… | |
… | |
714 | return without doing anything further. This can be used to add more text |
714 | return without doing anything further. This can be used to add more text |
715 | in as many chunks as you want. |
715 | in as many chunks as you want. |
716 | |
716 | |
717 | If the method is called in scalar context, then it will try to extract |
717 | If the method is called in scalar context, then it will try to extract |
718 | exactly I<one> JSON object. If that is successful, it will return this |
718 | exactly I<one> JSON object. If that is successful, it will return this |
719 | object, otherwise it will return C<undef>. This is the most common way of |
719 | object, otherwise it will return C<undef>. If there is a parse error, |
|
|
720 | this method will croak just as C<decode> would do (one can then use |
|
|
721 | C<incr_skip> to skip the errornous part). This is the most common way of |
720 | using the method. |
722 | using the method. |
721 | |
723 | |
722 | And finally, in list context, it will try to extract as many objects |
724 | And finally, in list context, it will try to extract as many objects |
723 | from the stream as it can find and return them, or the empty list |
725 | from the stream as it can find and return them, or the empty list |
724 | otherwise. For this to work, there must be no separators between the JSON |
726 | otherwise. For this to work, there must be no separators between the JSON |
725 | objects or arrays, instead they must be concatenated back-to-back. |
727 | objects or arrays, instead they must be concatenated back-to-back. If |
|
|
728 | an error occurs, an exception will be raised as in the scalar context |
|
|
729 | case. Note that in this case, any previously-parsed JSON texts will be |
|
|
730 | lost. |
726 | |
731 | |
727 | =item $lvalue_string = $json->incr_text |
732 | =item $lvalue_string = $json->incr_text |
728 | |
733 | |
729 | This method returns the currently stored JSON fragment as an lvalue, that |
734 | This method returns the currently stored JSON fragment as an lvalue, that |
730 | is, you can manipulate it. This I<only> works when a preceding call to |
735 | is, you can manipulate it. This I<only> works when a preceding call to |
… | |
… | |
735 | method before having parsed anything. |
740 | method before having parsed anything. |
736 | |
741 | |
737 | This function is useful in two cases: a) finding the trailing text after a |
742 | This function is useful in two cases: a) finding the trailing text after a |
738 | JSON object or b) parsing multiple JSON objects separated by non-JSON text |
743 | JSON object or b) parsing multiple JSON objects separated by non-JSON text |
739 | (such as commas). |
744 | (such as commas). |
|
|
745 | |
|
|
746 | =item $json->incr_skip |
|
|
747 | |
|
|
748 | This will reset the state of the incremental parser and will remove the |
|
|
749 | parsed text from the input buffer. This is useful after C<incr_parse> |
|
|
750 | died, in which case the input buffer and incremental parser state is left |
|
|
751 | unchanged, to skip the text parsed so far and to reset the parse state. |
740 | |
752 | |
741 | =back |
753 | =back |
742 | |
754 | |
743 | =head2 LIMITATIONS |
755 | =head2 LIMITATIONS |
744 | |
756 | |
… | |
… | |
1133 | as UTF-8, ISO-8859-1, ASCII, KOI8-R or most about any character set and |
1145 | as UTF-8, ISO-8859-1, ASCII, KOI8-R or most about any character set and |
1134 | 8-bit-encoding, and still get the same data structure back. This is useful |
1146 | 8-bit-encoding, and still get the same data structure back. This is useful |
1135 | when your channel for JSON transfer is not 8-bit clean or the encoding |
1147 | when your channel for JSON transfer is not 8-bit clean or the encoding |
1136 | might be mangled in between (e.g. in mail), and works because ASCII is a |
1148 | might be mangled in between (e.g. in mail), and works because ASCII is a |
1137 | proper subset of most 8-bit and multibyte encodings in use in the world. |
1149 | proper subset of most 8-bit and multibyte encodings in use in the world. |
1138 | |
|
|
1139 | =back |
|
|
1140 | |
|
|
1141 | |
|
|
1142 | =head1 COMPARISON |
|
|
1143 | |
|
|
1144 | As already mentioned, this module was created because none of the existing |
|
|
1145 | JSON modules could be made to work correctly. First I will describe the |
|
|
1146 | problems (or pleasures) I encountered with various existing JSON modules, |
|
|
1147 | followed by some benchmark values. JSON::XS was designed not to suffer |
|
|
1148 | from any of these problems or limitations. |
|
|
1149 | |
|
|
1150 | =over 4 |
|
|
1151 | |
|
|
1152 | =item JSON 2.xx |
|
|
1153 | |
|
|
1154 | A marvellous piece of engineering, this module either uses JSON::XS |
|
|
1155 | directly when available (so will be 100% compatible with it, including |
|
|
1156 | speed), or it uses JSON::PP, which is basically JSON::XS translated to |
|
|
1157 | Pure Perl, which should be 100% compatible with JSON::XS, just a bit |
|
|
1158 | slower. |
|
|
1159 | |
|
|
1160 | You cannot really lose by using this module, especially as it tries very |
|
|
1161 | hard to work even with ancient Perl versions, while JSON::XS does not. |
|
|
1162 | |
|
|
1163 | =item JSON 1.07 |
|
|
1164 | |
|
|
1165 | Slow (but very portable, as it is written in pure Perl). |
|
|
1166 | |
|
|
1167 | Undocumented/buggy Unicode handling (how JSON handles Unicode values is |
|
|
1168 | undocumented. One can get far by feeding it Unicode strings and doing |
|
|
1169 | en-/decoding oneself, but Unicode escapes are not working properly). |
|
|
1170 | |
|
|
1171 | No round-tripping (strings get clobbered if they look like numbers, e.g. |
|
|
1172 | the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will |
|
|
1173 | decode into the number 2. |
|
|
1174 | |
|
|
1175 | =item JSON::PC 0.01 |
|
|
1176 | |
|
|
1177 | Very fast. |
|
|
1178 | |
|
|
1179 | Undocumented/buggy Unicode handling. |
|
|
1180 | |
|
|
1181 | No round-tripping. |
|
|
1182 | |
|
|
1183 | Has problems handling many Perl values (e.g. regex results and other magic |
|
|
1184 | values will make it croak). |
|
|
1185 | |
|
|
1186 | Does not even generate valid JSON (C<{1,2}> gets converted to C<{1:2}> |
|
|
1187 | which is not a valid JSON text. |
|
|
1188 | |
|
|
1189 | Unmaintained (maintainer unresponsive for many months, bugs are not |
|
|
1190 | getting fixed). |
|
|
1191 | |
|
|
1192 | =item JSON::Syck 0.21 |
|
|
1193 | |
|
|
1194 | Very buggy (often crashes). |
|
|
1195 | |
|
|
1196 | Very inflexible (no human-readable format supported, format pretty much |
|
|
1197 | undocumented. I need at least a format for easy reading by humans and a |
|
|
1198 | single-line compact format for use in a protocol, and preferably a way to |
|
|
1199 | generate ASCII-only JSON texts). |
|
|
1200 | |
|
|
1201 | Completely broken (and confusingly documented) Unicode handling (Unicode |
|
|
1202 | escapes are not working properly, you need to set ImplicitUnicode to |
|
|
1203 | I<different> values on en- and decoding to get symmetric behaviour). |
|
|
1204 | |
|
|
1205 | No round-tripping (simple cases work, but this depends on whether the scalar |
|
|
1206 | value was used in a numeric context or not). |
|
|
1207 | |
|
|
1208 | Dumping hashes may skip hash values depending on iterator state. |
|
|
1209 | |
|
|
1210 | Unmaintained (maintainer unresponsive for many months, bugs are not |
|
|
1211 | getting fixed). |
|
|
1212 | |
|
|
1213 | Does not check input for validity (i.e. will accept non-JSON input and |
|
|
1214 | return "something" instead of raising an exception. This is a security |
|
|
1215 | issue: imagine two banks transferring money between each other using |
|
|
1216 | JSON. One bank might parse a given non-JSON request and deduct money, |
|
|
1217 | while the other might reject the transaction with a syntax error. While a |
|
|
1218 | good protocol will at least recover, that is extra unnecessary work and |
|
|
1219 | the transaction will still not succeed). |
|
|
1220 | |
|
|
1221 | =item JSON::DWIW 0.04 |
|
|
1222 | |
|
|
1223 | Very fast. Very natural. Very nice. |
|
|
1224 | |
|
|
1225 | Undocumented Unicode handling (but the best of the pack. Unicode escapes |
|
|
1226 | still don't get parsed properly). |
|
|
1227 | |
|
|
1228 | Very inflexible. |
|
|
1229 | |
|
|
1230 | No round-tripping. |
|
|
1231 | |
|
|
1232 | Does not generate valid JSON texts (key strings are often unquoted, empty keys |
|
|
1233 | result in nothing being output) |
|
|
1234 | |
|
|
1235 | Does not check input for validity. |
|
|
1236 | |
1150 | |
1237 | =back |
1151 | =back |
1238 | |
1152 | |
1239 | |
1153 | |
1240 | =head2 JSON and YAML |
1154 | =head2 JSON and YAML |