… | |
… | |
40 | Beginning with version 2.0 of the JSON module, when both JSON and |
40 | Beginning with version 2.0 of the JSON module, when both JSON and |
41 | JSON::XS are installed, then JSON will fall back on JSON::XS (this can be |
41 | JSON::XS are installed, then JSON will fall back on JSON::XS (this can be |
42 | overridden) with no overhead due to emulation (by inheriting constructor |
42 | overridden) with no overhead due to emulation (by inheriting constructor |
43 | and methods). If JSON::XS is not available, it will fall back to the |
43 | and methods). If JSON::XS is not available, it will fall back to the |
44 | compatible JSON::PP module as backend, so using JSON instead of JSON::XS |
44 | compatible JSON::PP module as backend, so using JSON instead of JSON::XS |
45 | gives you a portable JSON API that can be fast when you need and doesn't |
45 | gives you a portable JSON API that can be fast when you need it and |
46 | require a C compiler when that is a problem. |
46 | doesn't require a C compiler when that is a problem. |
47 | |
47 | |
48 | As this is the n-th-something JSON module on CPAN, what was the reason |
48 | As this is the n-th-something JSON module on CPAN, what was the reason |
49 | to write yet another JSON module? While it seems there are many JSON |
49 | to write yet another JSON module? While it seems there are many JSON |
50 | modules, none of them correctly handle all corner cases, and in most cases |
50 | modules, none of them correctly handle all corner cases, and in most cases |
51 | their maintainers are unresponsive, gone missing, or not listening to bug |
51 | their maintainers are unresponsive, gone missing, or not listening to bug |
… | |
… | |
101 | |
101 | |
102 | package JSON::XS; |
102 | package JSON::XS; |
103 | |
103 | |
104 | use common::sense; |
104 | use common::sense; |
105 | |
105 | |
106 | our $VERSION = 2.34; |
106 | our $VERSION = 3.04; |
107 | our @ISA = qw(Exporter); |
107 | our @ISA = qw(Exporter); |
108 | |
108 | |
109 | our @EXPORT = qw(encode_json decode_json); |
109 | our @EXPORT = qw(encode_json decode_json); |
110 | |
110 | |
111 | use Exporter; |
111 | use Exporter; |
… | |
… | |
131 | |
131 | |
132 | Except being faster. |
132 | Except being faster. |
133 | |
133 | |
134 | =item $perl_scalar = decode_json $json_text |
134 | =item $perl_scalar = decode_json $json_text |
135 | |
135 | |
136 | The opposite of C<encode_json>: expects an UTF-8 (binary) string and tries |
136 | The opposite of C<encode_json>: expects a UTF-8 (binary) string and tries |
137 | to parse that as an UTF-8 encoded JSON text, returning the resulting |
137 | to parse that as a UTF-8 encoded JSON text, returning the resulting |
138 | reference. Croaks on error. |
138 | reference. Croaks on error. |
139 | |
139 | |
140 | This function call is functionally identical to: |
140 | This function call is functionally identical to: |
141 | |
141 | |
142 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
142 | $perl_scalar = JSON::XS->new->utf8->decode ($json_text) |
… | |
… | |
202 | =over 4 |
202 | =over 4 |
203 | |
203 | |
204 | =item $json = new JSON::XS |
204 | =item $json = new JSON::XS |
205 | |
205 | |
206 | Creates a new JSON::XS object that can be used to de/encode JSON |
206 | Creates a new JSON::XS object that can be used to de/encode JSON |
207 | strings. All boolean flags described below are by default I<disabled>. |
207 | strings. All boolean flags described below are by default I<disabled> |
|
|
208 | (with the exception of C<allow_nonref>, which defaults to I<enabled> since |
|
|
209 | version C<4.0>). |
208 | |
210 | |
209 | The mutators for flags all return the JSON object again and thus calls can |
211 | The mutators for flags all return the JSON object again and thus calls can |
210 | be chained: |
212 | be chained: |
211 | |
213 | |
212 | my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]}) |
214 | my $json = JSON::XS->new->utf8->space_after->encode ({a => [1,2]}) |
… | |
… | |
270 | |
272 | |
271 | =item $enabled = $json->get_utf8 |
273 | =item $enabled = $json->get_utf8 |
272 | |
274 | |
273 | If C<$enable> is true (or missing), then the C<encode> method will encode |
275 | If C<$enable> is true (or missing), then the C<encode> method will encode |
274 | the JSON result into UTF-8, as required by many protocols, while the |
276 | the JSON result into UTF-8, as required by many protocols, while the |
275 | C<decode> method expects to be handled an UTF-8-encoded string. Please |
277 | C<decode> method expects to be handed a UTF-8-encoded string. Please |
276 | note that UTF-8-encoded strings do not contain any characters outside the |
278 | note that UTF-8-encoded strings do not contain any characters outside the |
277 | range C<0..255>, they are thus useful for bytewise/binary I/O. In future |
279 | range C<0..255>, they are thus useful for bytewise/binary I/O. In future |
278 | versions, enabling this option might enable autodetection of the UTF-16 |
280 | versions, enabling this option might enable autodetection of the UTF-16 |
279 | and UTF-32 encoding families, as described in RFC4627. |
281 | and UTF-32 encoding families, as described in RFC4627. |
280 | |
282 | |
… | |
… | |
365 | |
367 | |
366 | =item $enabled = $json->get_relaxed |
368 | =item $enabled = $json->get_relaxed |
367 | |
369 | |
368 | If C<$enable> is true (or missing), then C<decode> will accept some |
370 | If C<$enable> is true (or missing), then C<decode> will accept some |
369 | extensions to normal JSON syntax (see below). C<encode> will not be |
371 | extensions to normal JSON syntax (see below). C<encode> will not be |
370 | affected in anyway. I<Be aware that this option makes you accept invalid |
372 | affected in any way. I<Be aware that this option makes you accept invalid |
371 | JSON texts as if they were valid!>. I suggest only to use this option to |
373 | JSON texts as if they were valid!>. I suggest only to use this option to |
372 | parse application-specific files written by humans (configuration files, |
374 | parse application-specific files written by humans (configuration files, |
373 | resource files etc.) |
375 | resource files etc.) |
374 | |
376 | |
375 | If C<$enable> is false (the default), then C<decode> will only accept |
377 | If C<$enable> is false (the default), then C<decode> will only accept |
… | |
… | |
404 | [ |
406 | [ |
405 | 1, # this comment not allowed in JSON |
407 | 1, # this comment not allowed in JSON |
406 | # neither this one... |
408 | # neither this one... |
407 | ] |
409 | ] |
408 | |
410 | |
|
|
411 | =item * literal ASCII TAB characters in strings |
|
|
412 | |
|
|
413 | Literal ASCII TAB characters are now allowed in strings (and treated as |
|
|
414 | C<\t>). |
|
|
415 | |
|
|
416 | [ |
|
|
417 | "Hello\tWorld", |
|
|
418 | "Hello<TAB>World", # literal <TAB> would not normally be allowed |
|
|
419 | ] |
|
|
420 | |
409 | =back |
421 | =back |
410 | |
422 | |
411 | =item $json = $json->canonical ([$enable]) |
423 | =item $json = $json->canonical ([$enable]) |
412 | |
424 | |
413 | =item $enabled = $json->get_canonical |
425 | =item $enabled = $json->get_canonical |
… | |
… | |
431 | |
443 | |
432 | =item $json = $json->allow_nonref ([$enable]) |
444 | =item $json = $json->allow_nonref ([$enable]) |
433 | |
445 | |
434 | =item $enabled = $json->get_allow_nonref |
446 | =item $enabled = $json->get_allow_nonref |
435 | |
447 | |
|
|
448 | Unlike other boolean options, this opotion is enabled by default beginning |
|
|
449 | with version C<4.0>. See L<SECURITY CONSIDERATIONS> for the gory details. |
|
|
450 | |
436 | If C<$enable> is true (or missing), then the C<encode> method can convert a |
451 | If C<$enable> is true (or missing), then the C<encode> method can convert a |
437 | non-reference into its corresponding string, number or null JSON value, |
452 | non-reference into its corresponding string, number or null JSON value, |
438 | which is an extension to RFC4627. Likewise, C<decode> will accept those JSON |
453 | which is an extension to RFC4627. Likewise, C<decode> will accept those JSON |
439 | values instead of croaking. |
454 | values instead of croaking. |
440 | |
455 | |
441 | If C<$enable> is false, then the C<encode> method will croak if it isn't |
456 | If C<$enable> is false, then the C<encode> method will croak if it isn't |
442 | passed an arrayref or hashref, as JSON texts must either be an object |
457 | passed an arrayref or hashref, as JSON texts must either be an object |
443 | or array. Likewise, C<decode> will croak if given something that is not a |
458 | or array. Likewise, C<decode> will croak if given something that is not a |
444 | JSON object or array. |
459 | JSON object or array. |
445 | |
460 | |
446 | Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>, |
461 | Example, encode a Perl scalar as JSON value without enabled C<allow_nonref>, |
447 | resulting in an invalid JSON text: |
462 | resulting in an error: |
448 | |
463 | |
449 | JSON::XS->new->allow_nonref->encode ("Hello, World!") |
464 | JSON::XS->new->allow_nonref (0)->encode ("Hello, World!") |
450 | => "Hello, World!" |
465 | => hash- or arrayref expected... |
451 | |
466 | |
452 | =item $json = $json->allow_unknown ([$enable]) |
467 | =item $json = $json->allow_unknown ([$enable]) |
453 | |
468 | |
454 | =item $enabled = $json->get_allow_unknown |
469 | =item $enabled = $json->get_allow_unknown |
455 | |
470 | |
… | |
… | |
467 | |
482 | |
468 | =item $json = $json->allow_blessed ([$enable]) |
483 | =item $json = $json->allow_blessed ([$enable]) |
469 | |
484 | |
470 | =item $enabled = $json->get_allow_blessed |
485 | =item $enabled = $json->get_allow_blessed |
471 | |
486 | |
|
|
487 | See L<OBJECT SERIALISATION> for details. |
|
|
488 | |
472 | If C<$enable> is true (or missing), then the C<encode> method will not |
489 | If C<$enable> is true (or missing), then the C<encode> method will not |
473 | barf when it encounters a blessed reference. Instead, the value of the |
490 | barf when it encounters a blessed reference that it cannot convert |
474 | B<convert_blessed> option will decide whether C<null> (C<convert_blessed> |
491 | otherwise. Instead, a JSON C<null> value is encoded instead of the object. |
475 | disabled or no C<TO_JSON> method found) or a representation of the |
|
|
476 | object (C<convert_blessed> enabled and C<TO_JSON> method found) is being |
|
|
477 | encoded. Has no effect on C<decode>. |
|
|
478 | |
492 | |
479 | If C<$enable> is false (the default), then C<encode> will throw an |
493 | If C<$enable> is false (the default), then C<encode> will throw an |
480 | exception when it encounters a blessed object. |
494 | exception when it encounters a blessed object that it cannot convert |
|
|
495 | otherwise. |
|
|
496 | |
|
|
497 | This setting has no effect on C<decode>. |
481 | |
498 | |
482 | =item $json = $json->convert_blessed ([$enable]) |
499 | =item $json = $json->convert_blessed ([$enable]) |
483 | |
500 | |
484 | =item $enabled = $json->get_convert_blessed |
501 | =item $enabled = $json->get_convert_blessed |
|
|
502 | |
|
|
503 | See L<OBJECT SERIALISATION> for details. |
485 | |
504 | |
486 | If C<$enable> is true (or missing), then C<encode>, upon encountering a |
505 | If C<$enable> is true (or missing), then C<encode>, upon encountering a |
487 | blessed object, will check for the availability of the C<TO_JSON> method |
506 | blessed object, will check for the availability of the C<TO_JSON> method |
488 | on the object's class. If found, it will be called in scalar context |
507 | on the object's class. If found, it will be called in scalar context and |
489 | and the resulting scalar will be encoded instead of the object. If no |
508 | the resulting scalar will be encoded instead of the object. |
490 | C<TO_JSON> method is found, the value of C<allow_blessed> will decide what |
|
|
491 | to do. |
|
|
492 | |
509 | |
493 | The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON> |
510 | The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON> |
494 | returns other blessed objects, those will be handled in the same |
511 | returns other blessed objects, those will be handled in the same |
495 | way. C<TO_JSON> must take care of not causing an endless recursion cycle |
512 | way. C<TO_JSON> must take care of not causing an endless recursion cycle |
496 | (== crash) in this case. The name of C<TO_JSON> was chosen because other |
513 | (== crash) in this case. The name of C<TO_JSON> was chosen because other |
497 | methods called by the Perl core (== not by the user of the object) are |
514 | methods called by the Perl core (== not by the user of the object) are |
498 | usually in upper case letters and to avoid collisions with any C<to_json> |
515 | usually in upper case letters and to avoid collisions with any C<to_json> |
499 | function or method. |
516 | function or method. |
500 | |
517 | |
501 | This setting does not yet influence C<decode> in any way, but in the |
518 | If C<$enable> is false (the default), then C<encode> will not consider |
502 | future, global hooks might get installed that influence C<decode> and are |
519 | this type of conversion. |
503 | enabled by this setting. |
|
|
504 | |
520 | |
505 | If C<$enable> is false, then the C<allow_blessed> setting will decide what |
521 | This setting has no effect on C<decode>. |
506 | to do when a blessed object is found. |
522 | |
|
|
523 | =item $json = $json->allow_tags ([$enable]) |
|
|
524 | |
|
|
525 | =item $enabled = $json->get_allow_tags |
|
|
526 | |
|
|
527 | See L<OBJECT SERIALISATION> for details. |
|
|
528 | |
|
|
529 | If C<$enable> is true (or missing), then C<encode>, upon encountering a |
|
|
530 | blessed object, will check for the availability of the C<FREEZE> method on |
|
|
531 | the object's class. If found, it will be used to serialise the object into |
|
|
532 | a nonstandard tagged JSON value (that JSON decoders cannot decode). |
|
|
533 | |
|
|
534 | It also causes C<decode> to parse such tagged JSON values and deserialise |
|
|
535 | them via a call to the C<THAW> method. |
|
|
536 | |
|
|
537 | If C<$enable> is false (the default), then C<encode> will not consider |
|
|
538 | this type of conversion, and tagged JSON values will cause a parse error |
|
|
539 | in C<decode>, as if tags were not part of the grammar. |
507 | |
540 | |
508 | =item $json = $json->filter_json_object ([$coderef->($hashref)]) |
541 | =item $json = $json->filter_json_object ([$coderef->($hashref)]) |
509 | |
542 | |
510 | When C<$coderef> is specified, it will be called from C<decode> each |
543 | When C<$coderef> is specified, it will be called from C<decode> each |
511 | time it decodes a JSON object. The only argument is a reference to the |
544 | time it decodes a JSON object. The only argument is a reference to |
512 | newly-created hash. If the code references returns a single scalar (which |
545 | the newly-created hash. If the code reference returns a single scalar |
513 | need not be a reference), this value (i.e. a copy of that scalar to avoid |
546 | (which need not be a reference), this value (or rather a copy of it) is |
514 | aliasing) is inserted into the deserialised data structure. If it returns |
547 | inserted into the deserialised data structure. If it returns an empty |
515 | an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the |
548 | list (NOTE: I<not> C<undef>, which is a valid scalar), the original |
516 | original deserialised hash will be inserted. This setting can slow down |
549 | deserialised hash will be inserted. This setting can slow down decoding |
517 | decoding considerably. |
550 | considerably. |
518 | |
551 | |
519 | When C<$coderef> is omitted or undefined, any existing callback will |
552 | When C<$coderef> is omitted or undefined, any existing callback will |
520 | be removed and C<decode> will not change the deserialised hash in any |
553 | be removed and C<decode> will not change the deserialised hash in any |
521 | way. |
554 | way. |
522 | |
555 | |
… | |
… | |
669 | |
702 | |
670 | This is useful if your JSON texts are not delimited by an outer protocol |
703 | This is useful if your JSON texts are not delimited by an outer protocol |
671 | and you need to know where the JSON text ends. |
704 | and you need to know where the JSON text ends. |
672 | |
705 | |
673 | JSON::XS->new->decode_prefix ("[1] the tail") |
706 | JSON::XS->new->decode_prefix ("[1] the tail") |
674 | => ([], 3) |
707 | => ([1], 3) |
675 | |
708 | |
676 | =back |
709 | =back |
677 | |
710 | |
678 | |
711 | |
679 | =head1 INCREMENTAL PARSING |
712 | =head1 INCREMENTAL PARSING |
… | |
… | |
720 | C<incr_skip> to skip the erroneous part). This is the most common way of |
753 | C<incr_skip> to skip the erroneous part). This is the most common way of |
721 | using the method. |
754 | using the method. |
722 | |
755 | |
723 | And finally, in list context, it will try to extract as many objects |
756 | And finally, in list context, it will try to extract as many objects |
724 | from the stream as it can find and return them, or the empty list |
757 | from the stream as it can find and return them, or the empty list |
725 | otherwise. For this to work, there must be no separators between the JSON |
758 | otherwise. For this to work, there must be no separators (other than |
726 | objects or arrays, instead they must be concatenated back-to-back. If |
759 | whitespace) between the JSON objects or arrays, instead they must be |
727 | an error occurs, an exception will be raised as in the scalar context |
760 | concatenated back-to-back. If an error occurs, an exception will be |
728 | case. Note that in this case, any previously-parsed JSON texts will be |
761 | raised as in the scalar context case. Note that in this case, any |
729 | lost. |
762 | previously-parsed JSON texts will be lost. |
730 | |
763 | |
731 | Example: Parse some JSON arrays/objects in a given string and return |
764 | Example: Parse some JSON arrays/objects in a given string and return |
732 | them. |
765 | them. |
733 | |
766 | |
734 | my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]"); |
767 | my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]"); |
… | |
… | |
740 | C<incr_parse> in I<scalar context> successfully returned an object. Under |
773 | C<incr_parse> in I<scalar context> successfully returned an object. Under |
741 | all other circumstances you must not call this function (I mean it. |
774 | all other circumstances you must not call this function (I mean it. |
742 | although in simple tests it might actually work, it I<will> fail under |
775 | although in simple tests it might actually work, it I<will> fail under |
743 | real world conditions). As a special exception, you can also call this |
776 | real world conditions). As a special exception, you can also call this |
744 | method before having parsed anything. |
777 | method before having parsed anything. |
|
|
778 | |
|
|
779 | That means you can only use this function to look at or manipulate text |
|
|
780 | before or after complete JSON objects, not while the parser is in the |
|
|
781 | middle of parsing a JSON object. |
745 | |
782 | |
746 | This function is useful in two cases: a) finding the trailing text after a |
783 | This function is useful in two cases: a) finding the trailing text after a |
747 | JSON object or b) parsing multiple JSON objects separated by non-JSON text |
784 | JSON object or b) parsing multiple JSON objects separated by non-JSON text |
748 | (such as commas). |
785 | (such as commas). |
749 | |
786 | |
… | |
… | |
986 | |
1023 | |
987 | =item null |
1024 | =item null |
988 | |
1025 | |
989 | A JSON null atom becomes C<undef> in Perl. |
1026 | A JSON null atom becomes C<undef> in Perl. |
990 | |
1027 | |
|
|
1028 | =item shell-style comments (C<< # I<text> >>) |
|
|
1029 | |
|
|
1030 | As a nonstandard extension to the JSON syntax that is enabled by the |
|
|
1031 | C<relaxed> setting, shell-style comments are allowed. They can start |
|
|
1032 | anywhere outside strings and go till the end of the line. |
|
|
1033 | |
|
|
1034 | =item tagged values (C<< (I<tag>)I<value> >>). |
|
|
1035 | |
|
|
1036 | Another nonstandard extension to the JSON syntax, enabled with the |
|
|
1037 | C<allow_tags> setting, are tagged values. In this implementation, the |
|
|
1038 | I<tag> must be a perl package/class name encoded as a JSON string, and the |
|
|
1039 | I<value> must be a JSON array encoding optional constructor arguments. |
|
|
1040 | |
|
|
1041 | See L<OBJECT SERIALISATION>, below, for details. |
|
|
1042 | |
991 | =back |
1043 | =back |
992 | |
1044 | |
993 | |
1045 | |
994 | =head2 PERL -> JSON |
1046 | =head2 PERL -> JSON |
995 | |
1047 | |
… | |
… | |
1032 | and JSON false values, respectively. You can also use C<\1> and C<\0> |
1084 | and JSON false values, respectively. You can also use C<\1> and C<\0> |
1033 | directly if you want. |
1085 | directly if you want. |
1034 | |
1086 | |
1035 | =item blessed objects |
1087 | =item blessed objects |
1036 | |
1088 | |
1037 | Blessed objects are not directly representable in JSON. See the |
1089 | Blessed objects are not directly representable in JSON, but C<JSON::XS> |
1038 | C<allow_blessed> and C<convert_blessed> methods on various options on |
1090 | allows various ways of handling objects. See L<OBJECT SERIALISATION>, |
1039 | how to deal with this: basically, you can choose between throwing an |
1091 | below, for details. |
1040 | exception, encoding the reference as if it weren't blessed, or provide |
|
|
1041 | your own serialiser method. |
|
|
1042 | |
1092 | |
1043 | =item simple scalars |
1093 | =item simple scalars |
1044 | |
1094 | |
1045 | Simple Perl scalars (any scalar that is not a reference) are the most |
1095 | Simple Perl scalars (any scalar that is not a reference) are the most |
1046 | difficult objects to encode: JSON::XS will encode undefined scalars as |
1096 | difficult objects to encode: JSON::XS will encode undefined scalars as |
… | |
… | |
1082 | extensions to the floating point numbers of your platform, such as |
1132 | extensions to the floating point numbers of your platform, such as |
1083 | infinities or NaN's - these cannot be represented in JSON, and it is an |
1133 | infinities or NaN's - these cannot be represented in JSON, and it is an |
1084 | error to pass those in. |
1134 | error to pass those in. |
1085 | |
1135 | |
1086 | =back |
1136 | =back |
|
|
1137 | |
|
|
1138 | =head2 OBJECT SERIALISATION |
|
|
1139 | |
|
|
1140 | As JSON cannot directly represent Perl objects, you have to choose between |
|
|
1141 | a pure JSON representation (without the ability to deserialise the object |
|
|
1142 | automatically again), and a nonstandard extension to the JSON syntax, |
|
|
1143 | tagged values. |
|
|
1144 | |
|
|
1145 | =head3 SERIALISATION |
|
|
1146 | |
|
|
1147 | What happens when C<JSON::XS> encounters a Perl object depends on the |
|
|
1148 | C<allow_blessed>, C<convert_blessed> and C<allow_tags> settings, which are |
|
|
1149 | used in this order: |
|
|
1150 | |
|
|
1151 | =over 4 |
|
|
1152 | |
|
|
1153 | =item 1. C<allow_tags> is enabled and the object has a C<FREEZE> method. |
|
|
1154 | |
|
|
1155 | In this case, C<JSON::XS> uses the L<Types::Serialiser> object |
|
|
1156 | serialisation protocol to create a tagged JSON value, using a nonstandard |
|
|
1157 | extension to the JSON syntax. |
|
|
1158 | |
|
|
1159 | This works by invoking the C<FREEZE> method on the object, with the first |
|
|
1160 | argument being the object to serialise, and the second argument being the |
|
|
1161 | constant string C<JSON> to distinguish it from other serialisers. |
|
|
1162 | |
|
|
1163 | The C<FREEZE> method can return any number of values (i.e. zero or |
|
|
1164 | more). These values and the paclkage/classname of the object will then be |
|
|
1165 | encoded as a tagged JSON value in the following format: |
|
|
1166 | |
|
|
1167 | ("classname")[FREEZE return values...] |
|
|
1168 | |
|
|
1169 | e.g.: |
|
|
1170 | |
|
|
1171 | ("URI")["http://www.google.com/"] |
|
|
1172 | ("MyDate")[2013,10,29] |
|
|
1173 | ("ImageData::JPEG")["Z3...VlCg=="] |
|
|
1174 | |
|
|
1175 | For example, the hypothetical C<My::Object> C<FREEZE> method might use the |
|
|
1176 | objects C<type> and C<id> members to encode the object: |
|
|
1177 | |
|
|
1178 | sub My::Object::FREEZE { |
|
|
1179 | my ($self, $serialiser) = @_; |
|
|
1180 | |
|
|
1181 | ($self->{type}, $self->{id}) |
|
|
1182 | } |
|
|
1183 | |
|
|
1184 | =item 2. C<convert_blessed> is enabled and the object has a C<TO_JSON> method. |
|
|
1185 | |
|
|
1186 | In this case, the C<TO_JSON> method of the object is invoked in scalar |
|
|
1187 | context. It must return a single scalar that can be directly encoded into |
|
|
1188 | JSON. This scalar replaces the object in the JSON text. |
|
|
1189 | |
|
|
1190 | For example, the following C<TO_JSON> method will convert all L<URI> |
|
|
1191 | objects to JSON strings when serialised. The fatc that these values |
|
|
1192 | originally were L<URI> objects is lost. |
|
|
1193 | |
|
|
1194 | sub URI::TO_JSON { |
|
|
1195 | my ($uri) = @_; |
|
|
1196 | $uri->as_string |
|
|
1197 | } |
|
|
1198 | |
|
|
1199 | =item 3. C<allow_blessed> is enabled. |
|
|
1200 | |
|
|
1201 | The object will be serialised as a JSON null value. |
|
|
1202 | |
|
|
1203 | =item 4. none of the above |
|
|
1204 | |
|
|
1205 | If none of the settings are enabled or the respective methods are missing, |
|
|
1206 | C<JSON::XS> throws an exception. |
|
|
1207 | |
|
|
1208 | =back |
|
|
1209 | |
|
|
1210 | =head3 DESERIALISATION |
|
|
1211 | |
|
|
1212 | For deserialisation there are only two cases to consider: either |
|
|
1213 | nonstandard tagging was used, in which case C<allow_tags> decides, |
|
|
1214 | or objects cannot be automatically be deserialised, in which |
|
|
1215 | case you can use postprocessing or the C<filter_json_object> or |
|
|
1216 | C<filter_json_single_key_object> callbacks to get some real objects our of |
|
|
1217 | your JSON. |
|
|
1218 | |
|
|
1219 | This section only considers the tagged value case: I a tagged JSON object |
|
|
1220 | is encountered during decoding and C<allow_tags> is disabled, a parse |
|
|
1221 | error will result (as if tagged values were not part of the grammar). |
|
|
1222 | |
|
|
1223 | If C<allow_tags> is enabled, C<JSON::XS> will look up the C<THAW> method |
|
|
1224 | of the package/classname used during serialisation (it will not attempt |
|
|
1225 | to load the package as a Perl module). If there is no such method, the |
|
|
1226 | decoding will fail with an error. |
|
|
1227 | |
|
|
1228 | Otherwise, the C<THAW> method is invoked with the classname as first |
|
|
1229 | argument, the constant string C<JSON> as second argument, and all the |
|
|
1230 | values from the JSON array (the values originally returned by the |
|
|
1231 | C<FREEZE> method) as remaining arguments. |
|
|
1232 | |
|
|
1233 | The method must then return the object. While technically you can return |
|
|
1234 | any Perl scalar, you might have to enable the C<enable_nonref> setting to |
|
|
1235 | make that work in all cases, so better return an actual blessed reference. |
|
|
1236 | |
|
|
1237 | As an example, let's implement a C<THAW> function that regenerates the |
|
|
1238 | C<My::Object> from the C<FREEZE> example earlier: |
|
|
1239 | |
|
|
1240 | sub My::Object::THAW { |
|
|
1241 | my ($class, $serialiser, $type, $id) = @_; |
|
|
1242 | |
|
|
1243 | $class->new (type => $type, id => $id) |
|
|
1244 | } |
1087 | |
1245 | |
1088 | |
1246 | |
1089 | =head1 ENCODING/CODESET FLAG NOTES |
1247 | =head1 ENCODING/CODESET FLAG NOTES |
1090 | |
1248 | |
1091 | The interested reader might have seen a number of flags that signify |
1249 | The interested reader might have seen a number of flags that signify |
… | |
… | |
1136 | expect your input strings to be encoded as UTF-8, that is, no "character" |
1294 | expect your input strings to be encoded as UTF-8, that is, no "character" |
1137 | of the input string must have any value > 255, as UTF-8 does not allow |
1295 | of the input string must have any value > 255, as UTF-8 does not allow |
1138 | that. |
1296 | that. |
1139 | |
1297 | |
1140 | The C<utf8> flag therefore switches between two modes: disabled means you |
1298 | The C<utf8> flag therefore switches between two modes: disabled means you |
1141 | will get a Unicode string in Perl, enabled means you get an UTF-8 encoded |
1299 | will get a Unicode string in Perl, enabled means you get a UTF-8 encoded |
1142 | octet/binary string in Perl. |
1300 | octet/binary string in Perl. |
1143 | |
1301 | |
1144 | =item C<latin1> or C<ascii> flags enabled |
1302 | =item C<latin1> or C<ascii> flags enabled |
1145 | |
1303 | |
1146 | With C<latin1> (or C<ascii>) enabled, C<encode> will escape characters |
1304 | With C<latin1> (or C<ascii>) enabled, C<encode> will escape characters |
… | |
… | |
1414 | are browser design bugs, but it is still you who will have to deal with |
1572 | are browser design bugs, but it is still you who will have to deal with |
1415 | it, as major browser developers care only for features, not about getting |
1573 | it, as major browser developers care only for features, not about getting |
1416 | security right). |
1574 | security right). |
1417 | |
1575 | |
1418 | |
1576 | |
|
|
1577 | =head2 "OLD" VS. "NEW" JSON (RFC 4627 VS. RFC 7159) |
|
|
1578 | |
|
|
1579 | JSON originally required JSON texts to represent an array or object - |
|
|
1580 | scalar values were explicitly not allowed. This has changed, and versions |
|
|
1581 | of JSON::XS beginning with C<4.0> reflect this by allowing scalar values |
|
|
1582 | by default. |
|
|
1583 | |
|
|
1584 | One reason why one might not want this is that this removes a fundamental |
|
|
1585 | property of JSON texts, namely that they are self-delimited and |
|
|
1586 | self-contained, or in other words, you could take any number of "old" |
|
|
1587 | JSON texts and paste them together, and the result would be unambiguously |
|
|
1588 | parseable: |
|
|
1589 | |
|
|
1590 | [1,3]{"k":5}[][null] # four JSON texts, without doubt |
|
|
1591 | |
|
|
1592 | By allowing scalars, this property is lost: in the following example, is |
|
|
1593 | this one JSON text (the number 12) or two JSON texts (the numbers 1 and |
|
|
1594 | 2): |
|
|
1595 | |
|
|
1596 | 12 # could be 12, or 1 and 2 |
|
|
1597 | |
|
|
1598 | Another lost property of "old" JSON is that no lookahead is required to |
|
|
1599 | know the end of a JSON text, i.e. the JSON text definitely ended at the |
|
|
1600 | last C<]> or C<}> character, there was no need to read extra characters. |
|
|
1601 | |
|
|
1602 | For example, a viable network protocol with "old" JSON was to simply |
|
|
1603 | exchange JSON texts without delimiter. For "new" JSON, you have to use a |
|
|
1604 | suitable delimiter (such as a newline) after every JSON text or ensure you |
|
|
1605 | never encode/decode scalar values. |
|
|
1606 | |
|
|
1607 | Most protocols do work by only transferring arrays or objects, and the |
|
|
1608 | easiest way to avoid problems with the "new" JSON definition is to |
|
|
1609 | explicitly disallow scalar values in your encoder and decoder: |
|
|
1610 | |
|
|
1611 | $json_coder = JSON::XS->new->allow_nonref (0) |
|
|
1612 | |
|
|
1613 | This is a somewhat unhappy situation, and the blame can fully be put on |
|
|
1614 | JSON's inmventor, Douglas Crockford, who unilaterally changed the format |
|
|
1615 | in 2006 without consulting the IETF, forcing the IETF to either fork the |
|
|
1616 | format or go with it (as I was told, the IETF wasn't amused). |
|
|
1617 | |
|
|
1618 | |
1419 | =head1 INTEROPERABILITY WITH OTHER MODULES |
1619 | =head1 INTEROPERABILITY WITH OTHER MODULES |
1420 | |
1620 | |
1421 | C<JSON::XS> uses the L<Types::Serialiser> module to provide boolean |
1621 | C<JSON::XS> uses the L<Types::Serialiser> module to provide boolean |
1422 | constants. That means that the JSON true and false values will be |
1622 | constants. That means that the JSON true and false values will be |
1423 | comaptible to true and false values of iother modules that do the same, |
1623 | comaptible to true and false values of other modules that do the same, |
1424 | such as L<JSON::PP> and L<CBOR::XS>. |
1624 | such as L<JSON::PP> and L<CBOR::XS>. |
1425 | |
1625 | |
1426 | |
1626 | |
|
|
1627 | =head1 INTEROPERABILITY WITH OTHER JSON DECODERS |
|
|
1628 | |
|
|
1629 | As long as you only serialise data that can be directly expressed in JSON, |
|
|
1630 | C<JSON::XS> is incapable of generating invalid JSON output (modulo bugs, |
|
|
1631 | but C<JSON::XS> has found more bugs in the official JSON testsuite (1) |
|
|
1632 | than the official JSON testsuite has found in C<JSON::XS> (0)). |
|
|
1633 | |
|
|
1634 | When you have trouble decoding JSON generated by this module using other |
|
|
1635 | decoders, then it is very likely that you have an encoding mismatch or the |
|
|
1636 | other decoder is broken. |
|
|
1637 | |
|
|
1638 | When decoding, C<JSON::XS> is strict by default and will likely catch all |
|
|
1639 | errors. There are currently two settings that change this: C<relaxed> |
|
|
1640 | makes C<JSON::XS> accept (but not generate) some non-standard extensions, |
|
|
1641 | and C<allow_tags> will allow you to encode and decode Perl objects, at the |
|
|
1642 | cost of not outputting valid JSON anymore. |
|
|
1643 | |
|
|
1644 | =head2 TAGGED VALUE SYNTAX AND STANDARD JSON EN/DECODERS |
|
|
1645 | |
|
|
1646 | When you use C<allow_tags> to use the extended (and also nonstandard and |
|
|
1647 | invalid) JSON syntax for serialised objects, and you still want to decode |
|
|
1648 | the generated When you want to serialise objects, you can run a regex |
|
|
1649 | to replace the tagged syntax by standard JSON arrays (it only works for |
|
|
1650 | "normal" package names without comma, newlines or single colons). First, |
|
|
1651 | the readable Perl version: |
|
|
1652 | |
|
|
1653 | # if your FREEZE methods return no values, you need this replace first: |
|
|
1654 | $json =~ s/\( \s* (" (?: [^\\":,]+|\\.|::)* ") \s* \) \s* \[\s*\]/[$1]/gx; |
|
|
1655 | |
|
|
1656 | # this works for non-empty constructor arg lists: |
|
|
1657 | $json =~ s/\( \s* (" (?: [^\\":,]+|\\.|::)* ") \s* \) \s* \[/[$1,/gx; |
|
|
1658 | |
|
|
1659 | And here is a less readable version that is easy to adapt to other |
|
|
1660 | languages: |
|
|
1661 | |
|
|
1662 | $json =~ s/\(\s*("([^\\":,]+|\\.|::)*")\s*\)\s*\[/[$1,/g; |
|
|
1663 | |
|
|
1664 | Here is an ECMAScript version (same regex): |
|
|
1665 | |
|
|
1666 | json = json.replace (/\(\s*("([^\\":,]+|\\.|::)*")\s*\)\s*\[/g, "[$1,"); |
|
|
1667 | |
|
|
1668 | Since this syntax converts to standard JSON arrays, it might be hard to |
|
|
1669 | distinguish serialised objects from normal arrays. You can prepend a |
|
|
1670 | "magic number" as first array element to reduce chances of a collision: |
|
|
1671 | |
|
|
1672 | $json =~ s/\(\s*("([^\\":,]+|\\.|::)*")\s*\)\s*\[/["XU1peReLzT4ggEllLanBYq4G9VzliwKF",$1,/g; |
|
|
1673 | |
|
|
1674 | And after decoding the JSON text, you could walk the data |
|
|
1675 | structure looking for arrays with a first element of |
|
|
1676 | C<XU1peReLzT4ggEllLanBYq4G9VzliwKF>. |
|
|
1677 | |
|
|
1678 | The same approach can be used to create the tagged format with another |
|
|
1679 | encoder. First, you create an array with the magic string as first member, |
|
|
1680 | the classname as second, and constructor arguments last, encode it as part |
|
|
1681 | of your JSON structure, and then: |
|
|
1682 | |
|
|
1683 | $json =~ s/\[\s*"XU1peReLzT4ggEllLanBYq4G9VzliwKF"\s*,\s*("([^\\":,]+|\\.|::)*")\s*,/($1)[/g; |
|
|
1684 | |
|
|
1685 | Again, this has some limitations - the magic string must not be encoded |
|
|
1686 | with character escapes, and the constructor arguments must be non-empty. |
|
|
1687 | |
|
|
1688 | |
|
|
1689 | =head1 RFC7159 |
|
|
1690 | |
|
|
1691 | Since this module was written, Google has written a new JSON RFC, RFC 7159 |
|
|
1692 | (and RFC7158). Unfortunately, this RFC breaks compatibility with both the |
|
|
1693 | original JSON specification on www.json.org and RFC4627. |
|
|
1694 | |
|
|
1695 | As far as I can see, you can get partial compatibility when parsing by |
|
|
1696 | using C<< ->allow_nonref >>. However, consider the security implications |
|
|
1697 | of doing so. |
|
|
1698 | |
|
|
1699 | I haven't decided yet when to break compatibility with RFC4627 by default |
|
|
1700 | (and potentially leave applications insecure) and change the default to |
|
|
1701 | follow RFC7159, but application authors are well advised to call C<< |
|
|
1702 | ->allow_nonref(0) >> even if this is the current default, if they cannot |
|
|
1703 | handle non-reference values, in preparation for the day when the default |
|
|
1704 | will change. |
|
|
1705 | |
|
|
1706 | |
1427 | =head1 THREADS |
1707 | =head1 (I-)THREADS |
1428 | |
1708 | |
1429 | This module is I<not> guaranteed to be thread safe and there are no |
1709 | This module is I<not> guaranteed to be ithread (or MULTIPLICITY-) safe |
1430 | plans to change this until Perl gets thread support (as opposed to the |
1710 | and there are no plans to change this. Note that perl's builtin so-called |
1431 | horribly slow so-called "threads" which are simply slow and bloated |
1711 | threads/ithreads are officially deprecated and should not be used. |
1432 | process simulations - use fork, it's I<much> faster, cheaper, better). |
|
|
1433 | |
|
|
1434 | (It might actually work, but you have been warned). |
|
|
1435 | |
1712 | |
1436 | |
1713 | |
1437 | =head1 THE PERILS OF SETLOCALE |
1714 | =head1 THE PERILS OF SETLOCALE |
1438 | |
1715 | |
1439 | Sometimes people avoid the Perl locale support and directly call the |
1716 | Sometimes people avoid the Perl locale support and directly call the |