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1 | =encoding utf-8 |
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2 | |
1 | =head1 NAME |
3 | =head1 NAME |
2 | |
4 | |
3 | JSON::XS - JSON serialising/deserialising, done correctly and fast |
5 | JSON::XS - JSON serialising/deserialising, done correctly and fast |
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6 | |
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7 | JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ |
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8 | (http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html) |
4 | |
9 | |
5 | =head1 SYNOPSIS |
10 | =head1 SYNOPSIS |
6 | |
11 | |
7 | use JSON::XS; |
12 | use JSON::XS; |
8 | |
13 | |
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81 | |
86 | |
82 | package JSON::XS; |
87 | package JSON::XS; |
83 | |
88 | |
84 | use strict; |
89 | use strict; |
85 | |
90 | |
86 | our $VERSION = '1.4'; |
91 | our $VERSION = '1.51'; |
87 | our @ISA = qw(Exporter); |
92 | our @ISA = qw(Exporter); |
88 | |
93 | |
89 | our @EXPORT = qw(to_json from_json); |
94 | our @EXPORT = qw(to_json from_json); |
90 | |
95 | |
91 | use Exporter; |
96 | use Exporter; |
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98 | |
103 | |
99 | =over 4 |
104 | =over 4 |
100 | |
105 | |
101 | =item $json_text = to_json $perl_scalar |
106 | =item $json_text = to_json $perl_scalar |
102 | |
107 | |
103 | Converts the given Perl data structure (a simple scalar or a reference to |
108 | Converts the given Perl data structure to a UTF-8 encoded, binary string |
104 | a hash or array) to a UTF-8 encoded, binary string (that is, the string contains |
109 | (that is, the string contains octets only). Croaks on error. |
105 | octets only). Croaks on error. |
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106 | |
110 | |
107 | This function call is functionally identical to: |
111 | This function call is functionally identical to: |
108 | |
112 | |
109 | $json_text = JSON::XS->new->utf8->encode ($perl_scalar) |
113 | $json_text = JSON::XS->new->utf8->encode ($perl_scalar) |
110 | |
114 | |
111 | except being faster. |
115 | except being faster. |
112 | |
116 | |
113 | =item $perl_scalar = from_json $json_text |
117 | =item $perl_scalar = from_json $json_text |
114 | |
118 | |
115 | The opposite of C<to_json>: expects an UTF-8 (binary) string and tries to |
119 | The opposite of C<to_json>: expects an UTF-8 (binary) string and tries |
116 | parse that as an UTF-8 encoded JSON text, returning the resulting simple |
120 | to parse that as an UTF-8 encoded JSON text, returning the resulting |
117 | scalar or reference. Croaks on error. |
121 | reference. Croaks on error. |
118 | |
122 | |
119 | This function call is functionally identical to: |
123 | This function call is functionally identical to: |
120 | |
124 | |
121 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
125 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
122 | |
126 | |
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130 | |
134 | |
131 | See MAPPING, below, for more information on how JSON values are mapped to |
135 | See MAPPING, below, for more information on how JSON values are mapped to |
132 | Perl. |
136 | Perl. |
133 | |
137 | |
134 | =back |
138 | =back |
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139 | |
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140 | |
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141 | =head1 A FEW NOTES ON UNICODE AND PERL |
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142 | |
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143 | Since this often leads to confusion, here are a few very clear words on |
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144 | how Unicode works in Perl, modulo bugs. |
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145 | |
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146 | =over 4 |
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147 | |
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148 | =item 1. Perl strings can store characters with ordinal values > 255. |
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149 | |
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150 | This enables you to store unicode characters as single characters in a |
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151 | Perl string - very natural. |
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152 | |
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153 | =item 2. Perl does I<not> associate an encoding with your strings. |
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154 | |
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155 | Unless you force it to, e.g. when matching it against a regex, or printing |
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156 | the scalar to a file, in which case Perl either interprets your string as |
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157 | locale-encoded text, octets/binary, or as Unicode, depending on various |
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158 | settings. In no case is an encoding stored together with your data, it is |
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159 | I<use> that decides encoding, not any magical metadata. |
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160 | |
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161 | =item 3. The internal utf-8 flag has no meaning with regards to the |
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162 | encoding of your string. |
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163 | |
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164 | Just ignore that flag unless you debug a Perl bug, a module written in |
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165 | XS or want to dive into the internals of perl. Otherwise it will only |
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166 | confuse you, as, despite the name, it says nothing about how your string |
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167 | is encoded. You can have unicode strings with that flag set, with that |
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168 | flag clear, and you can have binary data with that flag set and that flag |
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169 | clear. Other possibilities exist, too. |
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170 | |
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171 | If you didn't know about that flag, just the better, pretend it doesn't |
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172 | exist. |
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173 | |
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174 | =item 4. A "Unicode String" is simply a string where each character can be |
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175 | validly interpreted as a Unicode codepoint. |
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176 | |
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177 | If you have UTF-8 encoded data, it is no longer a Unicode string, but a |
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178 | Unicode string encoded in UTF-8, giving you a binary string. |
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179 | |
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180 | =item 5. A string containing "high" (> 255) character values is I<not> a UTF-8 string. |
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181 | |
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182 | Its a fact. Learn to live with it. |
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183 | |
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184 | =back |
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185 | |
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186 | I hope this helps :) |
135 | |
187 | |
136 | |
188 | |
137 | =head1 OBJECT-ORIENTED INTERFACE |
189 | =head1 OBJECT-ORIENTED INTERFACE |
138 | |
190 | |
139 | The object oriented interface lets you configure your own encoding or |
191 | The object oriented interface lets you configure your own encoding or |
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278 | |
330 | |
279 | Example, space_before and indent disabled, space_after enabled: |
331 | Example, space_before and indent disabled, space_after enabled: |
280 | |
332 | |
281 | {"key": "value"} |
333 | {"key": "value"} |
282 | |
334 | |
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335 | =item $json = $json->relaxed ([$enable]) |
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336 | |
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337 | If C<$enable> is true (or missing), then C<decode> will accept some |
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338 | extensions to normal JSON syntax (see below). C<encode> will not be |
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339 | affected in anyway. I<Be aware that this option makes you accept invalid |
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340 | JSON texts as if they were valid!>. I suggest only to use this option to |
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341 | parse application-specific files written by humans (configuration files, |
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342 | resource files etc.) |
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343 | |
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344 | If C<$enable> is false (the default), then C<decode> will only accept |
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345 | valid JSON texts. |
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346 | |
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347 | Currently accepted extensions are: |
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348 | |
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349 | =over 4 |
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350 | |
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351 | =item * list items can have an end-comma |
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352 | |
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353 | JSON I<separates> array elements and key-value pairs with commas. This |
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354 | can be annoying if you write JSON texts manually and want to be able to |
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355 | quickly append elements, so this extension accepts comma at the end of |
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356 | such items not just between them: |
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357 | |
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358 | [ |
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359 | 1, |
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360 | 2, <- this comma not normally allowed |
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361 | ] |
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362 | { |
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363 | "k1": "v1", |
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364 | "k2": "v2", <- this comma not normally allowed |
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365 | } |
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366 | |
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367 | =item * shell-style '#'-comments |
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368 | |
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369 | Whenever JSON allows whitespace, shell-style comments are additionally |
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370 | allowed. They are terminated by the first carriage-return or line-feed |
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371 | character, after which more white-space and comments are allowed. |
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372 | |
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373 | [ |
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374 | 1, # this comment not allowed in JSON |
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375 | # neither this one... |
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376 | ] |
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377 | |
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378 | =back |
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379 | |
283 | =item $json = $json->canonical ([$enable]) |
380 | =item $json = $json->canonical ([$enable]) |
284 | |
381 | |
285 | If C<$enable> is true (or missing), then the C<encode> method will output JSON objects |
382 | If C<$enable> is true (or missing), then the C<encode> method will output JSON objects |
286 | by sorting their keys. This is adding a comparatively high overhead. |
383 | by sorting their keys. This is adding a comparatively high overhead. |
287 | |
384 | |
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347 | future, global hooks might get installed that influence C<decode> and are |
444 | future, global hooks might get installed that influence C<decode> and are |
348 | enabled by this setting. |
445 | enabled by this setting. |
349 | |
446 | |
350 | If C<$enable> is false, then the C<allow_blessed> setting will decide what |
447 | If C<$enable> is false, then the C<allow_blessed> setting will decide what |
351 | to do when a blessed object is found. |
448 | to do when a blessed object is found. |
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449 | |
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450 | =item $json = $json->filter_json_object ([$coderef->($hashref)]) |
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451 | |
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452 | When C<$coderef> is specified, it will be called from C<decode> each |
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453 | time it decodes a JSON object. The only argument is a reference to the |
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454 | newly-created hash. If the code references returns a single scalar (which |
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455 | need not be a reference), this value (i.e. a copy of that scalar to avoid |
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456 | aliasing) is inserted into the deserialised data structure. If it returns |
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457 | an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the |
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458 | original deserialised hash will be inserted. This setting can slow down |
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459 | decoding considerably. |
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460 | |
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461 | When C<$coderef> is omitted or undefined, any existing callback will |
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462 | be removed and C<decode> will not change the deserialised hash in any |
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463 | way. |
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464 | |
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465 | Example, convert all JSON objects into the integer 5: |
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466 | |
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467 | my $js = JSON::XS->new->filter_json_object (sub { 5 }); |
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468 | # returns [5] |
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469 | $js->decode ('[{}]') |
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470 | # throw an exception because allow_nonref is not enabled |
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471 | # so a lone 5 is not allowed. |
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472 | $js->decode ('{"a":1, "b":2}'); |
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473 | |
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474 | =item $json = $json->filter_json_single_key_object ($key [=> $coderef->($value)]) |
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475 | |
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476 | Works remotely similar to C<filter_json_object>, but is only called for |
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477 | JSON objects having a single key named C<$key>. |
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478 | |
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479 | This C<$coderef> is called before the one specified via |
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480 | C<filter_json_object>, if any. It gets passed the single value in the JSON |
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481 | object. If it returns a single value, it will be inserted into the data |
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482 | structure. If it returns nothing (not even C<undef> but the empty list), |
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483 | the callback from C<filter_json_object> will be called next, as if no |
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484 | single-key callback were specified. |
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485 | |
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486 | If C<$coderef> is omitted or undefined, the corresponding callback will be |
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487 | disabled. There can only ever be one callback for a given key. |
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488 | |
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489 | As this callback gets called less often then the C<filter_json_object> |
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490 | one, decoding speed will not usually suffer as much. Therefore, single-key |
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491 | objects make excellent targets to serialise Perl objects into, especially |
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492 | as single-key JSON objects are as close to the type-tagged value concept |
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493 | as JSON gets (its basically an ID/VALUE tuple). Of course, JSON does not |
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494 | support this in any way, so you need to make sure your data never looks |
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495 | like a serialised Perl hash. |
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496 | |
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497 | Typical names for the single object key are C<__class_whatever__>, or |
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498 | C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even |
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499 | things like C<__class_md5sum(classname)__>, to reduce the risk of clashing |
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500 | with real hashes. |
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501 | |
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502 | Example, decode JSON objects of the form C<< { "__widget__" => <id> } >> |
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503 | into the corresponding C<< $WIDGET{<id>} >> object: |
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504 | |
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505 | # return whatever is in $WIDGET{5}: |
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506 | JSON::XS |
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507 | ->new |
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508 | ->filter_json_single_key_object (__widget__ => sub { |
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509 | $WIDGET{ $_[0] } |
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510 | }) |
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511 | ->decode ('{"__widget__": 5') |
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512 | |
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513 | # this can be used with a TO_JSON method in some "widget" class |
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514 | # for serialisation to json: |
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515 | sub WidgetBase::TO_JSON { |
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516 | my ($self) = @_; |
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517 | |
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518 | unless ($self->{id}) { |
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519 | $self->{id} = ..get..some..id..; |
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520 | $WIDGET{$self->{id}} = $self; |
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521 | } |
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522 | |
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523 | { __widget__ => $self->{id} } |
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524 | } |
352 | |
525 | |
353 | =item $json = $json->shrink ([$enable]) |
526 | =item $json = $json->shrink ([$enable]) |
354 | |
527 | |
355 | Perl usually over-allocates memory a bit when allocating space for |
528 | Perl usually over-allocates memory a bit when allocating space for |
356 | strings. This flag optionally resizes strings generated by either |
529 | strings. This flag optionally resizes strings generated by either |
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477 | are represented by the same codepoints in the Perl string, so no manual |
650 | are represented by the same codepoints in the Perl string, so no manual |
478 | decoding is necessary. |
651 | decoding is necessary. |
479 | |
652 | |
480 | =item number |
653 | =item number |
481 | |
654 | |
482 | A JSON number becomes either an integer or numeric (floating point) |
655 | A JSON number becomes either an integer, numeric (floating point) or |
483 | scalar in perl, depending on its range and any fractional parts. On the |
656 | string scalar in perl, depending on its range and any fractional parts. On |
484 | Perl level, there is no difference between those as Perl handles all the |
657 | the Perl level, there is no difference between those as Perl handles all |
485 | conversion details, but an integer may take slightly less memory and might |
658 | the conversion details, but an integer may take slightly less memory and |
486 | represent more values exactly than (floating point) numbers. |
659 | might represent more values exactly than (floating point) numbers. |
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660 | |
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661 | If the number consists of digits only, JSON::XS will try to represent |
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662 | it as an integer value. If that fails, it will try to represent it as |
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663 | a numeric (floating point) value if that is possible without loss of |
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664 | precision. Otherwise it will preserve the number as a string value. |
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665 | |
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666 | Numbers containing a fractional or exponential part will always be |
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667 | represented as numeric (floating point) values, possibly at a loss of |
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668 | precision. |
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669 | |
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670 | This might create round-tripping problems as numbers might become strings, |
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671 | but as Perl is typeless there is no other way to do it. |
487 | |
672 | |
488 | =item true, false |
673 | =item true, false |
489 | |
674 | |
490 | These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>, |
675 | These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>, |
491 | respectively. They are overloaded to act almost exactly like the numbers |
676 | respectively. They are overloaded to act almost exactly like the numbers |
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533 | to_json [\0,JSON::XS::true] # yields [false,true] |
718 | to_json [\0,JSON::XS::true] # yields [false,true] |
534 | |
719 | |
535 | =item JSON::XS::true, JSON::XS::false |
720 | =item JSON::XS::true, JSON::XS::false |
536 | |
721 | |
537 | These special values become JSON true and JSON false values, |
722 | These special values become JSON true and JSON false values, |
538 | respectively. You cna alos use C<\1> and C<\0> directly if you want. |
723 | respectively. You can also use C<\1> and C<\0> directly if you want. |
539 | |
724 | |
540 | =item blessed objects |
725 | =item blessed objects |
541 | |
726 | |
542 | Blessed objects are not allowed. JSON::XS currently tries to encode their |
727 | Blessed objects are not allowed. JSON::XS currently tries to encode their |
543 | underlying representation (hash- or arrayref), but this behaviour might |
728 | underlying representation (hash- or arrayref), but this behaviour might |
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793 | design bugs, but it is still you who will have to deal with it, as major |
978 | design bugs, but it is still you who will have to deal with it, as major |
794 | browser developers care only for features, not about doing security |
979 | browser developers care only for features, not about doing security |
795 | right). |
980 | right). |
796 | |
981 | |
797 | |
982 | |
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983 | =head1 THREADS |
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984 | |
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985 | This module is I<not> guarenteed to be thread safe and there are no |
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986 | plans to change this until Perl gets thread support (as opposed to the |
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987 | horribly slow so-called "threads" which are simply slow and bloated |
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988 | process simulations - use fork, its I<much> faster, cheaper, better). |
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989 | |
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990 | (It might actually work, but you ahve ben warned). |
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991 | |
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992 | |
798 | =head1 BUGS |
993 | =head1 BUGS |
799 | |
994 | |
800 | While the goal of this module is to be correct, that unfortunately does |
995 | While the goal of this module is to be correct, that unfortunately does |
801 | not mean its bug-free, only that I think its design is bug-free. It is |
996 | not mean its bug-free, only that I think its design is bug-free. It is |
802 | still relatively early in its development. If you keep reporting bugs they |
997 | still relatively early in its development. If you keep reporting bugs they |
803 | will be fixed swiftly, though. |
998 | will be fixed swiftly, though. |
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999 | |
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1000 | Please refrain from using rt.cpan.org or any other bug reporting |
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1001 | service. I put the contact address into my modules for a reason. |
804 | |
1002 | |
805 | =cut |
1003 | =cut |
806 | |
1004 | |
807 | our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" }; |
1005 | our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" }; |
808 | our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" }; |
1006 | our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" }; |