| … | |
… | |
| 245 | "encode" or "decode" to their minimum size possible. This can save |
245 | "encode" or "decode" to their minimum size possible. This can save |
| 246 | memory when your JSON texts are either very very long or you have |
246 | memory when your JSON texts are either very very long or you have |
| 247 | many short strings. It will also try to downgrade any strings to |
247 | many short strings. It will also try to downgrade any strings to |
| 248 | octet-form if possible: perl stores strings internally either in an |
248 | octet-form if possible: perl stores strings internally either in an |
| 249 | encoding called UTF-X or in octet-form. The latter cannot store |
249 | encoding called UTF-X or in octet-form. The latter cannot store |
| 250 | everything but uses less space in general. |
250 | everything but uses less space in general (and some buggy Perl or C |
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251 | code might even rely on that internal representation being used). |
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252 | |
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253 | The actual definition of what shrink does might change in future |
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254 | versions, but it will always try to save space at the expense of |
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255 | time. |
| 251 | |
256 | |
| 252 | If $enable is true (or missing), the string returned by "encode" |
257 | If $enable is true (or missing), the string returned by "encode" |
| 253 | will be shrunk-to-fit, while all strings generated by "decode" will |
258 | will be shrunk-to-fit, while all strings generated by "decode" will |
| 254 | also be shrunk-to-fit. |
259 | also be shrunk-to-fit. |
| 255 | |
260 | |
| … | |
… | |
| 260 | converting strings that look like integers or floats into integers |
265 | converting strings that look like integers or floats into integers |
| 261 | or floats internally (there is no difference on the Perl level), |
266 | or floats internally (there is no difference on the Perl level), |
| 262 | saving space. |
267 | saving space. |
| 263 | |
268 | |
| 264 | $json = $json->max_depth ([$maximum_nesting_depth]) |
269 | $json = $json->max_depth ([$maximum_nesting_depth]) |
| 265 | Sets the maximum nesting level (default 8192) accepted while |
270 | Sets the maximum nesting level (default 4096) accepted while |
| 266 | encoding or decoding. If the JSON text or Perl data structure has an |
271 | encoding or decoding. If the JSON text or Perl data structure has an |
| 267 | equal or higher nesting level then this limit, then the encoder and |
272 | equal or higher nesting level then this limit, then the encoder and |
| 268 | decoder will stop and croak at that point. |
273 | decoder will stop and croak at that point. |
| 269 | |
274 | |
| 270 | Nesting level is defined by number of hash- or arrayrefs that the |
275 | Nesting level is defined by number of hash- or arrayrefs that the |
| … | |
… | |
| 344 | truly typeless language, so we can only guess which JSON type is meant |
349 | truly typeless language, so we can only guess which JSON type is meant |
| 345 | by a Perl value. |
350 | by a Perl value. |
| 346 | |
351 | |
| 347 | hash references |
352 | hash references |
| 348 | Perl hash references become JSON objects. As there is no inherent |
353 | Perl hash references become JSON objects. As there is no inherent |
| 349 | ordering in hash keys, they will usually be encoded in a |
354 | ordering in hash keys (or JSON objects), they will usually be |
| 350 | pseudo-random order that can change between runs of the same program |
355 | encoded in a pseudo-random order that can change between runs of the |
| 351 | but stays generally the same within a single run of a program. |
356 | same program but stays generally the same within a single run of a |
| 352 | JSON::XS can optionally sort the hash keys (determined by the |
357 | program. JSON::XS can optionally sort the hash keys (determined by |
| 353 | *canonical* flag), so the same datastructure will serialise to the |
358 | the *canonical* flag), so the same datastructure will serialise to |
| 354 | same JSON text (given same settings and version of JSON::XS), but |
359 | the same JSON text (given same settings and version of JSON::XS), |
| 355 | this incurs a runtime overhead. |
360 | but this incurs a runtime overhead and is only rarely useful, e.g. |
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361 | when you want to compare some JSON text against another for |
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362 | equality. |
| 356 | |
363 | |
| 357 | array references |
364 | array references |
| 358 | Perl array references become JSON arrays. |
365 | Perl array references become JSON arrays. |
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366 | |
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367 | other references |
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368 | Other unblessed references are generally not allowed and will cause |
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369 | an exception to be thrown, except for references to the integers 0 |
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370 | and 1, which get turned into "false" and "true" atoms in JSON. You |
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371 | can also use "JSON::XS::false" and "JSON::XS::true" to improve |
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372 | readability. |
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373 | |
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374 | to_json [\0,JSON::XS::true] # yields [false,true] |
| 359 | |
375 | |
| 360 | blessed objects |
376 | blessed objects |
| 361 | Blessed objects are not allowed. JSON::XS currently tries to encode |
377 | Blessed objects are not allowed. JSON::XS currently tries to encode |
| 362 | their underlying representation (hash- or arrayref), but this |
378 | their underlying representation (hash- or arrayref), but this |
| 363 | behaviour might change in future versions. |
379 | behaviour might change in future versions. |
| … | |
… | |
| 546 | |
562 | |
| 547 | Third, JSON::XS recurses using the C stack when decoding objects and |
563 | Third, JSON::XS recurses using the C stack when decoding objects and |
| 548 | arrays. The C stack is a limited resource: for instance, on my amd64 |
564 | arrays. The C stack is a limited resource: for instance, on my amd64 |
| 549 | machine with 8MB of stack size I can decode around 180k nested arrays |
565 | machine with 8MB of stack size I can decode around 180k nested arrays |
| 550 | but only 14k nested JSON objects. If that is exceeded, the program |
566 | but only 14k nested JSON objects. If that is exceeded, the program |
| 551 | crashes. Thats why the default nesting limit is set to 8192. If your |
567 | crashes. Thats why the default nesting limit is set to 4096. If your |
| 552 | process has a smaller stack, you should adjust this setting accordingly |
568 | process has a smaller stack, you should adjust this setting accordingly |
| 553 | with the "max_depth" method. |
569 | with the "max_depth" method. |
| 554 | |
570 | |
| 555 | And last but least, something else could bomb you that I forgot to think |
571 | And last but least, something else could bomb you that I forgot to think |
| 556 | of. In that case, you get to keep the pieces. I am alway sopen for |
572 | of. In that case, you get to keep the pieces. I am alway sopen for |
