File | /usr/local/lib/perl5/site_perl/5.10.1/darwin-2level/JSON/XS.pm |
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1 | 1 | 1 | 525µs | 590µs | BEGIN@97 | DynaLoader::
1 | 1 | 1 | 219µs | 229µs | BEGIN@104 | JSON::XS::
8 | 1 | 2 | 103µs | 103µs | encode (xsub) | JSON::XS::
13 | 2 | 2 | 74µs | 74µs | new (xsub) | JSON::XS::
5 | 1 | 2 | 66µs | 66µs | decode (xsub) | JSON::XS::
13 | 2 | 2 | 20µs | 20µs | DESTROY (xsub) | JSON::XS::
1 | 1 | 1 | 12µs | 39µs | BEGIN@121 | JSON::XS::
1 | 1 | 1 | 10µs | 40µs | BEGIN@1461 | JSON::XS::Boolean::
1 | 1 | 1 | 7µs | 7µs | BEGIN@122 | JSON::XS::
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0 | 0 | 0 | 0s | 0s | false | JSON::XS::
0 | 0 | 0 | 0s | 0s | from_json | JSON::XS::
0 | 0 | 0 | 0s | 0s | is_bool | JSON::XS::
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0 | 0 | 0 | 0s | 0s | true | JSON::XS::
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1 | 1 | 27µs | =head1 NAME | ||
2 | |||||
3 | JSON::XS - JSON serialising/deserialising, done correctly and fast | ||||
4 | |||||
5 | =encoding utf-8 | ||||
6 | |||||
7 | JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ | ||||
8 | (http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html) | ||||
9 | |||||
10 | =head1 SYNOPSIS | ||||
11 | |||||
12 | use JSON::XS; | ||||
13 | |||||
14 | # exported functions, they croak on error | ||||
15 | # and expect/generate UTF-8 | ||||
16 | |||||
17 | $utf8_encoded_json_text = encode_json $perl_hash_or_arrayref; | ||||
18 | $perl_hash_or_arrayref = decode_json $utf8_encoded_json_text; | ||||
19 | |||||
20 | # OO-interface | ||||
21 | |||||
22 | $coder = JSON::XS->new->ascii->pretty->allow_nonref; | ||||
23 | $pretty_printed_unencoded = $coder->encode ($perl_scalar); | ||||
24 | $perl_scalar = $coder->decode ($unicode_json_text); | ||||
25 | |||||
26 | # Note that JSON version 2.0 and above will automatically use JSON::XS | ||||
27 | # if available, at virtually no speed overhead either, so you should | ||||
28 | # be able to just: | ||||
29 | |||||
30 | use JSON; | ||||
31 | |||||
32 | # and do the same things, except that you have a pure-perl fallback now. | ||||
33 | |||||
34 | =head1 DESCRIPTION | ||||
35 | |||||
36 | This module converts Perl data structures to JSON and vice versa. Its | ||||
37 | primary goal is to be I<correct> and its secondary goal is to be | ||||
38 | I<fast>. To reach the latter goal it was written in C. | ||||
39 | |||||
40 | Beginning with version 2.0 of the JSON module, when both JSON and | ||||
41 | JSON::XS are installed, then JSON will fall back on JSON::XS (this can be | ||||
42 | overridden) with no overhead due to emulation (by inheriting constructor | ||||
43 | and methods). If JSON::XS is not available, it will fall back to the | ||||
44 | compatible JSON::PP module as backend, so using JSON instead of JSON::XS | ||||
45 | gives you a portable JSON API that can be fast when you need and doesn't | ||||
46 | require a C compiler when that is a problem. | ||||
47 | |||||
48 | As this is the n-th-something JSON module on CPAN, what was the reason | ||||
49 | to write yet another JSON module? While it seems there are many JSON | ||||
50 | modules, none of them correctly handle all corner cases, and in most cases | ||||
51 | their maintainers are unresponsive, gone missing, or not listening to bug | ||||
52 | reports for other reasons. | ||||
53 | |||||
54 | See MAPPING, below, on how JSON::XS maps perl values to JSON values and | ||||
55 | vice versa. | ||||
56 | |||||
57 | =head2 FEATURES | ||||
58 | |||||
59 | =over 4 | ||||
60 | |||||
61 | =item * correct Unicode handling | ||||
62 | |||||
63 | This module knows how to handle Unicode, documents how and when it does | ||||
64 | so, and even documents what "correct" means. | ||||
65 | |||||
66 | =item * round-trip integrity | ||||
67 | |||||
68 | When you serialise a perl data structure using only data types supported | ||||
69 | by JSON, the deserialised data structure is identical on the Perl level. | ||||
70 | (e.g. the string "2.0" doesn't suddenly become "2" just because it looks | ||||
71 | like a number). There minor I<are> exceptions to this, read the MAPPING | ||||
72 | section below to learn about those. | ||||
73 | |||||
74 | =item * strict checking of JSON correctness | ||||
75 | |||||
76 | There is no guessing, no generating of illegal JSON texts by default, | ||||
77 | and only JSON is accepted as input by default (the latter is a security | ||||
78 | feature). | ||||
79 | |||||
80 | =item * fast | ||||
81 | |||||
82 | Compared to other JSON modules and other serialisers such as Storable, | ||||
83 | this module usually compares favourably in terms of speed, too. | ||||
84 | |||||
85 | =item * simple to use | ||||
86 | |||||
87 | This module has both a simple functional interface as well as an object | ||||
88 | oriented interface interface. | ||||
89 | |||||
90 | =item * reasonably versatile output formats | ||||
91 | |||||
92 | You can choose between the most compact guaranteed-single-line format | ||||
93 | possible (nice for simple line-based protocols), a pure-ASCII format | ||||
94 | (for when your transport is not 8-bit clean, still supports the whole | ||||
95 | Unicode range), or a pretty-printed format (for when you want to read that | ||||
96 | stuff). Or you can combine those features in whatever way you like. | ||||
97 | # spent 590µs (525+65) within DynaLoader::BEGIN@97 which was called
# once (525µs+65µs) by XSLoader::load at line 0 | ||||
98 | =back | ||||
99 | |||||
100 | =cut | ||||
101 | |||||
102 | package JSON::XS; | ||||
103 | |||||
104 | 3 | 290µs | 2 | 240µs | # spent 229µs (219+10) within JSON::XS::BEGIN@104 which was called
# once (219µs+10µs) by JSON::BEGIN@2 at line 104 # spent 229µs making 1 call to JSON::XS::BEGIN@104
# spent 10µs making 1 call to common::sense::import |
105 | |||||
106 | 1 | 600ns | our $VERSION = '2.26'; | ||
107 | 1 | 6µs | our @ISA = qw(Exporter); | ||
108 | |||||
109 | 1 | 900ns | our @EXPORT = qw(encode_json decode_json to_json from_json); | ||
110 | |||||
111 | sub to_json($) { | ||||
112 | require Carp; | ||||
113 | Carp::croak ("JSON::XS::to_json has been renamed to encode_json, either downgrade to pre-2.0 versions of JSON::XS or rename the call"); | ||||
114 | } | ||||
115 | |||||
116 | sub from_json($) { | ||||
117 | require Carp; | ||||
118 | Carp::croak ("JSON::XS::from_json has been renamed to decode_json, either downgrade to pre-2.0 versions of JSON::XS or rename the call"); | ||||
119 | } | ||||
120 | |||||
121 | 3 | 25µs | 2 | 66µs | # spent 39µs (12+27) within JSON::XS::BEGIN@121 which was called
# once (12µs+27µs) by JSON::BEGIN@2 at line 121 # spent 39µs making 1 call to JSON::XS::BEGIN@121
# spent 27µs making 1 call to Exporter::import |
122 | 3 | 396µs | 1 | 7µs | # spent 7µs within JSON::XS::BEGIN@122 which was called
# once (7µs+0s) by JSON::BEGIN@2 at line 122 # spent 7µs making 1 call to JSON::XS::BEGIN@122 |
123 | |||||
124 | =head1 FUNCTIONAL INTERFACE | ||||
125 | |||||
126 | The following convenience methods are provided by this module. They are | ||||
127 | exported by default: | ||||
128 | |||||
129 | =over 4 | ||||
130 | |||||
131 | =item $json_text = encode_json $perl_scalar | ||||
132 | |||||
133 | Converts the given Perl data structure to a UTF-8 encoded, binary string | ||||
134 | (that is, the string contains octets only). Croaks on error. | ||||
135 | |||||
136 | This function call is functionally identical to: | ||||
137 | |||||
138 | $json_text = JSON::XS->new->utf8->encode ($perl_scalar) | ||||
139 | |||||
140 | Except being faster. | ||||
141 | |||||
142 | =item $perl_scalar = decode_json $json_text | ||||
143 | |||||
144 | The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries | ||||
145 | to parse that as an UTF-8 encoded JSON text, returning the resulting | ||||
146 | reference. Croaks on error. | ||||
147 | |||||
148 | This function call is functionally identical to: | ||||
149 | |||||
150 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) | ||||
151 | |||||
152 | Except being faster. | ||||
153 | |||||
154 | =item $is_boolean = JSON::XS::is_bool $scalar | ||||
155 | |||||
156 | Returns true if the passed scalar represents either JSON::XS::true or | ||||
157 | JSON::XS::false, two constants that act like C<1> and C<0>, respectively | ||||
158 | and are used to represent JSON C<true> and C<false> values in Perl. | ||||
159 | |||||
160 | See MAPPING, below, for more information on how JSON values are mapped to | ||||
161 | Perl. | ||||
162 | |||||
163 | =back | ||||
164 | |||||
165 | |||||
166 | =head1 A FEW NOTES ON UNICODE AND PERL | ||||
167 | |||||
168 | Since this often leads to confusion, here are a few very clear words on | ||||
169 | how Unicode works in Perl, modulo bugs. | ||||
170 | |||||
171 | =over 4 | ||||
172 | |||||
173 | =item 1. Perl strings can store characters with ordinal values > 255. | ||||
174 | |||||
175 | This enables you to store Unicode characters as single characters in a | ||||
176 | Perl string - very natural. | ||||
177 | |||||
178 | =item 2. Perl does I<not> associate an encoding with your strings. | ||||
179 | |||||
180 | ... until you force it to, e.g. when matching it against a regex, or | ||||
181 | printing the scalar to a file, in which case Perl either interprets your | ||||
182 | string as locale-encoded text, octets/binary, or as Unicode, depending | ||||
183 | on various settings. In no case is an encoding stored together with your | ||||
184 | data, it is I<use> that decides encoding, not any magical meta data. | ||||
185 | |||||
186 | =item 3. The internal utf-8 flag has no meaning with regards to the | ||||
187 | encoding of your string. | ||||
188 | |||||
189 | Just ignore that flag unless you debug a Perl bug, a module written in | ||||
190 | XS or want to dive into the internals of perl. Otherwise it will only | ||||
191 | confuse you, as, despite the name, it says nothing about how your string | ||||
192 | is encoded. You can have Unicode strings with that flag set, with that | ||||
193 | flag clear, and you can have binary data with that flag set and that flag | ||||
194 | clear. Other possibilities exist, too. | ||||
195 | |||||
196 | If you didn't know about that flag, just the better, pretend it doesn't | ||||
197 | exist. | ||||
198 | |||||
199 | =item 4. A "Unicode String" is simply a string where each character can be | ||||
200 | validly interpreted as a Unicode code point. | ||||
201 | |||||
202 | If you have UTF-8 encoded data, it is no longer a Unicode string, but a | ||||
203 | Unicode string encoded in UTF-8, giving you a binary string. | ||||
204 | |||||
205 | =item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string. | ||||
206 | |||||
207 | It's a fact. Learn to live with it. | ||||
208 | |||||
209 | =back | ||||
210 | |||||
211 | I hope this helps :) | ||||
212 | |||||
213 | |||||
214 | =head1 OBJECT-ORIENTED INTERFACE | ||||
215 | |||||
216 | The object oriented interface lets you configure your own encoding or | ||||
217 | decoding style, within the limits of supported formats. | ||||
218 | |||||
219 | =over 4 | ||||
220 | |||||
221 | =item $json = new JSON::XS | ||||
222 | |||||
223 | Creates a new JSON::XS object that can be used to de/encode JSON | ||||
224 | strings. All boolean flags described below are by default I<disabled>. | ||||
225 | |||||
226 | The mutators for flags all return the JSON object again and thus calls can | ||||
227 | be chained: | ||||
228 | |||||
229 | my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]}) | ||||
230 | => {"a": [1, 2]} | ||||
231 | |||||
232 | =item $json = $json->ascii ([$enable]) | ||||
233 | |||||
234 | =item $enabled = $json->get_ascii | ||||
235 | |||||
236 | If C<$enable> is true (or missing), then the C<encode> method will not | ||||
237 | generate characters outside the code range C<0..127> (which is ASCII). Any | ||||
238 | Unicode characters outside that range will be escaped using either a | ||||
239 | single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, | ||||
240 | as per RFC4627. The resulting encoded JSON text can be treated as a native | ||||
241 | Unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string, | ||||
242 | or any other superset of ASCII. | ||||
243 | |||||
244 | If C<$enable> is false, then the C<encode> method will not escape Unicode | ||||
245 | characters unless required by the JSON syntax or other flags. This results | ||||
246 | in a faster and more compact format. | ||||
247 | |||||
248 | See also the section I<ENCODING/CODESET FLAG NOTES> later in this | ||||
249 | document. | ||||
250 | |||||
251 | The main use for this flag is to produce JSON texts that can be | ||||
252 | transmitted over a 7-bit channel, as the encoded JSON texts will not | ||||
253 | contain any 8 bit characters. | ||||
254 | |||||
255 | JSON::XS->new->ascii (1)->encode ([chr 0x10401]) | ||||
256 | => ["\ud801\udc01"] | ||||
257 | |||||
258 | =item $json = $json->latin1 ([$enable]) | ||||
259 | |||||
260 | =item $enabled = $json->get_latin1 | ||||
261 | |||||
262 | If C<$enable> is true (or missing), then the C<encode> method will encode | ||||
263 | the resulting JSON text as latin1 (or iso-8859-1), escaping any characters | ||||
264 | outside the code range C<0..255>. The resulting string can be treated as a | ||||
265 | latin1-encoded JSON text or a native Unicode string. The C<decode> method | ||||
266 | will not be affected in any way by this flag, as C<decode> by default | ||||
267 | expects Unicode, which is a strict superset of latin1. | ||||
268 | |||||
269 | If C<$enable> is false, then the C<encode> method will not escape Unicode | ||||
270 | characters unless required by the JSON syntax or other flags. | ||||
271 | |||||
272 | See also the section I<ENCODING/CODESET FLAG NOTES> later in this | ||||
273 | document. | ||||
274 | |||||
275 | The main use for this flag is efficiently encoding binary data as JSON | ||||
276 | text, as most octets will not be escaped, resulting in a smaller encoded | ||||
277 | size. The disadvantage is that the resulting JSON text is encoded | ||||
278 | in latin1 (and must correctly be treated as such when storing and | ||||
279 | transferring), a rare encoding for JSON. It is therefore most useful when | ||||
280 | you want to store data structures known to contain binary data efficiently | ||||
281 | in files or databases, not when talking to other JSON encoders/decoders. | ||||
282 | |||||
283 | JSON::XS->new->latin1->encode (["\x{89}\x{abc}"] | ||||
284 | => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not) | ||||
285 | |||||
286 | =item $json = $json->utf8 ([$enable]) | ||||
287 | |||||
288 | =item $enabled = $json->get_utf8 | ||||
289 | |||||
290 | If C<$enable> is true (or missing), then the C<encode> method will encode | ||||
291 | the JSON result into UTF-8, as required by many protocols, while the | ||||
292 | C<decode> method expects to be handled an UTF-8-encoded string. Please | ||||
293 | note that UTF-8-encoded strings do not contain any characters outside the | ||||
294 | range C<0..255>, they are thus useful for bytewise/binary I/O. In future | ||||
295 | versions, enabling this option might enable autodetection of the UTF-16 | ||||
296 | and UTF-32 encoding families, as described in RFC4627. | ||||
297 | |||||
298 | If C<$enable> is false, then the C<encode> method will return the JSON | ||||
299 | string as a (non-encoded) Unicode string, while C<decode> expects thus a | ||||
300 | Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs | ||||
301 | to be done yourself, e.g. using the Encode module. | ||||
302 | |||||
303 | See also the section I<ENCODING/CODESET FLAG NOTES> later in this | ||||
304 | document. | ||||
305 | |||||
306 | Example, output UTF-16BE-encoded JSON: | ||||
307 | |||||
308 | use Encode; | ||||
309 | $jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object); | ||||
310 | |||||
311 | Example, decode UTF-32LE-encoded JSON: | ||||
312 | |||||
313 | use Encode; | ||||
314 | $object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext); | ||||
315 | |||||
316 | =item $json = $json->pretty ([$enable]) | ||||
317 | |||||
318 | This enables (or disables) all of the C<indent>, C<space_before> and | ||||
319 | C<space_after> (and in the future possibly more) flags in one call to | ||||
320 | generate the most readable (or most compact) form possible. | ||||
321 | |||||
322 | Example, pretty-print some simple structure: | ||||
323 | |||||
324 | my $json = JSON::XS->new->pretty(1)->encode ({a => [1,2]}) | ||||
325 | => | ||||
326 | { | ||||
327 | "a" : [ | ||||
328 | 1, | ||||
329 | 2 | ||||
330 | ] | ||||
331 | } | ||||
332 | |||||
333 | =item $json = $json->indent ([$enable]) | ||||
334 | |||||
335 | =item $enabled = $json->get_indent | ||||
336 | |||||
337 | If C<$enable> is true (or missing), then the C<encode> method will use a multiline | ||||
338 | format as output, putting every array member or object/hash key-value pair | ||||
339 | into its own line, indenting them properly. | ||||
340 | |||||
341 | If C<$enable> is false, no newlines or indenting will be produced, and the | ||||
342 | resulting JSON text is guaranteed not to contain any C<newlines>. | ||||
343 | |||||
344 | This setting has no effect when decoding JSON texts. | ||||
345 | |||||
346 | =item $json = $json->space_before ([$enable]) | ||||
347 | |||||
348 | =item $enabled = $json->get_space_before | ||||
349 | |||||
350 | If C<$enable> is true (or missing), then the C<encode> method will add an extra | ||||
351 | optional space before the C<:> separating keys from values in JSON objects. | ||||
352 | |||||
353 | If C<$enable> is false, then the C<encode> method will not add any extra | ||||
354 | space at those places. | ||||
355 | |||||
356 | This setting has no effect when decoding JSON texts. You will also | ||||
357 | most likely combine this setting with C<space_after>. | ||||
358 | |||||
359 | Example, space_before enabled, space_after and indent disabled: | ||||
360 | |||||
361 | {"key" :"value"} | ||||
362 | |||||
363 | =item $json = $json->space_after ([$enable]) | ||||
364 | |||||
365 | =item $enabled = $json->get_space_after | ||||
366 | |||||
367 | If C<$enable> is true (or missing), then the C<encode> method will add an extra | ||||
368 | optional space after the C<:> separating keys from values in JSON objects | ||||
369 | and extra whitespace after the C<,> separating key-value pairs and array | ||||
370 | members. | ||||
371 | |||||
372 | If C<$enable> is false, then the C<encode> method will not add any extra | ||||
373 | space at those places. | ||||
374 | |||||
375 | This setting has no effect when decoding JSON texts. | ||||
376 | |||||
377 | Example, space_before and indent disabled, space_after enabled: | ||||
378 | |||||
379 | {"key": "value"} | ||||
380 | |||||
381 | =item $json = $json->relaxed ([$enable]) | ||||
382 | |||||
383 | =item $enabled = $json->get_relaxed | ||||
384 | |||||
385 | If C<$enable> is true (or missing), then C<decode> will accept some | ||||
386 | extensions to normal JSON syntax (see below). C<encode> will not be | ||||
387 | affected in anyway. I<Be aware that this option makes you accept invalid | ||||
388 | JSON texts as if they were valid!>. I suggest only to use this option to | ||||
389 | parse application-specific files written by humans (configuration files, | ||||
390 | resource files etc.) | ||||
391 | |||||
392 | If C<$enable> is false (the default), then C<decode> will only accept | ||||
393 | valid JSON texts. | ||||
394 | |||||
395 | Currently accepted extensions are: | ||||
396 | |||||
397 | =over 4 | ||||
398 | |||||
399 | =item * list items can have an end-comma | ||||
400 | |||||
401 | JSON I<separates> array elements and key-value pairs with commas. This | ||||
402 | can be annoying if you write JSON texts manually and want to be able to | ||||
403 | quickly append elements, so this extension accepts comma at the end of | ||||
404 | such items not just between them: | ||||
405 | |||||
406 | [ | ||||
407 | 1, | ||||
408 | 2, <- this comma not normally allowed | ||||
409 | ] | ||||
410 | { | ||||
411 | "k1": "v1", | ||||
412 | "k2": "v2", <- this comma not normally allowed | ||||
413 | } | ||||
414 | |||||
415 | =item * shell-style '#'-comments | ||||
416 | |||||
417 | Whenever JSON allows whitespace, shell-style comments are additionally | ||||
418 | allowed. They are terminated by the first carriage-return or line-feed | ||||
419 | character, after which more white-space and comments are allowed. | ||||
420 | |||||
421 | [ | ||||
422 | 1, # this comment not allowed in JSON | ||||
423 | # neither this one... | ||||
424 | ] | ||||
425 | |||||
426 | =back | ||||
427 | |||||
428 | =item $json = $json->canonical ([$enable]) | ||||
429 | |||||
430 | =item $enabled = $json->get_canonical | ||||
431 | |||||
432 | If C<$enable> is true (or missing), then the C<encode> method will output JSON objects | ||||
433 | by sorting their keys. This is adding a comparatively high overhead. | ||||
434 | |||||
435 | If C<$enable> is false, then the C<encode> method will output key-value | ||||
436 | pairs in the order Perl stores them (which will likely change between runs | ||||
437 | of the same script). | ||||
438 | |||||
439 | This option is useful if you want the same data structure to be encoded as | ||||
440 | the same JSON text (given the same overall settings). If it is disabled, | ||||
441 | the same hash might be encoded differently even if contains the same data, | ||||
442 | as key-value pairs have no inherent ordering in Perl. | ||||
443 | |||||
444 | This setting has no effect when decoding JSON texts. | ||||
445 | |||||
446 | This setting has currently no effect on tied hashes. | ||||
447 | |||||
448 | =item $json = $json->allow_nonref ([$enable]) | ||||
449 | |||||
450 | =item $enabled = $json->get_allow_nonref | ||||
451 | |||||
452 | If C<$enable> is true (or missing), then the C<encode> method can convert a | ||||
453 | non-reference into its corresponding string, number or null JSON value, | ||||
454 | which is an extension to RFC4627. Likewise, C<decode> will accept those JSON | ||||
455 | values instead of croaking. | ||||
456 | |||||
457 | If C<$enable> is false, then the C<encode> method will croak if it isn't | ||||
458 | passed an arrayref or hashref, as JSON texts must either be an object | ||||
459 | or array. Likewise, C<decode> will croak if given something that is not a | ||||
460 | JSON object or array. | ||||
461 | |||||
462 | Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>, | ||||
463 | resulting in an invalid JSON text: | ||||
464 | |||||
465 | JSON::XS->new->allow_nonref->encode ("Hello, World!") | ||||
466 | => "Hello, World!" | ||||
467 | |||||
468 | =item $json = $json->allow_unknown ([$enable]) | ||||
469 | |||||
470 | =item $enabled = $json->get_allow_unknown | ||||
471 | |||||
472 | If C<$enable> is true (or missing), then C<encode> will I<not> throw an | ||||
473 | exception when it encounters values it cannot represent in JSON (for | ||||
474 | example, filehandles) but instead will encode a JSON C<null> value. Note | ||||
475 | that blessed objects are not included here and are handled separately by | ||||
476 | c<allow_nonref>. | ||||
477 | |||||
478 | If C<$enable> is false (the default), then C<encode> will throw an | ||||
479 | exception when it encounters anything it cannot encode as JSON. | ||||
480 | |||||
481 | This option does not affect C<decode> in any way, and it is recommended to | ||||
482 | leave it off unless you know your communications partner. | ||||
483 | |||||
484 | =item $json = $json->allow_blessed ([$enable]) | ||||
485 | |||||
486 | =item $enabled = $json->get_allow_blessed | ||||
487 | |||||
488 | If C<$enable> is true (or missing), then the C<encode> method will not | ||||
489 | barf when it encounters a blessed reference. Instead, the value of the | ||||
490 | B<convert_blessed> option will decide whether C<null> (C<convert_blessed> | ||||
491 | disabled or no C<TO_JSON> method found) or a representation of the | ||||
492 | object (C<convert_blessed> enabled and C<TO_JSON> method found) is being | ||||
493 | encoded. Has no effect on C<decode>. | ||||
494 | |||||
495 | If C<$enable> is false (the default), then C<encode> will throw an | ||||
496 | exception when it encounters a blessed object. | ||||
497 | |||||
498 | =item $json = $json->convert_blessed ([$enable]) | ||||
499 | |||||
500 | =item $enabled = $json->get_convert_blessed | ||||
501 | |||||
502 | If C<$enable> is true (or missing), then C<encode>, upon encountering a | ||||
503 | blessed object, will check for the availability of the C<TO_JSON> method | ||||
504 | on the object's class. If found, it will be called in scalar context | ||||
505 | and the resulting scalar will be encoded instead of the object. If no | ||||
506 | C<TO_JSON> method is found, the value of C<allow_blessed> will decide what | ||||
507 | to do. | ||||
508 | |||||
509 | The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON> | ||||
510 | returns other blessed objects, those will be handled in the same | ||||
511 | way. C<TO_JSON> must take care of not causing an endless recursion cycle | ||||
512 | (== crash) in this case. The name of C<TO_JSON> was chosen because other | ||||
513 | methods called by the Perl core (== not by the user of the object) are | ||||
514 | usually in upper case letters and to avoid collisions with any C<to_json> | ||||
515 | function or method. | ||||
516 | |||||
517 | This setting does not yet influence C<decode> in any way, but in the | ||||
518 | future, global hooks might get installed that influence C<decode> and are | ||||
519 | enabled by this setting. | ||||
520 | |||||
521 | If C<$enable> is false, then the C<allow_blessed> setting will decide what | ||||
522 | to do when a blessed object is found. | ||||
523 | |||||
524 | =item $json = $json->filter_json_object ([$coderef->($hashref)]) | ||||
525 | |||||
526 | When C<$coderef> is specified, it will be called from C<decode> each | ||||
527 | time it decodes a JSON object. The only argument is a reference to the | ||||
528 | newly-created hash. If the code references returns a single scalar (which | ||||
529 | need not be a reference), this value (i.e. a copy of that scalar to avoid | ||||
530 | aliasing) is inserted into the deserialised data structure. If it returns | ||||
531 | an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the | ||||
532 | original deserialised hash will be inserted. This setting can slow down | ||||
533 | decoding considerably. | ||||
534 | |||||
535 | When C<$coderef> is omitted or undefined, any existing callback will | ||||
536 | be removed and C<decode> will not change the deserialised hash in any | ||||
537 | way. | ||||
538 | |||||
539 | Example, convert all JSON objects into the integer 5: | ||||
540 | |||||
541 | my $js = JSON::XS->new->filter_json_object (sub { 5 }); | ||||
542 | # returns [5] | ||||
543 | $js->decode ('[{}]') | ||||
544 | # throw an exception because allow_nonref is not enabled | ||||
545 | # so a lone 5 is not allowed. | ||||
546 | $js->decode ('{"a":1, "b":2}'); | ||||
547 | |||||
548 | =item $json = $json->filter_json_single_key_object ($key [=> $coderef->($value)]) | ||||
549 | |||||
550 | Works remotely similar to C<filter_json_object>, but is only called for | ||||
551 | JSON objects having a single key named C<$key>. | ||||
552 | |||||
553 | This C<$coderef> is called before the one specified via | ||||
554 | C<filter_json_object>, if any. It gets passed the single value in the JSON | ||||
555 | object. If it returns a single value, it will be inserted into the data | ||||
556 | structure. If it returns nothing (not even C<undef> but the empty list), | ||||
557 | the callback from C<filter_json_object> will be called next, as if no | ||||
558 | single-key callback were specified. | ||||
559 | |||||
560 | If C<$coderef> is omitted or undefined, the corresponding callback will be | ||||
561 | disabled. There can only ever be one callback for a given key. | ||||
562 | |||||
563 | As this callback gets called less often then the C<filter_json_object> | ||||
564 | one, decoding speed will not usually suffer as much. Therefore, single-key | ||||
565 | objects make excellent targets to serialise Perl objects into, especially | ||||
566 | as single-key JSON objects are as close to the type-tagged value concept | ||||
567 | as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not | ||||
568 | support this in any way, so you need to make sure your data never looks | ||||
569 | like a serialised Perl hash. | ||||
570 | |||||
571 | Typical names for the single object key are C<__class_whatever__>, or | ||||
572 | C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even | ||||
573 | things like C<__class_md5sum(classname)__>, to reduce the risk of clashing | ||||
574 | with real hashes. | ||||
575 | |||||
576 | Example, decode JSON objects of the form C<< { "__widget__" => <id> } >> | ||||
577 | into the corresponding C<< $WIDGET{<id>} >> object: | ||||
578 | |||||
579 | # return whatever is in $WIDGET{5}: | ||||
580 | JSON::XS | ||||
581 | ->new | ||||
582 | ->filter_json_single_key_object (__widget__ => sub { | ||||
583 | $WIDGET{ $_[0] } | ||||
584 | }) | ||||
585 | ->decode ('{"__widget__": 5') | ||||
586 | |||||
587 | # this can be used with a TO_JSON method in some "widget" class | ||||
588 | # for serialisation to json: | ||||
589 | sub WidgetBase::TO_JSON { | ||||
590 | my ($self) = @_; | ||||
591 | |||||
592 | unless ($self->{id}) { | ||||
593 | $self->{id} = ..get..some..id..; | ||||
594 | $WIDGET{$self->{id}} = $self; | ||||
595 | } | ||||
596 | |||||
597 | { __widget__ => $self->{id} } | ||||
598 | } | ||||
599 | |||||
600 | =item $json = $json->shrink ([$enable]) | ||||
601 | |||||
602 | =item $enabled = $json->get_shrink | ||||
603 | |||||
604 | Perl usually over-allocates memory a bit when allocating space for | ||||
605 | strings. This flag optionally resizes strings generated by either | ||||
606 | C<encode> or C<decode> to their minimum size possible. This can save | ||||
607 | memory when your JSON texts are either very very long or you have many | ||||
608 | short strings. It will also try to downgrade any strings to octet-form | ||||
609 | if possible: perl stores strings internally either in an encoding called | ||||
610 | UTF-X or in octet-form. The latter cannot store everything but uses less | ||||
611 | space in general (and some buggy Perl or C code might even rely on that | ||||
612 | internal representation being used). | ||||
613 | |||||
614 | The actual definition of what shrink does might change in future versions, | ||||
615 | but it will always try to save space at the expense of time. | ||||
616 | |||||
617 | If C<$enable> is true (or missing), the string returned by C<encode> will | ||||
618 | be shrunk-to-fit, while all strings generated by C<decode> will also be | ||||
619 | shrunk-to-fit. | ||||
620 | |||||
621 | If C<$enable> is false, then the normal perl allocation algorithms are used. | ||||
622 | If you work with your data, then this is likely to be faster. | ||||
623 | |||||
624 | In the future, this setting might control other things, such as converting | ||||
625 | strings that look like integers or floats into integers or floats | ||||
626 | internally (there is no difference on the Perl level), saving space. | ||||
627 | |||||
628 | =item $json = $json->max_depth ([$maximum_nesting_depth]) | ||||
629 | |||||
630 | =item $max_depth = $json->get_max_depth | ||||
631 | |||||
632 | Sets the maximum nesting level (default C<512>) accepted while encoding | ||||
633 | or decoding. If a higher nesting level is detected in JSON text or a Perl | ||||
634 | data structure, then the encoder and decoder will stop and croak at that | ||||
635 | point. | ||||
636 | |||||
637 | Nesting level is defined by number of hash- or arrayrefs that the encoder | ||||
638 | needs to traverse to reach a given point or the number of C<{> or C<[> | ||||
639 | characters without their matching closing parenthesis crossed to reach a | ||||
640 | given character in a string. | ||||
641 | |||||
642 | Setting the maximum depth to one disallows any nesting, so that ensures | ||||
643 | that the object is only a single hash/object or array. | ||||
644 | |||||
645 | If no argument is given, the highest possible setting will be used, which | ||||
646 | is rarely useful. | ||||
647 | |||||
648 | Note that nesting is implemented by recursion in C. The default value has | ||||
649 | been chosen to be as large as typical operating systems allow without | ||||
650 | crashing. | ||||
651 | |||||
652 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. | ||||
653 | |||||
654 | =item $json = $json->max_size ([$maximum_string_size]) | ||||
655 | |||||
656 | =item $max_size = $json->get_max_size | ||||
657 | |||||
658 | Set the maximum length a JSON text may have (in bytes) where decoding is | ||||
659 | being attempted. The default is C<0>, meaning no limit. When C<decode> | ||||
660 | is called on a string that is longer then this many bytes, it will not | ||||
661 | attempt to decode the string but throw an exception. This setting has no | ||||
662 | effect on C<encode> (yet). | ||||
663 | |||||
664 | If no argument is given, the limit check will be deactivated (same as when | ||||
665 | C<0> is specified). | ||||
666 | |||||
667 | See SECURITY CONSIDERATIONS, below, for more info on why this is useful. | ||||
668 | |||||
669 | =item $json_text = $json->encode ($perl_scalar) | ||||
670 | |||||
671 | Converts the given Perl data structure (a simple scalar or a reference | ||||
672 | to a hash or array) to its JSON representation. Simple scalars will be | ||||
673 | converted into JSON string or number sequences, while references to arrays | ||||
674 | become JSON arrays and references to hashes become JSON objects. Undefined | ||||
675 | Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true> | ||||
676 | nor C<false> values will be generated. | ||||
677 | |||||
678 | =item $perl_scalar = $json->decode ($json_text) | ||||
679 | |||||
680 | The opposite of C<encode>: expects a JSON text and tries to parse it, | ||||
681 | returning the resulting simple scalar or reference. Croaks on error. | ||||
682 | |||||
683 | JSON numbers and strings become simple Perl scalars. JSON arrays become | ||||
684 | Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes | ||||
685 | C<1>, C<false> becomes C<0> and C<null> becomes C<undef>. | ||||
686 | |||||
687 | =item ($perl_scalar, $characters) = $json->decode_prefix ($json_text) | ||||
688 | |||||
689 | This works like the C<decode> method, but instead of raising an exception | ||||
690 | when there is trailing garbage after the first JSON object, it will | ||||
691 | silently stop parsing there and return the number of characters consumed | ||||
692 | so far. | ||||
693 | |||||
694 | This is useful if your JSON texts are not delimited by an outer protocol | ||||
695 | (which is not the brightest thing to do in the first place) and you need | ||||
696 | to know where the JSON text ends. | ||||
697 | |||||
698 | JSON::XS->new->decode_prefix ("[1] the tail") | ||||
699 | => ([], 3) | ||||
700 | |||||
701 | =back | ||||
702 | |||||
703 | |||||
704 | =head1 INCREMENTAL PARSING | ||||
705 | |||||
706 | In some cases, there is the need for incremental parsing of JSON | ||||
707 | texts. While this module always has to keep both JSON text and resulting | ||||
708 | Perl data structure in memory at one time, it does allow you to parse a | ||||
709 | JSON stream incrementally. It does so by accumulating text until it has | ||||
710 | a full JSON object, which it then can decode. This process is similar to | ||||
711 | using C<decode_prefix> to see if a full JSON object is available, but | ||||
712 | is much more efficient (and can be implemented with a minimum of method | ||||
713 | calls). | ||||
714 | |||||
715 | JSON::XS will only attempt to parse the JSON text once it is sure it | ||||
716 | has enough text to get a decisive result, using a very simple but | ||||
717 | truly incremental parser. This means that it sometimes won't stop as | ||||
718 | early as the full parser, for example, it doesn't detect parenthese | ||||
719 | mismatches. The only thing it guarantees is that it starts decoding as | ||||
720 | soon as a syntactically valid JSON text has been seen. This means you need | ||||
721 | to set resource limits (e.g. C<max_size>) to ensure the parser will stop | ||||
722 | parsing in the presence if syntax errors. | ||||
723 | |||||
724 | The following methods implement this incremental parser. | ||||
725 | |||||
726 | =over 4 | ||||
727 | |||||
728 | =item [void, scalar or list context] = $json->incr_parse ([$string]) | ||||
729 | |||||
730 | This is the central parsing function. It can both append new text and | ||||
731 | extract objects from the stream accumulated so far (both of these | ||||
732 | functions are optional). | ||||
733 | |||||
734 | If C<$string> is given, then this string is appended to the already | ||||
735 | existing JSON fragment stored in the C<$json> object. | ||||
736 | |||||
737 | After that, if the function is called in void context, it will simply | ||||
738 | return without doing anything further. This can be used to add more text | ||||
739 | in as many chunks as you want. | ||||
740 | |||||
741 | If the method is called in scalar context, then it will try to extract | ||||
742 | exactly I<one> JSON object. If that is successful, it will return this | ||||
743 | object, otherwise it will return C<undef>. If there is a parse error, | ||||
744 | this method will croak just as C<decode> would do (one can then use | ||||
745 | C<incr_skip> to skip the errornous part). This is the most common way of | ||||
746 | using the method. | ||||
747 | |||||
748 | And finally, in list context, it will try to extract as many objects | ||||
749 | from the stream as it can find and return them, or the empty list | ||||
750 | otherwise. For this to work, there must be no separators between the JSON | ||||
751 | objects or arrays, instead they must be concatenated back-to-back. If | ||||
752 | an error occurs, an exception will be raised as in the scalar context | ||||
753 | case. Note that in this case, any previously-parsed JSON texts will be | ||||
754 | lost. | ||||
755 | |||||
756 | =item $lvalue_string = $json->incr_text | ||||
757 | |||||
758 | This method returns the currently stored JSON fragment as an lvalue, that | ||||
759 | is, you can manipulate it. This I<only> works when a preceding call to | ||||
760 | C<incr_parse> in I<scalar context> successfully returned an object. Under | ||||
761 | all other circumstances you must not call this function (I mean it. | ||||
762 | although in simple tests it might actually work, it I<will> fail under | ||||
763 | real world conditions). As a special exception, you can also call this | ||||
764 | method before having parsed anything. | ||||
765 | |||||
766 | This function is useful in two cases: a) finding the trailing text after a | ||||
767 | JSON object or b) parsing multiple JSON objects separated by non-JSON text | ||||
768 | (such as commas). | ||||
769 | |||||
770 | =item $json->incr_skip | ||||
771 | |||||
772 | This will reset the state of the incremental parser and will remove | ||||
773 | the parsed text from the input buffer so far. This is useful after | ||||
774 | C<incr_parse> died, in which case the input buffer and incremental parser | ||||
775 | state is left unchanged, to skip the text parsed so far and to reset the | ||||
776 | parse state. | ||||
777 | |||||
778 | The difference to C<incr_reset> is that only text until the parse error | ||||
779 | occured is removed. | ||||
780 | |||||
781 | =item $json->incr_reset | ||||
782 | |||||
783 | This completely resets the incremental parser, that is, after this call, | ||||
784 | it will be as if the parser had never parsed anything. | ||||
785 | |||||
786 | This is useful if you want to repeatedly parse JSON objects and want to | ||||
787 | ignore any trailing data, which means you have to reset the parser after | ||||
788 | each successful decode. | ||||
789 | |||||
790 | =back | ||||
791 | |||||
792 | =head2 LIMITATIONS | ||||
793 | |||||
794 | All options that affect decoding are supported, except | ||||
795 | C<allow_nonref>. The reason for this is that it cannot be made to | ||||
796 | work sensibly: JSON objects and arrays are self-delimited, i.e. you can concatenate | ||||
797 | them back to back and still decode them perfectly. This does not hold true | ||||
798 | for JSON numbers, however. | ||||
799 | |||||
800 | For example, is the string C<1> a single JSON number, or is it simply the | ||||
801 | start of C<12>? Or is C<12> a single JSON number, or the concatenation | ||||
802 | of C<1> and C<2>? In neither case you can tell, and this is why JSON::XS | ||||
803 | takes the conservative route and disallows this case. | ||||
804 | |||||
805 | =head2 EXAMPLES | ||||
806 | |||||
807 | Some examples will make all this clearer. First, a simple example that | ||||
808 | works similarly to C<decode_prefix>: We want to decode the JSON object at | ||||
809 | the start of a string and identify the portion after the JSON object: | ||||
810 | |||||
811 | my $text = "[1,2,3] hello"; | ||||
812 | |||||
813 | my $json = new JSON::XS; | ||||
814 | |||||
815 | my $obj = $json->incr_parse ($text) | ||||
816 | or die "expected JSON object or array at beginning of string"; | ||||
817 | |||||
818 | my $tail = $json->incr_text; | ||||
819 | # $tail now contains " hello" | ||||
820 | |||||
821 | Easy, isn't it? | ||||
822 | |||||
823 | Now for a more complicated example: Imagine a hypothetical protocol where | ||||
824 | you read some requests from a TCP stream, and each request is a JSON | ||||
825 | array, without any separation between them (in fact, it is often useful to | ||||
826 | use newlines as "separators", as these get interpreted as whitespace at | ||||
827 | the start of the JSON text, which makes it possible to test said protocol | ||||
828 | with C<telnet>...). | ||||
829 | |||||
830 | Here is how you'd do it (it is trivial to write this in an event-based | ||||
831 | manner): | ||||
832 | |||||
833 | my $json = new JSON::XS; | ||||
834 | |||||
835 | # read some data from the socket | ||||
836 | while (sysread $socket, my $buf, 4096) { | ||||
837 | |||||
838 | # split and decode as many requests as possible | ||||
839 | for my $request ($json->incr_parse ($buf)) { | ||||
840 | # act on the $request | ||||
841 | } | ||||
842 | } | ||||
843 | |||||
844 | Another complicated example: Assume you have a string with JSON objects | ||||
845 | or arrays, all separated by (optional) comma characters (e.g. C<[1],[2], | ||||
846 | [3]>). To parse them, we have to skip the commas between the JSON texts, | ||||
847 | and here is where the lvalue-ness of C<incr_text> comes in useful: | ||||
848 | |||||
849 | my $text = "[1],[2], [3]"; | ||||
850 | my $json = new JSON::XS; | ||||
851 | |||||
852 | # void context, so no parsing done | ||||
853 | $json->incr_parse ($text); | ||||
854 | |||||
855 | # now extract as many objects as possible. note the | ||||
856 | # use of scalar context so incr_text can be called. | ||||
857 | while (my $obj = $json->incr_parse) { | ||||
858 | # do something with $obj | ||||
859 | |||||
860 | # now skip the optional comma | ||||
861 | $json->incr_text =~ s/^ \s* , //x; | ||||
862 | } | ||||
863 | |||||
864 | Now lets go for a very complex example: Assume that you have a gigantic | ||||
865 | JSON array-of-objects, many gigabytes in size, and you want to parse it, | ||||
866 | but you cannot load it into memory fully (this has actually happened in | ||||
867 | the real world :). | ||||
868 | |||||
869 | Well, you lost, you have to implement your own JSON parser. But JSON::XS | ||||
870 | can still help you: You implement a (very simple) array parser and let | ||||
871 | JSON decode the array elements, which are all full JSON objects on their | ||||
872 | own (this wouldn't work if the array elements could be JSON numbers, for | ||||
873 | example): | ||||
874 | |||||
875 | my $json = new JSON::XS; | ||||
876 | |||||
877 | # open the monster | ||||
878 | open my $fh, "<bigfile.json" | ||||
879 | or die "bigfile: $!"; | ||||
880 | |||||
881 | # first parse the initial "[" | ||||
882 | for (;;) { | ||||
883 | sysread $fh, my $buf, 65536 | ||||
884 | or die "read error: $!"; | ||||
885 | $json->incr_parse ($buf); # void context, so no parsing | ||||
886 | |||||
887 | # Exit the loop once we found and removed(!) the initial "[". | ||||
888 | # In essence, we are (ab-)using the $json object as a simple scalar | ||||
889 | # we append data to. | ||||
890 | last if $json->incr_text =~ s/^ \s* \[ //x; | ||||
891 | } | ||||
892 | |||||
893 | # now we have the skipped the initial "[", so continue | ||||
894 | # parsing all the elements. | ||||
895 | for (;;) { | ||||
896 | # in this loop we read data until we got a single JSON object | ||||
897 | for (;;) { | ||||
898 | if (my $obj = $json->incr_parse) { | ||||
899 | # do something with $obj | ||||
900 | last; | ||||
901 | } | ||||
902 | |||||
903 | # add more data | ||||
904 | sysread $fh, my $buf, 65536 | ||||
905 | or die "read error: $!"; | ||||
906 | $json->incr_parse ($buf); # void context, so no parsing | ||||
907 | } | ||||
908 | |||||
909 | # in this loop we read data until we either found and parsed the | ||||
910 | # separating "," between elements, or the final "]" | ||||
911 | for (;;) { | ||||
912 | # first skip whitespace | ||||
913 | $json->incr_text =~ s/^\s*//; | ||||
914 | |||||
915 | # if we find "]", we are done | ||||
916 | if ($json->incr_text =~ s/^\]//) { | ||||
917 | print "finished.\n"; | ||||
918 | exit; | ||||
919 | } | ||||
920 | |||||
921 | # if we find ",", we can continue with the next element | ||||
922 | if ($json->incr_text =~ s/^,//) { | ||||
923 | last; | ||||
924 | } | ||||
925 | |||||
926 | # if we find anything else, we have a parse error! | ||||
927 | if (length $json->incr_text) { | ||||
928 | die "parse error near ", $json->incr_text; | ||||
929 | } | ||||
930 | |||||
931 | # else add more data | ||||
932 | sysread $fh, my $buf, 65536 | ||||
933 | or die "read error: $!"; | ||||
934 | $json->incr_parse ($buf); # void context, so no parsing | ||||
935 | } | ||||
936 | |||||
937 | This is a complex example, but most of the complexity comes from the fact | ||||
938 | that we are trying to be correct (bear with me if I am wrong, I never ran | ||||
939 | the above example :). | ||||
940 | |||||
941 | |||||
942 | |||||
943 | =head1 MAPPING | ||||
944 | |||||
945 | This section describes how JSON::XS maps Perl values to JSON values and | ||||
946 | vice versa. These mappings are designed to "do the right thing" in most | ||||
947 | circumstances automatically, preserving round-tripping characteristics | ||||
948 | (what you put in comes out as something equivalent). | ||||
949 | |||||
950 | For the more enlightened: note that in the following descriptions, | ||||
951 | lowercase I<perl> refers to the Perl interpreter, while uppercase I<Perl> | ||||
952 | refers to the abstract Perl language itself. | ||||
953 | |||||
954 | |||||
955 | =head2 JSON -> PERL | ||||
956 | |||||
957 | =over 4 | ||||
958 | |||||
959 | =item object | ||||
960 | |||||
961 | A JSON object becomes a reference to a hash in Perl. No ordering of object | ||||
962 | keys is preserved (JSON does not preserve object key ordering itself). | ||||
963 | |||||
964 | =item array | ||||
965 | |||||
966 | A JSON array becomes a reference to an array in Perl. | ||||
967 | |||||
968 | =item string | ||||
969 | |||||
970 | A JSON string becomes a string scalar in Perl - Unicode codepoints in JSON | ||||
971 | are represented by the same codepoints in the Perl string, so no manual | ||||
972 | decoding is necessary. | ||||
973 | |||||
974 | =item number | ||||
975 | |||||
976 | A JSON number becomes either an integer, numeric (floating point) or | ||||
977 | string scalar in perl, depending on its range and any fractional parts. On | ||||
978 | the Perl level, there is no difference between those as Perl handles all | ||||
979 | the conversion details, but an integer may take slightly less memory and | ||||
980 | might represent more values exactly than floating point numbers. | ||||
981 | |||||
982 | If the number consists of digits only, JSON::XS will try to represent | ||||
983 | it as an integer value. If that fails, it will try to represent it as | ||||
984 | a numeric (floating point) value if that is possible without loss of | ||||
985 | precision. Otherwise it will preserve the number as a string value (in | ||||
986 | which case you lose roundtripping ability, as the JSON number will be | ||||
987 | re-encoded toa JSON string). | ||||
988 | |||||
989 | Numbers containing a fractional or exponential part will always be | ||||
990 | represented as numeric (floating point) values, possibly at a loss of | ||||
991 | precision (in which case you might lose perfect roundtripping ability, but | ||||
992 | the JSON number will still be re-encoded as a JSON number). | ||||
993 | |||||
994 | =item true, false | ||||
995 | |||||
996 | These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>, | ||||
997 | respectively. They are overloaded to act almost exactly like the numbers | ||||
998 | C<1> and C<0>. You can check whether a scalar is a JSON boolean by using | ||||
999 | the C<JSON::XS::is_bool> function. | ||||
1000 | |||||
1001 | =item null | ||||
1002 | |||||
1003 | A JSON null atom becomes C<undef> in Perl. | ||||
1004 | |||||
1005 | =back | ||||
1006 | |||||
1007 | |||||
1008 | =head2 PERL -> JSON | ||||
1009 | |||||
1010 | The mapping from Perl to JSON is slightly more difficult, as Perl is a | ||||
1011 | truly typeless language, so we can only guess which JSON type is meant by | ||||
1012 | a Perl value. | ||||
1013 | |||||
1014 | =over 4 | ||||
1015 | |||||
1016 | =item hash references | ||||
1017 | |||||
1018 | Perl hash references become JSON objects. As there is no inherent ordering | ||||
1019 | in hash keys (or JSON objects), they will usually be encoded in a | ||||
1020 | pseudo-random order that can change between runs of the same program but | ||||
1021 | stays generally the same within a single run of a program. JSON::XS can | ||||
1022 | optionally sort the hash keys (determined by the I<canonical> flag), so | ||||
1023 | the same datastructure will serialise to the same JSON text (given same | ||||
1024 | settings and version of JSON::XS), but this incurs a runtime overhead | ||||
1025 | and is only rarely useful, e.g. when you want to compare some JSON text | ||||
1026 | against another for equality. | ||||
1027 | |||||
1028 | =item array references | ||||
1029 | |||||
1030 | Perl array references become JSON arrays. | ||||
1031 | |||||
1032 | =item other references | ||||
1033 | |||||
1034 | Other unblessed references are generally not allowed and will cause an | ||||
1035 | exception to be thrown, except for references to the integers C<0> and | ||||
1036 | C<1>, which get turned into C<false> and C<true> atoms in JSON. You can | ||||
1037 | also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability. | ||||
1038 | |||||
1039 | encode_json [\0, JSON::XS::true] # yields [false,true] | ||||
1040 | |||||
1041 | =item JSON::XS::true, JSON::XS::false | ||||
1042 | |||||
1043 | These special values become JSON true and JSON false values, | ||||
1044 | respectively. You can also use C<\1> and C<\0> directly if you want. | ||||
1045 | |||||
1046 | =item blessed objects | ||||
1047 | |||||
1048 | Blessed objects are not directly representable in JSON. See the | ||||
1049 | C<allow_blessed> and C<convert_blessed> methods on various options on | ||||
1050 | how to deal with this: basically, you can choose between throwing an | ||||
1051 | exception, encoding the reference as if it weren't blessed, or provide | ||||
1052 | your own serialiser method. | ||||
1053 | |||||
1054 | =item simple scalars | ||||
1055 | |||||
1056 | Simple Perl scalars (any scalar that is not a reference) are the most | ||||
1057 | difficult objects to encode: JSON::XS will encode undefined scalars as | ||||
1058 | JSON C<null> values, scalars that have last been used in a string context | ||||
1059 | before encoding as JSON strings, and anything else as number value: | ||||
1060 | |||||
1061 | # dump as number | ||||
1062 | encode_json [2] # yields [2] | ||||
1063 | encode_json [-3.0e17] # yields [-3e+17] | ||||
1064 | my $value = 5; encode_json [$value] # yields [5] | ||||
1065 | |||||
1066 | # used as string, so dump as string | ||||
1067 | print $value; | ||||
1068 | encode_json [$value] # yields ["5"] | ||||
1069 | |||||
1070 | # undef becomes null | ||||
1071 | encode_json [undef] # yields [null] | ||||
1072 | |||||
1073 | You can force the type to be a JSON string by stringifying it: | ||||
1074 | |||||
1075 | my $x = 3.1; # some variable containing a number | ||||
1076 | "$x"; # stringified | ||||
1077 | $x .= ""; # another, more awkward way to stringify | ||||
1078 | print $x; # perl does it for you, too, quite often | ||||
1079 | |||||
1080 | You can force the type to be a JSON number by numifying it: | ||||
1081 | |||||
1082 | my $x = "3"; # some variable containing a string | ||||
1083 | $x += 0; # numify it, ensuring it will be dumped as a number | ||||
1084 | $x *= 1; # same thing, the choice is yours. | ||||
1085 | |||||
1086 | You can not currently force the type in other, less obscure, ways. Tell me | ||||
1087 | if you need this capability (but don't forget to explain why it's needed | ||||
1088 | :). | ||||
1089 | |||||
1090 | =back | ||||
1091 | |||||
1092 | |||||
1093 | =head1 ENCODING/CODESET FLAG NOTES | ||||
1094 | |||||
1095 | The interested reader might have seen a number of flags that signify | ||||
1096 | encodings or codesets - C<utf8>, C<latin1> and C<ascii>. There seems to be | ||||
1097 | some confusion on what these do, so here is a short comparison: | ||||
1098 | |||||
1099 | C<utf8> controls whether the JSON text created by C<encode> (and expected | ||||
1100 | by C<decode>) is UTF-8 encoded or not, while C<latin1> and C<ascii> only | ||||
1101 | control whether C<encode> escapes character values outside their respective | ||||
1102 | codeset range. Neither of these flags conflict with each other, although | ||||
1103 | some combinations make less sense than others. | ||||
1104 | |||||
1105 | Care has been taken to make all flags symmetrical with respect to | ||||
1106 | C<encode> and C<decode>, that is, texts encoded with any combination of | ||||
1107 | these flag values will be correctly decoded when the same flags are used | ||||
1108 | - in general, if you use different flag settings while encoding vs. when | ||||
1109 | decoding you likely have a bug somewhere. | ||||
1110 | |||||
1111 | Below comes a verbose discussion of these flags. Note that a "codeset" is | ||||
1112 | simply an abstract set of character-codepoint pairs, while an encoding | ||||
1113 | takes those codepoint numbers and I<encodes> them, in our case into | ||||
1114 | octets. Unicode is (among other things) a codeset, UTF-8 is an encoding, | ||||
1115 | and ISO-8859-1 (= latin 1) and ASCII are both codesets I<and> encodings at | ||||
1116 | the same time, which can be confusing. | ||||
1117 | |||||
1118 | =over 4 | ||||
1119 | |||||
1120 | =item C<utf8> flag disabled | ||||
1121 | |||||
1122 | When C<utf8> is disabled (the default), then C<encode>/C<decode> generate | ||||
1123 | and expect Unicode strings, that is, characters with high ordinal Unicode | ||||
1124 | values (> 255) will be encoded as such characters, and likewise such | ||||
1125 | characters are decoded as-is, no canges to them will be done, except | ||||
1126 | "(re-)interpreting" them as Unicode codepoints or Unicode characters, | ||||
1127 | respectively (to Perl, these are the same thing in strings unless you do | ||||
1128 | funny/weird/dumb stuff). | ||||
1129 | |||||
1130 | This is useful when you want to do the encoding yourself (e.g. when you | ||||
1131 | want to have UTF-16 encoded JSON texts) or when some other layer does | ||||
1132 | the encoding for you (for example, when printing to a terminal using a | ||||
1133 | filehandle that transparently encodes to UTF-8 you certainly do NOT want | ||||
1134 | to UTF-8 encode your data first and have Perl encode it another time). | ||||
1135 | |||||
1136 | =item C<utf8> flag enabled | ||||
1137 | |||||
1138 | If the C<utf8>-flag is enabled, C<encode>/C<decode> will encode all | ||||
1139 | characters using the corresponding UTF-8 multi-byte sequence, and will | ||||
1140 | expect your input strings to be encoded as UTF-8, that is, no "character" | ||||
1141 | of the input string must have any value > 255, as UTF-8 does not allow | ||||
1142 | that. | ||||
1143 | |||||
1144 | The C<utf8> flag therefore switches between two modes: disabled means you | ||||
1145 | will get a Unicode string in Perl, enabled means you get an UTF-8 encoded | ||||
1146 | octet/binary string in Perl. | ||||
1147 | |||||
1148 | =item C<latin1> or C<ascii> flags enabled | ||||
1149 | |||||
1150 | With C<latin1> (or C<ascii>) enabled, C<encode> will escape characters | ||||
1151 | with ordinal values > 255 (> 127 with C<ascii>) and encode the remaining | ||||
1152 | characters as specified by the C<utf8> flag. | ||||
1153 | |||||
1154 | If C<utf8> is disabled, then the result is also correctly encoded in those | ||||
1155 | character sets (as both are proper subsets of Unicode, meaning that a | ||||
1156 | Unicode string with all character values < 256 is the same thing as a | ||||
1157 | ISO-8859-1 string, and a Unicode string with all character values < 128 is | ||||
1158 | the same thing as an ASCII string in Perl). | ||||
1159 | |||||
1160 | If C<utf8> is enabled, you still get a correct UTF-8-encoded string, | ||||
1161 | regardless of these flags, just some more characters will be escaped using | ||||
1162 | C<\uXXXX> then before. | ||||
1163 | |||||
1164 | Note that ISO-8859-1-I<encoded> strings are not compatible with UTF-8 | ||||
1165 | encoding, while ASCII-encoded strings are. That is because the ISO-8859-1 | ||||
1166 | encoding is NOT a subset of UTF-8 (despite the ISO-8859-1 I<codeset> being | ||||
1167 | a subset of Unicode), while ASCII is. | ||||
1168 | |||||
1169 | Surprisingly, C<decode> will ignore these flags and so treat all input | ||||
1170 | values as governed by the C<utf8> flag. If it is disabled, this allows you | ||||
1171 | to decode ISO-8859-1- and ASCII-encoded strings, as both strict subsets of | ||||
1172 | Unicode. If it is enabled, you can correctly decode UTF-8 encoded strings. | ||||
1173 | |||||
1174 | So neither C<latin1> nor C<ascii> are incompatible with the C<utf8> flag - | ||||
1175 | they only govern when the JSON output engine escapes a character or not. | ||||
1176 | |||||
1177 | The main use for C<latin1> is to relatively efficiently store binary data | ||||
1178 | as JSON, at the expense of breaking compatibility with most JSON decoders. | ||||
1179 | |||||
1180 | The main use for C<ascii> is to force the output to not contain characters | ||||
1181 | with values > 127, which means you can interpret the resulting string | ||||
1182 | as UTF-8, ISO-8859-1, ASCII, KOI8-R or most about any character set and | ||||
1183 | 8-bit-encoding, and still get the same data structure back. This is useful | ||||
1184 | when your channel for JSON transfer is not 8-bit clean or the encoding | ||||
1185 | might be mangled in between (e.g. in mail), and works because ASCII is a | ||||
1186 | proper subset of most 8-bit and multibyte encodings in use in the world. | ||||
1187 | |||||
1188 | =back | ||||
1189 | |||||
1190 | |||||
1191 | =head2 JSON and ECMAscript | ||||
1192 | |||||
1193 | JSON syntax is based on how literals are represented in javascript (the | ||||
1194 | not-standardised predecessor of ECMAscript) which is presumably why it is | ||||
1195 | called "JavaScript Object Notation". | ||||
1196 | |||||
1197 | However, JSON is not a subset (and also not a superset of course) of | ||||
1198 | ECMAscript (the standard) or javascript (whatever browsers actually | ||||
1199 | implement). | ||||
1200 | |||||
1201 | If you want to use javascript's C<eval> function to "parse" JSON, you | ||||
1202 | might run into parse errors for valid JSON texts, or the resulting data | ||||
1203 | structure might not be queryable: | ||||
1204 | |||||
1205 | One of the problems is that U+2028 and U+2029 are valid characters inside | ||||
1206 | JSON strings, but are not allowed in ECMAscript string literals, so the | ||||
1207 | following Perl fragment will not output something that can be guaranteed | ||||
1208 | to be parsable by javascript's C<eval>: | ||||
1209 | |||||
1210 | use JSON::XS; | ||||
1211 | |||||
1212 | print encode_json [chr 0x2028]; | ||||
1213 | |||||
1214 | The right fix for this is to use a proper JSON parser in your javascript | ||||
1215 | programs, and not rely on C<eval> (see for example Douglas Crockford's | ||||
1216 | F<json2.js> parser). | ||||
1217 | |||||
1218 | If this is not an option, you can, as a stop-gap measure, simply encode to | ||||
1219 | ASCII-only JSON: | ||||
1220 | |||||
1221 | use JSON::XS; | ||||
1222 | |||||
1223 | print JSON::XS->new->ascii->encode ([chr 0x2028]); | ||||
1224 | |||||
1225 | Note that this will enlarge the resulting JSON text quite a bit if you | ||||
1226 | have many non-ASCII characters. You might be tempted to run some regexes | ||||
1227 | to only escape U+2028 and U+2029, e.g.: | ||||
1228 | |||||
1229 | # DO NOT USE THIS! | ||||
1230 | my $json = JSON::XS->new->utf8->encode ([chr 0x2028]); | ||||
1231 | $json =~ s/\xe2\x80\xa8/\\u2028/g; # escape U+2028 | ||||
1232 | $json =~ s/\xe2\x80\xa9/\\u2029/g; # escape U+2029 | ||||
1233 | print $json; | ||||
1234 | |||||
1235 | Note that I<this is a bad idea>: the above only works for U+2028 and | ||||
1236 | U+2029 and thus only for fully ECMAscript-compliant parsers. Many existing | ||||
1237 | javascript implementations, however, have issues with other characters as | ||||
1238 | well - using C<eval> naively simply I<will> cause problems. | ||||
1239 | |||||
1240 | Another problem is that some javascript implementations reserve | ||||
1241 | some property names for their own purposes (which probably makes | ||||
1242 | them non-ECMAscript-compliant). For example, Iceweasel reserves the | ||||
1243 | C<__proto__> property name for it's own purposes. | ||||
1244 | |||||
1245 | If that is a problem, you could parse try to filter the resulting JSON | ||||
1246 | output for these property strings, e.g.: | ||||
1247 | |||||
1248 | $json =~ s/"__proto__"\s*:/"__proto__renamed":/g; | ||||
1249 | |||||
1250 | This works because C<__proto__> is not valid outside of strings, so every | ||||
1251 | occurence of C<"__proto__"\s*:> must be a string used as property name. | ||||
1252 | |||||
1253 | If you know of other incompatibilities, please let me know. | ||||
1254 | |||||
1255 | |||||
1256 | =head2 JSON and YAML | ||||
1257 | |||||
1258 | You often hear that JSON is a subset of YAML. This is, however, a mass | ||||
1259 | hysteria(*) and very far from the truth (as of the time of this writing), | ||||
1260 | so let me state it clearly: I<in general, there is no way to configure | ||||
1261 | JSON::XS to output a data structure as valid YAML> that works in all | ||||
1262 | cases. | ||||
1263 | |||||
1264 | If you really must use JSON::XS to generate YAML, you should use this | ||||
1265 | algorithm (subject to change in future versions): | ||||
1266 | |||||
1267 | my $to_yaml = JSON::XS->new->utf8->space_after (1); | ||||
1268 | my $yaml = $to_yaml->encode ($ref) . "\n"; | ||||
1269 | |||||
1270 | This will I<usually> generate JSON texts that also parse as valid | ||||
1271 | YAML. Please note that YAML has hardcoded limits on (simple) object key | ||||
1272 | lengths that JSON doesn't have and also has different and incompatible | ||||
1273 | unicode character escape syntax, so you should make sure that your hash | ||||
1274 | keys are noticeably shorter than the 1024 "stream characters" YAML allows | ||||
1275 | and that you do not have characters with codepoint values outside the | ||||
1276 | Unicode BMP (basic multilingual page). YAML also does not allow C<\/> | ||||
1277 | sequences in strings (which JSON::XS does not I<currently> generate, but | ||||
1278 | other JSON generators might). | ||||
1279 | |||||
1280 | There might be other incompatibilities that I am not aware of (or the YAML | ||||
1281 | specification has been changed yet again - it does so quite often). In | ||||
1282 | general you should not try to generate YAML with a JSON generator or vice | ||||
1283 | versa, or try to parse JSON with a YAML parser or vice versa: chances are | ||||
1284 | high that you will run into severe interoperability problems when you | ||||
1285 | least expect it. | ||||
1286 | |||||
1287 | =over 4 | ||||
1288 | |||||
1289 | =item (*) | ||||
1290 | |||||
1291 | I have been pressured multiple times by Brian Ingerson (one of the | ||||
1292 | authors of the YAML specification) to remove this paragraph, despite him | ||||
1293 | acknowledging that the actual incompatibilities exist. As I was personally | ||||
1294 | bitten by this "JSON is YAML" lie, I refused and said I will continue to | ||||
1295 | educate people about these issues, so others do not run into the same | ||||
1296 | problem again and again. After this, Brian called me a (quote)I<complete | ||||
1297 | and worthless idiot>(unquote). | ||||
1298 | |||||
1299 | In my opinion, instead of pressuring and insulting people who actually | ||||
1300 | clarify issues with YAML and the wrong statements of some of its | ||||
1301 | proponents, I would kindly suggest reading the JSON spec (which is not | ||||
1302 | that difficult or long) and finally make YAML compatible to it, and | ||||
1303 | educating users about the changes, instead of spreading lies about the | ||||
1304 | real compatibility for many I<years> and trying to silence people who | ||||
1305 | point out that it isn't true. | ||||
1306 | |||||
1307 | Addendum/2009: the YAML 1.2 spec is still incomaptible with JSON, even | ||||
1308 | though the incompatibilities have been documented (and are known to | ||||
1309 | Brian) for many years and the spec makes explicit claims that YAML is a | ||||
1310 | superset of JSON. It would be so easy to fix, but apparently, bullying and | ||||
1311 | corrupting userdata is so much easier. | ||||
1312 | |||||
1313 | =back | ||||
1314 | |||||
1315 | |||||
1316 | =head2 SPEED | ||||
1317 | |||||
1318 | It seems that JSON::XS is surprisingly fast, as shown in the following | ||||
1319 | tables. They have been generated with the help of the C<eg/bench> program | ||||
1320 | in the JSON::XS distribution, to make it easy to compare on your own | ||||
1321 | system. | ||||
1322 | |||||
1323 | First comes a comparison between various modules using | ||||
1324 | a very short single-line JSON string (also available at | ||||
1325 | L<http://dist.schmorp.de/misc/json/short.json>). | ||||
1326 | |||||
1327 | {"method": "handleMessage", "params": ["user1", | ||||
1328 | "we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7, | ||||
1329 | true, false]} | ||||
1330 | |||||
1331 | It shows the number of encodes/decodes per second (JSON::XS uses | ||||
1332 | the functional interface, while JSON::XS/2 uses the OO interface | ||||
1333 | with pretty-printing and hashkey sorting enabled, JSON::XS/3 enables | ||||
1334 | shrink). Higher is better: | ||||
1335 | |||||
1336 | module | encode | decode | | ||||
1337 | -----------|------------|------------| | ||||
1338 | JSON 1.x | 4990.842 | 4088.813 | | ||||
1339 | JSON::DWIW | 51653.990 | 71575.154 | | ||||
1340 | JSON::PC | 65948.176 | 74631.744 | | ||||
1341 | JSON::PP | 8931.652 | 3817.168 | | ||||
1342 | JSON::Syck | 24877.248 | 27776.848 | | ||||
1343 | JSON::XS | 388361.481 | 227951.304 | | ||||
1344 | JSON::XS/2 | 227951.304 | 218453.333 | | ||||
1345 | JSON::XS/3 | 338250.323 | 218453.333 | | ||||
1346 | Storable | 16500.016 | 135300.129 | | ||||
1347 | -----------+------------+------------+ | ||||
1348 | |||||
1349 | That is, JSON::XS is about five times faster than JSON::DWIW on encoding, | ||||
1350 | about three times faster on decoding, and over forty times faster | ||||
1351 | than JSON, even with pretty-printing and key sorting. It also compares | ||||
1352 | favourably to Storable for small amounts of data. | ||||
1353 | |||||
1354 | Using a longer test string (roughly 18KB, generated from Yahoo! Locals | ||||
1355 | search API (L<http://dist.schmorp.de/misc/json/long.json>). | ||||
1356 | |||||
1357 | module | encode | decode | | ||||
1358 | -----------|------------|------------| | ||||
1359 | JSON 1.x | 55.260 | 34.971 | | ||||
1360 | JSON::DWIW | 825.228 | 1082.513 | | ||||
1361 | JSON::PC | 3571.444 | 2394.829 | | ||||
1362 | JSON::PP | 210.987 | 32.574 | | ||||
1363 | JSON::Syck | 552.551 | 787.544 | | ||||
1364 | JSON::XS | 5780.463 | 4854.519 | | ||||
1365 | JSON::XS/2 | 3869.998 | 4798.975 | | ||||
1366 | JSON::XS/3 | 5862.880 | 4798.975 | | ||||
1367 | Storable | 4445.002 | 5235.027 | | ||||
1368 | -----------+------------+------------+ | ||||
1369 | |||||
1370 | Again, JSON::XS leads by far (except for Storable which non-surprisingly | ||||
1371 | decodes faster). | ||||
1372 | |||||
1373 | On large strings containing lots of high Unicode characters, some modules | ||||
1374 | (such as JSON::PC) seem to decode faster than JSON::XS, but the result | ||||
1375 | will be broken due to missing (or wrong) Unicode handling. Others refuse | ||||
1376 | to decode or encode properly, so it was impossible to prepare a fair | ||||
1377 | comparison table for that case. | ||||
1378 | |||||
1379 | |||||
1380 | =head1 SECURITY CONSIDERATIONS | ||||
1381 | |||||
1382 | When you are using JSON in a protocol, talking to untrusted potentially | ||||
1383 | hostile creatures requires relatively few measures. | ||||
1384 | |||||
1385 | First of all, your JSON decoder should be secure, that is, should not have | ||||
1386 | any buffer overflows. Obviously, this module should ensure that and I am | ||||
1387 | trying hard on making that true, but you never know. | ||||
1388 | |||||
1389 | Second, you need to avoid resource-starving attacks. That means you should | ||||
1390 | limit the size of JSON texts you accept, or make sure then when your | ||||
1391 | resources run out, that's just fine (e.g. by using a separate process that | ||||
1392 | can crash safely). The size of a JSON text in octets or characters is | ||||
1393 | usually a good indication of the size of the resources required to decode | ||||
1394 | it into a Perl structure. While JSON::XS can check the size of the JSON | ||||
1395 | text, it might be too late when you already have it in memory, so you | ||||
1396 | might want to check the size before you accept the string. | ||||
1397 | |||||
1398 | Third, JSON::XS recurses using the C stack when decoding objects and | ||||
1399 | arrays. The C stack is a limited resource: for instance, on my amd64 | ||||
1400 | machine with 8MB of stack size I can decode around 180k nested arrays but | ||||
1401 | only 14k nested JSON objects (due to perl itself recursing deeply on croak | ||||
1402 | to free the temporary). If that is exceeded, the program crashes. To be | ||||
1403 | conservative, the default nesting limit is set to 512. If your process | ||||
1404 | has a smaller stack, you should adjust this setting accordingly with the | ||||
1405 | C<max_depth> method. | ||||
1406 | |||||
1407 | Something else could bomb you, too, that I forgot to think of. In that | ||||
1408 | case, you get to keep the pieces. I am always open for hints, though... | ||||
1409 | |||||
1410 | Also keep in mind that JSON::XS might leak contents of your Perl data | ||||
1411 | structures in its error messages, so when you serialise sensitive | ||||
1412 | information you might want to make sure that exceptions thrown by JSON::XS | ||||
1413 | will not end up in front of untrusted eyes. | ||||
1414 | |||||
1415 | If you are using JSON::XS to return packets to consumption | ||||
1416 | by JavaScript scripts in a browser you should have a look at | ||||
1417 | L<http://jpsykes.com/47/practical-csrf-and-json-security> to see whether | ||||
1418 | you are vulnerable to some common attack vectors (which really are browser | ||||
1419 | design bugs, but it is still you who will have to deal with it, as major | ||||
1420 | browser developers care only for features, not about getting security | ||||
1421 | right). | ||||
1422 | |||||
1423 | |||||
1424 | =head1 THREADS | ||||
1425 | |||||
1426 | This module is I<not> guaranteed to be thread safe and there are no | ||||
1427 | plans to change this until Perl gets thread support (as opposed to the | ||||
1428 | horribly slow so-called "threads" which are simply slow and bloated | ||||
1429 | process simulations - use fork, it's I<much> faster, cheaper, better). | ||||
1430 | |||||
1431 | (It might actually work, but you have been warned). | ||||
1432 | |||||
1433 | |||||
1434 | =head1 BUGS | ||||
1435 | |||||
1436 | While the goal of this module is to be correct, that unfortunately does | ||||
1437 | not mean it's bug-free, only that I think its design is bug-free. If you | ||||
1438 | keep reporting bugs they will be fixed swiftly, though. | ||||
1439 | |||||
1440 | Please refrain from using rt.cpan.org or any other bug reporting | ||||
1441 | service. I put the contact address into my modules for a reason. | ||||
1442 | |||||
1443 | =cut | ||||
1444 | |||||
1445 | 1 | 22µs | our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" }; | ||
1446 | 1 | 700ns | our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" }; | ||
1447 | |||||
1448 | sub true() { $true } | ||||
1449 | sub false() { $false } | ||||
1450 | |||||
1451 | sub is_bool($) { | ||||
1452 | UNIVERSAL::isa $_[0], "JSON::XS::Boolean" | ||||
1453 | # or UNIVERSAL::isa $_[0], "JSON::Literal" | ||||
1454 | } | ||||
1455 | |||||
1456 | 1 | 390µs | 1 | 1.00ms | XSLoader::load "JSON::XS", $VERSION; # spent 1.00ms making 1 call to XSLoader::load |
1457 | |||||
1458 | package JSON::XS::Boolean; | ||||
1459 | |||||
1460 | use overload | ||||
1461 | # spent 40µs (10+30) within JSON::XS::Boolean::BEGIN@1461 which was called
# once (10µs+30µs) by JSON::BEGIN@2 at line 1464 | ||||
1462 | "++" => sub { $_[0] = ${$_[0]} + 1 }, | ||||
1463 | "--" => sub { $_[0] = ${$_[0]} - 1 }, | ||||
1464 | 3 | 35µs | 2 | 69µs | fallback => 1; # spent 40µs making 1 call to JSON::XS::Boolean::BEGIN@1461
# spent 30µs making 1 call to overload::import |
1465 | |||||
1466 | 1 | 12µs | 1; | ||
1467 | |||||
1468 | =head1 SEE ALSO | ||||
1469 | |||||
1470 | The F<json_xs> command line utility for quick experiments. | ||||
1471 | |||||
1472 | =head1 AUTHOR | ||||
1473 | |||||
1474 | Marc Lehmann <schmorp@schmorp.de> | ||||
1475 | http://home.schmorp.de/ | ||||
1476 | |||||
1477 | =cut | ||||
1478 | |||||
# spent 20µs within JSON::XS::DESTROY which was called 13 times, avg 2µs/call:
# 8 times (13µs+0s) by JSON::to_json at line 165 of ../lib/SimpleDB/Class/Types.pm, avg 2µs/call
# 5 times (7µs+0s) by JSON::from_json at line 213 of ../lib/SimpleDB/Class/Types.pm, avg 1µs/call | |||||
# spent 66µs within JSON::XS::decode which was called 5 times, avg 13µs/call:
# 5 times (66µs+0s) by JSON::from_json at line 154 of JSON.pm, avg 13µs/call | |||||
# spent 103µs within JSON::XS::encode which was called 8 times, avg 13µs/call:
# 8 times (103µs+0s) by JSON::to_json at line 140 of JSON.pm, avg 13µs/call | |||||
# spent 74µs within JSON::XS::new which was called 13 times, avg 6µs/call:
# 8 times (54µs+0s) by JSON::to_json at line 131 of JSON.pm, avg 7µs/call
# 5 times (20µs+0s) by JSON::from_json at line 145 of JSON.pm, avg 4µs/call |