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Comparing JSON-XS/XS.pm (file contents):
Revision 1.114 by root, Wed Jan 21 05:34:08 2009 UTC vs.
Revision 1.126 by root, Wed Jan 6 08:02:18 2010 UTC

… …
99 99
100=cut 100=cut
101 101
102package JSON::XS; 102package JSON::XS;
103 103
104no warnings; 104use common::sense;
105use strict;
106 105
107our $VERSION = '2.231'; 106our $VERSION = '2.27';
108our @ISA = qw(Exporter); 107our @ISA = qw(Exporter);
109 108
110our @EXPORT = qw(encode_json decode_json to_json from_json); 109our @EXPORT = qw(encode_json decode_json to_json from_json);
111 110
112sub to_json($) { 111sub to_json($) {
… …
441the same JSON text (given the same overall settings). If it is disabled, 440the same JSON text (given the same overall settings). If it is disabled,
442the same hash might be encoded differently even if contains the same data, 441the same hash might be encoded differently even if contains the same data,
443as key-value pairs have no inherent ordering in Perl. 442as key-value pairs have no inherent ordering in Perl.
444 443
445This setting has no effect when decoding JSON texts. 444This setting has no effect when decoding JSON texts.
445
446This setting has currently no effect on tied hashes.
446 447
447=item $json = $json->allow_nonref ([$enable]) 448=item $json = $json->allow_nonref ([$enable])
448 449
449=item $enabled = $json->get_allow_nonref 450=item $enabled = $json->get_allow_nonref
450 451
… …
1185proper subset of most 8-bit and multibyte encodings in use in the world. 1186proper subset of most 8-bit and multibyte encodings in use in the world.
1186 1187
1187=back 1188=back
1188 1189
1189 1190
1191=head2 JSON and ECMAscript
1192
1193JSON syntax is based on how literals are represented in javascript (the
1194not-standardised predecessor of ECMAscript) which is presumably why it is
1195called "JavaScript Object Notation".
1196
1197However, JSON is not a subset (and also not a superset of course) of
1198ECMAscript (the standard) or javascript (whatever browsers actually
1199implement).
1200
1201If you want to use javascript's C<eval> function to "parse" JSON, you
1202might run into parse errors for valid JSON texts, or the resulting data
1203structure might not be queryable:
1204
1205One of the problems is that U+2028 and U+2029 are valid characters inside
1206JSON strings, but are not allowed in ECMAscript string literals, so the
1207following Perl fragment will not output something that can be guaranteed
1208to be parsable by javascript's C<eval>:
1209
1210 use JSON::XS;
1211
1212 print encode_json [chr 0x2028];
1213
1214The right fix for this is to use a proper JSON parser in your javascript
1215programs, and not rely on C<eval> (see for example Douglas Crockford's
1216F<json2.js> parser).
1217
1218If this is not an option, you can, as a stop-gap measure, simply encode to
1219ASCII-only JSON:
1220
1221 use JSON::XS;
1222
1223 print JSON::XS->new->ascii->encode ([chr 0x2028]);
1224
1225Note that this will enlarge the resulting JSON text quite a bit if you
1226have many non-ASCII characters. You might be tempted to run some regexes
1227to only escape U+2028 and U+2029, e.g.:
1228
1229 # DO NOT USE THIS!
1230 my $json = JSON::XS->new->utf8->encode ([chr 0x2028]);
1231 $json =~ s/\xe2\x80\xa8/\\u2028/g; # escape U+2028
1232 $json =~ s/\xe2\x80\xa9/\\u2029/g; # escape U+2029
1233 print $json;
1234
1235Note that I<this is a bad idea>: the above only works for U+2028 and
1236U+2029 and thus only for fully ECMAscript-compliant parsers. Many existing
1237javascript implementations, however, have issues with other characters as
1238well - using C<eval> naively simply I<will> cause problems.
1239
1240Another problem is that some javascript implementations reserve
1241some property names for their own purposes (which probably makes
1242them non-ECMAscript-compliant). For example, Iceweasel reserves the
1243C<__proto__> property name for it's own purposes.
1244
1245If that is a problem, you could parse try to filter the resulting JSON
1246output for these property strings, e.g.:
1247
1248 $json =~ s/"__proto__"\s*:/"__proto__renamed":/g;
1249
1250This works because C<__proto__> is not valid outside of strings, so every
1251occurence of C<"__proto__"\s*:> must be a string used as property name.
1252
1253If you know of other incompatibilities, please let me know.
1254
1255
1190=head2 JSON and YAML 1256=head2 JSON and YAML
1191 1257
1192You often hear that JSON is a subset of YAML. This is, however, a mass 1258You often hear that JSON is a subset of YAML. This is, however, a mass
1193hysteria(*) and very far from the truth (as of the time of this writing), 1259hysteria(*) and very far from the truth (as of the time of this writing),
1194so let me state it clearly: I<in general, there is no way to configure 1260so let me state it clearly: I<in general, there is no way to configure
… …
1202 my $yaml = $to_yaml->encode ($ref) . "\n"; 1268 my $yaml = $to_yaml->encode ($ref) . "\n";
1203 1269
1204This will I<usually> generate JSON texts that also parse as valid 1270This will I<usually> generate JSON texts that also parse as valid
1205YAML. Please note that YAML has hardcoded limits on (simple) object key 1271YAML. Please note that YAML has hardcoded limits on (simple) object key
1206lengths that JSON doesn't have and also has different and incompatible 1272lengths that JSON doesn't have and also has different and incompatible
1207unicode handling, so you should make sure that your hash keys are 1273unicode character escape syntax, so you should make sure that your hash
1208noticeably shorter than the 1024 "stream characters" YAML allows and that 1274keys are noticeably shorter than the 1024 "stream characters" YAML allows
1209you do not have characters with codepoint values outside the Unicode BMP 1275and that you do not have characters with codepoint values outside the
1210(basic multilingual page). YAML also does not allow C<\/> sequences in 1276Unicode BMP (basic multilingual page). YAML also does not allow C<\/>
1211strings (which JSON::XS does not I<currently> generate, but other JSON 1277sequences in strings (which JSON::XS does not I<currently> generate, but
1212generators might). 1278other JSON generators might).
1213 1279
1214There might be other incompatibilities that I am not aware of (or the YAML 1280There might be other incompatibilities that I am not aware of (or the YAML
1215specification has been changed yet again - it does so quite often). In 1281specification has been changed yet again - it does so quite often). In
1216general you should not try to generate YAML with a JSON generator or vice 1282general you should not try to generate YAML with a JSON generator or vice
1217versa, or try to parse JSON with a YAML parser or vice versa: chances are 1283versa, or try to parse JSON with a YAML parser or vice versa: chances are
… …
1235proponents, I would kindly suggest reading the JSON spec (which is not 1301proponents, I would kindly suggest reading the JSON spec (which is not
1236that difficult or long) and finally make YAML compatible to it, and 1302that difficult or long) and finally make YAML compatible to it, and
1237educating users about the changes, instead of spreading lies about the 1303educating users about the changes, instead of spreading lies about the
1238real compatibility for many I<years> and trying to silence people who 1304real compatibility for many I<years> and trying to silence people who
1239point out that it isn't true. 1305point out that it isn't true.
1306
1307Addendum/2009: the YAML 1.2 spec is still incomaptible with JSON, even
1308though the incompatibilities have been documented (and are known to
1309Brian) for many years and the spec makes explicit claims that YAML is a
1310superset of JSON. It would be so easy to fix, but apparently, bullying and
1311corrupting userdata is so much easier.
1240 1312
1241=back 1313=back
1242 1314
1243 1315
1244=head2 SPEED 1316=head2 SPEED

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