… | |
… | |
26 | substr $many_cbor_strings, 0, $length, ""; # remove decoded cbor string |
26 | substr $many_cbor_strings, 0, $length, ""; # remove decoded cbor string |
27 | } |
27 | } |
28 | |
28 | |
29 | =head1 DESCRIPTION |
29 | =head1 DESCRIPTION |
30 | |
30 | |
31 | WARNING! This module is very new, and not very well tested (that's up |
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32 | to you to do). Furthermore, details of the implementation might change |
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33 | freely before version 1.0. And lastly, most extensions depend on an IANA |
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34 | assignment, and until that assignment is official, this implementation is |
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35 | not interoperable with other implementations (even future versions of this |
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36 | module) until the assignment is done. |
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37 | |
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38 | You are still invited to try out CBOR, and this module. |
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39 | |
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40 | This module converts Perl data structures to the Concise Binary Object |
31 | This module converts Perl data structures to the Concise Binary Object |
41 | Representation (CBOR) and vice versa. CBOR is a fast binary serialisation |
32 | Representation (CBOR) and vice versa. CBOR is a fast binary serialisation |
42 | format that aims to use a superset of the JSON data model, i.e. when you |
33 | format that aims to use an (almost) superset of the JSON data model, i.e. |
43 | can represent something in JSON, you should be able to represent it in |
34 | when you can represent something useful in JSON, you should be able to |
44 | CBOR. |
35 | represent it in CBOR. |
45 | |
36 | |
46 | In short, CBOR is a faster and very compact binary alternative to JSON, |
37 | In short, CBOR is a faster and quite compact binary alternative to JSON, |
47 | with the added ability of supporting serialisation of Perl objects. (JSON |
38 | with the added ability of supporting serialisation of Perl objects. (JSON |
48 | often compresses better than CBOR though, so if you plan to compress the |
39 | often compresses better than CBOR though, so if you plan to compress the |
49 | data later you might want to compare both formats first). |
40 | data later and speed is less important you might want to compare both |
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41 | formats first). |
50 | |
42 | |
51 | To give you a general idea about speed, with texts in the megabyte range, |
43 | To give you a general idea about speed, with texts in the megabyte range, |
52 | C<CBOR::XS> usually encodes roughly twice as fast as L<Storable> or |
44 | C<CBOR::XS> usually encodes roughly twice as fast as L<Storable> or |
53 | L<JSON::XS> and decodes about 15%-30% faster than those. The shorter the |
45 | L<JSON::XS> and decodes about 15%-30% faster than those. The shorter the |
54 | data, the worse L<Storable> performs in comparison. |
46 | data, the worse L<Storable> performs in comparison. |
55 | |
47 | |
56 | As for compactness, C<CBOR::XS> encoded data structures are usually about |
48 | Regarding compactness, C<CBOR::XS>-encoded data structures are usually |
57 | 20% smaller than the same data encoded as (compact) JSON or L<Storable>. |
49 | about 20% smaller than the same data encoded as (compact) JSON or |
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50 | L<Storable>. |
58 | |
51 | |
59 | In addition to the core CBOR data format, this module implements a number |
52 | In addition to the core CBOR data format, this module implements a |
60 | of extensions, to support cyclic and self-referencing data structures |
53 | number of extensions, to support cyclic and shared data structures |
61 | (see C<allow_sharing>), string deduplication (see C<pack_strings>) and |
54 | (see C<allow_sharing> and C<allow_cycles>), string deduplication (see |
62 | scalar references (always enabled). |
55 | C<pack_strings>) and scalar references (always enabled). |
63 | |
56 | |
64 | The primary goal of this module is to be I<correct> and the secondary goal |
57 | The primary goal of this module is to be I<correct> and the secondary goal |
65 | is to be I<fast>. To reach the latter goal it was written in C. |
58 | is to be I<fast>. To reach the latter goal it was written in C. |
66 | |
59 | |
67 | See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and |
60 | See MAPPING, below, on how CBOR::XS maps perl values to CBOR values and |
… | |
… | |
71 | |
64 | |
72 | package CBOR::XS; |
65 | package CBOR::XS; |
73 | |
66 | |
74 | use common::sense; |
67 | use common::sense; |
75 | |
68 | |
76 | our $VERSION = 0.09; |
69 | our $VERSION = 1.41; |
77 | our @ISA = qw(Exporter); |
70 | our @ISA = qw(Exporter); |
78 | |
71 | |
79 | our @EXPORT = qw(encode_cbor decode_cbor); |
72 | our @EXPORT = qw(encode_cbor decode_cbor); |
80 | |
73 | |
81 | use Exporter; |
74 | use Exporter; |
… | |
… | |
187 | reference to the earlier value. |
180 | reference to the earlier value. |
188 | |
181 | |
189 | This means that such values will only be encoded once, and will not result |
182 | This means that such values will only be encoded once, and will not result |
190 | in a deep cloning of the value on decode, in decoders supporting the value |
183 | in a deep cloning of the value on decode, in decoders supporting the value |
191 | sharing extension. This also makes it possible to encode cyclic data |
184 | sharing extension. This also makes it possible to encode cyclic data |
192 | structures. |
185 | structures (which need C<allow_cycles> to ne enabled to be decoded by this |
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186 | module). |
193 | |
187 | |
194 | It is recommended to leave it off unless you know your |
188 | It is recommended to leave it off unless you know your |
195 | communication partner supports the value sharing extensions to CBOR |
189 | communication partner supports the value sharing extensions to CBOR |
196 | (L<http://cbor.schmorp.de/value-sharing>), as without decoder support, the |
190 | (L<http://cbor.schmorp.de/value-sharing>), as without decoder support, the |
197 | resulting data structure might be unusable. |
191 | resulting data structure might be unusable. |
198 | |
192 | |
199 | Detecting shared values incurs a runtime overhead when values are encoded |
193 | Detecting shared values incurs a runtime overhead when values are encoded |
200 | that have a reference counter large than one, and might unnecessarily |
194 | that have a reference counter large than one, and might unnecessarily |
201 | increase the encoded size, as potentially shared values are encode as |
195 | increase the encoded size, as potentially shared values are encode as |
202 | sharable whether or not they are actually shared. |
196 | shareable whether or not they are actually shared. |
203 | |
197 | |
204 | At the moment, only targets of references can be shared (e.g. scalars, |
198 | At the moment, only targets of references can be shared (e.g. scalars, |
205 | arrays or hashes pointed to by a reference). Weirder constructs, such as |
199 | arrays or hashes pointed to by a reference). Weirder constructs, such as |
206 | an array with multiple "copies" of the I<same> string, which are hard but |
200 | an array with multiple "copies" of the I<same> string, which are hard but |
207 | not impossible to create in Perl, are not supported (this is the same as |
201 | not impossible to create in Perl, are not supported (this is the same as |
… | |
… | |
212 | structures cannot be encoded in this mode. |
206 | structures cannot be encoded in this mode. |
213 | |
207 | |
214 | This option does not affect C<decode> in any way - shared values and |
208 | This option does not affect C<decode> in any way - shared values and |
215 | references will always be decoded properly if present. |
209 | references will always be decoded properly if present. |
216 | |
210 | |
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211 | =item $cbor = $cbor->allow_cycles ([$enable]) |
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212 | |
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213 | =item $enabled = $cbor->get_allow_cycles |
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214 | |
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215 | If C<$enable> is true (or missing), then C<decode> will happily decode |
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216 | self-referential (cyclic) data structures. By default these will not be |
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217 | decoded, as they need manual cleanup to avoid memory leaks, so code that |
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218 | isn't prepared for this will not leak memory. |
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219 | |
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220 | If C<$enable> is false (the default), then C<decode> will throw an error |
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221 | when it encounters a self-referential/cyclic data structure. |
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222 | |
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223 | FUTURE DIRECTION: the motivation behind this option is to avoid I<real> |
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224 | cycles - future versions of this module might chose to decode cyclic data |
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225 | structures using weak references when this option is off, instead of |
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226 | throwing an error. |
|
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227 | |
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228 | This option does not affect C<encode> in any way - shared values and |
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229 | references will always be encoded properly if present. |
|
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230 | |
217 | =item $cbor = $cbor->pack_strings ([$enable]) |
231 | =item $cbor = $cbor->pack_strings ([$enable]) |
218 | |
232 | |
219 | =item $enabled = $cbor->get_pack_strings |
233 | =item $enabled = $cbor->get_pack_strings |
220 | |
234 | |
221 | If C<$enable> is true (or missing), then C<encode> will try not to encode |
235 | If C<$enable> is true (or missing), then C<encode> will try not to encode |
… | |
… | |
233 | the standard CBOR way. |
247 | the standard CBOR way. |
234 | |
248 | |
235 | This option does not affect C<decode> in any way - string references will |
249 | This option does not affect C<decode> in any way - string references will |
236 | always be decoded properly if present. |
250 | always be decoded properly if present. |
237 | |
251 | |
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252 | =item $cbor = $cbor->text_keys ([$enable]) |
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253 | |
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254 | =item $enabled = $cbor->get_text_keys |
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255 | |
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256 | If C<$enabled> is true (or missing), then C<encode> will encode all |
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257 | perl hash keys as CBOR text strings/UTF-8 string, upgrading them as needed. |
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258 | |
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259 | If C<$enable> is false (the default), then C<encode> will encode hash keys |
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260 | normally - upgraded perl strings (strings internally encoded as UTF-8) as |
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261 | CBOR text strings, and downgraded perl strings as CBOR byte strings. |
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262 | |
|
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263 | This option does not affect C<decode> in any way. |
|
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264 | |
|
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265 | This option is useful for interoperability with CBOR decoders that don't |
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266 | treat byte strings as a form of text. It is especially useful as Perl |
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267 | gives very little control over hash keys. |
|
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268 | |
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269 | Enabling this option can be slow, as all downgraded hash keys that are |
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270 | encoded need to be scanned and converted to UTF-8. |
|
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271 | |
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272 | =item $cbor = $cbor->text_strings ([$enable]) |
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273 | |
|
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274 | =item $enabled = $cbor->get_text_strings |
|
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275 | |
|
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276 | This option works similar to C<text_keys>, above, but works on all strings |
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277 | (including hash keys), so C<text_keys> has no further effect after |
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278 | enabling C<text_strings>. |
|
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279 | |
|
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280 | If C<$enabled> is true (or missing), then C<encode> will encode all perl |
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281 | strings as CBOR text strings/UTF-8 strings, upgrading them as needed. |
|
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282 | |
|
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283 | If C<$enable> is false (the default), then C<encode> will encode strings |
|
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284 | normally (but see C<text_keys>) - upgraded perl strings (strings |
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285 | internally encoded as UTF-8) as CBOR text strings, and downgraded perl |
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286 | strings as CBOR byte strings. |
|
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287 | |
|
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288 | This option does not affect C<decode> in any way. |
|
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289 | |
|
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290 | This option has similar advantages and disadvantages as C<text_keys>. In |
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291 | addition, this option effectively removes the ability to encode byte |
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292 | strings, which might break some C<FREEZE> and C<TO_CBOR> methods that rely |
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293 | on this, such as bignum encoding, so this option is mainly useful for very |
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294 | simple data. |
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295 | |
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296 | =item $cbor = $cbor->validate_utf8 ([$enable]) |
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297 | |
|
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298 | =item $enabled = $cbor->get_validate_utf8 |
|
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299 | |
|
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300 | If C<$enable> is true (or missing), then C<decode> will validate that |
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301 | elements (text strings) containing UTF-8 data in fact contain valid UTF-8 |
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302 | data (instead of blindly accepting it). This validation obviously takes |
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303 | extra time during decoding. |
|
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304 | |
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305 | The concept of "valid UTF-8" used is perl's concept, which is a superset |
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306 | of the official UTF-8. |
|
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307 | |
|
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308 | If C<$enable> is false (the default), then C<decode> will blindly accept |
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309 | UTF-8 data, marking them as valid UTF-8 in the resulting data structure |
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310 | regardless of whether that's true or not. |
|
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311 | |
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312 | Perl isn't too happy about corrupted UTF-8 in strings, but should |
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313 | generally not crash or do similarly evil things. Extensions might be not |
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314 | so forgiving, so it's recommended to turn on this setting if you receive |
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315 | untrusted CBOR. |
|
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316 | |
|
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317 | This option does not affect C<encode> in any way - strings that are |
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318 | supposedly valid UTF-8 will simply be dumped into the resulting CBOR |
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319 | string without checking whether that is, in fact, true or not. |
|
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320 | |
238 | =item $cbor = $cbor->filter ([$cb->($tag, $value)]) |
321 | =item $cbor = $cbor->filter ([$cb->($tag, $value)]) |
239 | |
322 | |
240 | =item $cb_or_undef = $cbor->get_filter |
323 | =item $cb_or_undef = $cbor->get_filter |
241 | |
324 | |
242 | Sets or replaces the tagged value decoding filter (when C<$cb> is |
325 | Sets or replaces the tagged value decoding filter (when C<$cb> is |
… | |
… | |
259 | function, C<CBOR::XS::default_filter>, is used. This function simply looks |
342 | function, C<CBOR::XS::default_filter>, is used. This function simply looks |
260 | up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists it must be |
343 | up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists it must be |
261 | a code reference that is called with tag and value, and is responsible for |
344 | a code reference that is called with tag and value, and is responsible for |
262 | decoding the value. If no entry exists, it returns no values. |
345 | decoding the value. If no entry exists, it returns no values. |
263 | |
346 | |
264 | Example: decode all tags not handled internally into CBOR::XS::Tagged |
347 | Example: decode all tags not handled internally into C<CBOR::XS::Tagged> |
265 | objects, with no other special handling (useful when working with |
348 | objects, with no other special handling (useful when working with |
266 | potentially "unsafe" CBOR data). |
349 | potentially "unsafe" CBOR data). |
267 | |
350 | |
268 | CBOR::XS->new->filter (sub { })->decode ($cbor_data); |
351 | CBOR::XS->new->filter (sub { })->decode ($cbor_data); |
269 | |
352 | |
… | |
… | |
296 | and you need to know where the first CBOR string ends amd the next one |
379 | and you need to know where the first CBOR string ends amd the next one |
297 | starts. |
380 | starts. |
298 | |
381 | |
299 | CBOR::XS->new->decode_prefix ("......") |
382 | CBOR::XS->new->decode_prefix ("......") |
300 | => ("...", 3) |
383 | => ("...", 3) |
|
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384 | |
|
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385 | =back |
|
|
386 | |
|
|
387 | =head2 INCREMENTAL PARSING |
|
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388 | |
|
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389 | In some cases, there is the need for incremental parsing of JSON |
|
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390 | texts. While this module always has to keep both CBOR text and resulting |
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391 | Perl data structure in memory at one time, it does allow you to parse a |
|
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392 | CBOR stream incrementally, using a similar to using "decode_prefix" to see |
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393 | if a full CBOR object is available, but is much more efficient. |
|
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394 | |
|
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395 | It basically works by parsing as much of a CBOR string as possible - if |
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396 | the CBOR data is not complete yet, the pasrer will remember where it was, |
|
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397 | to be able to restart when more data has been accumulated. Once enough |
|
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398 | data is available to either decode a complete CBOR value or raise an |
|
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399 | error, a real decode will be attempted. |
|
|
400 | |
|
|
401 | A typical use case would be a network protocol that consists of sending |
|
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402 | and receiving CBOR-encoded messages. The solution that works with CBOR and |
|
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403 | about anything else is by prepending a length to every CBOR value, so the |
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404 | receiver knows how many octets to read. More compact (and slightly slower) |
|
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405 | would be to just send CBOR values back-to-back, as C<CBOR::XS> knows where |
|
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406 | a CBOR value ends, and doesn't need an explicit length. |
|
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407 | |
|
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408 | The following methods help with this: |
|
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409 | |
|
|
410 | =over 4 |
|
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411 | |
|
|
412 | =item @decoded = $cbor->incr_parse ($buffer) |
|
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413 | |
|
|
414 | This method attempts to decode exactly one CBOR value from the beginning |
|
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415 | of the given C<$buffer>. The value is removed from the C<$buffer> on |
|
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416 | success. When C<$buffer> doesn't contain a complete value yet, it returns |
|
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417 | nothing. Finally, when the C<$buffer> doesn't start with something |
|
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418 | that could ever be a valid CBOR value, it raises an exception, just as |
|
|
419 | C<decode> would. In the latter case the decoder state is undefined and |
|
|
420 | must be reset before being able to parse further. |
|
|
421 | |
|
|
422 | This method modifies the C<$buffer> in place. When no CBOR value can be |
|
|
423 | decoded, the decoder stores the current string offset. On the next call, |
|
|
424 | continues decoding at the place where it stopped before. For this to make |
|
|
425 | sense, the C<$buffer> must begin with the same octets as on previous |
|
|
426 | unsuccessful calls. |
|
|
427 | |
|
|
428 | You can call this method in scalar context, in which case it either |
|
|
429 | returns a decoded value or C<undef>. This makes it impossible to |
|
|
430 | distinguish between CBOR null values (which decode to C<undef>) and an |
|
|
431 | unsuccessful decode, which is often acceptable. |
|
|
432 | |
|
|
433 | =item @decoded = $cbor->incr_parse_multiple ($buffer) |
|
|
434 | |
|
|
435 | Same as C<incr_parse>, but attempts to decode as many CBOR values as |
|
|
436 | possible in one go, instead of at most one. Calls to C<incr_parse> and |
|
|
437 | C<incr_parse_multiple> can be interleaved. |
|
|
438 | |
|
|
439 | =item $cbor->incr_reset |
|
|
440 | |
|
|
441 | Resets the incremental decoder. This throws away any saved state, so that |
|
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442 | subsequent calls to C<incr_parse> or C<incr_parse_multiple> start to parse |
|
|
443 | a new CBOR value from the beginning of the C<$buffer> again. |
|
|
444 | |
|
|
445 | This method can be caled at any time, but it I<must> be called if you want |
|
|
446 | to change your C<$buffer> or there was a decoding error and you want to |
|
|
447 | reuse the C<$cbor> object for future incremental parsings. |
301 | |
448 | |
302 | =back |
449 | =back |
303 | |
450 | |
304 | |
451 | |
305 | =head1 MAPPING |
452 | =head1 MAPPING |
… | |
… | |
323 | CBOR integers become (numeric) perl scalars. On perls without 64 bit |
470 | CBOR integers become (numeric) perl scalars. On perls without 64 bit |
324 | support, 64 bit integers will be truncated or otherwise corrupted. |
471 | support, 64 bit integers will be truncated or otherwise corrupted. |
325 | |
472 | |
326 | =item byte strings |
473 | =item byte strings |
327 | |
474 | |
328 | Byte strings will become octet strings in Perl (the byte values 0..255 |
475 | Byte strings will become octet strings in Perl (the Byte values 0..255 |
329 | will simply become characters of the same value in Perl). |
476 | will simply become characters of the same value in Perl). |
330 | |
477 | |
331 | =item UTF-8 strings |
478 | =item UTF-8 strings |
332 | |
479 | |
333 | UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be |
480 | UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be |
… | |
… | |
356 | =item tagged values |
503 | =item tagged values |
357 | |
504 | |
358 | Tagged items consists of a numeric tag and another CBOR value. |
505 | Tagged items consists of a numeric tag and another CBOR value. |
359 | |
506 | |
360 | See L<TAG HANDLING AND EXTENSIONS> and the description of C<< ->filter >> |
507 | See L<TAG HANDLING AND EXTENSIONS> and the description of C<< ->filter >> |
361 | for details. |
508 | for details on which tags are handled how. |
362 | |
509 | |
363 | =item anything else |
510 | =item anything else |
364 | |
511 | |
365 | Anything else (e.g. unsupported simple values) will raise a decoding |
512 | Anything else (e.g. unsupported simple values) will raise a decoding |
366 | error. |
513 | error. |
… | |
… | |
369 | |
516 | |
370 | |
517 | |
371 | =head2 PERL -> CBOR |
518 | =head2 PERL -> CBOR |
372 | |
519 | |
373 | The mapping from Perl to CBOR is slightly more difficult, as Perl is a |
520 | The mapping from Perl to CBOR is slightly more difficult, as Perl is a |
374 | truly typeless language, so we can only guess which CBOR type is meant by |
521 | typeless language. That means this module can only guess which CBOR type |
375 | a Perl value. |
522 | is meant by a perl value. |
376 | |
523 | |
377 | =over 4 |
524 | =over 4 |
378 | |
525 | |
379 | =item hash references |
526 | =item hash references |
380 | |
527 | |
381 | Perl hash references become CBOR maps. As there is no inherent ordering in |
528 | Perl hash references become CBOR maps. As there is no inherent ordering in |
382 | hash keys (or CBOR maps), they will usually be encoded in a pseudo-random |
529 | hash keys (or CBOR maps), they will usually be encoded in a pseudo-random |
383 | order. |
530 | order. This order can be different each time a hash is encoded. |
384 | |
531 | |
385 | Currently, tied hashes will use the indefinite-length format, while normal |
532 | Currently, tied hashes will use the indefinite-length format, while normal |
386 | hashes will use the fixed-length format. |
533 | hashes will use the fixed-length format. |
387 | |
534 | |
388 | =item array references |
535 | =item array references |
389 | |
536 | |
390 | Perl array references become fixed-length CBOR arrays. |
537 | Perl array references become fixed-length CBOR arrays. |
391 | |
538 | |
392 | =item other references |
539 | =item other references |
393 | |
540 | |
394 | Other unblessed references are generally not allowed and will cause an |
541 | Other unblessed references will be represented using |
395 | exception to be thrown, except for references to the integers C<0> and |
542 | the indirection tag extension (tag value C<22098>, |
396 | C<1>, which get turned into false and true in CBOR. |
543 | L<http://cbor.schmorp.de/indirection>). CBOR decoders are guaranteed |
|
|
544 | to be able to decode these values somehow, by either "doing the right |
|
|
545 | thing", decoding into a generic tagged object, simply ignoring the tag, or |
|
|
546 | something else. |
397 | |
547 | |
398 | =item CBOR::XS::Tagged objects |
548 | =item CBOR::XS::Tagged objects |
399 | |
549 | |
400 | Objects of this type must be arrays consisting of a single C<[tag, value]> |
550 | Objects of this type must be arrays consisting of a single C<[tag, value]> |
401 | pair. The (numerical) tag will be encoded as a CBOR tag, the value will |
551 | pair. The (numerical) tag will be encoded as a CBOR tag, the value will |
402 | be encoded as appropriate for the value. You cna use C<CBOR::XS::tag> to |
552 | be encoded as appropriate for the value. You must use C<CBOR::XS::tag> to |
403 | create such objects. |
553 | create such objects. |
404 | |
554 | |
405 | =item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error |
555 | =item Types::Serialiser::true, Types::Serialiser::false, Types::Serialiser::error |
406 | |
556 | |
407 | These special values become CBOR true, CBOR false and CBOR undefined |
557 | These special values become CBOR true, CBOR false and CBOR undefined |
… | |
… | |
424 | # dump as number |
574 | # dump as number |
425 | encode_cbor [2] # yields [2] |
575 | encode_cbor [2] # yields [2] |
426 | encode_cbor [-3.0e17] # yields [-3e+17] |
576 | encode_cbor [-3.0e17] # yields [-3e+17] |
427 | my $value = 5; encode_cbor [$value] # yields [5] |
577 | my $value = 5; encode_cbor [$value] # yields [5] |
428 | |
578 | |
429 | # used as string, so dump as string |
579 | # used as string, so dump as string (either byte or text) |
430 | print $value; |
580 | print $value; |
431 | encode_cbor [$value] # yields ["5"] |
581 | encode_cbor [$value] # yields ["5"] |
432 | |
582 | |
433 | # undef becomes null |
583 | # undef becomes null |
434 | encode_cbor [undef] # yields [null] |
584 | encode_cbor [undef] # yields [null] |
… | |
… | |
437 | |
587 | |
438 | my $x = 3.1; # some variable containing a number |
588 | my $x = 3.1; # some variable containing a number |
439 | "$x"; # stringified |
589 | "$x"; # stringified |
440 | $x .= ""; # another, more awkward way to stringify |
590 | $x .= ""; # another, more awkward way to stringify |
441 | print $x; # perl does it for you, too, quite often |
591 | print $x; # perl does it for you, too, quite often |
|
|
592 | |
|
|
593 | You can force whether a string ie encoded as byte or text string by using |
|
|
594 | C<utf8::upgrade> and C<utf8::downgrade>): |
|
|
595 | |
|
|
596 | utf8::upgrade $x; # encode $x as text string |
|
|
597 | utf8::downgrade $x; # encode $x as byte string |
|
|
598 | |
|
|
599 | Perl doesn't define what operations up- and downgrade strings, so if the |
|
|
600 | difference between byte and text is important, you should up- or downgrade |
|
|
601 | your string as late as possible before encoding. |
442 | |
602 | |
443 | You can force the type to be a CBOR number by numifying it: |
603 | You can force the type to be a CBOR number by numifying it: |
444 | |
604 | |
445 | my $x = "3"; # some variable containing a string |
605 | my $x = "3"; # some variable containing a string |
446 | $x += 0; # numify it, ensuring it will be dumped as a number |
606 | $x += 0; # numify it, ensuring it will be dumped as a number |
… | |
… | |
459 | |
619 | |
460 | =back |
620 | =back |
461 | |
621 | |
462 | =head2 OBJECT SERIALISATION |
622 | =head2 OBJECT SERIALISATION |
463 | |
623 | |
|
|
624 | This module implements both a CBOR-specific and the generic |
|
|
625 | L<Types::Serialier> object serialisation protocol. The following |
|
|
626 | subsections explain both methods. |
|
|
627 | |
|
|
628 | =head3 ENCODING |
|
|
629 | |
464 | This module knows two way to serialise a Perl object: The CBOR-specific |
630 | This module knows two way to serialise a Perl object: The CBOR-specific |
465 | way, and the generic way. |
631 | way, and the generic way. |
466 | |
632 | |
467 | Whenever the encoder encounters a Perl object that it cnanot serialise |
633 | Whenever the encoder encounters a Perl object that it cannot serialise |
468 | directly (most of them), it will first look up the C<TO_CBOR> method on |
634 | directly (most of them), it will first look up the C<TO_CBOR> method on |
469 | it. |
635 | it. |
470 | |
636 | |
471 | If it has a C<TO_CBOR> method, it will call it with the object as only |
637 | If it has a C<TO_CBOR> method, it will call it with the object as only |
472 | argument, and expects exactly one return value, which it will then |
638 | argument, and expects exactly one return value, which it will then |
… | |
… | |
478 | |
644 | |
479 | The C<FREEZE> method can return any number of values (i.e. zero or |
645 | The C<FREEZE> method can return any number of values (i.e. zero or |
480 | more). These will be encoded as CBOR perl object, together with the |
646 | more). These will be encoded as CBOR perl object, together with the |
481 | classname. |
647 | classname. |
482 | |
648 | |
|
|
649 | These methods I<MUST NOT> change the data structure that is being |
|
|
650 | serialised. Failure to comply to this can result in memory corruption - |
|
|
651 | and worse. |
|
|
652 | |
483 | If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail |
653 | If an object supports neither C<TO_CBOR> nor C<FREEZE>, encoding will fail |
484 | with an error. |
654 | with an error. |
485 | |
655 | |
|
|
656 | =head3 DECODING |
|
|
657 | |
486 | Objects encoded via C<TO_CBOR> cannot be automatically decoded, but |
658 | Objects encoded via C<TO_CBOR> cannot (normally) be automatically decoded, |
487 | objects encoded via C<FREEZE> can be decoded using the following protocol: |
659 | but objects encoded via C<FREEZE> can be decoded using the following |
|
|
660 | protocol: |
488 | |
661 | |
489 | When an encoded CBOR perl object is encountered by the decoder, it will |
662 | When an encoded CBOR perl object is encountered by the decoder, it will |
490 | look up the C<THAW> method, by using the stored classname, and will fail |
663 | look up the C<THAW> method, by using the stored classname, and will fail |
491 | if the method cannot be found. |
664 | if the method cannot be found. |
492 | |
665 | |
493 | After the lookup it will call the C<THAW> method with the stored classname |
666 | After the lookup it will call the C<THAW> method with the stored classname |
494 | as first argument, the constant string C<CBOR> as second argument, and all |
667 | as first argument, the constant string C<CBOR> as second argument, and all |
495 | values returned by C<FREEZE> as remaining arguments. |
668 | values returned by C<FREEZE> as remaining arguments. |
496 | |
669 | |
497 | =head4 EXAMPLES |
670 | =head3 EXAMPLES |
498 | |
671 | |
499 | Here is an example C<TO_CBOR> method: |
672 | Here is an example C<TO_CBOR> method: |
500 | |
673 | |
501 | sub My::Object::TO_CBOR { |
674 | sub My::Object::TO_CBOR { |
502 | my ($obj) = @_; |
675 | my ($obj) = @_; |
… | |
… | |
513 | |
686 | |
514 | sub URI::TO_CBOR { |
687 | sub URI::TO_CBOR { |
515 | my ($self) = @_; |
688 | my ($self) = @_; |
516 | my $uri = "$self"; # stringify uri |
689 | my $uri = "$self"; # stringify uri |
517 | utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string |
690 | utf8::upgrade $uri; # make sure it will be encoded as UTF-8 string |
518 | CBOR::XS::tagged 32, "$_[0]" |
691 | CBOR::XS::tag 32, "$_[0]" |
519 | } |
692 | } |
520 | |
693 | |
521 | This will encode URIs as a UTF-8 string with tag 32, which indicates an |
694 | This will encode URIs as a UTF-8 string with tag 32, which indicates an |
522 | URI. |
695 | URI. |
523 | |
696 | |
… | |
… | |
534 | "$self" # encode url string |
707 | "$self" # encode url string |
535 | } |
708 | } |
536 | |
709 | |
537 | sub URI::THAW { |
710 | sub URI::THAW { |
538 | my ($class, $serialiser, $uri) = @_; |
711 | my ($class, $serialiser, $uri) = @_; |
539 | |
|
|
540 | $class->new ($uri) |
712 | $class->new ($uri) |
541 | } |
713 | } |
542 | |
714 | |
543 | Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For |
715 | Unlike C<TO_CBOR>, multiple values can be returned by C<FREEZE>. For |
544 | example, a C<FREEZE> method that returns "type", "id" and "variant" values |
716 | example, a C<FREEZE> method that returns "type", "id" and "variant" values |
… | |
… | |
675 | additional tags (such as base64url). |
847 | additional tags (such as base64url). |
676 | |
848 | |
677 | =head2 ENFORCED TAGS |
849 | =head2 ENFORCED TAGS |
678 | |
850 | |
679 | These tags are always handled when decoding, and their handling cannot be |
851 | These tags are always handled when decoding, and their handling cannot be |
680 | overriden by the user. |
852 | overridden by the user. |
681 | |
853 | |
682 | =over 4 |
854 | =over 4 |
683 | |
855 | |
684 | =item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>) |
856 | =item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>) |
685 | |
857 | |
686 | These tags are automatically created (and decoded) for serialisable |
858 | These tags are automatically created (and decoded) for serialisable |
687 | objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object |
859 | objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object |
688 | serialisation protocol). See L<OBJECT SERIALISATION> for details. |
860 | serialisation protocol). See L<OBJECT SERIALISATION> for details. |
689 | |
861 | |
690 | =item 28, 29 (sharable, sharedref, L <http://cbor.schmorp.de/value-sharing>) |
862 | =item 28, 29 (shareable, sharedref, L<http://cbor.schmorp.de/value-sharing>) |
691 | |
863 | |
692 | These tags are automatically decoded when encountered, resulting in |
864 | These tags are automatically decoded when encountered (and they do not |
|
|
865 | result in a cyclic data structure, see C<allow_cycles>), resulting in |
693 | shared values in the decoded object. They are only encoded, however, when |
866 | shared values in the decoded object. They are only encoded, however, when |
694 | C<allow_sharable> is enabled. |
867 | C<allow_sharing> is enabled. |
695 | |
868 | |
|
|
869 | Not all shared values can be successfully decoded: values that reference |
|
|
870 | themselves will I<currently> decode as C<undef> (this is not the same |
|
|
871 | as a reference pointing to itself, which will be represented as a value |
|
|
872 | that contains an indirect reference to itself - these will be decoded |
|
|
873 | properly). |
|
|
874 | |
|
|
875 | Note that considerably more shared value data structures can be decoded |
|
|
876 | than will be encoded - currently, only values pointed to by references |
|
|
877 | will be shared, others will not. While non-reference shared values can be |
|
|
878 | generated in Perl with some effort, they were considered too unimportant |
|
|
879 | to be supported in the encoder. The decoder, however, will decode these |
|
|
880 | values as shared values. |
|
|
881 | |
696 | =item 256, 25 (stringref-namespace, stringref, L <http://cbor.schmorp.de/stringref>) |
882 | =item 256, 25 (stringref-namespace, stringref, L<http://cbor.schmorp.de/stringref>) |
697 | |
883 | |
698 | These tags are automatically decoded when encountered. They are only |
884 | These tags are automatically decoded when encountered. They are only |
699 | encoded, however, when C<pack_strings> is enabled. |
885 | encoded, however, when C<pack_strings> is enabled. |
700 | |
886 | |
701 | =item 22098 (indirection, L<http://cbor.schmorp.de/indirection>) |
887 | =item 22098 (indirection, L<http://cbor.schmorp.de/indirection>) |
702 | |
888 | |
703 | This tag is automatically generated when a reference are encountered (with |
889 | This tag is automatically generated when a reference are encountered (with |
704 | the exception of hash and array refernces). It is converted to a reference |
890 | the exception of hash and array references). It is converted to a reference |
705 | when decoding. |
891 | when decoding. |
706 | |
892 | |
707 | =item 55799 (self-describe CBOR, RFC 7049) |
893 | =item 55799 (self-describe CBOR, RFC 7049) |
708 | |
894 | |
709 | This value is not generated on encoding (unless explicitly requested by |
895 | This value is not generated on encoding (unless explicitly requested by |
… | |
… | |
712 | =back |
898 | =back |
713 | |
899 | |
714 | =head2 NON-ENFORCED TAGS |
900 | =head2 NON-ENFORCED TAGS |
715 | |
901 | |
716 | These tags have default filters provided when decoding. Their handling can |
902 | These tags have default filters provided when decoding. Their handling can |
717 | be overriden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by |
903 | be overridden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by |
718 | providing a custom C<filter> callback when decoding. |
904 | providing a custom C<filter> callback when decoding. |
719 | |
905 | |
720 | When they result in decoding into a specific Perl class, the module |
906 | When they result in decoding into a specific Perl class, the module |
721 | usually provides a corresponding C<TO_CBOR> method as well. |
907 | usually provides a corresponding C<TO_CBOR> method as well. |
722 | |
908 | |
… | |
… | |
725 | provide these modules. The decoding usually fails with an exception if the |
911 | provide these modules. The decoding usually fails with an exception if the |
726 | required module cannot be loaded. |
912 | required module cannot be loaded. |
727 | |
913 | |
728 | =over 4 |
914 | =over 4 |
729 | |
915 | |
|
|
916 | =item 0, 1 (date/time string, seconds since the epoch) |
|
|
917 | |
|
|
918 | These tags are decoded into L<Time::Piece> objects. The corresponding |
|
|
919 | C<Time::Piece::TO_CBOR> method always encodes into tag 1 values currently. |
|
|
920 | |
|
|
921 | The L<Time::Piece> API is generally surprisingly bad, and fractional |
|
|
922 | seconds are only accidentally kept intact, so watch out. On the plus side, |
|
|
923 | the module comes with perl since 5.10, which has to count for something. |
|
|
924 | |
730 | =item 2, 3 (positive/negative bignum) |
925 | =item 2, 3 (positive/negative bignum) |
731 | |
926 | |
732 | These tags are decoded into L<Math::BigInt> objects. The corresponding |
927 | These tags are decoded into L<Math::BigInt> objects. The corresponding |
733 | C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR |
928 | C<Math::BigInt::TO_CBOR> method encodes "small" bigints into normal CBOR |
734 | integers, and others into positive/negative CBOR bignums. |
929 | integers, and others into positive/negative CBOR bignums. |
… | |
… | |
755 | C<URI::TO_CBOR> method again results in a CBOR URI value. |
950 | C<URI::TO_CBOR> method again results in a CBOR URI value. |
756 | |
951 | |
757 | =back |
952 | =back |
758 | |
953 | |
759 | =cut |
954 | =cut |
760 | |
|
|
761 | our %FILTER = ( |
|
|
762 | # 0 # rfc4287 datetime, utf-8 |
|
|
763 | # 1 # unix timestamp, any |
|
|
764 | |
|
|
765 | 2 => sub { # pos bigint |
|
|
766 | require Math::BigInt; |
|
|
767 | Math::BigInt->new ("0x" . unpack "H*", pop) |
|
|
768 | }, |
|
|
769 | |
|
|
770 | 3 => sub { # neg bigint |
|
|
771 | require Math::BigInt; |
|
|
772 | -Math::BigInt->new ("0x" . unpack "H*", pop) |
|
|
773 | }, |
|
|
774 | |
|
|
775 | 4 => sub { # decimal fraction, array |
|
|
776 | require Math::BigFloat; |
|
|
777 | Math::BigFloat->new ($_[1][1] . "E" . $_[1][0]) |
|
|
778 | }, |
|
|
779 | |
|
|
780 | 5 => sub { # bigfloat, array |
|
|
781 | require Math::BigFloat; |
|
|
782 | scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2) |
|
|
783 | }, |
|
|
784 | |
|
|
785 | 21 => sub { pop }, # expected conversion to base64url encoding |
|
|
786 | 22 => sub { pop }, # expected conversion to base64 encoding |
|
|
787 | 23 => sub { pop }, # expected conversion to base16 encoding |
|
|
788 | |
|
|
789 | # 24 # embedded cbor, byte string |
|
|
790 | |
|
|
791 | 32 => sub { |
|
|
792 | require URI; |
|
|
793 | URI->new (pop) |
|
|
794 | }, |
|
|
795 | |
|
|
796 | # 33 # base64url rfc4648, utf-8 |
|
|
797 | # 34 # base64 rfc46484, utf-8 |
|
|
798 | # 35 # regex pcre/ecma262, utf-8 |
|
|
799 | # 36 # mime message rfc2045, utf-8 |
|
|
800 | ); |
|
|
801 | |
|
|
802 | |
955 | |
803 | =head1 CBOR and JSON |
956 | =head1 CBOR and JSON |
804 | |
957 | |
805 | CBOR is supposed to implement a superset of the JSON data model, and is, |
958 | CBOR is supposed to implement a superset of the JSON data model, and is, |
806 | with some coercion, able to represent all JSON texts (something that other |
959 | with some coercion, able to represent all JSON texts (something that other |
… | |
… | |
867 | properly. Half precision types are accepted, but not encoded. |
1020 | properly. Half precision types are accepted, but not encoded. |
868 | |
1021 | |
869 | Strict mode and canonical mode are not implemented. |
1022 | Strict mode and canonical mode are not implemented. |
870 | |
1023 | |
871 | |
1024 | |
|
|
1025 | =head1 LIMITATIONS ON PERLS WITHOUT 64-BIT INTEGER SUPPORT |
|
|
1026 | |
|
|
1027 | On perls that were built without 64 bit integer support (these are rare |
|
|
1028 | nowadays, even on 32 bit architectures, as all major Perl distributions |
|
|
1029 | are built with 64 bit integer support), support for any kind of 64 bit |
|
|
1030 | integer in CBOR is very limited - most likely, these 64 bit values will |
|
|
1031 | be truncated, corrupted, or otherwise not decoded correctly. This also |
|
|
1032 | includes string, array and map sizes that are stored as 64 bit integers. |
|
|
1033 | |
|
|
1034 | |
872 | =head1 THREADS |
1035 | =head1 THREADS |
873 | |
1036 | |
874 | This module is I<not> guaranteed to be thread safe and there are no |
1037 | This module is I<not> guaranteed to be thread safe and there are no |
875 | plans to change this until Perl gets thread support (as opposed to the |
1038 | plans to change this until Perl gets thread support (as opposed to the |
876 | horribly slow so-called "threads" which are simply slow and bloated |
1039 | horribly slow so-called "threads" which are simply slow and bloated |
… | |
… | |
889 | service. I put the contact address into my modules for a reason. |
1052 | service. I put the contact address into my modules for a reason. |
890 | |
1053 | |
891 | =cut |
1054 | =cut |
892 | |
1055 | |
893 | our %FILTER = ( |
1056 | our %FILTER = ( |
894 | # 0 # rfc4287 datetime, utf-8 |
1057 | 0 => sub { # rfc4287 datetime, utf-8 |
895 | # 1 # unix timestamp, any |
1058 | require Time::Piece; |
|
|
1059 | # Time::Piece::Strptime uses the "incredibly flexible date parsing routine" |
|
|
1060 | # from FreeBSD, which can't parse ISO 8601, RFC3339, RFC4287 or much of anything |
|
|
1061 | # else either. Whats incredibe over standard strptime totally escapes me. |
|
|
1062 | # doesn't do fractional times, either. sigh. |
|
|
1063 | # In fact, it's all a lie, it uses whatever strptime it wants, and of course, |
|
|
1064 | # they are all incompatible. The openbsd one simply ignores %z (but according to the |
|
|
1065 | # docs, it would be much more incredibly flexible indeed. If it worked, that is.). |
|
|
1066 | scalar eval { |
|
|
1067 | my $s = $_[1]; |
|
|
1068 | |
|
|
1069 | $s =~ s/Z$/+00:00/; |
|
|
1070 | $s =~ s/(\.[0-9]+)?([+-][0-9][0-9]):([0-9][0-9])$// |
|
|
1071 | or die; |
|
|
1072 | |
|
|
1073 | my $b = $1 - ($2 * 60 + $3) * 60; # fractional part + offset. hopefully |
|
|
1074 | my $d = Time::Piece->strptime ($s, "%Y-%m-%dT%H:%M:%S"); |
|
|
1075 | |
|
|
1076 | Time::Piece::gmtime ($d->epoch + $b) |
|
|
1077 | } || die "corrupted CBOR date/time string ($_[0])"; |
|
|
1078 | }, |
|
|
1079 | |
|
|
1080 | 1 => sub { # seconds since the epoch, possibly fractional |
|
|
1081 | require Time::Piece; |
|
|
1082 | scalar Time::Piece::gmtime (pop) |
|
|
1083 | }, |
896 | |
1084 | |
897 | 2 => sub { # pos bigint |
1085 | 2 => sub { # pos bigint |
898 | require Math::BigInt; |
1086 | require Math::BigInt; |
899 | Math::BigInt->new ("0x" . unpack "H*", pop) |
1087 | Math::BigInt->new ("0x" . unpack "H*", pop) |
900 | }, |
1088 | }, |
… | |
… | |
909 | Math::BigFloat->new ($_[1][1] . "E" . $_[1][0]) |
1097 | Math::BigFloat->new ($_[1][1] . "E" . $_[1][0]) |
910 | }, |
1098 | }, |
911 | |
1099 | |
912 | 5 => sub { # bigfloat, array |
1100 | 5 => sub { # bigfloat, array |
913 | require Math::BigFloat; |
1101 | require Math::BigFloat; |
914 | scalar Math::BigFloat->new ($_[1][1])->blsft ($_[1][0], 2) |
1102 | scalar Math::BigFloat->new ($_[1][1]) * Math::BigFloat->new (2)->bpow ($_[1][0]) |
915 | }, |
1103 | }, |
916 | |
1104 | |
917 | 21 => sub { pop }, # expected conversion to base64url encoding |
1105 | 21 => sub { pop }, # expected conversion to base64url encoding |
918 | 22 => sub { pop }, # expected conversion to base64 encoding |
1106 | 22 => sub { pop }, # expected conversion to base64 encoding |
919 | 23 => sub { pop }, # expected conversion to base16 encoding |
1107 | 23 => sub { pop }, # expected conversion to base16 encoding |
… | |
… | |
936 | } |
1124 | } |
937 | |
1125 | |
938 | sub URI::TO_CBOR { |
1126 | sub URI::TO_CBOR { |
939 | my $uri = $_[0]->as_string; |
1127 | my $uri = $_[0]->as_string; |
940 | utf8::upgrade $uri; |
1128 | utf8::upgrade $uri; |
941 | CBOR::XS::tag 32, $uri |
1129 | tag 32, $uri |
942 | } |
1130 | } |
943 | |
1131 | |
944 | sub Math::BigInt::TO_CBOR { |
1132 | sub Math::BigInt::TO_CBOR { |
945 | if ($_[0] >= -2147483648 && $_[0] <= 2147483647) { |
1133 | if ($_[0] >= -2147483648 && $_[0] <= 2147483647) { |
946 | $_[0]->numify |
1134 | $_[0]->numify |
947 | } else { |
1135 | } else { |
948 | my $hex = substr $_[0]->as_hex, 2; |
1136 | my $hex = substr $_[0]->as_hex, 2; |
949 | $hex = "0$hex" if 1 & length $hex; # sigh |
1137 | $hex = "0$hex" if 1 & length $hex; # sigh |
950 | CBOR::XS::tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex |
1138 | tag $_[0] >= 0 ? 2 : 3, pack "H*", $hex |
951 | } |
1139 | } |
952 | } |
1140 | } |
953 | |
1141 | |
954 | sub Math::BigFloat::TO_CBOR { |
1142 | sub Math::BigFloat::TO_CBOR { |
955 | my ($m, $e) = $_[0]->parts; |
1143 | my ($m, $e) = $_[0]->parts; |
956 | CBOR::XS::tag 4, [$e->numify, $m] |
1144 | tag 4, [$e->numify, $m] |
|
|
1145 | } |
|
|
1146 | |
|
|
1147 | sub Time::Piece::TO_CBOR { |
|
|
1148 | tag 1, 0 + $_[0]->epoch |
957 | } |
1149 | } |
958 | |
1150 | |
959 | XSLoader::load "CBOR::XS", $VERSION; |
1151 | XSLoader::load "CBOR::XS", $VERSION; |
960 | |
1152 | |
961 | =head1 SEE ALSO |
1153 | =head1 SEE ALSO |