.704 | |
651 | JSON::DWIW | 1014.244 | 1087.678 | |
| 569 | JSON::PC | 3097.419 | 2393.921 | |
652 | JSON::PC | 3602.116 | 2307.352 | |
| 570 | JSON::Syck | 514.060 | 843.053 | |
653 | JSON::Syck | 558.035 | 776.263 | |
| 571 | JSON::XS | 6479.668 | 3636.364 | |
654 | JSON::XS | 5747.196 | 3543.684 | |
| 572 | JSON::XS/2 | 3774.221 | 3599.124 | |
655 | JSON::XS/2 | 3968.121 | 3589.170 | |
|
|
656 | JSON::XS/3 | 6105.246 | 3561.134 | |
|
|
657 | Storable | 4456.337 | 5320.020 | |
| 573 | -----------+------------+------------+ |
658 | -----------+------------+------------+ |
| 574 | |
659 | |
| 575 | Again, JSON::XS leads by far. |
660 | Again, JSON::XS leads by far. |
| 576 | |
661 | |
| 577 | On large strings containing lots of high unicode characters, some modules |
662 | On large strings containing lots of high unicode characters, some modules |
| 578 | (such as JSON::PC) seem to decode faster than JSON::XS, but the result |
663 | (such as JSON::PC) seem to decode faster than JSON::XS, but the result |
| 579 | will be broken due to missing (or wrong) unicode handling. Others refuse |
664 | will be broken due to missing (or wrong) unicode handling. Others refuse |
| 580 | to decode or encode properly, so it was impossible to prepare a fair |
665 | to decode or encode properly, so it was impossible to prepare a fair |
| 581 | comparison table for that case. |
666 | comparison table for that case. |
| 582 | |
667 | |
| 583 | =head1 RESOURCE LIMITS |
|
|
| 584 | |
668 | |
| 585 | JSON::XS does not impose any limits on the size of JSON texts or Perl |
669 | =head1 SECURITY CONSIDERATIONS |
| 586 | values they represent - if your machine can handle it, JSON::XS will |
670 | |
| 587 | encode or decode it. Future versions might optionally impose structure |
671 | When you are using JSON in a protocol, talking to untrusted potentially |
| 588 | depth and memory use resource limits. |
672 | hostile creatures requires relatively few measures. |
|
|
673 | |
|
|
674 | First of all, your JSON decoder should be secure, that is, should not have |
|
|
675 | any buffer overflows. Obviously, this module should ensure that and I am |
|
|
676 | trying hard on making that true, but you never know. |
|
|
677 | |
|
|
678 | Second, you need to avoid resource-starving attacks. That means you should |
|
|
679 | limit the size of JSON texts you accept, or make sure then when your |
|
|
680 | resources run out, thats just fine (e.g. by using a separate process that |
|
|
681 | can crash safely). The size of a JSON text in octets or characters is |
|
|
682 | usually a good indication of the size of the resources required to decode |
|
|
683 | it into a Perl structure. |
|
|
684 | |
|
|
685 | Third, JSON::XS recurses using the C stack when decoding objects and |
|
|
686 | arrays. The C stack is a limited resource: for instance, on my amd64 |
|
|
687 | machine with 8MB of stack size I can decode around 180k nested arrays but |
|
|
688 | only 14k nested JSON objects (due to perl itself recursing deeply on croak |
|
|
689 | to free the temporary). If that is exceeded, the program crashes. to be |
|
|
690 | conservative, the default nesting limit is set to 512. If your process |
|
|
691 | has a smaller stack, you should adjust this setting accordingly with the |
|
|
692 | C<max_depth> method. |
|
|
693 | |
|
|
694 | And last but least, something else could bomb you that I forgot to think |
|
|
695 | of. In that case, you get to keep the pieces. I am always open for hints, |
|
|
696 | though... |
|
|
697 | |
| 589 | |
698 | |
| 590 | =head1 BUGS |
699 | =head1 BUGS |
| 591 | |
700 | |
| 592 | While the goal of this module is to be correct, that unfortunately does |
701 | While the goal of this module is to be correct, that unfortunately does |
| 593 | not mean its bug-free, only that I think its design is bug-free. It is |
702 | not mean its bug-free, only that I think its design is bug-free. It is |
| 594 | still very young and not well-tested. If you keep reporting bugs they will |
703 | still relatively early in its development. If you keep reporting bugs they |
| 595 | be fixed swiftly, though. |
704 | will be fixed swiftly, though. |
| 596 | |
705 | |
| 597 | =cut |
706 | =cut |
|
|
707 | |
|
|
708 | sub true() { \1 } |
|
|
709 | sub false() { \0 } |
| 598 | |
710 | |
| 599 | 1; |
711 | 1; |
| 600 | |
712 | |
| 601 | =head1 AUTHOR |
713 | =head1 AUTHOR |
| 602 | |
714 | |
