ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/JSON-XS/XS.pm
(Generate patch)

Comparing JSON-XS/XS.pm (file contents):
Revision 1.133 by root, Tue Aug 17 23:27:36 2010 UTC vs.
Revision 1.144 by root, Mon Oct 28 23:19:54 2013 UTC

83this module usually compares favourably in terms of speed, too. 83this module usually compares favourably in terms of speed, too.
84 84
85=item * simple to use 85=item * simple to use
86 86
87This module has both a simple functional interface as well as an object 87This module has both a simple functional interface as well as an object
88oriented interface interface. 88oriented interface.
89 89
90=item * reasonably versatile output formats 90=item * reasonably versatile output formats
91 91
92You can choose between the most compact guaranteed-single-line format 92You can choose between the most compact guaranteed-single-line format
93possible (nice for simple line-based protocols), a pure-ASCII format 93possible (nice for simple line-based protocols), a pure-ASCII format
101 101
102package JSON::XS; 102package JSON::XS;
103 103
104use common::sense; 104use common::sense;
105 105
106our $VERSION = '2.3'; 106our $VERSION = 2.34;
107our @ISA = qw(Exporter); 107our @ISA = qw(Exporter);
108 108
109our @EXPORT = qw(encode_json decode_json to_json from_json); 109our @EXPORT = qw(encode_json decode_json);
110
111sub to_json($) {
112 require Carp;
113 Carp::croak ("JSON::XS::to_json has been renamed to encode_json, either downgrade to pre-2.0 versions of JSON::XS or rename the call");
114}
115
116sub from_json($) {
117 require Carp;
118 Carp::croak ("JSON::XS::from_json has been renamed to decode_json, either downgrade to pre-2.0 versions of JSON::XS or rename the call");
119}
120 110
121use Exporter; 111use Exporter;
122use XSLoader; 112use XSLoader;
113
114use Types::Serialiser ();
123 115
124=head1 FUNCTIONAL INTERFACE 116=head1 FUNCTIONAL INTERFACE
125 117
126The following convenience methods are provided by this module. They are 118The following convenience methods are provided by this module. They are
127exported by default: 119exported by default:
148This function call is functionally identical to: 140This function call is functionally identical to:
149 141
150 $perl_scalar = JSON::XS->new->utf8->decode ($json_text) 142 $perl_scalar = JSON::XS->new->utf8->decode ($json_text)
151 143
152Except being faster. 144Except being faster.
153
154=item $is_boolean = JSON::XS::is_bool $scalar
155
156Returns true if the passed scalar represents either JSON::XS::true or
157JSON::XS::false, two constants that act like C<1> and C<0>, respectively
158and are used to represent JSON C<true> and C<false> values in Perl.
159
160See MAPPING, below, for more information on how JSON values are mapped to
161Perl.
162 145
163=back 146=back
164 147
165 148
166=head1 A FEW NOTES ON UNICODE AND PERL 149=head1 A FEW NOTES ON UNICODE AND PERL
432If C<$enable> is true (or missing), then the C<encode> method will output JSON objects 415If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
433by sorting their keys. This is adding a comparatively high overhead. 416by sorting their keys. This is adding a comparatively high overhead.
434 417
435If C<$enable> is false, then the C<encode> method will output key-value 418If C<$enable> is false, then the C<encode> method will output key-value
436pairs in the order Perl stores them (which will likely change between runs 419pairs in the order Perl stores them (which will likely change between runs
437of the same script). 420of the same script, and can change even within the same run from 5.18
421onwards).
438 422
439This option is useful if you want the same data structure to be encoded as 423This option is useful if you want the same data structure to be encoded as
440the same JSON text (given the same overall settings). If it is disabled, 424the same JSON text (given the same overall settings). If it is disabled,
441the same hash might be encoded differently even if contains the same data, 425the same hash might be encoded differently even if contains the same data,
442as key-value pairs have no inherent ordering in Perl. 426as key-value pairs have no inherent ordering in Perl.
666 650
667See SECURITY CONSIDERATIONS, below, for more info on why this is useful. 651See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
668 652
669=item $json_text = $json->encode ($perl_scalar) 653=item $json_text = $json->encode ($perl_scalar)
670 654
671Converts the given Perl data structure (a simple scalar or a reference 655Converts the given Perl value or data structure to its JSON
672to a hash or array) to its JSON representation. Simple scalars will be 656representation. Croaks on error.
673converted into JSON string or number sequences, while references to arrays
674become JSON arrays and references to hashes become JSON objects. Undefined
675Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
676nor C<false> values will be generated.
677 657
678=item $perl_scalar = $json->decode ($json_text) 658=item $perl_scalar = $json->decode ($json_text)
679 659
680The opposite of C<encode>: expects a JSON text and tries to parse it, 660The opposite of C<encode>: expects a JSON text and tries to parse it,
681returning the resulting simple scalar or reference. Croaks on error. 661returning the resulting simple scalar or reference. Croaks on error.
682
683JSON numbers and strings become simple Perl scalars. JSON arrays become
684Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
685C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
686 662
687=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text) 663=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
688 664
689This works like the C<decode> method, but instead of raising an exception 665This works like the C<decode> method, but instead of raising an exception
690when there is trailing garbage after the first JSON object, it will 666when there is trailing garbage after the first JSON object, it will
691silently stop parsing there and return the number of characters consumed 667silently stop parsing there and return the number of characters consumed
692so far. 668so far.
693 669
694This is useful if your JSON texts are not delimited by an outer protocol 670This is useful if your JSON texts are not delimited by an outer protocol
695(which is not the brightest thing to do in the first place) and you need
696to know where the JSON text ends. 671and you need to know where the JSON text ends.
697 672
698 JSON::XS->new->decode_prefix ("[1] the tail") 673 JSON::XS->new->decode_prefix ("[1] the tail")
699 => ([], 3) 674 => ([], 3)
700 675
701=back 676=back
713calls). 688calls).
714 689
715JSON::XS will only attempt to parse the JSON text once it is sure it 690JSON::XS will only attempt to parse the JSON text once it is sure it
716has enough text to get a decisive result, using a very simple but 691has enough text to get a decisive result, using a very simple but
717truly incremental parser. This means that it sometimes won't stop as 692truly incremental parser. This means that it sometimes won't stop as
718early as the full parser, for example, it doesn't detect parenthese 693early as the full parser, for example, it doesn't detect mismatched
719mismatches. The only thing it guarantees is that it starts decoding as 694parentheses. The only thing it guarantees is that it starts decoding as
720soon as a syntactically valid JSON text has been seen. This means you need 695soon as a syntactically valid JSON text has been seen. This means you need
721to set resource limits (e.g. C<max_size>) to ensure the parser will stop 696to set resource limits (e.g. C<max_size>) to ensure the parser will stop
722parsing in the presence if syntax errors. 697parsing in the presence if syntax errors.
723 698
724The following methods implement this incremental parser. 699The following methods implement this incremental parser.
740 715
741If the method is called in scalar context, then it will try to extract 716If the method is called in scalar context, then it will try to extract
742exactly I<one> JSON object. If that is successful, it will return this 717exactly I<one> JSON object. If that is successful, it will return this
743object, otherwise it will return C<undef>. If there is a parse error, 718object, otherwise it will return C<undef>. If there is a parse error,
744this method will croak just as C<decode> would do (one can then use 719this method will croak just as C<decode> would do (one can then use
745C<incr_skip> to skip the errornous part). This is the most common way of 720C<incr_skip> to skip the erroneous part). This is the most common way of
746using the method. 721using the method.
747 722
748And finally, in list context, it will try to extract as many objects 723And finally, in list context, it will try to extract as many objects
749from the stream as it can find and return them, or the empty list 724from the stream as it can find and return them, or the empty list
750otherwise. For this to work, there must be no separators between the JSON 725otherwise. For this to work, there must be no separators between the JSON
779C<incr_parse> died, in which case the input buffer and incremental parser 754C<incr_parse> died, in which case the input buffer and incremental parser
780state is left unchanged, to skip the text parsed so far and to reset the 755state is left unchanged, to skip the text parsed so far and to reset the
781parse state. 756parse state.
782 757
783The difference to C<incr_reset> is that only text until the parse error 758The difference to C<incr_reset> is that only text until the parse error
784occured is removed. 759occurred is removed.
785 760
786=item $json->incr_reset 761=item $json->incr_reset
787 762
788This completely resets the incremental parser, that is, after this call, 763This completely resets the incremental parser, that is, after this call,
789it will be as if the parser had never parsed anything. 764it will be as if the parser had never parsed anything.
795=back 770=back
796 771
797=head2 LIMITATIONS 772=head2 LIMITATIONS
798 773
799All options that affect decoding are supported, except 774All options that affect decoding are supported, except
800C<allow_nonref>. The reason for this is that it cannot be made to 775C<allow_nonref>. The reason for this is that it cannot be made to work
801work sensibly: JSON objects and arrays are self-delimited, i.e. you can concatenate 776sensibly: JSON objects and arrays are self-delimited, i.e. you can
802them back to back and still decode them perfectly. This does not hold true 777concatenate them back to back and still decode them perfectly. This does
803for JSON numbers, however. 778not hold true for JSON numbers, however.
804 779
805For example, is the string C<1> a single JSON number, or is it simply the 780For example, is the string C<1> a single JSON number, or is it simply the
806start of C<12>? Or is C<12> a single JSON number, or the concatenation 781start of C<12>? Or is C<12> a single JSON number, or the concatenation
807of C<1> and C<2>? In neither case you can tell, and this is why JSON::XS 782of C<1> and C<2>? In neither case you can tell, and this is why JSON::XS
808takes the conservative route and disallows this case. 783takes the conservative route and disallows this case.
987If the number consists of digits only, JSON::XS will try to represent 962If the number consists of digits only, JSON::XS will try to represent
988it as an integer value. If that fails, it will try to represent it as 963it as an integer value. If that fails, it will try to represent it as
989a numeric (floating point) value if that is possible without loss of 964a numeric (floating point) value if that is possible without loss of
990precision. Otherwise it will preserve the number as a string value (in 965precision. Otherwise it will preserve the number as a string value (in
991which case you lose roundtripping ability, as the JSON number will be 966which case you lose roundtripping ability, as the JSON number will be
992re-encoded toa JSON string). 967re-encoded to a JSON string).
993 968
994Numbers containing a fractional or exponential part will always be 969Numbers containing a fractional or exponential part will always be
995represented as numeric (floating point) values, possibly at a loss of 970represented as numeric (floating point) values, possibly at a loss of
996precision (in which case you might lose perfect roundtripping ability, but 971precision (in which case you might lose perfect roundtripping ability, but
997the JSON number will still be re-encoded as a JSON number). 972the JSON number will still be re-encoded as a JSON number).
998 973
999Note that precision is not accuracy - binary floating point values cannot 974Note that precision is not accuracy - binary floating point values cannot
1000represent most decimal fractions exactly, and when converting from and to 975represent most decimal fractions exactly, and when converting from and to
1001floating point, JSON::XS only guarantees precision up to but not including 976floating point, JSON::XS only guarantees precision up to but not including
1002the leats significant bit. 977the least significant bit.
1003 978
1004=item true, false 979=item true, false
1005 980
1006These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>, 981These JSON atoms become C<Types::Serialiser::true> and
1007respectively. They are overloaded to act almost exactly like the numbers 982C<Types::Serialiser::false>, respectively. They are overloaded to act
1008C<1> and C<0>. You can check whether a scalar is a JSON boolean by using 983almost exactly like the numbers C<1> and C<0>. You can check whether
1009the C<JSON::XS::is_bool> function. 984a scalar is a JSON boolean by using the C<Types::Serialiser::is_bool>
985function (after C<use Types::Serialier>, of course).
1010 986
1011=item null 987=item null
1012 988
1013A JSON null atom becomes C<undef> in Perl. 989A JSON null atom becomes C<undef> in Perl.
1014 990
1023 999
1024=over 4 1000=over 4
1025 1001
1026=item hash references 1002=item hash references
1027 1003
1028Perl hash references become JSON objects. As there is no inherent ordering 1004Perl hash references become JSON objects. As there is no inherent
1029in hash keys (or JSON objects), they will usually be encoded in a 1005ordering in hash keys (or JSON objects), they will usually be encoded
1030pseudo-random order that can change between runs of the same program but 1006in a pseudo-random order. JSON::XS can optionally sort the hash keys
1031stays generally the same within a single run of a program. JSON::XS can 1007(determined by the I<canonical> flag), so the same datastructure will
1032optionally sort the hash keys (determined by the I<canonical> flag), so 1008serialise to the same JSON text (given same settings and version of
1033the same datastructure will serialise to the same JSON text (given same 1009JSON::XS), but this incurs a runtime overhead and is only rarely useful,
1034settings and version of JSON::XS), but this incurs a runtime overhead 1010e.g. when you want to compare some JSON text against another for equality.
1035and is only rarely useful, e.g. when you want to compare some JSON text
1036against another for equality.
1037 1011
1038=item array references 1012=item array references
1039 1013
1040Perl array references become JSON arrays. 1014Perl array references become JSON arrays.
1041 1015
1042=item other references 1016=item other references
1043 1017
1044Other unblessed references are generally not allowed and will cause an 1018Other unblessed references are generally not allowed and will cause an
1045exception to be thrown, except for references to the integers C<0> and 1019exception to be thrown, except for references to the integers C<0> and
1046C<1>, which get turned into C<false> and C<true> atoms in JSON. You can 1020C<1>, which get turned into C<false> and C<true> atoms in JSON.
1047also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
1048 1021
1022Since C<JSON::XS> uses the boolean model from L<Types::Serialiser>, you
1023can also C<use Types::Serialiser> and then use C<Types::Serialiser::false>
1024and C<Types::Serialiser::true> to improve readability.
1025
1026 use Types::Serialiser;
1049 encode_json [\0, JSON::XS::true] # yields [false,true] 1027 encode_json [\0, Types::Serialiser::true] # yields [false,true]
1050 1028
1051=item JSON::XS::true, JSON::XS::false 1029=item Types::Serialiser::true, Types::Serialiser::false
1052 1030
1053These special values become JSON true and JSON false values, 1031These special values from the L<Types::Serialiser> module become JSON true
1054respectively. You can also use C<\1> and C<\0> directly if you want. 1032and JSON false values, respectively. You can also use C<\1> and C<\0>
1033directly if you want.
1055 1034
1056=item blessed objects 1035=item blessed objects
1057 1036
1058Blessed objects are not directly representable in JSON. See the 1037Blessed objects are not directly representable in JSON. See the
1059C<allow_blessed> and C<convert_blessed> methods on various options on 1038C<allow_blessed> and C<convert_blessed> methods on various options on
1137=item C<utf8> flag disabled 1116=item C<utf8> flag disabled
1138 1117
1139When C<utf8> is disabled (the default), then C<encode>/C<decode> generate 1118When C<utf8> is disabled (the default), then C<encode>/C<decode> generate
1140and expect Unicode strings, that is, characters with high ordinal Unicode 1119and expect Unicode strings, that is, characters with high ordinal Unicode
1141values (> 255) will be encoded as such characters, and likewise such 1120values (> 255) will be encoded as such characters, and likewise such
1142characters are decoded as-is, no canges to them will be done, except 1121characters are decoded as-is, no changes to them will be done, except
1143"(re-)interpreting" them as Unicode codepoints or Unicode characters, 1122"(re-)interpreting" them as Unicode codepoints or Unicode characters,
1144respectively (to Perl, these are the same thing in strings unless you do 1123respectively (to Perl, these are the same thing in strings unless you do
1145funny/weird/dumb stuff). 1124funny/weird/dumb stuff).
1146 1125
1147This is useful when you want to do the encoding yourself (e.g. when you 1126This is useful when you want to do the encoding yourself (e.g. when you
1255well - using C<eval> naively simply I<will> cause problems. 1234well - using C<eval> naively simply I<will> cause problems.
1256 1235
1257Another problem is that some javascript implementations reserve 1236Another problem is that some javascript implementations reserve
1258some property names for their own purposes (which probably makes 1237some property names for their own purposes (which probably makes
1259them non-ECMAscript-compliant). For example, Iceweasel reserves the 1238them non-ECMAscript-compliant). For example, Iceweasel reserves the
1260C<__proto__> property name for it's own purposes. 1239C<__proto__> property name for its own purposes.
1261 1240
1262If that is a problem, you could parse try to filter the resulting JSON 1241If that is a problem, you could parse try to filter the resulting JSON
1263output for these property strings, e.g.: 1242output for these property strings, e.g.:
1264 1243
1265 $json =~ s/"__proto__"\s*:/"__proto__renamed":/g; 1244 $json =~ s/"__proto__"\s*:/"__proto__renamed":/g;
1266 1245
1267This works because C<__proto__> is not valid outside of strings, so every 1246This works because C<__proto__> is not valid outside of strings, so every
1268occurence of C<"__proto__"\s*:> must be a string used as property name. 1247occurrence of C<"__proto__"\s*:> must be a string used as property name.
1269 1248
1270If you know of other incompatibilities, please let me know. 1249If you know of other incompatibilities, please let me know.
1271 1250
1272 1251
1273=head2 JSON and YAML 1252=head2 JSON and YAML
1319that difficult or long) and finally make YAML compatible to it, and 1298that difficult or long) and finally make YAML compatible to it, and
1320educating users about the changes, instead of spreading lies about the 1299educating users about the changes, instead of spreading lies about the
1321real compatibility for many I<years> and trying to silence people who 1300real compatibility for many I<years> and trying to silence people who
1322point out that it isn't true. 1301point out that it isn't true.
1323 1302
1324Addendum/2009: the YAML 1.2 spec is still incomaptible with JSON, even 1303Addendum/2009: the YAML 1.2 spec is still incompatible with JSON, even
1325though the incompatibilities have been documented (and are known to 1304though the incompatibilities have been documented (and are known to Brian)
1326Brian) for many years and the spec makes explicit claims that YAML is a 1305for many years and the spec makes explicit claims that YAML is a superset
1327superset of JSON. It would be so easy to fix, but apparently, bullying and 1306of JSON. It would be so easy to fix, but apparently, bullying people and
1328corrupting userdata is so much easier. 1307corrupting userdata is so much easier.
1329 1308
1330=back 1309=back
1331 1310
1332 1311
1435are browser design bugs, but it is still you who will have to deal with 1414are browser design bugs, but it is still you who will have to deal with
1436it, as major browser developers care only for features, not about getting 1415it, as major browser developers care only for features, not about getting
1437security right). 1416security right).
1438 1417
1439 1418
1419=head1 INTEROPERABILITY WITH OTHER MODULES
1420
1421C<JSON::XS> uses the L<Types::Serialiser> module to provide boolean
1422constants. That means that the JSON true and false values will be
1423comaptible to true and false values of iother modules that do the same,
1424such as L<JSON::PP> and L<CBOR::XS>.
1425
1426
1440=head1 THREADS 1427=head1 THREADS
1441 1428
1442This module is I<not> guaranteed to be thread safe and there are no 1429This module is I<not> guaranteed to be thread safe and there are no
1443plans to change this until Perl gets thread support (as opposed to the 1430plans to change this until Perl gets thread support (as opposed to the
1444horribly slow so-called "threads" which are simply slow and bloated 1431horribly slow so-called "threads" which are simply slow and bloated
1445process simulations - use fork, it's I<much> faster, cheaper, better). 1432process simulations - use fork, it's I<much> faster, cheaper, better).
1446 1433
1447(It might actually work, but you have been warned). 1434(It might actually work, but you have been warned).
1448 1435
1449 1436
1437=head1 THE PERILS OF SETLOCALE
1438
1439Sometimes people avoid the Perl locale support and directly call the
1440system's setlocale function with C<LC_ALL>.
1441
1442This breaks both perl and modules such as JSON::XS, as stringification of
1443numbers no longer works correctly (e.g. C<$x = 0.1; print "$x"+1> might
1444print C<1>, and JSON::XS might output illegal JSON as JSON::XS relies on
1445perl to stringify numbers).
1446
1447The solution is simple: don't call C<setlocale>, or use it for only those
1448categories you need, such as C<LC_MESSAGES> or C<LC_CTYPE>.
1449
1450If you need C<LC_NUMERIC>, you should enable it only around the code that
1451actually needs it (avoiding stringification of numbers), and restore it
1452afterwards.
1453
1454
1450=head1 BUGS 1455=head1 BUGS
1451 1456
1452While the goal of this module is to be correct, that unfortunately does 1457While the goal of this module is to be correct, that unfortunately does
1453not mean it's bug-free, only that I think its design is bug-free. If you 1458not mean it's bug-free, only that I think its design is bug-free. If you
1454keep reporting bugs they will be fixed swiftly, though. 1459keep reporting bugs they will be fixed swiftly, though.
1456Please refrain from using rt.cpan.org or any other bug reporting 1461Please refrain from using rt.cpan.org or any other bug reporting
1457service. I put the contact address into my modules for a reason. 1462service. I put the contact address into my modules for a reason.
1458 1463
1459=cut 1464=cut
1460 1465
1461our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" }; 1466BEGIN {
1462our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" }; 1467 *true = \$Types::Serialiser::true;
1468 *true = \&Types::Serialiser::true;
1469 *false = \$Types::Serialiser::false;
1470 *false = \&Types::Serialiser::false;
1471 *is_bool = \&Types::Serialiser::is_bool;
1463 1472
1464sub true() { $true } 1473 *JSON::XS::Boolean:: = *Types::Serialiser::Boolean::;
1465sub false() { $false }
1466
1467sub is_bool($) {
1468 UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
1469# or UNIVERSAL::isa $_[0], "JSON::Literal"
1470} 1474}
1471 1475
1472XSLoader::load "JSON::XS", $VERSION; 1476XSLoader::load "JSON::XS", $VERSION;
1473
1474package JSON::XS::Boolean;
1475
1476use overload
1477 "0+" => sub { ${$_[0]} },
1478 "++" => sub { $_[0] = ${$_[0]} + 1 },
1479 "--" => sub { $_[0] = ${$_[0]} - 1 },
1480 fallback => 1;
1481
14821;
1483 1477
1484=head1 SEE ALSO 1478=head1 SEE ALSO
1485 1479
1486The F<json_xs> command line utility for quick experiments. 1480The F<json_xs> command line utility for quick experiments.
1487 1481
1490 Marc Lehmann <schmorp@schmorp.de> 1484 Marc Lehmann <schmorp@schmorp.de>
1491 http://home.schmorp.de/ 1485 http://home.schmorp.de/
1492 1486
1493=cut 1487=cut
1494 1488
14891
1490

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines