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64 | |
64 | |
65 | package CBOR::XS; |
65 | package CBOR::XS; |
66 | |
66 | |
67 | use common::sense; |
67 | use common::sense; |
68 | |
68 | |
69 | our $VERSION = 1.12; |
69 | our $VERSION = 1.25; |
70 | our @ISA = qw(Exporter); |
70 | our @ISA = qw(Exporter); |
71 | |
71 | |
72 | our @EXPORT = qw(encode_cbor decode_cbor); |
72 | our @EXPORT = qw(encode_cbor decode_cbor); |
73 | |
73 | |
74 | use Exporter; |
74 | use Exporter; |
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218 | isn't prepared for this will not leak memory. |
218 | isn't prepared for this will not leak memory. |
219 | |
219 | |
220 | If C<$enable> is false (the default), then C<decode> will throw an error |
220 | If C<$enable> is false (the default), then C<decode> will throw an error |
221 | when it encounters a self-referential/cyclic data structure. |
221 | when it encounters a self-referential/cyclic data structure. |
222 | |
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 | |
223 | This option does not affect C<encode> in any way - shared values and |
228 | This option does not affect C<encode> in any way - shared values and |
224 | references will always be decoded properly if present. |
229 | references will always be decoded properly if present. |
225 | |
230 | |
226 | =item $cbor = $cbor->pack_strings ([$enable]) |
231 | =item $cbor = $cbor->pack_strings ([$enable]) |
227 | |
232 | |
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330 | and you need to know where the first CBOR string ends amd the next one |
335 | and you need to know where the first CBOR string ends amd the next one |
331 | starts. |
336 | starts. |
332 | |
337 | |
333 | CBOR::XS->new->decode_prefix ("......") |
338 | CBOR::XS->new->decode_prefix ("......") |
334 | => ("...", 3) |
339 | => ("...", 3) |
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340 | |
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341 | =back |
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342 | |
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343 | =head2 INCREMENTAL PARSING |
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344 | |
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345 | In some cases, there is the need for incremental parsing of JSON |
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346 | texts. While this module always has to keep both CBOR text and resulting |
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347 | Perl data structure in memory at one time, it does allow you to parse a |
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348 | CBOR stream incrementally, using a similar to using "decode_prefix" to see |
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349 | if a full CBOR object is available, but is much more efficient. |
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350 | |
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351 | It basically works by parsing as much of a CBOR string as possible - if |
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352 | the CBOR data is not complete yet, the pasrer will remember where it was, |
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353 | to be able to restart when more data has been accumulated. Once enough |
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354 | data is available to either decode a complete CBOR value or raise an |
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355 | error, a real decode will be attempted. |
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356 | |
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357 | A typical use case would be a network protocol that consists of sending |
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358 | and receiving CBOR-encoded messages. The solution that works with CBOR and |
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359 | about anything else is by prepending a length to every CBOR value, so the |
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360 | receiver knows how many octets to read. More compact (and slightly slower) |
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361 | would be to just send CBOR values back-to-back, as C<CBOR::XS> knows where |
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362 | a CBOR value ends, and doesn't need an explicit length. |
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363 | |
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364 | The following methods help with this: |
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365 | |
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366 | =over 4 |
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367 | |
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368 | =item @decoded = $cbor->incr_parse ($buffer) |
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369 | |
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370 | This method attempts to decode exactly one CBOR value from the beginning |
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371 | of the given C<$buffer>. The value is removed from the C<$buffer> on |
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372 | success. When C<$buffer> doesn't contain a complete value yet, it returns |
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373 | nothing. Finally, when the C<$buffer> doesn't start with something |
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374 | that could ever be a valid CBOR value, it raises an exception, just as |
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375 | C<decode> would. In the latter case the decoder state is undefined and |
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376 | must be reset before being able to parse further. |
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377 | |
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378 | This method modifies the C<$buffer> in place. When no CBOR value can be |
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379 | decoded, the decoder stores the current string offset. On the next call, |
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380 | continues decoding at the place where it stopped before. For this to make |
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381 | sense, the C<$buffer> must begin with the same octets as on previous |
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382 | unsuccessful calls. |
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383 | |
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384 | You can call this method in scalar context, in which case it either |
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385 | returns a decoded value or C<undef>. This makes it impossible to |
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386 | distinguish between CBOR null values (which decode to C<undef>) and an |
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387 | unsuccessful decode, which is often acceptable. |
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388 | |
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389 | =item @decoded = $cbor->incr_parse_multiple ($buffer) |
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390 | |
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391 | Same as C<incr_parse>, but attempts to decode as many CBOR values as |
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392 | possible in one go, instead of at most one. Calls to C<incr_parse> and |
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393 | C<incr_parse_multiple> can be interleaved. |
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394 | |
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395 | =item $cbor->incr_reset |
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396 | |
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397 | Resets the incremental decoder. This throws away any saved state, so that |
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398 | subsequent calls to C<incr_parse> or C<incr_parse_multiple> start to parse |
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399 | a new CBOR value from the beginning of the C<$buffer> again. |
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400 | |
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401 | This method can be caled at any time, but it I<must> be called if you want |
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402 | to change your C<$buffer> or there was a decoding error and you want to |
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403 | reuse the C<$cbor> object for future incremental parsings. |
335 | |
404 | |
336 | =back |
405 | =back |
337 | |
406 | |
338 | |
407 | |
339 | =head1 MAPPING |
408 | =head1 MAPPING |
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1072 | my ($m, $e) = $_[0]->parts; |
1141 | my ($m, $e) = $_[0]->parts; |
1073 | tag 4, [$e->numify, $m] |
1142 | tag 4, [$e->numify, $m] |
1074 | } |
1143 | } |
1075 | |
1144 | |
1076 | sub Time::Piece::TO_CBOR { |
1145 | sub Time::Piece::TO_CBOR { |
1077 | tag 1, $_[0]->epoch |
1146 | tag 1, 0 + $_[0]->epoch |
1078 | } |
1147 | } |
1079 | |
1148 | |
1080 | XSLoader::load "CBOR::XS", $VERSION; |
1149 | XSLoader::load "CBOR::XS", $VERSION; |
1081 | |
1150 | |
1082 | =head1 SEE ALSO |
1151 | =head1 SEE ALSO |