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56 | As for compactness, C<CBOR::XS> encoded data structures are usually about |
56 | As for compactness, C<CBOR::XS> encoded data structures are usually about |
57 | 20% smaller than the same data encoded as (compact) JSON or L<Storable>. |
57 | 20% smaller than the same data encoded as (compact) JSON or L<Storable>. |
58 | |
58 | |
59 | In addition to the core CBOR data format, this module implements a number |
59 | In addition to the core CBOR data format, this module implements a number |
60 | of extensions, to support cyclic and self-referencing data structures |
60 | of extensions, to support cyclic and self-referencing data structures |
61 | (see C<allow_sharing>), string deduplication (see C<allow_stringref>) and |
61 | (see C<allow_sharing>), string deduplication (see C<pack_strings>) and |
62 | scalar references (always enabled). |
62 | scalar references (always enabled). |
63 | |
63 | |
64 | The primary goal of this module is to be I<correct> and the secondary goal |
64 | 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. |
65 | is to be I<fast>. To reach the latter goal it was written in C. |
66 | |
66 | |
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71 | |
71 | |
72 | package CBOR::XS; |
72 | package CBOR::XS; |
73 | |
73 | |
74 | use common::sense; |
74 | use common::sense; |
75 | |
75 | |
76 | our $VERSION = 0.08; |
76 | our $VERSION = 0.09; |
77 | our @ISA = qw(Exporter); |
77 | our @ISA = qw(Exporter); |
78 | |
78 | |
79 | our @EXPORT = qw(encode_cbor decode_cbor); |
79 | our @EXPORT = qw(encode_cbor decode_cbor); |
80 | |
80 | |
81 | use Exporter; |
81 | use Exporter; |
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… | |
186 | as an array, is referenced multiple times), but instead will emit a |
186 | as an array, is referenced multiple times), but instead will emit a |
187 | reference to the earlier value. |
187 | reference to the earlier value. |
188 | |
188 | |
189 | This means that such values will only be encoded once, and will not result |
189 | 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 |
190 | in a deep cloning of the value on decode, in decoders supporting the value |
191 | sharing extension. |
191 | sharing extension. This also makes it possible to encode cyclic data |
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192 | structures. |
192 | |
193 | |
193 | It is recommended to leave it off unless you know your |
194 | It is recommended to leave it off unless you know your |
194 | communication partner supports the value sharing extensions to CBOR |
195 | communication partner supports the value sharing extensions to CBOR |
195 | (http://cbor.schmorp.de/value-sharing). |
196 | (L<http://cbor.schmorp.de/value-sharing>), as without decoder support, the |
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197 | resulting data structure might be unusable. |
196 | |
198 | |
197 | Detecting shared values incurs a runtime overhead when values are encoded |
199 | Detecting shared values incurs a runtime overhead when values are encoded |
198 | that have a reference counter large than one, and might unnecessarily |
200 | that have a reference counter large than one, and might unnecessarily |
199 | increase the encoded size, as potentially shared values are encode as |
201 | increase the encoded size, as potentially shared values are encode as |
200 | sharable whether or not they are actually shared. |
202 | sharable whether or not they are actually shared. |
201 | |
203 | |
202 | At the moment, only targets of references can be shared (e.g. scalars, |
204 | At the moment, only targets of references can be shared (e.g. scalars, |
203 | arrays or hashes pointed to by a reference). Weirder constructs, such as |
205 | arrays or hashes pointed to by a reference). Weirder constructs, such as |
204 | an array with multiple "copies" of the I<same> string, which are hard but |
206 | an array with multiple "copies" of the I<same> string, which are hard but |
205 | not impossible to create in Perl, are not supported (this is the same as |
207 | not impossible to create in Perl, are not supported (this is the same as |
206 | for L<Storable>). |
208 | with L<Storable>). |
207 | |
209 | |
208 | If C<$enable> is false (the default), then C<encode> will encode |
210 | If C<$enable> is false (the default), then C<encode> will encode shared |
209 | exception when it encounters anything it cannot encode as CBOR. |
211 | data structures repeatedly, unsharing them in the process. Cyclic data |
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212 | structures cannot be encoded in this mode. |
210 | |
213 | |
211 | This option does not affect C<decode> in any way - shared values and |
214 | This option does not affect C<decode> in any way - shared values and |
212 | references will always be decoded properly if present. |
215 | references will always be decoded properly if present. |
213 | |
216 | |
214 | =item $cbor = $cbor->allow_stringref ([$enable]) |
217 | =item $cbor = $cbor->pack_strings ([$enable]) |
215 | |
218 | |
216 | =item $enabled = $cbor->get_allow_stringref |
219 | =item $enabled = $cbor->get_pack_strings |
217 | |
220 | |
218 | If C<$enable> is true (or missing), then C<encode> will try not to encode |
221 | If C<$enable> is true (or missing), then C<encode> will try not to encode |
219 | the same string twice, but will instead encode a reference to the string |
222 | the same string twice, but will instead encode a reference to the string |
220 | instead. Depending on your data format. this can save a lot of space, but |
223 | instead. Depending on your data format, this can save a lot of space, but |
221 | also results in a very large runtime overhead (expect encoding times to be |
224 | also results in a very large runtime overhead (expect encoding times to be |
222 | 2-4 times as high as without). |
225 | 2-4 times as high as without). |
223 | |
226 | |
224 | It is recommended to leave it off unless you know your |
227 | It is recommended to leave it off unless you know your |
225 | communications partner supports the stringref extension to CBOR |
228 | communications partner supports the stringref extension to CBOR |
226 | (http://cbor.schmorp.de/stringref). |
229 | (L<http://cbor.schmorp.de/stringref>), as without decoder support, the |
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230 | resulting data structure might not be usable. |
227 | |
231 | |
228 | If C<$enable> is false (the default), then C<encode> will encode |
232 | If C<$enable> is false (the default), then C<encode> will encode strings |
229 | exception when it encounters anything it cannot encode as CBOR. |
233 | the standard CBOR way. |
230 | |
234 | |
231 | This option does not affect C<decode> in any way - string references will |
235 | This option does not affect C<decode> in any way - string references will |
232 | always be decoded properly if present. |
236 | always be decoded properly if present. |
233 | |
237 | |
234 | =item $cbor = $cbor->filter ([$cb->($tag, $value)]) |
238 | =item $cbor = $cbor->filter ([$cb->($tag, $value)]) |
235 | |
239 | |
236 | =item $cb_or_undef = $cbor->get_filter |
240 | =item $cb_or_undef = $cbor->get_filter |
237 | |
241 | |
238 | TODO |
242 | Sets or replaces the tagged value decoding filter (when C<$cb> is |
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243 | specified) or clears the filter (if no argument or C<undef> is provided). |
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244 | |
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245 | The filter callback is called only during decoding, when a non-enforced |
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246 | tagged value has been decoded (see L<TAG HANDLING AND EXTENSIONS> for a |
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247 | list of enforced tags). For specific tags, it's often better to provide a |
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248 | default converter using the C<%CBOR::XS::FILTER> hash (see below). |
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249 | |
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250 | The first argument is the numerical tag, the second is the (decoded) value |
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251 | that has been tagged. |
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252 | |
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253 | The filter function should return either exactly one value, which will |
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254 | replace the tagged value in the decoded data structure, or no values, |
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255 | which will result in default handling, which currently means the decoder |
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256 | creates a C<CBOR::XS::Tagged> object to hold the tag and the value. |
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257 | |
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258 | When the filter is cleared (the default state), the default filter |
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259 | function, C<CBOR::XS::default_filter>, is used. This function simply looks |
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260 | up the tag in the C<%CBOR::XS::FILTER> hash. If an entry exists it must be |
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261 | a code reference that is called with tag and value, and is responsible for |
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262 | decoding the value. If no entry exists, it returns no values. |
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263 | |
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264 | Example: decode all tags not handled internally into CBOR::XS::Tagged |
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265 | objects, with no other special handling (useful when working with |
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266 | potentially "unsafe" CBOR data). |
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267 | |
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268 | CBOR::XS->new->filter (sub { })->decode ($cbor_data); |
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269 | |
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270 | Example: provide a global filter for tag 1347375694, converting the value |
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271 | into some string form. |
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272 | |
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273 | $CBOR::XS::FILTER{1347375694} = sub { |
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274 | my ($tag, $value); |
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275 | |
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276 | "tag 1347375694 value $value" |
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277 | }; |
239 | |
278 | |
240 | =item $cbor_data = $cbor->encode ($perl_scalar) |
279 | =item $cbor_data = $cbor->encode ($perl_scalar) |
241 | |
280 | |
242 | Converts the given Perl data structure (a scalar value) to its CBOR |
281 | Converts the given Perl data structure (a scalar value) to its CBOR |
243 | representation. |
282 | representation. |
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284 | CBOR integers become (numeric) perl scalars. On perls without 64 bit |
323 | CBOR integers become (numeric) perl scalars. On perls without 64 bit |
285 | support, 64 bit integers will be truncated or otherwise corrupted. |
324 | support, 64 bit integers will be truncated or otherwise corrupted. |
286 | |
325 | |
287 | =item byte strings |
326 | =item byte strings |
288 | |
327 | |
289 | Byte strings will become octet strings in Perl (the byte values 0..255 |
328 | Byte strings will become octet strings in Perl (the Byte values 0..255 |
290 | will simply become characters of the same value in Perl). |
329 | will simply become characters of the same value in Perl). |
291 | |
330 | |
292 | =item UTF-8 strings |
331 | =item UTF-8 strings |
293 | |
332 | |
294 | UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be |
333 | UTF-8 strings in CBOR will be decoded, i.e. the UTF-8 octets will be |
… | |
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385 | # dump as number |
424 | # dump as number |
386 | encode_cbor [2] # yields [2] |
425 | encode_cbor [2] # yields [2] |
387 | encode_cbor [-3.0e17] # yields [-3e+17] |
426 | encode_cbor [-3.0e17] # yields [-3e+17] |
388 | my $value = 5; encode_cbor [$value] # yields [5] |
427 | my $value = 5; encode_cbor [$value] # yields [5] |
389 | |
428 | |
390 | # used as string, so dump as string |
429 | # used as string, so dump as string (either byte or text) |
391 | print $value; |
430 | print $value; |
392 | encode_cbor [$value] # yields ["5"] |
431 | encode_cbor [$value] # yields ["5"] |
393 | |
432 | |
394 | # undef becomes null |
433 | # undef becomes null |
395 | encode_cbor [undef] # yields [null] |
434 | encode_cbor [undef] # yields [null] |
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398 | |
437 | |
399 | my $x = 3.1; # some variable containing a number |
438 | my $x = 3.1; # some variable containing a number |
400 | "$x"; # stringified |
439 | "$x"; # stringified |
401 | $x .= ""; # another, more awkward way to stringify |
440 | $x .= ""; # another, more awkward way to stringify |
402 | print $x; # perl does it for you, too, quite often |
441 | print $x; # perl does it for you, too, quite often |
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442 | |
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443 | You can force whether a string ie encoded as byte or text string by using |
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444 | C<utf8::upgrade> and C<utf8::downgrade>): |
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445 | |
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446 | utf8::upgrade $x; # encode $x as text string |
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447 | utf8::downgrade $x; # encode $x as byte string |
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448 | |
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449 | Perl doesn't define what operations up- and downgrade strings, so if the |
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450 | difference between byte and text is important, you should up- or downgrade |
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451 | your string as late as possible before encoding. |
403 | |
452 | |
404 | You can force the type to be a CBOR number by numifying it: |
453 | You can force the type to be a CBOR number by numifying it: |
405 | |
454 | |
406 | my $x = "3"; # some variable containing a string |
455 | my $x = "3"; # some variable containing a string |
407 | $x += 0; # numify it, ensuring it will be dumped as a number |
456 | $x += 0; # numify it, ensuring it will be dumped as a number |
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640 | These tags are always handled when decoding, and their handling cannot be |
689 | These tags are always handled when decoding, and their handling cannot be |
641 | overriden by the user. |
690 | overriden by the user. |
642 | |
691 | |
643 | =over 4 |
692 | =over 4 |
644 | |
693 | |
645 | =item <unassigned> (perl-object, L<http://cbor.schmorp.de/perl-object>) |
694 | =item 26 (perl-object, L<http://cbor.schmorp.de/perl-object>) |
646 | |
695 | |
647 | These tags are automatically created (and decoded) for serialisable |
696 | These tags are automatically created (and decoded) for serialisable |
648 | objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object |
697 | objects using the C<FREEZE/THAW> methods (the L<Types::Serialier> object |
649 | serialisation protocol). See L<OBJECT SERIALISATION> for details. |
698 | serialisation protocol). See L<OBJECT SERIALISATION> for details. |
650 | |
699 | |
651 | =item <unassigned>, <unassigned> (sharable, sharedref, L <http://cbor.schmorp.de/value-sharing>) |
700 | =item 28, 29 (sharable, sharedref, L <http://cbor.schmorp.de/value-sharing>) |
652 | |
701 | |
653 | These tags are automatically decoded when encountered, resulting in |
702 | These tags are automatically decoded when encountered, resulting in |
654 | shared values in the decoded object. They are only encoded, however, when |
703 | shared values in the decoded object. They are only encoded, however, when |
655 | C<allow_sharable> is enabled. |
704 | C<allow_sharable> is enabled. |
656 | |
705 | |
657 | =item <unassigned>, <unassigned> (stringref-namespace, stringref, L <http://cbor.schmorp.de/stringref>) |
706 | =item 256, 25 (stringref-namespace, stringref, L <http://cbor.schmorp.de/stringref>) |
658 | |
707 | |
659 | These tags are automatically decoded when encountered. They are only |
708 | These tags are automatically decoded when encountered. They are only |
660 | encoded, however, when C<allow_stringref> is enabled. |
709 | encoded, however, when C<pack_strings> is enabled. |
661 | |
710 | |
662 | =item 22098 (indirection, L<http://cbor.schmorp.de/indirection>) |
711 | =item 22098 (indirection, L<http://cbor.schmorp.de/indirection>) |
663 | |
712 | |
664 | This tag is automatically generated when a reference are encountered (with |
713 | This tag is automatically generated when a reference are encountered (with |
665 | the exception of hash and array refernces). It is converted to a reference |
714 | the exception of hash and array refernces). It is converted to a reference |
… | |
… | |
670 | This value is not generated on encoding (unless explicitly requested by |
719 | This value is not generated on encoding (unless explicitly requested by |
671 | the user), and is simply ignored when decoding. |
720 | the user), and is simply ignored when decoding. |
672 | |
721 | |
673 | =back |
722 | =back |
674 | |
723 | |
675 | =head2 OPTIONAL TAGS |
724 | =head2 NON-ENFORCED TAGS |
676 | |
725 | |
677 | These tags have default filters provided when decoding. Their handling can |
726 | These tags have default filters provided when decoding. Their handling can |
678 | be overriden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by |
727 | be overriden by changing the C<%CBOR::XS::FILTER> entry for the tag, or by |
679 | providing a custom C<filter> function when decoding. |
728 | providing a custom C<filter> callback when decoding. |
680 | |
729 | |
681 | When they result in decoding into a specific Perl class, the module |
730 | When they result in decoding into a specific Perl class, the module |
682 | usually provides a corresponding C<TO_CBOR> method as well. |
731 | usually provides a corresponding C<TO_CBOR> method as well. |
683 | |
732 | |
684 | When any of these need to load additional modules that are not part of the |
733 | When any of these need to load additional modules that are not part of the |