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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 = '1.02'; |
91 | our $VERSION = '1.23'; |
92 | our @ISA = qw(Exporter); |
92 | our @ISA = qw(Exporter); |
93 | |
93 | |
94 | our @EXPORT = qw(to_json from_json objToJson jsonToObj); |
94 | our @EXPORT = qw(to_json from_json objToJson jsonToObj); |
95 | require Exporter; |
95 | require Exporter; |
96 | |
96 | |
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154 | |
154 | |
155 | If C<$enable> is true (or missing), then the C<encode> method will not |
155 | If C<$enable> is true (or missing), then the C<encode> method will not |
156 | generate characters outside the code range C<0..127> (which is ASCII). Any |
156 | generate characters outside the code range C<0..127> (which is ASCII). Any |
157 | unicode characters outside that range will be escaped using either a |
157 | unicode characters outside that range will be escaped using either a |
158 | single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, |
158 | single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, |
159 | as per RFC4627. |
159 | as per RFC4627. The resulting encoded JSON text can be treated as a native |
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160 | unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string, |
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161 | or any other superset of ASCII. |
160 | |
162 | |
161 | If C<$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 |
162 | 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 |
163 | and more compact format. |
165 | in a faster and more compact format. |
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166 | |
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167 | The main use for this flag is to produce JSON texts that can be |
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168 | transmitted over a 7-bit channel, as the encoded JSON texts will not |
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169 | contain 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"] |
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173 | |
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174 | =item $json = $json->latin1 ([$enable]) |
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175 | |
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176 | If C<$enable> is true (or missing), then the C<encode> method will encode |
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177 | the resulting JSON text as latin1 (or iso-8859-1), escaping any characters |
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178 | outside the code range C<0..255>. The resulting string can be treated as a |
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179 | latin1-encoded JSON text or a native unicode string. The C<decode> method |
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180 | will not be affected in any way by this flag, as C<decode> by default |
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181 | expects unicode, which is a strict superset of latin1. |
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182 | |
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183 | If C<$enable> is false, then the C<encode> method will not escape Unicode |
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184 | characters unless required by the JSON syntax or other flags. |
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185 | |
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186 | The main use for this flag is efficiently encoding binary data as JSON |
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187 | text, as most octets will not be escaped, resulting in a smaller encoded |
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188 | size. The disadvantage is that the resulting JSON text is encoded |
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189 | in latin1 (and must correctly be treated as such when storing and |
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190 | transfering), a rare encoding for JSON. It is therefore most useful when |
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191 | you want to store data structures known to contain binary data efficiently |
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192 | in files or databases, not when talking to other JSON encoders/decoders. |
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193 | |
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194 | JSON::XS->new->latin1->encode (["\x{89}\x{abc}"] |
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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 | |
170 | 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 |
171 | 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 |
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309 | strings that look like integers or floats into integers or floats |
338 | strings that look like integers or floats into integers or floats |
310 | internally (there is no difference on the Perl level), saving space. |
339 | internally (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 | |
314 | Sets the maximum nesting level (default C<4096>) accepted while encoding |
343 | Sets the maximum nesting level (default C<512>) accepted while encoding |
315 | or decoding. If the JSON text or Perl data structure has an equal or |
344 | or decoding. If the JSON text or Perl data structure has an equal or |
316 | higher nesting level then this limit, then the encoder and decoder will |
345 | higher nesting level then this limit, then the encoder and decoder will |
317 | stop and croak at that point. |
346 | stop and croak at that point. |
318 | |
347 | |
319 | Nesting level is defined by number of hash- or arrayrefs that the encoder |
348 | Nesting level is defined by number of hash- or arrayrefs that the encoder |
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345 | |
374 | |
346 | JSON numbers and strings become simple Perl scalars. JSON arrays become |
375 | JSON numbers and strings become simple Perl scalars. JSON arrays become |
347 | Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes |
376 | Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes |
348 | 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>. |
349 | |
378 | |
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379 | =item ($perl_scalar, $characters) = $json->decode_prefix ($json_text) |
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380 | |
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381 | This works like the C<decode> method, but instead of raising an exception |
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382 | when there is trailing garbage after the first JSON object, it will |
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383 | silently stop parsing there and return the number of characters consumed |
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384 | so far. |
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385 | |
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386 | This is useful if your JSON texts are not delimited by an outer protocol |
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387 | (which is not the brightest thing to do in the first place) and you need |
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388 | to know where the JSON text ends. |
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389 | |
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390 | JSON::XS->new->decode_prefix ("[1] the tail") |
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391 | => ([], 3) |
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392 | |
350 | =back |
393 | =back |
351 | |
394 | |
352 | |
395 | |
353 | =head1 MAPPING |
396 | =head1 MAPPING |
354 | |
397 | |
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358 | (what you put in comes out as something equivalent). |
401 | (what you put in comes out as something equivalent). |
359 | |
402 | |
360 | For the more enlightened: note that in the following descriptions, |
403 | For the more enlightened: note that in the following descriptions, |
361 | lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> |
404 | lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> |
362 | refers to the abstract Perl language itself. |
405 | refers to the abstract Perl language itself. |
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406 | |
363 | |
407 | |
364 | =head2 JSON -> PERL |
408 | =head2 JSON -> PERL |
365 | |
409 | |
366 | =over 4 |
410 | =over 4 |
367 | |
411 | |
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398 | =item null |
442 | =item null |
399 | |
443 | |
400 | A JSON null atom becomes C<undef> in Perl. |
444 | A JSON null atom becomes C<undef> in Perl. |
401 | |
445 | |
402 | =back |
446 | =back |
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447 | |
403 | |
448 | |
404 | =head2 PERL -> JSON |
449 | =head2 PERL -> JSON |
405 | |
450 | |
406 | The mapping from Perl to JSON is slightly more difficult, as Perl is a |
451 | The mapping from Perl to JSON is slightly more difficult, as Perl is a |
407 | truly typeless language, so we can only guess which JSON type is meant by |
452 | truly typeless language, so we can only guess which JSON type is meant by |
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562 | |
607 | |
563 | Does not check input for validity. |
608 | Does not check input for validity. |
564 | |
609 | |
565 | =back |
610 | =back |
566 | |
611 | |
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612 | |
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613 | =head2 JSON and YAML |
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614 | |
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615 | You often hear that JSON is a subset (or a close subset) of YAML. This is, |
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616 | however, a mass hysteria and very far from the truth. In general, there is |
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617 | no way to configure JSON::XS to output a data structure as valid YAML. |
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618 | |
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619 | If you really must use JSON::XS to generate YAML, you should this |
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620 | algorithm (subject to change in future versions): |
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621 | |
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622 | my $to_yaml = JSON::XS->new->utf8->space_after (1); |
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623 | my $yaml = $to_yaml->encode ($ref) . "\n"; |
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624 | |
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625 | This will usually generate JSON texts that also parse as valid |
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626 | YAML. Please note that YAML has hardcoded limits on object key lengths |
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627 | that JSON doesn't have, so you should make sure that your hash keys are |
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628 | noticably shorter than 1024 characters. |
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629 | |
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630 | There might be other incompatibilities that I am not aware of. In general |
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631 | you should not try to generate YAML with a JSON generator or vice versa, |
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632 | or try to parse JSON with a YAML parser or vice versa. |
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633 | |
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634 | |
567 | =head2 SPEED |
635 | =head2 SPEED |
568 | |
636 | |
569 | It seems that JSON::XS is surprisingly fast, as shown in the following |
637 | It seems that JSON::XS is surprisingly fast, as shown in the following |
570 | tables. They have been generated with the help of the C<eg/bench> program |
638 | tables. They have been generated with the help of the C<eg/bench> program |
571 | in the JSON::XS distribution, to make it easy to compare on your own |
639 | in the JSON::XS distribution, to make it easy to compare on your own |
572 | system. |
640 | system. |
573 | |
641 | |
574 | First comes a comparison between various modules using a very short JSON |
642 | First comes a comparison between various modules using a very short |
575 | string: |
643 | single-line JSON string: |
576 | |
644 | |
577 | {"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null} |
645 | {"method": "handleMessage", "params": ["user1", "we were just talking"], \ |
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646 | "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]} |
578 | |
647 | |
579 | It shows the number of encodes/decodes per second (JSON::XS uses the |
648 | It shows the number of encodes/decodes per second (JSON::XS uses |
580 | functional interface, while JSON::XS/2 uses the OO interface with |
649 | the functional interface, while JSON::XS/2 uses the OO interface |
581 | pretty-printing and hashkey sorting enabled). Higher is better: |
650 | with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables |
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651 | shrink). Higher is better: |
582 | |
652 | |
583 | module | encode | decode | |
653 | module | encode | decode | |
584 | -----------|------------|------------| |
654 | -----------|------------|------------| |
585 | JSON | 11488.516 | 7823.035 | |
655 | JSON | 7645.468 | 4208.613 | |
586 | JSON::DWIW | 94708.054 | 129094.260 | |
656 | JSON::DWIW | 68534.379 | 79437.576 | |
587 | JSON::PC | 63884.157 | 128528.212 | |
657 | JSON::PC | 65948.176 | 78251.940 | |
588 | JSON::Syck | 34898.677 | 42096.911 | |
658 | JSON::Syck | 23379.621 | 28416.694 | |
589 | JSON::XS | 654027.064 | 396423.669 | |
659 | JSON::XS | 388361.481 | 199728.762 | |
590 | JSON::XS/2 | 371564.190 | 371725.613 | |
660 | JSON::XS/2 | 218453.333 | 192399.266 | |
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661 | JSON::XS/3 | 338250.323 | 192399.266 | |
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662 | Storable | 15732.573 | 28571.553 | |
591 | -----------+------------+------------+ |
663 | -----------+------------+------------+ |
592 | |
664 | |
593 | That is, JSON::XS is more than six times faster than JSON::DWIW on |
665 | That is, JSON::XS is about five times faster than JSON::DWIW on encoding, |
594 | encoding, more than three times faster on decoding, and about thirty times |
666 | about three times faster on decoding, and over fourty times faster |
595 | faster than JSON, even with pretty-printing and key sorting. |
667 | than JSON, even with pretty-printing and key sorting. It also compares |
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668 | favourably to Storable for small amounts of data. |
596 | |
669 | |
597 | Using a longer test string (roughly 18KB, generated from Yahoo! Locals |
670 | Using a longer test string (roughly 18KB, generated from Yahoo! Locals |
598 | search API (http://nanoref.com/yahooapis/mgPdGg): |
671 | search API (http://nanoref.com/yahooapis/mgPdGg): |
599 | |
672 | |
600 | module | encode | decode | |
673 | module | encode | decode | |
601 | -----------|------------|------------| |
674 | -----------|------------|------------| |
602 | JSON | 273.023 | 44.674 | |
675 | JSON | 254.685 | 37.665 | |
603 | JSON::DWIW | 1089.383 | 1145.704 | |
676 | JSON::DWIW | 1014.244 | 1087.678 | |
604 | JSON::PC | 3097.419 | 2393.921 | |
677 | JSON::PC | 3602.116 | 2307.352 | |
605 | JSON::Syck | 514.060 | 843.053 | |
678 | JSON::Syck | 558.035 | 776.263 | |
606 | JSON::XS | 6479.668 | 3636.364 | |
679 | JSON::XS | 5747.196 | 3543.684 | |
607 | JSON::XS/2 | 3774.221 | 3599.124 | |
680 | JSON::XS/2 | 3968.121 | 3589.170 | |
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681 | JSON::XS/3 | 6105.246 | 3561.134 | |
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682 | Storable | 4456.337 | 5320.020 | |
608 | -----------+------------+------------+ |
683 | -----------+------------+------------+ |
609 | |
684 | |
610 | Again, JSON::XS leads by far. |
685 | Again, JSON::XS leads by far. |
611 | |
686 | |
612 | On large strings containing lots of high unicode characters, some modules |
687 | On large strings containing lots of high unicode characters, some modules |
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632 | usually a good indication of the size of the resources required to decode |
707 | usually a good indication of the size of the resources required to decode |
633 | it into a Perl structure. |
708 | it into a Perl structure. |
634 | |
709 | |
635 | Third, JSON::XS recurses using the C stack when decoding objects and |
710 | Third, JSON::XS recurses using the C stack when decoding objects and |
636 | arrays. The C stack is a limited resource: for instance, on my amd64 |
711 | arrays. The C stack is a limited resource: for instance, on my amd64 |
637 | machine with 8MB of stack size I can decode around 180k nested arrays |
712 | machine with 8MB of stack size I can decode around 180k nested arrays but |
638 | but only 14k nested JSON objects. If that is exceeded, the program |
713 | only 14k nested JSON objects (due to perl itself recursing deeply on croak |
639 | crashes. Thats why the default nesting limit is set to 4096. If your |
714 | to free the temporary). If that is exceeded, the program crashes. to be |
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715 | conservative, the default nesting limit is set to 512. If your process |
640 | process has a smaller stack, you should adjust this setting accordingly |
716 | has a smaller stack, you should adjust this setting accordingly with the |
641 | with the C<max_depth> method. |
717 | C<max_depth> method. |
642 | |
718 | |
643 | And last but least, something else could bomb you that I forgot to think |
719 | And last but least, something else could bomb you that I forgot to think |
644 | of. In that case, you get to keep the pieces. I am alway sopen for hints, |
720 | of. In that case, you get to keep the pieces. I am always open for hints, |
645 | though... |
721 | though... |
646 | |
722 | |
647 | |
723 | |
648 | =head1 BUGS |
724 | =head1 BUGS |
649 | |
725 | |