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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 1.43 by root, Sat Jun 23 23:49:29 2007 UTC

… …
85 85
86package JSON::XS; 86package JSON::XS;
87 87
88use strict; 88use strict;
89 89
90BEGIN {
91 our $VERSION = '1.12'; 90our $VERSION = '1.3';
92 our @ISA = qw(Exporter); 91our @ISA = qw(Exporter);
93 92
94 our @EXPORT = qw(to_json from_json objToJson jsonToObj); 93our @EXPORT = qw(to_json from_json objToJson jsonToObj);
95 require Exporter;
96 94
97 require XSLoader; 95use Exporter;
98 XSLoader::load JSON::XS::, $VERSION; 96use XSLoader;
99}
100 97
101=head1 FUNCTIONAL INTERFACE 98=head1 FUNCTIONAL INTERFACE
102 99
103The following convinience methods are provided by this module. They are 100The following convinience methods are provided by this module. They are
104exported by default: 101exported by default:
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126This function call is functionally identical to: 123This function call is functionally identical to:
127 124
128 $perl_scalar = JSON::XS->new->utf8->decode ($json_text) 125 $perl_scalar = JSON::XS->new->utf8->decode ($json_text)
129 126
130except being faster. 127except being faster.
128
129=item $is_boolean = JSON::XS::is_bool $scalar
130
131Returns true if the passed scalar represents either JSON::XS::true or
132JSON::XS::false, two constants that act like C<1> and C<0>, respectively
133and are used to represent JSON C<true> and C<false> values in Perl.
134
135See MAPPING, below, for more information on how JSON values are mapped to
136Perl.
131 137
132=back 138=back
133 139
134 140
135=head1 OBJECT-ORIENTED INTERFACE 141=head1 OBJECT-ORIENTED INTERFACE
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154 160
155If C<$enable> is true (or missing), then the C<encode> method will not 161If C<$enable> is true (or missing), then the C<encode> method will not
156generate characters outside the code range C<0..127> (which is ASCII). Any 162generate characters outside the code range C<0..127> (which is ASCII). Any
157unicode characters outside that range will be escaped using either a 163unicode characters outside that range will be escaped using either a
158single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, 164single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
159as per RFC4627. 165as per RFC4627. The resulting encoded JSON text can be treated as a native
166unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
167or any other superset of ASCII.
160 168
161If C<$enable> is false, then the C<encode> method will not escape Unicode 169If 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 170characters unless required by the JSON syntax or other flags. This results
163and more compact format. 171in a faster and more compact format.
172
173The main use for this flag is to produce JSON texts that can be
174transmitted over a 7-bit channel, as the encoded JSON texts will not
175contain any 8 bit characters.
164 176
165 JSON::XS->new->ascii (1)->encode ([chr 0x10401]) 177 JSON::XS->new->ascii (1)->encode ([chr 0x10401])
166 => ["\ud801\udc01"] 178 => ["\ud801\udc01"]
179
180=item $json = $json->latin1 ([$enable])
181
182If C<$enable> is true (or missing), then the C<encode> method will encode
183the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
184outside the code range C<0..255>. The resulting string can be treated as a
185latin1-encoded JSON text or a native unicode string. The C<decode> method
186will not be affected in any way by this flag, as C<decode> by default
187expects unicode, which is a strict superset of latin1.
188
189If C<$enable> is false, then the C<encode> method will not escape Unicode
190characters unless required by the JSON syntax or other flags.
191
192The main use for this flag is efficiently encoding binary data as JSON
193text, as most octets will not be escaped, resulting in a smaller encoded
194size. The disadvantage is that the resulting JSON text is encoded
195in latin1 (and must correctly be treated as such when storing and
196transfering), a rare encoding for JSON. It is therefore most useful when
197you want to store data structures known to contain binary data efficiently
198in files or databases, not when talking to other JSON encoders/decoders.
199
200 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
201 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
167 202
168=item $json = $json->utf8 ([$enable]) 203=item $json = $json->utf8 ([$enable])
169 204
170If C<$enable> is true (or missing), then the C<encode> method will encode 205If C<$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 206the JSON result into UTF-8, as required by many protocols, while the
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345 380
346JSON numbers and strings become simple Perl scalars. JSON arrays become 381JSON numbers and strings become simple Perl scalars. JSON arrays become
347Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes 382Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
348C<1>, C<false> becomes C<0> and C<null> becomes C<undef>. 383C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
349 384
385=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
386
387This works like the C<decode> method, but instead of raising an exception
388when there is trailing garbage after the first JSON object, it will
389silently stop parsing there and return the number of characters consumed
390so far.
391
392This is useful if your JSON texts are not delimited by an outer protocol
393(which is not the brightest thing to do in the first place) and you need
394to know where the JSON text ends.
395
396 JSON::XS->new->decode_prefix ("[1] the tail")
397 => ([], 3)
398
350=back 399=back
351 400
352 401
353=head1 MAPPING 402=head1 MAPPING
354 403
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358(what you put in comes out as something equivalent). 407(what you put in comes out as something equivalent).
359 408
360For the more enlightened: note that in the following descriptions, 409For the more enlightened: note that in the following descriptions,
361lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> 410lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl>
362refers to the abstract Perl language itself. 411refers to the abstract Perl language itself.
412
363 413
364=head2 JSON -> PERL 414=head2 JSON -> PERL
365 415
366=over 4 416=over 4
367 417
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388conversion details, but an integer may take slightly less memory and might 438conversion details, but an integer may take slightly less memory and might
389represent more values exactly than (floating point) numbers. 439represent more values exactly than (floating point) numbers.
390 440
391=item true, false 441=item true, false
392 442
393These JSON atoms become C<0>, C<1>, respectively. Information is lost in 443These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
394this process. Future versions might represent those values differently, 444respectively. They are overloaded to act almost exactly like the numbers
395but they will be guarenteed to act like these integers would normally in 445C<1> and C<0>. You can check wether a scalar is a JSON boolean by using
396Perl. 446the C<JSON::XS::is_bool> function.
397 447
398=item null 448=item null
399 449
400A JSON null atom becomes C<undef> in Perl. 450A JSON null atom becomes C<undef> in Perl.
401 451
402=back 452=back
453
403 454
404=head2 PERL -> JSON 455=head2 PERL -> JSON
405 456
406The mapping from Perl to JSON is slightly more difficult, as Perl is a 457The 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 458truly typeless language, so we can only guess which JSON type is meant by
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432C<1>, which get turned into C<false> and C<true> atoms in JSON. You can 483C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
433also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. 484also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
434 485
435 to_json [\0,JSON::XS::true] # yields [false,true] 486 to_json [\0,JSON::XS::true] # yields [false,true]
436 487
488=item JSON::XS::true, JSON::XS::false
489
490These special values become JSON true and JSON false values,
491respectively. You cna alos use C<\1> and C<\0> directly if you want.
492
437=item blessed objects 493=item blessed objects
438 494
439Blessed objects are not allowed. JSON::XS currently tries to encode their 495Blessed objects are not allowed. JSON::XS currently tries to encode their
440underlying representation (hash- or arrayref), but this behaviour might 496underlying representation (hash- or arrayref), but this behaviour might
441change in future versions. 497change in future versions.
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562 618
563Does not check input for validity. 619Does not check input for validity.
564 620
565=back 621=back
566 622
623
624=head2 JSON and YAML
625
626You often hear that JSON is a subset (or a close subset) of YAML. This is,
627however, a mass hysteria and very far from the truth. In general, there is
628no way to configure JSON::XS to output a data structure as valid YAML.
629
630If you really must use JSON::XS to generate YAML, you should use this
631algorithm (subject to change in future versions):
632
633 my $to_yaml = JSON::XS->new->utf8->space_after (1);
634 my $yaml = $to_yaml->encode ($ref) . "\n";
635
636This will usually generate JSON texts that also parse as valid
637YAML. Please note that YAML has hardcoded limits on (simple) object key
638lengths that JSON doesn't have, so you should make sure that your hash
639keys are noticably shorter than the 1024 characters YAML allows.
640
641There might be other incompatibilities that I am not aware of. In general
642you should not try to generate YAML with a JSON generator or vice versa,
643or try to parse JSON with a YAML parser or vice versa: chances are high
644that you will run into severe interoperability problems.
645
646
567=head2 SPEED 647=head2 SPEED
568 648
569It seems that JSON::XS is surprisingly fast, as shown in the following 649It 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 650tables. 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 651in the JSON::XS distribution, to make it easy to compare on your own
572system. 652system.
573 653
574First comes a comparison between various modules using a very short JSON 654First comes a comparison between various modules using a very short
575string: 655single-line JSON string:
576 656
577 {"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null} 657 {"method": "handleMessage", "params": ["user1", "we were just talking"], \
658 "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]}
578 659
579It shows the number of encodes/decodes per second (JSON::XS uses the 660It shows the number of encodes/decodes per second (JSON::XS uses
580functional interface, while JSON::XS/2 uses the OO interface with 661the functional interface, while JSON::XS/2 uses the OO interface
581pretty-printing and hashkey sorting enabled). Higher is better: 662with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
663shrink). Higher is better:
582 664
583 module | encode | decode | 665 module | encode | decode |
584 -----------|------------|------------| 666 -----------|------------|------------|
585 JSON | 11488.516 | 7823.035 | 667 JSON | 7645.468 | 4208.613 |
586 JSON::DWIW | 94708.054 | 129094.260 | 668 JSON::DWIW | 40721.398 | 77101.176 |
587 JSON::PC | 63884.157 | 128528.212 | 669 JSON::PC | 65948.176 | 78251.940 |
588 JSON::Syck | 34898.677 | 42096.911 | 670 JSON::Syck | 22844.793 | 26479.192 |
589 JSON::XS | 654027.064 | 396423.669 | 671 JSON::XS | 388361.481 | 199728.762 |
590 JSON::XS/2 | 371564.190 | 371725.613 | 672 JSON::XS/2 | 218453.333 | 192399.266 |
673 JSON::XS/3 | 338250.323 | 192399.266 |
674 Storable | 15779.925 | 14169.946 |
591 -----------+------------+------------+ 675 -----------+------------+------------+
592 676
593That is, JSON::XS is more than six times faster than JSON::DWIW on 677That 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 678about three times faster on decoding, and over fourty times faster
595faster than JSON, even with pretty-printing and key sorting. 679than JSON, even with pretty-printing and key sorting. It also compares
680favourably to Storable for small amounts of data.
596 681
597Using a longer test string (roughly 18KB, generated from Yahoo! Locals 682Using a longer test string (roughly 18KB, generated from Yahoo! Locals
598search API (http://nanoref.com/yahooapis/mgPdGg): 683search API (http://nanoref.com/yahooapis/mgPdGg):
599 684
600 module | encode | decode | 685 module | encode | decode |
601 -----------|------------|------------| 686 -----------|------------|------------|
602 JSON | 273.023 | 44.674 | 687 JSON | 254.685 | 37.665 |
603 JSON::DWIW | 1089.383 | 1145.704 | 688 JSON::DWIW | 843.343 | 1049.731 |
604 JSON::PC | 3097.419 | 2393.921 | 689 JSON::PC | 3602.116 | 2307.352 |
605 JSON::Syck | 514.060 | 843.053 | 690 JSON::Syck | 505.107 | 787.899 |
606 JSON::XS | 6479.668 | 3636.364 | 691 JSON::XS | 5747.196 | 3690.220 |
607 JSON::XS/2 | 3774.221 | 3599.124 | 692 JSON::XS/2 | 3968.121 | 3676.634 |
693 JSON::XS/3 | 6105.246 | 3662.508 |
694 Storable | 4417.337 | 5285.161 |
608 -----------+------------+------------+ 695 -----------+------------+------------+
609 696
610Again, JSON::XS leads by far. 697Again, JSON::XS leads by far (except for Storable which non-surprisingly
698decodes faster).
611 699
612On large strings containing lots of high unicode characters, some modules 700On 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 701(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 702will be broken due to missing (or wrong) unicode handling. Others refuse
615to decode or encode properly, so it was impossible to prepare a fair 703to decode or encode properly, so it was impossible to prepare a fair
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643 731
644And last but least, something else could bomb you that I forgot to think 732And last but least, something else could bomb you that I forgot to think
645of. In that case, you get to keep the pieces. I am always open for hints, 733of. In that case, you get to keep the pieces. I am always open for hints,
646though... 734though...
647 735
736If you are using JSON::XS to return packets to consumption
737by javascript scripts in a browser you should have a look at
738L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether
739you are vulnerable to some common attack vectors (which really are browser
740design bugs, but it is still you who will have to deal with it, as major
741browser developers care only for features, not about doing security
742right).
743
648 744
649=head1 BUGS 745=head1 BUGS
650 746
651While the goal of this module is to be correct, that unfortunately does 747While the goal of this module is to be correct, that unfortunately does
652not mean its bug-free, only that I think its design is bug-free. It is 748not mean its bug-free, only that I think its design is bug-free. It is
653still relatively early in its development. If you keep reporting bugs they 749still relatively early in its development. If you keep reporting bugs they
654will be fixed swiftly, though. 750will be fixed swiftly, though.
655 751
656=cut 752=cut
657 753
754our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
755our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
756
658sub true() { \1 } 757sub true() { $true }
659sub false() { \0 } 758sub false() { $false }
759
760sub is_bool($) {
761 UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
762 or UNIVERSAL::isa $_[0], "JSON::Literal"
763}
764
765XSLoader::load "JSON::XS", $VERSION;
766
767package JSON::XS::Boolean;
768
769use overload
770 "0+" => sub { ${$_[0]} },
771 "++" => sub { $_[0] = ${$_[0]} + 1 },
772 "--" => sub { $_[0] = ${$_[0]} - 1 },
773 fallback => 1;
660 774
6611; 7751;
662 776
663=head1 AUTHOR 777=head1 AUTHOR
664 778

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