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Comparing JSON-XS/XS.pm (file contents):
Revision 1.67 by root, Mon Oct 15 01:22:34 2007 UTC vs.
Revision 1.77 by root, Tue Dec 4 10:37:42 2007 UTC

19 19
20 $coder = JSON::XS->new->ascii->pretty->allow_nonref; 20 $coder = JSON::XS->new->ascii->pretty->allow_nonref;
21 $pretty_printed_unencoded = $coder->encode ($perl_scalar); 21 $pretty_printed_unencoded = $coder->encode ($perl_scalar);
22 $perl_scalar = $coder->decode ($unicode_json_text); 22 $perl_scalar = $coder->decode ($unicode_json_text);
23 23
24 # Note that JSON version 2.0 and above will automatically use JSON::XS
25 # if available, at virtually no speed overhead either, so you should
26 # be able to just:
27
28 use JSON;
29
30 # and do the same things, except that you have a pure-perl fallback now.
31
24=head1 DESCRIPTION 32=head1 DESCRIPTION
25 33
26This module converts Perl data structures to JSON and vice versa. Its 34This module converts Perl data structures to JSON and vice versa. Its
27primary goal is to be I<correct> and its secondary goal is to be 35primary goal is to be I<correct> and its secondary goal is to be
28I<fast>. To reach the latter goal it was written in C. 36I<fast>. To reach the latter goal it was written in C.
37
38Beginning with version 2.0 of the JSON module, when both JSON and
39JSON::XS are installed, then JSON will fall back on JSON::XS (this can be
40overriden) with no overhead due to emulation (by inheritign constructor
41and methods). If JSON::XS is not available, it will fall back to the
42compatible JSON::PP module as backend, so using JSON instead of JSON::XS
43gives you a portable JSON API that can be fast when you need and doesn't
44require a C compiler when that is a problem.
29 45
30As this is the n-th-something JSON module on CPAN, what was the reason 46As this is the n-th-something JSON module on CPAN, what was the reason
31to write yet another JSON module? While it seems there are many JSON 47to write yet another JSON module? While it seems there are many JSON
32modules, none of them correctly handle all corner cases, and in most cases 48modules, none of them correctly handle all corner cases, and in most cases
33their maintainers are unresponsive, gone missing, or not listening to bug 49their maintainers are unresponsive, gone missing, or not listening to bug
40 56
41=head2 FEATURES 57=head2 FEATURES
42 58
43=over 4 59=over 4
44 60
45=item * correct unicode handling 61=item * correct Unicode handling
46 62
47This module knows how to handle Unicode, and even documents how and when 63This module knows how to handle Unicode, and even documents how and when
48it does so. 64it does so.
49 65
50=item * round-trip integrity 66=item * round-trip integrity
70This module has both a simple functional interface as well as an OO 86This module has both a simple functional interface as well as an OO
71interface. 87interface.
72 88
73=item * reasonably versatile output formats 89=item * reasonably versatile output formats
74 90
75You can choose between the most compact guarenteed single-line format 91You can choose between the most compact guaranteed single-line format
76possible (nice for simple line-based protocols), a pure-ascii format 92possible (nice for simple line-based protocols), a pure-ascii format
77(for when your transport is not 8-bit clean, still supports the whole 93(for when your transport is not 8-bit clean, still supports the whole
78unicode range), or a pretty-printed format (for when you want to read that 94Unicode range), or a pretty-printed format (for when you want to read that
79stuff). Or you can combine those features in whatever way you like. 95stuff). Or you can combine those features in whatever way you like.
80 96
81=back 97=back
82 98
83=cut 99=cut
84 100
85package JSON::XS; 101package JSON::XS;
86 102
87use strict; 103use strict;
88 104
89our $VERSION = '1.52'; 105our $VERSION = '2.0';
90our @ISA = qw(Exporter); 106our @ISA = qw(Exporter);
91 107
92our @EXPORT = qw(to_json from_json); 108our @EXPORT = qw(to_json from_json);
93 109
94use Exporter; 110use Exporter;
95use XSLoader; 111use XSLoader;
96 112
97=head1 FUNCTIONAL INTERFACE 113=head1 FUNCTIONAL INTERFACE
98 114
99The following convinience methods are provided by this module. They are 115The following convenience methods are provided by this module. They are
100exported by default: 116exported by default:
101 117
102=over 4 118=over 4
103 119
104=item $json_text = to_json $perl_scalar 120=item $json_text = to_json $perl_scalar
143 159
144=over 4 160=over 4
145 161
146=item 1. Perl strings can store characters with ordinal values > 255. 162=item 1. Perl strings can store characters with ordinal values > 255.
147 163
148This enables you to store unicode characters as single characters in a 164This enables you to store Unicode characters as single characters in a
149Perl string - very natural. 165Perl string - very natural.
150 166
151=item 2. Perl does I<not> associate an encoding with your strings. 167=item 2. Perl does I<not> associate an encoding with your strings.
152 168
153Unless you force it to, e.g. when matching it against a regex, or printing 169Unless you force it to, e.g. when matching it against a regex, or printing
160encoding of your string. 176encoding of your string.
161 177
162Just ignore that flag unless you debug a Perl bug, a module written in 178Just ignore that flag unless you debug a Perl bug, a module written in
163XS or want to dive into the internals of perl. Otherwise it will only 179XS or want to dive into the internals of perl. Otherwise it will only
164confuse you, as, despite the name, it says nothing about how your string 180confuse you, as, despite the name, it says nothing about how your string
165is encoded. You can have unicode strings with that flag set, with that 181is encoded. You can have Unicode strings with that flag set, with that
166flag clear, and you can have binary data with that flag set and that flag 182flag clear, and you can have binary data with that flag set and that flag
167clear. Other possibilities exist, too. 183clear. Other possibilities exist, too.
168 184
169If you didn't know about that flag, just the better, pretend it doesn't 185If you didn't know about that flag, just the better, pretend it doesn't
170exist. 186exist.
175If you have UTF-8 encoded data, it is no longer a Unicode string, but a 191If you have UTF-8 encoded data, it is no longer a Unicode string, but a
176Unicode string encoded in UTF-8, giving you a binary string. 192Unicode string encoded in UTF-8, giving you a binary string.
177 193
178=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string. 194=item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string.
179 195
180Its a fact. Learn to live with it. 196It's a fact. Learn to live with it.
181 197
182=back 198=back
183 199
184I hope this helps :) 200I hope this helps :)
185 201
202 my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]}) 218 my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]})
203 => {"a": [1, 2]} 219 => {"a": [1, 2]}
204 220
205=item $json = $json->ascii ([$enable]) 221=item $json = $json->ascii ([$enable])
206 222
223=item $enabled = $json->get_ascii
224
207If C<$enable> is true (or missing), then the C<encode> method will not 225If C<$enable> is true (or missing), then the C<encode> method will not
208generate characters outside the code range C<0..127> (which is ASCII). Any 226generate characters outside the code range C<0..127> (which is ASCII). Any
209unicode characters outside that range will be escaped using either a 227Unicode characters outside that range will be escaped using either a
210single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, 228single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
211as per RFC4627. The resulting encoded JSON text can be treated as a native 229as per RFC4627. The resulting encoded JSON text can be treated as a native
212unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string, 230Unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string,
213or any other superset of ASCII. 231or any other superset of ASCII.
214 232
215If C<$enable> is false, then the C<encode> method will not escape Unicode 233If C<$enable> is false, then the C<encode> method will not escape Unicode
216characters unless required by the JSON syntax or other flags. This results 234characters unless required by the JSON syntax or other flags. This results
217in a faster and more compact format. 235in a faster and more compact format.
223 JSON::XS->new->ascii (1)->encode ([chr 0x10401]) 241 JSON::XS->new->ascii (1)->encode ([chr 0x10401])
224 => ["\ud801\udc01"] 242 => ["\ud801\udc01"]
225 243
226=item $json = $json->latin1 ([$enable]) 244=item $json = $json->latin1 ([$enable])
227 245
246=item $enabled = $json->get_latin1
247
228If C<$enable> is true (or missing), then the C<encode> method will encode 248If C<$enable> is true (or missing), then the C<encode> method will encode
229the resulting JSON text as latin1 (or iso-8859-1), escaping any characters 249the resulting JSON text as latin1 (or iso-8859-1), escaping any characters
230outside the code range C<0..255>. The resulting string can be treated as a 250outside the code range C<0..255>. The resulting string can be treated as a
231latin1-encoded JSON text or a native unicode string. The C<decode> method 251latin1-encoded JSON text or a native Unicode string. The C<decode> method
232will not be affected in any way by this flag, as C<decode> by default 252will not be affected in any way by this flag, as C<decode> by default
233expects unicode, which is a strict superset of latin1. 253expects Unicode, which is a strict superset of latin1.
234 254
235If C<$enable> is false, then the C<encode> method will not escape Unicode 255If C<$enable> is false, then the C<encode> method will not escape Unicode
236characters unless required by the JSON syntax or other flags. 256characters unless required by the JSON syntax or other flags.
237 257
238The main use for this flag is efficiently encoding binary data as JSON 258The main use for this flag is efficiently encoding binary data as JSON
239text, as most octets will not be escaped, resulting in a smaller encoded 259text, as most octets will not be escaped, resulting in a smaller encoded
240size. The disadvantage is that the resulting JSON text is encoded 260size. The disadvantage is that the resulting JSON text is encoded
241in latin1 (and must correctly be treated as such when storing and 261in latin1 (and must correctly be treated as such when storing and
242transfering), a rare encoding for JSON. It is therefore most useful when 262transferring), a rare encoding for JSON. It is therefore most useful when
243you want to store data structures known to contain binary data efficiently 263you want to store data structures known to contain binary data efficiently
244in files or databases, not when talking to other JSON encoders/decoders. 264in files or databases, not when talking to other JSON encoders/decoders.
245 265
246 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"] 266 JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
247 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not) 267 => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
248 268
249=item $json = $json->utf8 ([$enable]) 269=item $json = $json->utf8 ([$enable])
270
271=item $enabled = $json->get_utf8
250 272
251If C<$enable> is true (or missing), then the C<encode> method will encode 273If C<$enable> is true (or missing), then the C<encode> method will encode
252the JSON result into UTF-8, as required by many protocols, while the 274the JSON result into UTF-8, as required by many protocols, while the
253C<decode> method expects to be handled an UTF-8-encoded string. Please 275C<decode> method expects to be handled an UTF-8-encoded string. Please
254note that UTF-8-encoded strings do not contain any characters outside the 276note that UTF-8-encoded strings do not contain any characters outside the
255range C<0..255>, they are thus useful for bytewise/binary I/O. In future 277range C<0..255>, they are thus useful for bytewise/binary I/O. In future
256versions, enabling this option might enable autodetection of the UTF-16 278versions, enabling this option might enable autodetection of the UTF-16
257and UTF-32 encoding families, as described in RFC4627. 279and UTF-32 encoding families, as described in RFC4627.
258 280
259If C<$enable> is false, then the C<encode> method will return the JSON 281If C<$enable> is false, then the C<encode> method will return the JSON
260string as a (non-encoded) unicode string, while C<decode> expects thus a 282string as a (non-encoded) Unicode string, while C<decode> expects thus a
261unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs 283Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs
262to be done yourself, e.g. using the Encode module. 284to be done yourself, e.g. using the Encode module.
263 285
264Example, output UTF-16BE-encoded JSON: 286Example, output UTF-16BE-encoded JSON:
265 287
266 use Encode; 288 use Encode;
288 ] 310 ]
289 } 311 }
290 312
291=item $json = $json->indent ([$enable]) 313=item $json = $json->indent ([$enable])
292 314
315=item $enabled = $json->get_indent
316
293If C<$enable> is true (or missing), then the C<encode> method will use a multiline 317If C<$enable> is true (or missing), then the C<encode> method will use a multiline
294format as output, putting every array member or object/hash key-value pair 318format as output, putting every array member or object/hash key-value pair
295into its own line, identing them properly. 319into its own line, indenting them properly.
296 320
297If C<$enable> is false, no newlines or indenting will be produced, and the 321If C<$enable> is false, no newlines or indenting will be produced, and the
298resulting JSON text is guarenteed not to contain any C<newlines>. 322resulting JSON text is guaranteed not to contain any C<newlines>.
299 323
300This setting has no effect when decoding JSON texts. 324This setting has no effect when decoding JSON texts.
301 325
302=item $json = $json->space_before ([$enable]) 326=item $json = $json->space_before ([$enable])
327
328=item $enabled = $json->get_space_before
303 329
304If C<$enable> is true (or missing), then the C<encode> method will add an extra 330If C<$enable> is true (or missing), then the C<encode> method will add an extra
305optional space before the C<:> separating keys from values in JSON objects. 331optional space before the C<:> separating keys from values in JSON objects.
306 332
307If C<$enable> is false, then the C<encode> method will not add any extra 333If C<$enable> is false, then the C<encode> method will not add any extra
313Example, space_before enabled, space_after and indent disabled: 339Example, space_before enabled, space_after and indent disabled:
314 340
315 {"key" :"value"} 341 {"key" :"value"}
316 342
317=item $json = $json->space_after ([$enable]) 343=item $json = $json->space_after ([$enable])
344
345=item $enabled = $json->get_space_after
318 346
319If C<$enable> is true (or missing), then the C<encode> method will add an extra 347If C<$enable> is true (or missing), then the C<encode> method will add an extra
320optional space after the C<:> separating keys from values in JSON objects 348optional space after the C<:> separating keys from values in JSON objects
321and extra whitespace after the C<,> separating key-value pairs and array 349and extra whitespace after the C<,> separating key-value pairs and array
322members. 350members.
329Example, space_before and indent disabled, space_after enabled: 357Example, space_before and indent disabled, space_after enabled:
330 358
331 {"key": "value"} 359 {"key": "value"}
332 360
333=item $json = $json->relaxed ([$enable]) 361=item $json = $json->relaxed ([$enable])
362
363=item $enabled = $json->get_relaxed
334 364
335If C<$enable> is true (or missing), then C<decode> will accept some 365If C<$enable> is true (or missing), then C<decode> will accept some
336extensions to normal JSON syntax (see below). C<encode> will not be 366extensions to normal JSON syntax (see below). C<encode> will not be
337affected in anyway. I<Be aware that this option makes you accept invalid 367affected in anyway. I<Be aware that this option makes you accept invalid
338JSON texts as if they were valid!>. I suggest only to use this option to 368JSON texts as if they were valid!>. I suggest only to use this option to
375 405
376=back 406=back
377 407
378=item $json = $json->canonical ([$enable]) 408=item $json = $json->canonical ([$enable])
379 409
410=item $enabled = $json->get_canonical
411
380If C<$enable> is true (or missing), then the C<encode> method will output JSON objects 412If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
381by sorting their keys. This is adding a comparatively high overhead. 413by sorting their keys. This is adding a comparatively high overhead.
382 414
383If C<$enable> is false, then the C<encode> method will output key-value 415If C<$enable> is false, then the C<encode> method will output key-value
384pairs in the order Perl stores them (which will likely change between runs 416pairs in the order Perl stores them (which will likely change between runs
385of the same script). 417of the same script).
386 418
387This option is useful if you want the same data structure to be encoded as 419This option is useful if you want the same data structure to be encoded as
388the same JSON text (given the same overall settings). If it is disabled, 420the same JSON text (given the same overall settings). If it is disabled,
389the same hash migh be encoded differently even if contains the same data, 421the same hash might be encoded differently even if contains the same data,
390as key-value pairs have no inherent ordering in Perl. 422as key-value pairs have no inherent ordering in Perl.
391 423
392This setting has no effect when decoding JSON texts. 424This setting has no effect when decoding JSON texts.
393 425
394=item $json = $json->allow_nonref ([$enable]) 426=item $json = $json->allow_nonref ([$enable])
427
428=item $enabled = $json->get_allow_nonref
395 429
396If C<$enable> is true (or missing), then the C<encode> method can convert a 430If C<$enable> is true (or missing), then the C<encode> method can convert a
397non-reference into its corresponding string, number or null JSON value, 431non-reference into its corresponding string, number or null JSON value,
398which is an extension to RFC4627. Likewise, C<decode> will accept those JSON 432which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
399values instead of croaking. 433values instead of croaking.
409 JSON::XS->new->allow_nonref->encode ("Hello, World!") 443 JSON::XS->new->allow_nonref->encode ("Hello, World!")
410 => "Hello, World!" 444 => "Hello, World!"
411 445
412=item $json = $json->allow_blessed ([$enable]) 446=item $json = $json->allow_blessed ([$enable])
413 447
448=item $enabled = $json->get_allow_blessed
449
414If C<$enable> is true (or missing), then the C<encode> method will not 450If C<$enable> is true (or missing), then the C<encode> method will not
415barf when it encounters a blessed reference. Instead, the value of the 451barf when it encounters a blessed reference. Instead, the value of the
416B<convert_blessed> option will decide wether C<null> (C<convert_blessed> 452B<convert_blessed> option will decide whether C<null> (C<convert_blessed>
417disabled or no C<to_json> method found) or a representation of the 453disabled or no C<TO_JSON> method found) or a representation of the
418object (C<convert_blessed> enabled and C<to_json> method found) is being 454object (C<convert_blessed> enabled and C<TO_JSON> method found) is being
419encoded. Has no effect on C<decode>. 455encoded. Has no effect on C<decode>.
420 456
421If C<$enable> is false (the default), then C<encode> will throw an 457If C<$enable> is false (the default), then C<encode> will throw an
422exception when it encounters a blessed object. 458exception when it encounters a blessed object.
423 459
424=item $json = $json->convert_blessed ([$enable]) 460=item $json = $json->convert_blessed ([$enable])
461
462=item $enabled = $json->get_convert_blessed
425 463
426If C<$enable> is true (or missing), then C<encode>, upon encountering a 464If C<$enable> is true (or missing), then C<encode>, upon encountering a
427blessed object, will check for the availability of the C<TO_JSON> method 465blessed object, will check for the availability of the C<TO_JSON> method
428on the object's class. If found, it will be called in scalar context 466on the object's class. If found, it will be called in scalar context
429and the resulting scalar will be encoded instead of the object. If no 467and the resulting scalar will be encoded instead of the object. If no
486 524
487As this callback gets called less often then the C<filter_json_object> 525As this callback gets called less often then the C<filter_json_object>
488one, decoding speed will not usually suffer as much. Therefore, single-key 526one, decoding speed will not usually suffer as much. Therefore, single-key
489objects make excellent targets to serialise Perl objects into, especially 527objects make excellent targets to serialise Perl objects into, especially
490as single-key JSON objects are as close to the type-tagged value concept 528as single-key JSON objects are as close to the type-tagged value concept
491as JSON gets (its basically an ID/VALUE tuple). Of course, JSON does not 529as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not
492support this in any way, so you need to make sure your data never looks 530support this in any way, so you need to make sure your data never looks
493like a serialised Perl hash. 531like a serialised Perl hash.
494 532
495Typical names for the single object key are C<__class_whatever__>, or 533Typical names for the single object key are C<__class_whatever__>, or
496C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even 534C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even
520 558
521 { __widget__ => $self->{id} } 559 { __widget__ => $self->{id} }
522 } 560 }
523 561
524=item $json = $json->shrink ([$enable]) 562=item $json = $json->shrink ([$enable])
563
564=item $enabled = $json->get_shrink
525 565
526Perl usually over-allocates memory a bit when allocating space for 566Perl usually over-allocates memory a bit when allocating space for
527strings. This flag optionally resizes strings generated by either 567strings. This flag optionally resizes strings generated by either
528C<encode> or C<decode> to their minimum size possible. This can save 568C<encode> or C<decode> to their minimum size possible. This can save
529memory when your JSON texts are either very very long or you have many 569memory when your JSON texts are either very very long or you have many
547strings that look like integers or floats into integers or floats 587strings that look like integers or floats into integers or floats
548internally (there is no difference on the Perl level), saving space. 588internally (there is no difference on the Perl level), saving space.
549 589
550=item $json = $json->max_depth ([$maximum_nesting_depth]) 590=item $json = $json->max_depth ([$maximum_nesting_depth])
551 591
592=item $max_depth = $json->get_max_depth
593
552Sets the maximum nesting level (default C<512>) accepted while encoding 594Sets the maximum nesting level (default C<512>) accepted while encoding
553or decoding. If the JSON text or Perl data structure has an equal or 595or decoding. If the JSON text or Perl data structure has an equal or
554higher nesting level then this limit, then the encoder and decoder will 596higher nesting level then this limit, then the encoder and decoder will
555stop and croak at that point. 597stop and croak at that point.
556 598
567used, which is rarely useful. 609used, which is rarely useful.
568 610
569See SECURITY CONSIDERATIONS, below, for more info on why this is useful. 611See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
570 612
571=item $json = $json->max_size ([$maximum_string_size]) 613=item $json = $json->max_size ([$maximum_string_size])
614
615=item $max_size = $json->get_max_size
572 616
573Set the maximum length a JSON text may have (in bytes) where decoding is 617Set the maximum length a JSON text may have (in bytes) where decoding is
574being attempted. The default is C<0>, meaning no limit. When C<decode> 618being attempted. The default is C<0>, meaning no limit. When C<decode>
575is called on a string longer then this number of characters it will not 619is called on a string longer then this number of characters it will not
576attempt to decode the string but throw an exception. This setting has no 620attempt to decode the string but throw an exception. This setting has no
623vice versa. These mappings are designed to "do the right thing" in most 667vice versa. These mappings are designed to "do the right thing" in most
624circumstances automatically, preserving round-tripping characteristics 668circumstances automatically, preserving round-tripping characteristics
625(what you put in comes out as something equivalent). 669(what you put in comes out as something equivalent).
626 670
627For the more enlightened: note that in the following descriptions, 671For the more enlightened: note that in the following descriptions,
628lowercase I<perl> refers to the Perl interpreter, while uppcercase I<Perl> 672lowercase I<perl> refers to the Perl interpreter, while uppercase I<Perl>
629refers to the abstract Perl language itself. 673refers to the abstract Perl language itself.
630 674
631 675
632=head2 JSON -> PERL 676=head2 JSON -> PERL
633 677
634=over 4 678=over 4
635 679
636=item object 680=item object
637 681
638A JSON object becomes a reference to a hash in Perl. No ordering of object 682A JSON object becomes a reference to a hash in Perl. No ordering of object
639keys is preserved (JSON does not preserver object key ordering itself). 683keys is preserved (JSON does not preserve object key ordering itself).
640 684
641=item array 685=item array
642 686
643A JSON array becomes a reference to an array in Perl. 687A JSON array becomes a reference to an array in Perl.
644 688
670 714
671=item true, false 715=item true, false
672 716
673These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>, 717These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
674respectively. They are overloaded to act almost exactly like the numbers 718respectively. They are overloaded to act almost exactly like the numbers
675C<1> and C<0>. You can check wether a scalar is a JSON boolean by using 719C<1> and C<0>. You can check whether a scalar is a JSON boolean by using
676the C<JSON::XS::is_bool> function. 720the C<JSON::XS::is_bool> function.
677 721
678=item null 722=item null
679 723
680A JSON null atom becomes C<undef> in Perl. 724A JSON null atom becomes C<undef> in Perl.
743 to_json [$value] # yields ["5"] 787 to_json [$value] # yields ["5"]
744 788
745 # undef becomes null 789 # undef becomes null
746 to_json [undef] # yields [null] 790 to_json [undef] # yields [null]
747 791
748You can force the type to be a string by stringifying it: 792You can force the type to be a JSON string by stringifying it:
749 793
750 my $x = 3.1; # some variable containing a number 794 my $x = 3.1; # some variable containing a number
751 "$x"; # stringified 795 "$x"; # stringified
752 $x .= ""; # another, more awkward way to stringify 796 $x .= ""; # another, more awkward way to stringify
753 print $x; # perl does it for you, too, quite often 797 print $x; # perl does it for you, too, quite often
754 798
755You can force the type to be a number by numifying it: 799You can force the type to be a JSON number by numifying it:
756 800
757 my $x = "3"; # some variable containing a string 801 my $x = "3"; # some variable containing a string
758 $x += 0; # numify it, ensuring it will be dumped as a number 802 $x += 0; # numify it, ensuring it will be dumped as a number
759 $x *= 1; # same thing, the choise is yours. 803 $x *= 1; # same thing, the choice is yours.
760 804
761You can not currently output JSON booleans or force the type in other, 805You can not currently force the type in other, less obscure, ways. Tell me
762less obscure, ways. Tell me if you need this capability. 806if you need this capability.
763 807
764=back 808=back
765 809
766 810
767=head1 COMPARISON 811=head1 COMPARISON
776 820
777=item JSON 1.07 821=item JSON 1.07
778 822
779Slow (but very portable, as it is written in pure Perl). 823Slow (but very portable, as it is written in pure Perl).
780 824
781Undocumented/buggy Unicode handling (how JSON handles unicode values is 825Undocumented/buggy Unicode handling (how JSON handles Unicode values is
782undocumented. One can get far by feeding it unicode strings and doing 826undocumented. One can get far by feeding it Unicode strings and doing
783en-/decoding oneself, but unicode escapes are not working properly). 827en-/decoding oneself, but Unicode escapes are not working properly).
784 828
785No roundtripping (strings get clobbered if they look like numbers, e.g. 829No round-tripping (strings get clobbered if they look like numbers, e.g.
786the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will 830the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will
787decode into the number 2. 831decode into the number 2.
788 832
789=item JSON::PC 0.01 833=item JSON::PC 0.01
790 834
791Very fast. 835Very fast.
792 836
793Undocumented/buggy Unicode handling. 837Undocumented/buggy Unicode handling.
794 838
795No roundtripping. 839No round-tripping.
796 840
797Has problems handling many Perl values (e.g. regex results and other magic 841Has problems handling many Perl values (e.g. regex results and other magic
798values will make it croak). 842values will make it croak).
799 843
800Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}> 844Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}>
810Very inflexible (no human-readable format supported, format pretty much 854Very inflexible (no human-readable format supported, format pretty much
811undocumented. I need at least a format for easy reading by humans and a 855undocumented. I need at least a format for easy reading by humans and a
812single-line compact format for use in a protocol, and preferably a way to 856single-line compact format for use in a protocol, and preferably a way to
813generate ASCII-only JSON texts). 857generate ASCII-only JSON texts).
814 858
815Completely broken (and confusingly documented) Unicode handling (unicode 859Completely broken (and confusingly documented) Unicode handling (Unicode
816escapes are not working properly, you need to set ImplicitUnicode to 860escapes are not working properly, you need to set ImplicitUnicode to
817I<different> values on en- and decoding to get symmetric behaviour). 861I<different> values on en- and decoding to get symmetric behaviour).
818 862
819No roundtripping (simple cases work, but this depends on wether the scalar 863No round-tripping (simple cases work, but this depends on whether the scalar
820value was used in a numeric context or not). 864value was used in a numeric context or not).
821 865
822Dumping hashes may skip hash values depending on iterator state. 866Dumping hashes may skip hash values depending on iterator state.
823 867
824Unmaintained (maintainer unresponsive for many months, bugs are not 868Unmaintained (maintainer unresponsive for many months, bugs are not
825getting fixed). 869getting fixed).
826 870
827Does not check input for validity (i.e. will accept non-JSON input and 871Does not check input for validity (i.e. will accept non-JSON input and
828return "something" instead of raising an exception. This is a security 872return "something" instead of raising an exception. This is a security
829issue: imagine two banks transfering money between each other using 873issue: imagine two banks transferring money between each other using
830JSON. One bank might parse a given non-JSON request and deduct money, 874JSON. One bank might parse a given non-JSON request and deduct money,
831while the other might reject the transaction with a syntax error. While a 875while the other might reject the transaction with a syntax error. While a
832good protocol will at least recover, that is extra unnecessary work and 876good protocol will at least recover, that is extra unnecessary work and
833the transaction will still not succeed). 877the transaction will still not succeed).
834 878
835=item JSON::DWIW 0.04 879=item JSON::DWIW 0.04
836 880
837Very fast. Very natural. Very nice. 881Very fast. Very natural. Very nice.
838 882
839Undocumented unicode handling (but the best of the pack. Unicode escapes 883Undocumented Unicode handling (but the best of the pack. Unicode escapes
840still don't get parsed properly). 884still don't get parsed properly).
841 885
842Very inflexible. 886Very inflexible.
843 887
844No roundtripping. 888No round-tripping.
845 889
846Does not generate valid JSON texts (key strings are often unquoted, empty keys 890Does not generate valid JSON texts (key strings are often unquoted, empty keys
847result in nothing being output) 891result in nothing being output)
848 892
849Does not check input for validity. 893Does not check input for validity.
864 my $yaml = $to_yaml->encode ($ref) . "\n"; 908 my $yaml = $to_yaml->encode ($ref) . "\n";
865 909
866This will usually generate JSON texts that also parse as valid 910This will usually generate JSON texts that also parse as valid
867YAML. Please note that YAML has hardcoded limits on (simple) object key 911YAML. Please note that YAML has hardcoded limits on (simple) object key
868lengths that JSON doesn't have, so you should make sure that your hash 912lengths that JSON doesn't have, so you should make sure that your hash
869keys are noticably shorter than the 1024 characters YAML allows. 913keys are noticeably shorter than the 1024 characters YAML allows.
870 914
871There might be other incompatibilities that I am not aware of. In general 915There might be other incompatibilities that I am not aware of. In general
872you should not try to generate YAML with a JSON generator or vice versa, 916you should not try to generate YAML with a JSON generator or vice versa,
873or try to parse JSON with a YAML parser or vice versa: chances are high 917or try to parse JSON with a YAML parser or vice versa: chances are high
874that you will run into severe interoperability problems. 918that you will run into severe interoperability problems.
890It shows the number of encodes/decodes per second (JSON::XS uses 934It shows the number of encodes/decodes per second (JSON::XS uses
891the functional interface, while JSON::XS/2 uses the OO interface 935the functional interface, while JSON::XS/2 uses the OO interface
892with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables 936with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables
893shrink). Higher is better: 937shrink). Higher is better:
894 938
895 Storable | 15779.925 | 14169.946 |
896 -----------+------------+------------+
897 module | encode | decode | 939 module | encode | decode |
898 -----------|------------|------------| 940 -----------|------------|------------|
899 JSON | 4990.842 | 4088.813 | 941 JSON 1.x | 4990.842 | 4088.813 |
900 JSON::DWIW | 51653.990 | 71575.154 | 942 JSON::DWIW | 51653.990 | 71575.154 |
901 JSON::PC | 65948.176 | 74631.744 | 943 JSON::PC | 65948.176 | 74631.744 |
902 JSON::PP | 8931.652 | 3817.168 | 944 JSON::PP | 8931.652 | 3817.168 |
903 JSON::Syck | 24877.248 | 27776.848 | 945 JSON::Syck | 24877.248 | 27776.848 |
904 JSON::XS | 388361.481 | 227951.304 | 946 JSON::XS | 388361.481 | 227951.304 |
906 JSON::XS/3 | 338250.323 | 218453.333 | 948 JSON::XS/3 | 338250.323 | 218453.333 |
907 Storable | 16500.016 | 135300.129 | 949 Storable | 16500.016 | 135300.129 |
908 -----------+------------+------------+ 950 -----------+------------+------------+
909 951
910That is, JSON::XS is about five times faster than JSON::DWIW on encoding, 952That is, JSON::XS is about five times faster than JSON::DWIW on encoding,
911about three times faster on decoding, and over fourty times faster 953about three times faster on decoding, and over forty times faster
912than JSON, even with pretty-printing and key sorting. It also compares 954than JSON, even with pretty-printing and key sorting. It also compares
913favourably to Storable for small amounts of data. 955favourably to Storable for small amounts of data.
914 956
915Using a longer test string (roughly 18KB, generated from Yahoo! Locals 957Using a longer test string (roughly 18KB, generated from Yahoo! Locals
916search API (http://nanoref.com/yahooapis/mgPdGg): 958search API (http://nanoref.com/yahooapis/mgPdGg):
917 959
918 module | encode | decode | 960 module | encode | decode |
919 -----------|------------|------------| 961 -----------|------------|------------|
920 JSON | 55.260 | 34.971 | 962 JSON 1.x | 55.260 | 34.971 |
921 JSON::DWIW | 825.228 | 1082.513 | 963 JSON::DWIW | 825.228 | 1082.513 |
922 JSON::PC | 3571.444 | 2394.829 | 964 JSON::PC | 3571.444 | 2394.829 |
923 JSON::PP | 210.987 | 32.574 | 965 JSON::PP | 210.987 | 32.574 |
924 JSON::Syck | 552.551 | 787.544 | 966 JSON::Syck | 552.551 | 787.544 |
925 JSON::XS | 5780.463 | 4854.519 | 967 JSON::XS | 5780.463 | 4854.519 |
929 -----------+------------+------------+ 971 -----------+------------+------------+
930 972
931Again, JSON::XS leads by far (except for Storable which non-surprisingly 973Again, JSON::XS leads by far (except for Storable which non-surprisingly
932decodes faster). 974decodes faster).
933 975
934On large strings containing lots of high unicode characters, some modules 976On large strings containing lots of high Unicode characters, some modules
935(such as JSON::PC) seem to decode faster than JSON::XS, but the result 977(such as JSON::PC) seem to decode faster than JSON::XS, but the result
936will be broken due to missing (or wrong) unicode handling. Others refuse 978will be broken due to missing (or wrong) Unicode handling. Others refuse
937to decode or encode properly, so it was impossible to prepare a fair 979to decode or encode properly, so it was impossible to prepare a fair
938comparison table for that case. 980comparison table for that case.
939 981
940 982
941=head1 SECURITY CONSIDERATIONS 983=head1 SECURITY CONSIDERATIONS
947any buffer overflows. Obviously, this module should ensure that and I am 989any buffer overflows. Obviously, this module should ensure that and I am
948trying hard on making that true, but you never know. 990trying hard on making that true, but you never know.
949 991
950Second, you need to avoid resource-starving attacks. That means you should 992Second, you need to avoid resource-starving attacks. That means you should
951limit the size of JSON texts you accept, or make sure then when your 993limit the size of JSON texts you accept, or make sure then when your
952resources run out, thats just fine (e.g. by using a separate process that 994resources run out, that's just fine (e.g. by using a separate process that
953can crash safely). The size of a JSON text in octets or characters is 995can crash safely). The size of a JSON text in octets or characters is
954usually a good indication of the size of the resources required to decode 996usually a good indication of the size of the resources required to decode
955it into a Perl structure. While JSON::XS can check the size of the JSON 997it into a Perl structure. While JSON::XS can check the size of the JSON
956text, it might be too late when you already have it in memory, so you 998text, it might be too late when you already have it in memory, so you
957might want to check the size before you accept the string. 999might want to check the size before you accept the string.
968And last but least, something else could bomb you that I forgot to think 1010And last but least, something else could bomb you that I forgot to think
969of. In that case, you get to keep the pieces. I am always open for hints, 1011of. In that case, you get to keep the pieces. I am always open for hints,
970though... 1012though...
971 1013
972If you are using JSON::XS to return packets to consumption 1014If you are using JSON::XS to return packets to consumption
973by javascript scripts in a browser you should have a look at 1015by JavaScript scripts in a browser you should have a look at
974L<http://jpsykes.com/47/practical-csrf-and-json-security> to see wether 1016L<http://jpsykes.com/47/practical-csrf-and-json-security> to see whether
975you are vulnerable to some common attack vectors (which really are browser 1017you are vulnerable to some common attack vectors (which really are browser
976design bugs, but it is still you who will have to deal with it, as major 1018design bugs, but it is still you who will have to deal with it, as major
977browser developers care only for features, not about doing security 1019browser developers care only for features, not about doing security
978right). 1020right).
979 1021
980 1022
981=head1 THREADS 1023=head1 THREADS
982 1024
983This module is I<not> guarenteed to be thread safe and there are no 1025This module is I<not> guaranteed to be thread safe and there are no
984plans to change this until Perl gets thread support (as opposed to the 1026plans to change this until Perl gets thread support (as opposed to the
985horribly slow so-called "threads" which are simply slow and bloated 1027horribly slow so-called "threads" which are simply slow and bloated
986process simulations - use fork, its I<much> faster, cheaper, better). 1028process simulations - use fork, its I<much> faster, cheaper, better).
987 1029
988(It might actually work, but you ahve ben warned). 1030(It might actually work, but you have been warned).
989 1031
990 1032
991=head1 BUGS 1033=head1 BUGS
992 1034
993While the goal of this module is to be correct, that unfortunately does 1035While the goal of this module is to be correct, that unfortunately does

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