| 1 | NAME |
1 | NAME |
| 2 | JSON::XS - JSON serialising/deserialising, done correctly and fast |
2 | JSON::XS - JSON serialising/deserialising, done correctly and fast |
| 3 | |
3 | |
| 4 | JSON::XS - 正しくて高速な JSON |
4 | JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ |
| 5 | シリアライザ/デシリアライザ |
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| 6 | (http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html) |
5 | (http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html) |
| 7 | |
6 | |
| 8 | SYNOPSIS |
7 | SYNOPSIS |
| 9 | use JSON::XS; |
8 | use JSON::XS; |
| 10 | |
9 | |
| 11 | # exported functions, they croak on error |
10 | # exported functions, they croak on error |
| 12 | # and expect/generate UTF-8 |
11 | # and expect/generate UTF-8 |
| 13 | |
12 | |
| 14 | $utf8_encoded_json_text = to_json $perl_hash_or_arrayref; |
13 | $utf8_encoded_json_text = encode_json $perl_hash_or_arrayref; |
| 15 | $perl_hash_or_arrayref = from_json $utf8_encoded_json_text; |
14 | $perl_hash_or_arrayref = decode_json $utf8_encoded_json_text; |
| 16 | |
15 | |
| 17 | # OO-interface |
16 | # OO-interface |
| 18 | |
17 | |
| 19 | $coder = JSON::XS->new->ascii->pretty->allow_nonref; |
18 | $coder = JSON::XS->new->ascii->pretty->allow_nonref; |
| 20 | $pretty_printed_unencoded = $coder->encode ($perl_scalar); |
19 | $pretty_printed_unencoded = $coder->encode ($perl_scalar); |
| 21 | $perl_scalar = $coder->decode ($unicode_json_text); |
20 | $perl_scalar = $coder->decode ($unicode_json_text); |
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21 | |
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22 | # Note that JSON version 2.0 and above will automatically use JSON::XS |
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23 | # if available, at virtually no speed overhead either, so you should |
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24 | # be able to just: |
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25 | |
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26 | use JSON; |
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27 | |
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28 | # and do the same things, except that you have a pure-perl fallback now. |
| 22 | |
29 | |
| 23 | DESCRIPTION |
30 | DESCRIPTION |
| 24 | This module converts Perl data structures to JSON and vice versa. Its |
31 | This module converts Perl data structures to JSON and vice versa. Its |
| 25 | primary goal is to be *correct* and its secondary goal is to be *fast*. |
32 | primary goal is to be *correct* and its secondary goal is to be *fast*. |
| 26 | To reach the latter goal it was written in C. |
33 | To reach the latter goal it was written in C. |
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34 | |
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35 | Beginning with version 2.0 of the JSON module, when both JSON and |
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36 | JSON::XS are installed, then JSON will fall back on JSON::XS (this can |
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37 | be overriden) with no overhead due to emulation (by inheritign |
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38 | constructor and methods). If JSON::XS is not available, it will fall |
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39 | back to the compatible JSON::PP module as backend, so using JSON instead |
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40 | of JSON::XS gives you a portable JSON API that can be fast when you need |
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41 | and doesn't require a C compiler when that is a problem. |
| 27 | |
42 | |
| 28 | As this is the n-th-something JSON module on CPAN, what was the reason |
43 | As this is the n-th-something JSON module on CPAN, what was the reason |
| 29 | to write yet another JSON module? While it seems there are many JSON |
44 | to write yet another JSON module? While it seems there are many JSON |
| 30 | modules, none of them correctly handle all corner cases, and in most |
45 | modules, none of them correctly handle all corner cases, and in most |
| 31 | cases their maintainers are unresponsive, gone missing, or not listening |
46 | cases their maintainers are unresponsive, gone missing, or not listening |
| … | |
… | |
| 35 | |
50 | |
| 36 | See MAPPING, below, on how JSON::XS maps perl values to JSON values and |
51 | See MAPPING, below, on how JSON::XS maps perl values to JSON values and |
| 37 | vice versa. |
52 | vice versa. |
| 38 | |
53 | |
| 39 | FEATURES |
54 | FEATURES |
| 40 | * correct Unicode handling |
55 | * correct Unicode handling |
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56 | |
| 41 | This module knows how to handle Unicode, and even documents how and |
57 | This module knows how to handle Unicode, documents how and when it |
| 42 | when it does so. |
58 | does so, and even documents what "correct" means. |
| 43 | |
59 | |
| 44 | * round-trip integrity |
60 | * round-trip integrity |
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61 | |
| 45 | When you serialise a perl data structure using only datatypes |
62 | When you serialise a perl data structure using only datatypes |
| 46 | supported by JSON, the deserialised data structure is identical on |
63 | supported by JSON, the deserialised data structure is identical on |
| 47 | the Perl level. (e.g. the string "2.0" doesn't suddenly become "2" |
64 | the Perl level. (e.g. the string "2.0" doesn't suddenly become "2" |
| 48 | just because it looks like a number). |
65 | just because it looks like a number). There minor *are* exceptions |
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66 | to this, read the MAPPING section below to learn about those. |
| 49 | |
67 | |
| 50 | * strict checking of JSON correctness |
68 | * strict checking of JSON correctness |
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69 | |
| 51 | There is no guessing, no generating of illegal JSON texts by |
70 | There is no guessing, no generating of illegal JSON texts by |
| 52 | default, and only JSON is accepted as input by default (the latter |
71 | default, and only JSON is accepted as input by default (the latter |
| 53 | is a security feature). |
72 | is a security feature). |
| 54 | |
73 | |
| 55 | * fast |
74 | * fast |
| 56 | Compared to other JSON modules, this module compares favourably in |
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| 57 | terms of speed, too. |
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| 58 | |
75 | |
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76 | Compared to other JSON modules and other serialisers such as |
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77 | Storable, this module usually compares favourably in terms of speed, |
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78 | too. |
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79 | |
| 59 | * simple to use |
80 | * simple to use |
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81 | |
| 60 | This module has both a simple functional interface as well as an OO |
82 | This module has both a simple functional interface as well as an |
| 61 | interface. |
83 | objetc oriented interface interface. |
| 62 | |
84 | |
| 63 | * reasonably versatile output formats |
85 | * reasonably versatile output formats |
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86 | |
| 64 | You can choose between the most compact guaranteed single-line |
87 | You can choose between the most compact guaranteed-single-line |
| 65 | format possible (nice for simple line-based protocols), a pure-ascii |
88 | format possible (nice for simple line-based protocols), a pure-ascii |
| 66 | format (for when your transport is not 8-bit clean, still supports |
89 | format (for when your transport is not 8-bit clean, still supports |
| 67 | the whole Unicode range), or a pretty-printed format (for when you |
90 | the whole Unicode range), or a pretty-printed format (for when you |
| 68 | want to read that stuff). Or you can combine those features in |
91 | want to read that stuff). Or you can combine those features in |
| 69 | whatever way you like. |
92 | whatever way you like. |
| 70 | |
93 | |
| 71 | FUNCTIONAL INTERFACE |
94 | FUNCTIONAL INTERFACE |
| 72 | The following convenience methods are provided by this module. They are |
95 | The following convenience methods are provided by this module. They are |
| 73 | exported by default: |
96 | exported by default: |
| 74 | |
97 | |
| 75 | $json_text = to_json $perl_scalar |
98 | $json_text = encode_json $perl_scalar |
| 76 | Converts the given Perl data structure to a UTF-8 encoded, binary |
99 | Converts the given Perl data structure to a UTF-8 encoded, binary |
| 77 | string (that is, the string contains octets only). Croaks on error. |
100 | string (that is, the string contains octets only). Croaks on error. |
| 78 | |
101 | |
| 79 | This function call is functionally identical to: |
102 | This function call is functionally identical to: |
| 80 | |
103 | |
| 81 | $json_text = JSON::XS->new->utf8->encode ($perl_scalar) |
104 | $json_text = JSON::XS->new->utf8->encode ($perl_scalar) |
| 82 | |
105 | |
| 83 | except being faster. |
106 | except being faster. |
| 84 | |
107 | |
| 85 | $perl_scalar = from_json $json_text |
108 | $perl_scalar = decode_json $json_text |
| 86 | The opposite of "to_json": expects an UTF-8 (binary) string and |
109 | The opposite of "encode_json": expects an UTF-8 (binary) string and |
| 87 | tries to parse that as an UTF-8 encoded JSON text, returning the |
110 | tries to parse that as an UTF-8 encoded JSON text, returning the |
| 88 | resulting reference. Croaks on error. |
111 | resulting reference. Croaks on error. |
| 89 | |
112 | |
| 90 | This function call is functionally identical to: |
113 | This function call is functionally identical to: |
| 91 | |
114 | |
| … | |
… | |
| 109 | 1. Perl strings can store characters with ordinal values > 255. |
132 | 1. Perl strings can store characters with ordinal values > 255. |
| 110 | This enables you to store Unicode characters as single characters in |
133 | This enables you to store Unicode characters as single characters in |
| 111 | a Perl string - very natural. |
134 | a Perl string - very natural. |
| 112 | |
135 | |
| 113 | 2. Perl does *not* associate an encoding with your strings. |
136 | 2. Perl does *not* associate an encoding with your strings. |
| 114 | Unless you force it to, e.g. when matching it against a regex, or |
137 | ... until you force it to, e.g. when matching it against a regex, or |
| 115 | printing the scalar to a file, in which case Perl either interprets |
138 | printing the scalar to a file, in which case Perl either interprets |
| 116 | your string as locale-encoded text, octets/binary, or as Unicode, |
139 | your string as locale-encoded text, octets/binary, or as Unicode, |
| 117 | depending on various settings. In no case is an encoding stored |
140 | depending on various settings. In no case is an encoding stored |
| 118 | together with your data, it is *use* that decides encoding, not any |
141 | together with your data, it is *use* that decides encoding, not any |
| 119 | magical metadata. |
142 | magical meta data. |
| 120 | |
143 | |
| 121 | 3. The internal utf-8 flag has no meaning with regards to the encoding |
144 | 3. The internal utf-8 flag has no meaning with regards to the encoding |
| 122 | of your string. |
145 | of your string. |
| 123 | Just ignore that flag unless you debug a Perl bug, a module written |
146 | Just ignore that flag unless you debug a Perl bug, a module written |
| 124 | in XS or want to dive into the internals of perl. Otherwise it will |
147 | in XS or want to dive into the internals of perl. Otherwise it will |
| … | |
… | |
| 155 | |
178 | |
| 156 | my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]}) |
179 | my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]}) |
| 157 | => {"a": [1, 2]} |
180 | => {"a": [1, 2]} |
| 158 | |
181 | |
| 159 | $json = $json->ascii ([$enable]) |
182 | $json = $json->ascii ([$enable]) |
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183 | $enabled = $json->get_ascii |
| 160 | If $enable is true (or missing), then the "encode" method will not |
184 | If $enable is true (or missing), then the "encode" method will not |
| 161 | generate characters outside the code range 0..127 (which is ASCII). |
185 | generate characters outside the code range 0..127 (which is ASCII). |
| 162 | Any Unicode characters outside that range will be escaped using |
186 | Any Unicode characters outside that range will be escaped using |
| 163 | either a single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL |
187 | either a single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL |
| 164 | escape sequence, as per RFC4627. The resulting encoded JSON text can |
188 | escape sequence, as per RFC4627. The resulting encoded JSON text can |
| … | |
… | |
| 168 | |
192 | |
| 169 | If $enable is false, then the "encode" method will not escape |
193 | If $enable is false, then the "encode" method will not escape |
| 170 | Unicode characters unless required by the JSON syntax or other |
194 | Unicode characters unless required by the JSON syntax or other |
| 171 | flags. This results in a faster and more compact format. |
195 | flags. This results in a faster and more compact format. |
| 172 | |
196 | |
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197 | See also the section *ENCODING/CODESET FLAG NOTES* later in this |
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198 | document. |
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199 | |
| 173 | The main use for this flag is to produce JSON texts that can be |
200 | The main use for this flag is to produce JSON texts that can be |
| 174 | transmitted over a 7-bit channel, as the encoded JSON texts will not |
201 | transmitted over a 7-bit channel, as the encoded JSON texts will not |
| 175 | contain any 8 bit characters. |
202 | contain any 8 bit characters. |
| 176 | |
203 | |
| 177 | JSON::XS->new->ascii (1)->encode ([chr 0x10401]) |
204 | JSON::XS->new->ascii (1)->encode ([chr 0x10401]) |
| 178 | => ["\ud801\udc01"] |
205 | => ["\ud801\udc01"] |
| 179 | |
206 | |
| 180 | $json = $json->latin1 ([$enable]) |
207 | $json = $json->latin1 ([$enable]) |
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208 | $enabled = $json->get_latin1 |
| 181 | If $enable is true (or missing), then the "encode" method will |
209 | If $enable is true (or missing), then the "encode" method will |
| 182 | encode the resulting JSON text as latin1 (or iso-8859-1), escaping |
210 | encode the resulting JSON text as latin1 (or iso-8859-1), escaping |
| 183 | any characters outside the code range 0..255. The resulting string |
211 | any characters outside the code range 0..255. The resulting string |
| 184 | can be treated as a latin1-encoded JSON text or a native Unicode |
212 | can be treated as a latin1-encoded JSON text or a native Unicode |
| 185 | string. The "decode" method will not be affected in any way by this |
213 | string. The "decode" method will not be affected in any way by this |
| … | |
… | |
| 187 | superset of latin1. |
215 | superset of latin1. |
| 188 | |
216 | |
| 189 | If $enable is false, then the "encode" method will not escape |
217 | If $enable is false, then the "encode" method will not escape |
| 190 | Unicode characters unless required by the JSON syntax or other |
218 | Unicode characters unless required by the JSON syntax or other |
| 191 | flags. |
219 | flags. |
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220 | |
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221 | See also the section *ENCODING/CODESET FLAG NOTES* later in this |
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222 | document. |
| 192 | |
223 | |
| 193 | The main use for this flag is efficiently encoding binary data as |
224 | The main use for this flag is efficiently encoding binary data as |
| 194 | JSON text, as most octets will not be escaped, resulting in a |
225 | JSON text, as most octets will not be escaped, resulting in a |
| 195 | smaller encoded size. The disadvantage is that the resulting JSON |
226 | smaller encoded size. The disadvantage is that the resulting JSON |
| 196 | text is encoded in latin1 (and must correctly be treated as such |
227 | text is encoded in latin1 (and must correctly be treated as such |
| … | |
… | |
| 201 | |
232 | |
| 202 | JSON::XS->new->latin1->encode (["\x{89}\x{abc}"] |
233 | JSON::XS->new->latin1->encode (["\x{89}\x{abc}"] |
| 203 | => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not) |
234 | => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not) |
| 204 | |
235 | |
| 205 | $json = $json->utf8 ([$enable]) |
236 | $json = $json->utf8 ([$enable]) |
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237 | $enabled = $json->get_utf8 |
| 206 | If $enable is true (or missing), then the "encode" method will |
238 | If $enable is true (or missing), then the "encode" method will |
| 207 | encode the JSON result into UTF-8, as required by many protocols, |
239 | encode the JSON result into UTF-8, as required by many protocols, |
| 208 | while the "decode" method expects to be handled an UTF-8-encoded |
240 | while the "decode" method expects to be handled an UTF-8-encoded |
| 209 | string. Please note that UTF-8-encoded strings do not contain any |
241 | string. Please note that UTF-8-encoded strings do not contain any |
| 210 | characters outside the range 0..255, they are thus useful for |
242 | characters outside the range 0..255, they are thus useful for |
| … | |
… | |
| 215 | If $enable is false, then the "encode" method will return the JSON |
247 | If $enable is false, then the "encode" method will return the JSON |
| 216 | string as a (non-encoded) Unicode string, while "decode" expects |
248 | string as a (non-encoded) Unicode string, while "decode" expects |
| 217 | thus a Unicode string. Any decoding or encoding (e.g. to UTF-8 or |
249 | thus a Unicode string. Any decoding or encoding (e.g. to UTF-8 or |
| 218 | UTF-16) needs to be done yourself, e.g. using the Encode module. |
250 | UTF-16) needs to be done yourself, e.g. using the Encode module. |
| 219 | |
251 | |
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252 | See also the section *ENCODING/CODESET FLAG NOTES* later in this |
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253 | document. |
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254 | |
| 220 | Example, output UTF-16BE-encoded JSON: |
255 | Example, output UTF-16BE-encoded JSON: |
| 221 | |
256 | |
| 222 | use Encode; |
257 | use Encode; |
| 223 | $jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object); |
258 | $jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object); |
| 224 | |
259 | |
| … | |
… | |
| 242 | 2 |
277 | 2 |
| 243 | ] |
278 | ] |
| 244 | } |
279 | } |
| 245 | |
280 | |
| 246 | $json = $json->indent ([$enable]) |
281 | $json = $json->indent ([$enable]) |
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282 | $enabled = $json->get_indent |
| 247 | If $enable is true (or missing), then the "encode" method will use a |
283 | If $enable is true (or missing), then the "encode" method will use a |
| 248 | multiline format as output, putting every array member or |
284 | multiline format as output, putting every array member or |
| 249 | object/hash key-value pair into its own line, indenting them |
285 | object/hash key-value pair into its own line, indenting them |
| 250 | properly. |
286 | properly. |
| 251 | |
287 | |
| … | |
… | |
| 253 | the resulting JSON text is guaranteed not to contain any "newlines". |
289 | the resulting JSON text is guaranteed not to contain any "newlines". |
| 254 | |
290 | |
| 255 | This setting has no effect when decoding JSON texts. |
291 | This setting has no effect when decoding JSON texts. |
| 256 | |
292 | |
| 257 | $json = $json->space_before ([$enable]) |
293 | $json = $json->space_before ([$enable]) |
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294 | $enabled = $json->get_space_before |
| 258 | If $enable is true (or missing), then the "encode" method will add |
295 | If $enable is true (or missing), then the "encode" method will add |
| 259 | an extra optional space before the ":" separating keys from values |
296 | an extra optional space before the ":" separating keys from values |
| 260 | in JSON objects. |
297 | in JSON objects. |
| 261 | |
298 | |
| 262 | If $enable is false, then the "encode" method will not add any extra |
299 | If $enable is false, then the "encode" method will not add any extra |
| … | |
… | |
| 268 | Example, space_before enabled, space_after and indent disabled: |
305 | Example, space_before enabled, space_after and indent disabled: |
| 269 | |
306 | |
| 270 | {"key" :"value"} |
307 | {"key" :"value"} |
| 271 | |
308 | |
| 272 | $json = $json->space_after ([$enable]) |
309 | $json = $json->space_after ([$enable]) |
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310 | $enabled = $json->get_space_after |
| 273 | If $enable is true (or missing), then the "encode" method will add |
311 | If $enable is true (or missing), then the "encode" method will add |
| 274 | an extra optional space after the ":" separating keys from values in |
312 | an extra optional space after the ":" separating keys from values in |
| 275 | JSON objects and extra whitespace after the "," separating key-value |
313 | JSON objects and extra whitespace after the "," separating key-value |
| 276 | pairs and array members. |
314 | pairs and array members. |
| 277 | |
315 | |
| … | |
… | |
| 283 | Example, space_before and indent disabled, space_after enabled: |
321 | Example, space_before and indent disabled, space_after enabled: |
| 284 | |
322 | |
| 285 | {"key": "value"} |
323 | {"key": "value"} |
| 286 | |
324 | |
| 287 | $json = $json->relaxed ([$enable]) |
325 | $json = $json->relaxed ([$enable]) |
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326 | $enabled = $json->get_relaxed |
| 288 | If $enable is true (or missing), then "decode" will accept some |
327 | If $enable is true (or missing), then "decode" will accept some |
| 289 | extensions to normal JSON syntax (see below). "encode" will not be |
328 | extensions to normal JSON syntax (see below). "encode" will not be |
| 290 | affected in anyway. *Be aware that this option makes you accept |
329 | affected in anyway. *Be aware that this option makes you accept |
| 291 | invalid JSON texts as if they were valid!*. I suggest only to use |
330 | invalid JSON texts as if they were valid!*. I suggest only to use |
| 292 | this option to parse application-specific files written by humans |
331 | this option to parse application-specific files written by humans |
| … | |
… | |
| 295 | If $enable is false (the default), then "decode" will only accept |
334 | If $enable is false (the default), then "decode" will only accept |
| 296 | valid JSON texts. |
335 | valid JSON texts. |
| 297 | |
336 | |
| 298 | Currently accepted extensions are: |
337 | Currently accepted extensions are: |
| 299 | |
338 | |
| 300 | * list items can have an end-comma |
339 | * list items can have an end-comma |
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340 | |
| 301 | JSON *separates* array elements and key-value pairs with commas. |
341 | JSON *separates* array elements and key-value pairs with commas. |
| 302 | This can be annoying if you write JSON texts manually and want |
342 | This can be annoying if you write JSON texts manually and want |
| 303 | to be able to quickly append elements, so this extension accepts |
343 | to be able to quickly append elements, so this extension accepts |
| 304 | comma at the end of such items not just between them: |
344 | comma at the end of such items not just between them: |
| 305 | |
345 | |
| … | |
… | |
| 310 | { |
350 | { |
| 311 | "k1": "v1", |
351 | "k1": "v1", |
| 312 | "k2": "v2", <- this comma not normally allowed |
352 | "k2": "v2", <- this comma not normally allowed |
| 313 | } |
353 | } |
| 314 | |
354 | |
| 315 | * shell-style '#'-comments |
355 | * shell-style '#'-comments |
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356 | |
| 316 | Whenever JSON allows whitespace, shell-style comments are |
357 | Whenever JSON allows whitespace, shell-style comments are |
| 317 | additionally allowed. They are terminated by the first |
358 | additionally allowed. They are terminated by the first |
| 318 | carriage-return or line-feed character, after which more |
359 | carriage-return or line-feed character, after which more |
| 319 | white-space and comments are allowed. |
360 | white-space and comments are allowed. |
| 320 | |
361 | |
| … | |
… | |
| 322 | 1, # this comment not allowed in JSON |
363 | 1, # this comment not allowed in JSON |
| 323 | # neither this one... |
364 | # neither this one... |
| 324 | ] |
365 | ] |
| 325 | |
366 | |
| 326 | $json = $json->canonical ([$enable]) |
367 | $json = $json->canonical ([$enable]) |
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368 | $enabled = $json->get_canonical |
| 327 | If $enable is true (or missing), then the "encode" method will |
369 | If $enable is true (or missing), then the "encode" method will |
| 328 | output JSON objects by sorting their keys. This is adding a |
370 | output JSON objects by sorting their keys. This is adding a |
| 329 | comparatively high overhead. |
371 | comparatively high overhead. |
| 330 | |
372 | |
| 331 | If $enable is false, then the "encode" method will output key-value |
373 | If $enable is false, then the "encode" method will output key-value |
| … | |
… | |
| 339 | in Perl. |
381 | in Perl. |
| 340 | |
382 | |
| 341 | This setting has no effect when decoding JSON texts. |
383 | This setting has no effect when decoding JSON texts. |
| 342 | |
384 | |
| 343 | $json = $json->allow_nonref ([$enable]) |
385 | $json = $json->allow_nonref ([$enable]) |
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386 | $enabled = $json->get_allow_nonref |
| 344 | If $enable is true (or missing), then the "encode" method can |
387 | If $enable is true (or missing), then the "encode" method can |
| 345 | convert a non-reference into its corresponding string, number or |
388 | convert a non-reference into its corresponding string, number or |
| 346 | null JSON value, which is an extension to RFC4627. Likewise, |
389 | null JSON value, which is an extension to RFC4627. Likewise, |
| 347 | "decode" will accept those JSON values instead of croaking. |
390 | "decode" will accept those JSON values instead of croaking. |
| 348 | |
391 | |
| … | |
… | |
| 356 | |
399 | |
| 357 | JSON::XS->new->allow_nonref->encode ("Hello, World!") |
400 | JSON::XS->new->allow_nonref->encode ("Hello, World!") |
| 358 | => "Hello, World!" |
401 | => "Hello, World!" |
| 359 | |
402 | |
| 360 | $json = $json->allow_blessed ([$enable]) |
403 | $json = $json->allow_blessed ([$enable]) |
|
|
404 | $enabled = $json->get_allow_blessed |
| 361 | If $enable is true (or missing), then the "encode" method will not |
405 | If $enable is true (or missing), then the "encode" method will not |
| 362 | barf when it encounters a blessed reference. Instead, the value of |
406 | barf when it encounters a blessed reference. Instead, the value of |
| 363 | the convert_blessed option will decide whether "null" |
407 | the convert_blessed option will decide whether "null" |
| 364 | ("convert_blessed" disabled or no "to_json" method found) or a |
408 | ("convert_blessed" disabled or no "TO_JSON" method found) or a |
| 365 | representation of the object ("convert_blessed" enabled and |
409 | representation of the object ("convert_blessed" enabled and |
| 366 | "to_json" method found) is being encoded. Has no effect on "decode". |
410 | "TO_JSON" method found) is being encoded. Has no effect on "decode". |
| 367 | |
411 | |
| 368 | If $enable is false (the default), then "encode" will throw an |
412 | If $enable is false (the default), then "encode" will throw an |
| 369 | exception when it encounters a blessed object. |
413 | exception when it encounters a blessed object. |
| 370 | |
414 | |
| 371 | $json = $json->convert_blessed ([$enable]) |
415 | $json = $json->convert_blessed ([$enable]) |
|
|
416 | $enabled = $json->get_convert_blessed |
| 372 | If $enable is true (or missing), then "encode", upon encountering a |
417 | If $enable is true (or missing), then "encode", upon encountering a |
| 373 | blessed object, will check for the availability of the "TO_JSON" |
418 | blessed object, will check for the availability of the "TO_JSON" |
| 374 | method on the object's class. If found, it will be called in scalar |
419 | method on the object's class. If found, it will be called in scalar |
| 375 | context and the resulting scalar will be encoded instead of the |
420 | context and the resulting scalar will be encoded instead of the |
| 376 | object. If no "TO_JSON" method is found, the value of |
421 | object. If no "TO_JSON" method is found, the value of |
| … | |
… | |
| 380 | returns other blessed objects, those will be handled in the same |
425 | returns other blessed objects, those will be handled in the same |
| 381 | way. "TO_JSON" must take care of not causing an endless recursion |
426 | way. "TO_JSON" must take care of not causing an endless recursion |
| 382 | cycle (== crash) in this case. The name of "TO_JSON" was chosen |
427 | cycle (== crash) in this case. The name of "TO_JSON" was chosen |
| 383 | because other methods called by the Perl core (== not by the user of |
428 | because other methods called by the Perl core (== not by the user of |
| 384 | the object) are usually in upper case letters and to avoid |
429 | the object) are usually in upper case letters and to avoid |
| 385 | collisions with the "to_json" function. |
430 | collisions with any "to_json" function or method. |
| 386 | |
431 | |
| 387 | This setting does not yet influence "decode" in any way, but in the |
432 | This setting does not yet influence "decode" in any way, but in the |
| 388 | future, global hooks might get installed that influence "decode" and |
433 | future, global hooks might get installed that influence "decode" and |
| 389 | are enabled by this setting. |
434 | are enabled by this setting. |
| 390 | |
435 | |
| … | |
… | |
| 466 | |
511 | |
| 467 | { __widget__ => $self->{id} } |
512 | { __widget__ => $self->{id} } |
| 468 | } |
513 | } |
| 469 | |
514 | |
| 470 | $json = $json->shrink ([$enable]) |
515 | $json = $json->shrink ([$enable]) |
|
|
516 | $enabled = $json->get_shrink |
| 471 | Perl usually over-allocates memory a bit when allocating space for |
517 | Perl usually over-allocates memory a bit when allocating space for |
| 472 | strings. This flag optionally resizes strings generated by either |
518 | strings. This flag optionally resizes strings generated by either |
| 473 | "encode" or "decode" to their minimum size possible. This can save |
519 | "encode" or "decode" to their minimum size possible. This can save |
| 474 | memory when your JSON texts are either very very long or you have |
520 | memory when your JSON texts are either very very long or you have |
| 475 | many short strings. It will also try to downgrade any strings to |
521 | many short strings. It will also try to downgrade any strings to |
| … | |
… | |
| 493 | converting strings that look like integers or floats into integers |
539 | converting strings that look like integers or floats into integers |
| 494 | or floats internally (there is no difference on the Perl level), |
540 | or floats internally (there is no difference on the Perl level), |
| 495 | saving space. |
541 | saving space. |
| 496 | |
542 | |
| 497 | $json = $json->max_depth ([$maximum_nesting_depth]) |
543 | $json = $json->max_depth ([$maximum_nesting_depth]) |
|
|
544 | $max_depth = $json->get_max_depth |
| 498 | Sets the maximum nesting level (default 512) accepted while encoding |
545 | Sets the maximum nesting level (default 512) accepted while encoding |
| 499 | or decoding. If the JSON text or Perl data structure has an equal or |
546 | or decoding. If the JSON text or Perl data structure has an equal or |
| 500 | higher nesting level then this limit, then the encoder and decoder |
547 | higher nesting level then this limit, then the encoder and decoder |
| 501 | will stop and croak at that point. |
548 | will stop and croak at that point. |
| 502 | |
549 | |
| … | |
… | |
| 514 | |
561 | |
| 515 | See SECURITY CONSIDERATIONS, below, for more info on why this is |
562 | See SECURITY CONSIDERATIONS, below, for more info on why this is |
| 516 | useful. |
563 | useful. |
| 517 | |
564 | |
| 518 | $json = $json->max_size ([$maximum_string_size]) |
565 | $json = $json->max_size ([$maximum_string_size]) |
|
|
566 | $max_size = $json->get_max_size |
| 519 | Set the maximum length a JSON text may have (in bytes) where |
567 | Set the maximum length a JSON text may have (in bytes) where |
| 520 | decoding is being attempted. The default is 0, meaning no limit. |
568 | decoding is being attempted. The default is 0, meaning no limit. |
| 521 | When "decode" is called on a string longer then this number of |
569 | When "decode" is called on a string longer then this number of |
| 522 | characters it will not attempt to decode the string but throw an |
570 | characters it will not attempt to decode the string but throw an |
| 523 | exception. This setting has no effect on "encode" (yet). |
571 | exception. This setting has no effect on "encode" (yet). |
| … | |
… | |
| 588 | A JSON number becomes either an integer, numeric (floating point) or |
636 | A JSON number becomes either an integer, numeric (floating point) or |
| 589 | string scalar in perl, depending on its range and any fractional |
637 | string scalar in perl, depending on its range and any fractional |
| 590 | parts. On the Perl level, there is no difference between those as |
638 | parts. On the Perl level, there is no difference between those as |
| 591 | Perl handles all the conversion details, but an integer may take |
639 | Perl handles all the conversion details, but an integer may take |
| 592 | slightly less memory and might represent more values exactly than |
640 | slightly less memory and might represent more values exactly than |
| 593 | (floating point) numbers. |
641 | floating point numbers. |
| 594 | |
642 | |
| 595 | If the number consists of digits only, JSON::XS will try to |
643 | If the number consists of digits only, JSON::XS will try to |
| 596 | represent it as an integer value. If that fails, it will try to |
644 | represent it as an integer value. If that fails, it will try to |
| 597 | represent it as a numeric (floating point) value if that is possible |
645 | represent it as a numeric (floating point) value if that is possible |
| 598 | without loss of precision. Otherwise it will preserve the number as |
646 | without loss of precision. Otherwise it will preserve the number as |
| 599 | a string value. |
647 | a string value (in which case you lose roundtripping ability, as the |
|
|
648 | JSON number will be re-encoded toa JSON string). |
| 600 | |
649 | |
| 601 | Numbers containing a fractional or exponential part will always be |
650 | Numbers containing a fractional or exponential part will always be |
| 602 | represented as numeric (floating point) values, possibly at a loss |
651 | represented as numeric (floating point) values, possibly at a loss |
| 603 | of precision. |
652 | of precision (in which case you might lose perfect roundtripping |
| 604 | |
653 | ability, but the JSON number will still be re-encoded as a JSON |
| 605 | This might create round-tripping problems as numbers might become |
654 | number). |
| 606 | strings, but as Perl is typeless there is no other way to do it. |
|
|
| 607 | |
655 | |
| 608 | true, false |
656 | true, false |
| 609 | These JSON atoms become "JSON::XS::true" and "JSON::XS::false", |
657 | These JSON atoms become "JSON::XS::true" and "JSON::XS::false", |
| 610 | respectively. They are overloaded to act almost exactly like the |
658 | respectively. They are overloaded to act almost exactly like the |
| 611 | numbers 1 and 0. You can check whether a scalar is a JSON boolean by |
659 | numbers 1 and 0. You can check whether a scalar is a JSON boolean by |
| … | |
… | |
| 639 | an exception to be thrown, except for references to the integers 0 |
687 | an exception to be thrown, except for references to the integers 0 |
| 640 | and 1, which get turned into "false" and "true" atoms in JSON. You |
688 | and 1, which get turned into "false" and "true" atoms in JSON. You |
| 641 | can also use "JSON::XS::false" and "JSON::XS::true" to improve |
689 | can also use "JSON::XS::false" and "JSON::XS::true" to improve |
| 642 | readability. |
690 | readability. |
| 643 | |
691 | |
| 644 | to_json [\0,JSON::XS::true] # yields [false,true] |
692 | encode_json [\0,JSON::XS::true] # yields [false,true] |
| 645 | |
693 | |
| 646 | JSON::XS::true, JSON::XS::false |
694 | JSON::XS::true, JSON::XS::false |
| 647 | These special values become JSON true and JSON false values, |
695 | These special values become JSON true and JSON false values, |
| 648 | respectively. You can also use "\1" and "\0" directly if you want. |
696 | respectively. You can also use "\1" and "\0" directly if you want. |
| 649 | |
697 | |
| 650 | blessed objects |
698 | blessed objects |
| 651 | Blessed objects are not allowed. JSON::XS currently tries to encode |
699 | Blessed objects are not directly representable in JSON. See the |
| 652 | their underlying representation (hash- or arrayref), but this |
700 | "allow_blessed" and "convert_blessed" methods on various options on |
| 653 | behaviour might change in future versions. |
701 | how to deal with this: basically, you can choose between throwing an |
|
|
702 | exception, encoding the reference as if it weren't blessed, or |
|
|
703 | provide your own serialiser method. |
| 654 | |
704 | |
| 655 | simple scalars |
705 | simple scalars |
| 656 | Simple Perl scalars (any scalar that is not a reference) are the |
706 | Simple Perl scalars (any scalar that is not a reference) are the |
| 657 | most difficult objects to encode: JSON::XS will encode undefined |
707 | most difficult objects to encode: JSON::XS will encode undefined |
| 658 | scalars as JSON null value, scalars that have last been used in a |
708 | scalars as JSON "null" values, scalars that have last been used in a |
| 659 | string context before encoding as JSON strings and anything else as |
709 | string context before encoding as JSON strings, and anything else as |
| 660 | number value: |
710 | number value: |
| 661 | |
711 | |
| 662 | # dump as number |
712 | # dump as number |
| 663 | to_json [2] # yields [2] |
713 | encode_json [2] # yields [2] |
| 664 | to_json [-3.0e17] # yields [-3e+17] |
714 | encode_json [-3.0e17] # yields [-3e+17] |
| 665 | my $value = 5; to_json [$value] # yields [5] |
715 | my $value = 5; encode_json [$value] # yields [5] |
| 666 | |
716 | |
| 667 | # used as string, so dump as string |
717 | # used as string, so dump as string |
| 668 | print $value; |
718 | print $value; |
| 669 | to_json [$value] # yields ["5"] |
719 | encode_json [$value] # yields ["5"] |
| 670 | |
720 | |
| 671 | # undef becomes null |
721 | # undef becomes null |
| 672 | to_json [undef] # yields [null] |
722 | encode_json [undef] # yields [null] |
| 673 | |
723 | |
| 674 | You can force the type to be a JSON string by stringifying it: |
724 | You can force the type to be a JSON string by stringifying it: |
| 675 | |
725 | |
| 676 | my $x = 3.1; # some variable containing a number |
726 | my $x = 3.1; # some variable containing a number |
| 677 | "$x"; # stringified |
727 | "$x"; # stringified |
| … | |
… | |
| 683 | my $x = "3"; # some variable containing a string |
733 | my $x = "3"; # some variable containing a string |
| 684 | $x += 0; # numify it, ensuring it will be dumped as a number |
734 | $x += 0; # numify it, ensuring it will be dumped as a number |
| 685 | $x *= 1; # same thing, the choice is yours. |
735 | $x *= 1; # same thing, the choice is yours. |
| 686 | |
736 | |
| 687 | You can not currently force the type in other, less obscure, ways. |
737 | You can not currently force the type in other, less obscure, ways. |
| 688 | Tell me if you need this capability. |
738 | Tell me if you need this capability (but don't forget to explain why |
|
|
739 | its needed :). |
|
|
740 | |
|
|
741 | ENCODING/CODESET FLAG NOTES |
|
|
742 | The interested reader might have seen a number of flags that signify |
|
|
743 | encodings or codesets - "utf8", "latin1" and "ascii". There seems to be |
|
|
744 | some confusion on what these do, so here is a short comparison: |
|
|
745 | |
|
|
746 | "utf8" controls wether the JSON text created by "encode" (and expected |
|
|
747 | by "decode") is UTF-8 encoded or not, while "latin1" and "ascii" only |
|
|
748 | control wether "encode" escapes character values outside their |
|
|
749 | respective codeset range. Neither of these flags conflict with each |
|
|
750 | other, although some combinations make less sense than others. |
|
|
751 | |
|
|
752 | Care has been taken to make all flags symmetrical with respect to |
|
|
753 | "encode" and "decode", that is, texts encoded with any combination of |
|
|
754 | these flag values will be correctly decoded when the same flags are used |
|
|
755 | - in general, if you use different flag settings while encoding vs. when |
|
|
756 | decoding you likely have a bug somewhere. |
|
|
757 | |
|
|
758 | Below comes a verbose discussion of these flags. Note that a "codeset" |
|
|
759 | is simply an abstract set of character-codepoint pairs, while an |
|
|
760 | encoding takes those codepoint numbers and *encodes* them, in our case |
|
|
761 | into octets. Unicode is (among other things) a codeset, UTF-8 is an |
|
|
762 | encoding, and ISO-8859-1 (= latin 1) and ASCII are both codesets *and* |
|
|
763 | encodings at the same time, which can be confusing. |
|
|
764 | |
|
|
765 | "utf8" flag disabled |
|
|
766 | When "utf8" is disabled (the default), then "encode"/"decode" |
|
|
767 | generate and expect Unicode strings, that is, characters with high |
|
|
768 | ordinal Unicode values (> 255) will be encoded as such characters, |
|
|
769 | and likewise such characters are decoded as-is, no canges to them |
|
|
770 | will be done, except "(re-)interpreting" them as Unicode codepoints |
|
|
771 | or Unicode characters, respectively (to Perl, these are the same |
|
|
772 | thing in strings unless you do funny/weird/dumb stuff). |
|
|
773 | |
|
|
774 | This is useful when you want to do the encoding yourself (e.g. when |
|
|
775 | you want to have UTF-16 encoded JSON texts) or when some other layer |
|
|
776 | does the encoding for you (for example, when printing to a terminal |
|
|
777 | using a filehandle that transparently encodes to UTF-8 you certainly |
|
|
778 | do NOT want to UTF-8 encode your data first and have Perl encode it |
|
|
779 | another time). |
|
|
780 | |
|
|
781 | "utf8" flag enabled |
|
|
782 | If the "utf8"-flag is enabled, "encode"/"decode" will encode all |
|
|
783 | characters using the corresponding UTF-8 multi-byte sequence, and |
|
|
784 | will expect your input strings to be encoded as UTF-8, that is, no |
|
|
785 | "character" of the input string must have any value > 255, as UTF-8 |
|
|
786 | does not allow that. |
|
|
787 | |
|
|
788 | The "utf8" flag therefore switches between two modes: disabled means |
|
|
789 | you will get a Unicode string in Perl, enabled means you get an |
|
|
790 | UTF-8 encoded octet/binary string in Perl. |
|
|
791 | |
|
|
792 | "latin1" or "ascii" flags enabled |
|
|
793 | With "latin1" (or "ascii") enabled, "encode" will escape characters |
|
|
794 | with ordinal values > 255 (> 127 with "ascii") and encode the |
|
|
795 | remaining characters as specified by the "utf8" flag. |
|
|
796 | |
|
|
797 | If "utf8" is disabled, then the result is also correctly encoded in |
|
|
798 | those character sets (as both are proper subsets of Unicode, meaning |
|
|
799 | that a Unicode string with all character values < 256 is the same |
|
|
800 | thing as a ISO-8859-1 string, and a Unicode string with all |
|
|
801 | character values < 128 is the same thing as an ASCII string in |
|
|
802 | Perl). |
|
|
803 | |
|
|
804 | If "utf8" is enabled, you still get a correct UTF-8-encoded string, |
|
|
805 | regardless of these flags, just some more characters will be escaped |
|
|
806 | using "\uXXXX" then before. |
|
|
807 | |
|
|
808 | Note that ISO-8859-1-*encoded* strings are not compatible with UTF-8 |
|
|
809 | encoding, while ASCII-encoded strings are. That is because the |
|
|
810 | ISO-8859-1 encoding is NOT a subset of UTF-8 (despite the ISO-8859-1 |
|
|
811 | *codeset* being a subset of Unicode), while ASCII is. |
|
|
812 | |
|
|
813 | Surprisingly, "decode" will ignore these flags and so treat all |
|
|
814 | input values as governed by the "utf8" flag. If it is disabled, this |
|
|
815 | allows you to decode ISO-8859-1- and ASCII-encoded strings, as both |
|
|
816 | strict subsets of Unicode. If it is enabled, you can correctly |
|
|
817 | decode UTF-8 encoded strings. |
|
|
818 | |
|
|
819 | So neither "latin1" nor "ascii" are incompatible with the "utf8" |
|
|
820 | flag - they only govern when the JSON output engine escapes a |
|
|
821 | character or not. |
|
|
822 | |
|
|
823 | The main use for "latin1" is to relatively efficiently store binary |
|
|
824 | data as JSON, at the expense of breaking compatibility with most |
|
|
825 | JSON decoders. |
|
|
826 | |
|
|
827 | The main use for "ascii" is to force the output to not contain |
|
|
828 | characters with values > 127, which means you can interpret the |
|
|
829 | resulting string as UTF-8, ISO-8859-1, ASCII, KOI8-R or most about |
|
|
830 | any character set and 8-bit-encoding, and still get the same data |
|
|
831 | structure back. This is useful when your channel for JSON transfer |
|
|
832 | is not 8-bit clean or the encoding might be mangled in between (e.g. |
|
|
833 | in mail), and works because ASCII is a proper subset of most 8-bit |
|
|
834 | and multibyte encodings in use in the world. |
| 689 | |
835 | |
| 690 | COMPARISON |
836 | COMPARISON |
| 691 | As already mentioned, this module was created because none of the |
837 | As already mentioned, this module was created because none of the |
| 692 | existing JSON modules could be made to work correctly. First I will |
838 | existing JSON modules could be made to work correctly. First I will |
| 693 | describe the problems (or pleasures) I encountered with various existing |
839 | describe the problems (or pleasures) I encountered with various existing |
| 694 | JSON modules, followed by some benchmark values. JSON::XS was designed |
840 | JSON modules, followed by some benchmark values. JSON::XS was designed |
| 695 | not to suffer from any of these problems or limitations. |
841 | not to suffer from any of these problems or limitations. |
|
|
842 | |
|
|
843 | JSON 2.xx |
|
|
844 | A marvellous piece of engineering, this module either uses JSON::XS |
|
|
845 | directly when available (so will be 100% compatible with it, |
|
|
846 | including speed), or it uses JSON::PP, which is basically JSON::XS |
|
|
847 | translated to Pure Perl, which should be 100% compatible with |
|
|
848 | JSON::XS, just a bit slower. |
|
|
849 | |
|
|
850 | You cannot really lose by using this module, especially as it tries |
|
|
851 | very hard to work even with ancient Perl versions, while JSON::XS |
|
|
852 | does not. |
| 696 | |
853 | |
| 697 | JSON 1.07 |
854 | JSON 1.07 |
| 698 | Slow (but very portable, as it is written in pure Perl). |
855 | Slow (but very portable, as it is written in pure Perl). |
| 699 | |
856 | |
| 700 | Undocumented/buggy Unicode handling (how JSON handles Unicode values |
857 | Undocumented/buggy Unicode handling (how JSON handles Unicode values |
| … | |
… | |
| 765 | empty keys result in nothing being output) |
922 | empty keys result in nothing being output) |
| 766 | |
923 | |
| 767 | Does not check input for validity. |
924 | Does not check input for validity. |
| 768 | |
925 | |
| 769 | JSON and YAML |
926 | JSON and YAML |
| 770 | You often hear that JSON is a subset (or a close subset) of YAML. This |
927 | You often hear that JSON is a subset of YAML. This is, however, a mass |
| 771 | is, however, a mass hysteria and very far from the truth. In general, |
928 | hysteria(*) and very far from the truth (as of the time of this |
| 772 | there is no way to configure JSON::XS to output a data structure as |
929 | writing), so let me state it clearly: *in general, there is no way to |
| 773 | valid YAML. |
930 | configure JSON::XS to output a data structure as valid YAML* that works |
|
|
931 | in all cases. |
| 774 | |
932 | |
| 775 | If you really must use JSON::XS to generate YAML, you should use this |
933 | If you really must use JSON::XS to generate YAML, you should use this |
| 776 | algorithm (subject to change in future versions): |
934 | algorithm (subject to change in future versions): |
| 777 | |
935 | |
| 778 | my $to_yaml = JSON::XS->new->utf8->space_after (1); |
936 | my $to_yaml = JSON::XS->new->utf8->space_after (1); |
| 779 | my $yaml = $to_yaml->encode ($ref) . "\n"; |
937 | my $yaml = $to_yaml->encode ($ref) . "\n"; |
| 780 | |
938 | |
| 781 | This will usually generate JSON texts that also parse as valid YAML. |
939 | This will *usually* generate JSON texts that also parse as valid YAML. |
| 782 | Please note that YAML has hardcoded limits on (simple) object key |
940 | Please note that YAML has hardcoded limits on (simple) object key |
| 783 | lengths that JSON doesn't have, so you should make sure that your hash |
941 | lengths that JSON doesn't have and also has different and incompatible |
|
|
942 | unicode handling, so you should make sure that your hash keys are |
| 784 | keys are noticeably shorter than the 1024 characters YAML allows. |
943 | noticeably shorter than the 1024 "stream characters" YAML allows and |
|
|
944 | that you do not have characters with codepoint values outside the |
|
|
945 | Unicode BMP (basic multilingual page). YAML also does not allow "\/" |
|
|
946 | sequences in strings (which JSON::XS does not *currently* generate, but |
|
|
947 | other JSON generators might). |
| 785 | |
948 | |
| 786 | There might be other incompatibilities that I am not aware of. In |
949 | There might be other incompatibilities that I am not aware of (or the |
|
|
950 | YAML specification has been changed yet again - it does so quite often). |
| 787 | general you should not try to generate YAML with a JSON generator or |
951 | In general you should not try to generate YAML with a JSON generator or |
| 788 | vice versa, or try to parse JSON with a YAML parser or vice versa: |
952 | vice versa, or try to parse JSON with a YAML parser or vice versa: |
| 789 | chances are high that you will run into severe interoperability |
953 | chances are high that you will run into severe interoperability problems |
| 790 | problems. |
954 | when you least expect it. |
|
|
955 | |
|
|
956 | (*) I have been pressured multiple times by Brian Ingerson (one of the |
|
|
957 | authors of the YAML specification) to remove this paragraph, despite |
|
|
958 | him acknowledging that the actual incompatibilities exist. As I was |
|
|
959 | personally bitten by this "JSON is YAML" lie, I refused and said I |
|
|
960 | will continue to educate people about these issues, so others do not |
|
|
961 | run into the same problem again and again. After this, Brian called |
|
|
962 | me a (quote)*complete and worthless idiot*(unquote). |
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963 | |
|
|
964 | In my opinion, instead of pressuring and insulting people who |
|
|
965 | actually clarify issues with YAML and the wrong statements of some |
|
|
966 | of its proponents, I would kindly suggest reading the JSON spec |
|
|
967 | (which is not that difficult or long) and finally make YAML |
|
|
968 | compatible to it, and educating users about the changes, instead of |
|
|
969 | spreading lies about the real compatibility for many *years* and |
|
|
970 | trying to silence people who point out that it isn't true. |
| 791 | |
971 | |
| 792 | SPEED |
972 | SPEED |
| 793 | It seems that JSON::XS is surprisingly fast, as shown in the following |
973 | It seems that JSON::XS is surprisingly fast, as shown in the following |
| 794 | tables. They have been generated with the help of the "eg/bench" program |
974 | tables. They have been generated with the help of the "eg/bench" program |
| 795 | in the JSON::XS distribution, to make it easy to compare on your own |
975 | in the JSON::XS distribution, to make it easy to compare on your own |
| 796 | system. |
976 | system. |
| 797 | |
977 | |
| 798 | First comes a comparison between various modules using a very short |
978 | First comes a comparison between various modules using a very short |
| 799 | single-line JSON string: |
979 | single-line JSON string (also available at |
|
|
980 | <http://dist.schmorp.de/misc/json/short.json>). |
| 800 | |
981 | |
| 801 | {"method": "handleMessage", "params": ["user1", "we were just talking"], \ |
982 | {"method": "handleMessage", "params": ["user1", "we were just talking"], \ |
| 802 | "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]} |
983 | "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]} |
| 803 | |
984 | |
| 804 | It shows the number of encodes/decodes per second (JSON::XS uses the |
985 | It shows the number of encodes/decodes per second (JSON::XS uses the |
| 805 | functional interface, while JSON::XS/2 uses the OO interface with |
986 | functional interface, while JSON::XS/2 uses the OO interface with |
| 806 | pretty-printing and hashkey sorting enabled, JSON::XS/3 enables shrink). |
987 | pretty-printing and hashkey sorting enabled, JSON::XS/3 enables shrink). |
| 807 | Higher is better: |
988 | Higher is better: |
| 808 | |
989 | |
| 809 | Storable | 15779.925 | 14169.946 | |
|
|
| 810 | -----------+------------+------------+ |
|
|
| 811 | module | encode | decode | |
990 | module | encode | decode | |
| 812 | -----------|------------|------------| |
991 | -----------|------------|------------| |
| 813 | JSON | 4990.842 | 4088.813 | |
992 | JSON 1.x | 4990.842 | 4088.813 | |
| 814 | JSON::DWIW | 51653.990 | 71575.154 | |
993 | JSON::DWIW | 51653.990 | 71575.154 | |
| 815 | JSON::PC | 65948.176 | 74631.744 | |
994 | JSON::PC | 65948.176 | 74631.744 | |
| 816 | JSON::PP | 8931.652 | 3817.168 | |
995 | JSON::PP | 8931.652 | 3817.168 | |
| 817 | JSON::Syck | 24877.248 | 27776.848 | |
996 | JSON::Syck | 24877.248 | 27776.848 | |
| 818 | JSON::XS | 388361.481 | 227951.304 | |
997 | JSON::XS | 388361.481 | 227951.304 | |
| … | |
… | |
| 825 | encoding, about three times faster on decoding, and over forty times |
1004 | encoding, about three times faster on decoding, and over forty times |
| 826 | faster than JSON, even with pretty-printing and key sorting. It also |
1005 | faster than JSON, even with pretty-printing and key sorting. It also |
| 827 | compares favourably to Storable for small amounts of data. |
1006 | compares favourably to Storable for small amounts of data. |
| 828 | |
1007 | |
| 829 | Using a longer test string (roughly 18KB, generated from Yahoo! Locals |
1008 | Using a longer test string (roughly 18KB, generated from Yahoo! Locals |
| 830 | search API (http://nanoref.com/yahooapis/mgPdGg): |
1009 | search API (<http://dist.schmorp.de/misc/json/long.json>). |
| 831 | |
1010 | |
| 832 | module | encode | decode | |
1011 | module | encode | decode | |
| 833 | -----------|------------|------------| |
1012 | -----------|------------|------------| |
| 834 | JSON | 55.260 | 34.971 | |
1013 | JSON 1.x | 55.260 | 34.971 | |
| 835 | JSON::DWIW | 825.228 | 1082.513 | |
1014 | JSON::DWIW | 825.228 | 1082.513 | |
| 836 | JSON::PC | 3571.444 | 2394.829 | |
1015 | JSON::PC | 3571.444 | 2394.829 | |
| 837 | JSON::PP | 210.987 | 32.574 | |
1016 | JSON::PP | 210.987 | 32.574 | |
| 838 | JSON::Syck | 552.551 | 787.544 | |
1017 | JSON::Syck | 552.551 | 787.544 | |
| 839 | JSON::XS | 5780.463 | 4854.519 | |
1018 | JSON::XS | 5780.463 | 4854.519 | |
| … | |
… | |
| 872 | Third, JSON::XS recurses using the C stack when decoding objects and |
1051 | Third, JSON::XS recurses using the C stack when decoding objects and |
| 873 | arrays. The C stack is a limited resource: for instance, on my amd64 |
1052 | arrays. The C stack is a limited resource: for instance, on my amd64 |
| 874 | machine with 8MB of stack size I can decode around 180k nested arrays |
1053 | machine with 8MB of stack size I can decode around 180k nested arrays |
| 875 | but only 14k nested JSON objects (due to perl itself recursing deeply on |
1054 | but only 14k nested JSON objects (due to perl itself recursing deeply on |
| 876 | croak to free the temporary). If that is exceeded, the program crashes. |
1055 | croak to free the temporary). If that is exceeded, the program crashes. |
| 877 | to be conservative, the default nesting limit is set to 512. If your |
1056 | To be conservative, the default nesting limit is set to 512. If your |
| 878 | process has a smaller stack, you should adjust this setting accordingly |
1057 | process has a smaller stack, you should adjust this setting accordingly |
| 879 | with the "max_depth" method. |
1058 | with the "max_depth" method. |
| 880 | |
1059 | |
| 881 | And last but least, something else could bomb you that I forgot to think |
1060 | Something else could bomb you, too, that I forgot to think of. In that |
| 882 | of. In that case, you get to keep the pieces. I am always open for |
1061 | case, you get to keep the pieces. I am always open for hints, though... |
| 883 | hints, though... |
1062 | |
|
|
1063 | Also keep in mind that JSON::XS might leak contents of your Perl data |
|
|
1064 | structures in its error messages, so when you serialise sensitive |
|
|
1065 | information you might want to make sure that exceptions thrown by |
|
|
1066 | JSON::XS will not end up in front of untrusted eyes. |
| 884 | |
1067 | |
| 885 | If you are using JSON::XS to return packets to consumption by JavaScript |
1068 | If you are using JSON::XS to return packets to consumption by JavaScript |
| 886 | scripts in a browser you should have a look at |
1069 | scripts in a browser you should have a look at |
| 887 | <http://jpsykes.com/47/practical-csrf-and-json-security> to see whether |
1070 | <http://jpsykes.com/47/practical-csrf-and-json-security> to see whether |
| 888 | you are vulnerable to some common attack vectors (which really are |
1071 | you are vulnerable to some common attack vectors (which really are |
| 889 | browser design bugs, but it is still you who will have to deal with it, |
1072 | browser design bugs, but it is still you who will have to deal with it, |
| 890 | as major browser developers care only for features, not about doing |
1073 | as major browser developers care only for features, not about getting |
| 891 | security right). |
1074 | security right). |
| 892 | |
1075 | |
| 893 | THREADS |
1076 | THREADS |
| 894 | This module is *not* guaranteed to be thread safe and there are no plans |
1077 | This module is *not* guaranteed to be thread safe and there are no plans |
| 895 | to change this until Perl gets thread support (as opposed to the |
1078 | to change this until Perl gets thread support (as opposed to the |
