… | |
… | |
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 |
52 | reports for other reasons. |
52 | reports for other reasons. |
53 | |
53 | |
54 | See COMPARISON, below, for a comparison to some other JSON modules. |
|
|
55 | |
|
|
56 | See MAPPING, below, on how JSON::XS maps perl values to JSON values and |
54 | See MAPPING, below, on how JSON::XS maps perl values to JSON values and |
57 | vice versa. |
55 | vice versa. |
58 | |
56 | |
59 | =head2 FEATURES |
57 | =head2 FEATURES |
60 | |
58 | |
… | |
… | |
101 | |
99 | |
102 | =cut |
100 | =cut |
103 | |
101 | |
104 | package JSON::XS; |
102 | package JSON::XS; |
105 | |
103 | |
106 | use strict; |
104 | use common::sense; |
107 | |
105 | |
108 | our $VERSION = '2.2'; |
106 | our $VERSION = '2.25'; |
109 | our @ISA = qw(Exporter); |
107 | our @ISA = qw(Exporter); |
110 | |
108 | |
111 | our @EXPORT = qw(encode_json decode_json to_json from_json); |
109 | our @EXPORT = qw(encode_json decode_json to_json from_json); |
112 | |
110 | |
113 | sub to_json($) { |
111 | sub to_json($) { |
… | |
… | |
442 | the same JSON text (given the same overall settings). If it is disabled, |
440 | the same JSON text (given the same overall settings). If it is disabled, |
443 | the same hash might be encoded differently even if contains the same data, |
441 | the same hash might be encoded differently even if contains the same data, |
444 | as key-value pairs have no inherent ordering in Perl. |
442 | as key-value pairs have no inherent ordering in Perl. |
445 | |
443 | |
446 | This setting has no effect when decoding JSON texts. |
444 | This setting has no effect when decoding JSON texts. |
|
|
445 | |
|
|
446 | This setting has currently no effect on tied hashes. |
447 | |
447 | |
448 | =item $json = $json->allow_nonref ([$enable]) |
448 | =item $json = $json->allow_nonref ([$enable]) |
449 | |
449 | |
450 | =item $enabled = $json->get_allow_nonref |
450 | =item $enabled = $json->get_allow_nonref |
451 | |
451 | |
… | |
… | |
706 | In some cases, there is the need for incremental parsing of JSON |
706 | In some cases, there is the need for incremental parsing of JSON |
707 | texts. While this module always has to keep both JSON text and resulting |
707 | texts. While this module always has to keep both JSON text and resulting |
708 | Perl data structure in memory at one time, it does allow you to parse a |
708 | Perl data structure in memory at one time, it does allow you to parse a |
709 | JSON stream incrementally. It does so by accumulating text until it has |
709 | JSON stream incrementally. It does so by accumulating text until it has |
710 | a full JSON object, which it then can decode. This process is similar to |
710 | a full JSON object, which it then can decode. This process is similar to |
711 | using C<decode_prefix> to see if a full JSON object is available, but is |
711 | using C<decode_prefix> to see if a full JSON object is available, but |
712 | much more efficient (JSON::XS will only attempt to parse the JSON text |
712 | is much more efficient (and can be implemented with a minimum of method |
|
|
713 | calls). |
|
|
714 | |
|
|
715 | JSON::XS will only attempt to parse the JSON text once it is sure it |
713 | once it is sure it has enough text to get a decisive result, using a very |
716 | has enough text to get a decisive result, using a very simple but |
714 | simple but truly incremental parser). |
717 | truly incremental parser. This means that it sometimes won't stop as |
|
|
718 | early as the full parser, for example, it doesn't detect parenthese |
|
|
719 | mismatches. The only thing it guarantees is that it starts decoding as |
|
|
720 | soon as a syntactically valid JSON text has been seen. This means you need |
|
|
721 | to set resource limits (e.g. C<max_size>) to ensure the parser will stop |
|
|
722 | parsing in the presence if syntax errors. |
715 | |
723 | |
716 | The following two methods deal with this. |
724 | The following methods implement this incremental parser. |
717 | |
725 | |
718 | =over 4 |
726 | =over 4 |
719 | |
727 | |
720 | =item [void, scalar or list context] = $json->incr_parse ([$string]) |
728 | =item [void, scalar or list context] = $json->incr_parse ([$string]) |
721 | |
729 | |
… | |
… | |
759 | JSON object or b) parsing multiple JSON objects separated by non-JSON text |
767 | JSON object or b) parsing multiple JSON objects separated by non-JSON text |
760 | (such as commas). |
768 | (such as commas). |
761 | |
769 | |
762 | =item $json->incr_skip |
770 | =item $json->incr_skip |
763 | |
771 | |
764 | This will reset the state of the incremental parser and will remove the |
772 | This will reset the state of the incremental parser and will remove |
765 | parsed text from the input buffer. This is useful after C<incr_parse> |
773 | the parsed text from the input buffer so far. This is useful after |
766 | died, in which case the input buffer and incremental parser state is left |
774 | C<incr_parse> died, in which case the input buffer and incremental parser |
767 | unchanged, to skip the text parsed so far and to reset the parse state. |
775 | state is left unchanged, to skip the text parsed so far and to reset the |
|
|
776 | parse state. |
|
|
777 | |
|
|
778 | The difference to C<incr_reset> is that only text until the parse error |
|
|
779 | occured is removed. |
768 | |
780 | |
769 | =item $json->incr_reset |
781 | =item $json->incr_reset |
770 | |
782 | |
771 | This completely resets the incremental parser, that is, after this call, |
783 | This completely resets the incremental parser, that is, after this call, |
772 | it will be as if the parser had never parsed anything. |
784 | it will be as if the parser had never parsed anything. |
773 | |
785 | |
774 | This is useful if you want ot repeatedly parse JSON objects and want to |
786 | This is useful if you want to repeatedly parse JSON objects and want to |
775 | ignore any trailing data, which means you have to reset the parser after |
787 | ignore any trailing data, which means you have to reset the parser after |
776 | each successful decode. |
788 | each successful decode. |
777 | |
789 | |
778 | =back |
790 | =back |
779 | |
791 | |
… | |
… | |
1174 | proper subset of most 8-bit and multibyte encodings in use in the world. |
1186 | proper subset of most 8-bit and multibyte encodings in use in the world. |
1175 | |
1187 | |
1176 | =back |
1188 | =back |
1177 | |
1189 | |
1178 | |
1190 | |
|
|
1191 | =head2 JSON and ECMAscript |
|
|
1192 | |
|
|
1193 | JSON syntax is based on how literals are represented in javascript (the |
|
|
1194 | not-standardised predecessor of ECMAscript) which is presumably why it is |
|
|
1195 | called "JavaScript Object Notation". |
|
|
1196 | |
|
|
1197 | However, JSON is not a subset (and also not a superset of course) of |
|
|
1198 | ECMAscript (the standard) or javascript (whatever browsers actually |
|
|
1199 | implement). |
|
|
1200 | |
|
|
1201 | If you want to use javascript's C<eval> function to "parse" JSON, you |
|
|
1202 | might run into parse errors for valid JSON texts, or the resulting data |
|
|
1203 | structure might not be queryable: |
|
|
1204 | |
|
|
1205 | One of the problems is that U+2028 and U+2029 are valid characters inside |
|
|
1206 | JSON strings, but are not allowed in ECMAscript string literals, so the |
|
|
1207 | following Perl fragment will not output something that can be guaranteed |
|
|
1208 | to be parsable by javascript's C<eval>: |
|
|
1209 | |
|
|
1210 | use JSON::XS; |
|
|
1211 | |
|
|
1212 | print encode_json [chr 0x2028]; |
|
|
1213 | |
|
|
1214 | The right fix for this is to use a proper JSON parser in your javascript |
|
|
1215 | programs, and not rely on C<eval> (see for example Douglas Crockford's |
|
|
1216 | F<json2.js> parser). |
|
|
1217 | |
|
|
1218 | If this is not an option, you can, as a stop-gap measure, simply encode to |
|
|
1219 | ASCII-only JSON: |
|
|
1220 | |
|
|
1221 | use JSON::XS; |
|
|
1222 | |
|
|
1223 | print JSON::XS->new->ascii->encode ([chr 0x2028]); |
|
|
1224 | |
|
|
1225 | Note that this will enlarge the resulting JSON text quite a bit if you |
|
|
1226 | have many non-ASCII characters. You might be tempted to run some regexes |
|
|
1227 | to 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 | |
|
|
1235 | Note that I<this is a bad idea>: the above only works for U+2028 and |
|
|
1236 | U+2029 and thus only for fully ECMAscript-compliant parsers. Many existing |
|
|
1237 | javascript implementations, however, have issues with other characters as |
|
|
1238 | well - using C<eval> naively simply I<will> cause problems. |
|
|
1239 | |
|
|
1240 | Another problem is that some javascript implementations reserve |
|
|
1241 | some property names for their own purposes (which probably makes |
|
|
1242 | them non-ECMAscript-compliant). For example, Iceweasel reserves the |
|
|
1243 | C<__proto__> property name for it's own purposes. |
|
|
1244 | |
|
|
1245 | If that is a problem, you could parse try to filter the resulting JSON |
|
|
1246 | output for these property strings, e.g.: |
|
|
1247 | |
|
|
1248 | $json =~ s/"__proto__"\s*:/"__proto__renamed":/g; |
|
|
1249 | |
|
|
1250 | This works because C<__proto__> is not valid outside of strings, so every |
|
|
1251 | occurence of C<"__proto__"\s*:> must be a string used as property name. |
|
|
1252 | |
|
|
1253 | If you know of other incompatibilities, please let me know. |
|
|
1254 | |
|
|
1255 | |
1179 | =head2 JSON and YAML |
1256 | =head2 JSON and YAML |
1180 | |
1257 | |
1181 | You often hear that JSON is a subset of YAML. This is, however, a mass |
1258 | You often hear that JSON is a subset of YAML. This is, however, a mass |
1182 | hysteria(*) and very far from the truth (as of the time of this writing), |
1259 | hysteria(*) and very far from the truth (as of the time of this writing), |
1183 | so let me state it clearly: I<in general, there is no way to configure |
1260 | so let me state it clearly: I<in general, there is no way to configure |
… | |
… | |
1191 | my $yaml = $to_yaml->encode ($ref) . "\n"; |
1268 | my $yaml = $to_yaml->encode ($ref) . "\n"; |
1192 | |
1269 | |
1193 | This will I<usually> generate JSON texts that also parse as valid |
1270 | This will I<usually> generate JSON texts that also parse as valid |
1194 | YAML. Please note that YAML has hardcoded limits on (simple) object key |
1271 | YAML. Please note that YAML has hardcoded limits on (simple) object key |
1195 | lengths that JSON doesn't have and also has different and incompatible |
1272 | lengths that JSON doesn't have and also has different and incompatible |
1196 | unicode handling, so you should make sure that your hash keys are |
1273 | unicode character escape syntax, so you should make sure that your hash |
1197 | noticeably shorter than the 1024 "stream characters" YAML allows and that |
1274 | keys are noticeably shorter than the 1024 "stream characters" YAML allows |
1198 | you do not have characters with codepoint values outside the Unicode BMP |
1275 | and that you do not have characters with codepoint values outside the |
1199 | (basic multilingual page). YAML also does not allow C<\/> sequences in |
1276 | Unicode BMP (basic multilingual page). YAML also does not allow C<\/> |
1200 | strings (which JSON::XS does not I<currently> generate, but other JSON |
1277 | sequences in strings (which JSON::XS does not I<currently> generate, but |
1201 | generators might). |
1278 | other JSON generators might). |
1202 | |
1279 | |
1203 | There might be other incompatibilities that I am not aware of (or the YAML |
1280 | There might be other incompatibilities that I am not aware of (or the YAML |
1204 | specification has been changed yet again - it does so quite often). In |
1281 | specification has been changed yet again - it does so quite often). In |
1205 | general you should not try to generate YAML with a JSON generator or vice |
1282 | general you should not try to generate YAML with a JSON generator or vice |
1206 | versa, or try to parse JSON with a YAML parser or vice versa: chances are |
1283 | versa, or try to parse JSON with a YAML parser or vice versa: chances are |
… | |
… | |
1224 | proponents, I would kindly suggest reading the JSON spec (which is not |
1301 | proponents, I would kindly suggest reading the JSON spec (which is not |
1225 | that difficult or long) and finally make YAML compatible to it, and |
1302 | that difficult or long) and finally make YAML compatible to it, and |
1226 | educating users about the changes, instead of spreading lies about the |
1303 | educating users about the changes, instead of spreading lies about the |
1227 | real compatibility for many I<years> and trying to silence people who |
1304 | real compatibility for many I<years> and trying to silence people who |
1228 | point out that it isn't true. |
1305 | point out that it isn't true. |
|
|
1306 | |
|
|
1307 | Addendum/2009: the YAML 1.2 spec is still incomaptible with JSON, even |
|
|
1308 | though the incompatibilities have been documented (and are known to |
|
|
1309 | Brian) for many years and the spec makes explicit claims that YAML is a |
|
|
1310 | superset of JSON. It would be so easy to fix, but apparently, bullying and |
|
|
1311 | corrupting userdata is so much easier. |
1229 | |
1312 | |
1230 | =back |
1313 | =back |
1231 | |
1314 | |
1232 | |
1315 | |
1233 | =head2 SPEED |
1316 | =head2 SPEED |