--- JSON-XS/README 2009/10/10 01:48:50 1.32 +++ JSON-XS/README 2010/03/11 19:31:37 1.35 @@ -58,10 +58,11 @@ * round-trip integrity When you serialise a perl data structure using only data types - supported by JSON, the deserialised data structure is identical on - the Perl level. (e.g. the string "2.0" doesn't suddenly become "2" - just because it looks like a number). There minor *are* exceptions - to this, read the MAPPING section below to learn about those. + supported by JSON and Perl, the deserialised data structure is + identical on the Perl level. (e.g. the string "2.0" doesn't suddenly + become "2" just because it looks like a number). There *are* minor + exceptions to this, read the MAPPING section below to learn about + those. * strict checking of JSON correctness @@ -672,6 +673,11 @@ the scalar context case. Note that in this case, any previously-parsed JSON texts will be lost. + Example: Parse some JSON arrays/objects in a given string and return + them. + + my @objs = JSON::XS->new->incr_parse ("[5][7][1,2]"); + $lvalue_string = $json->incr_text This method returns the currently stored JSON fragment as an lvalue, that is, you can manipulate it. This *only* works when a preceding @@ -896,6 +902,11 @@ ability, but the JSON number will still be re-encoded as a JSON number). + Note that precision is not accuracy - binary floating point values + cannot represent most decimal fractions exactly, and when converting + from and to floating point, JSON::XS only guarantees precision up to + but not including the leats significant bit. + true, false These JSON atoms become "JSON::XS::true" and "JSON::XS::false", respectively. They are overloaded to act almost exactly like the @@ -981,6 +992,13 @@ Tell me if you need this capability (but don't forget to explain why it's needed :). + Note that numerical precision has the same meaning as under Perl (so + binary to decimal conversion follows the same rules as in Perl, + which can differ to other languages). Also, your perl interpreter + might expose extensions to the floating point numbers of your + platform, such as infinities or NaN's - these cannot be represented + in JSON, and it is an error to pass those in. + ENCODING/CODESET FLAG NOTES The interested reader might have seen a number of flags that signify encodings or codesets - "utf8", "latin1" and "ascii". There seems to be @@ -1203,49 +1221,48 @@ {"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7, - true, false]} + 1, 0]} It shows the number of encodes/decodes per second (JSON::XS uses the functional interface, while JSON::XS/2 uses the OO interface with - pretty-printing and hashkey sorting enabled, JSON::XS/3 enables shrink). - Higher is better: - - module | encode | decode | - -----------|------------|------------| - JSON 1.x | 4990.842 | 4088.813 | - JSON::DWIW | 51653.990 | 71575.154 | - JSON::PC | 65948.176 | 74631.744 | - JSON::PP | 8931.652 | 3817.168 | - JSON::Syck | 24877.248 | 27776.848 | - JSON::XS | 388361.481 | 227951.304 | - JSON::XS/2 | 227951.304 | 218453.333 | - JSON::XS/3 | 338250.323 | 218453.333 | - Storable | 16500.016 | 135300.129 | - -----------+------------+------------+ - - That is, JSON::XS is about five times faster than JSON::DWIW on - encoding, about three times faster on decoding, and over forty times - faster than JSON, even with pretty-printing and key sorting. It also + pretty-printing and hashkey sorting enabled, JSON::XS/3 enables shrink. + JSON::DWIW/DS uses the deserialise function, while JSON::DWIW::FJ uses + the from_json method). Higher is better: + + module | encode | decode | + --------------|------------|------------| + JSON::DWIW/DS | 86302.551 | 102300.098 | + JSON::DWIW/FJ | 86302.551 | 75983.768 | + JSON::PP | 15827.562 | 6638.658 | + JSON::Syck | 63358.066 | 47662.545 | + JSON::XS | 511500.488 | 511500.488 | + JSON::XS/2 | 291271.111 | 388361.481 | + JSON::XS/3 | 361577.931 | 361577.931 | + Storable | 66788.280 | 265462.278 | + --------------+------------+------------+ + + That is, JSON::XS is almost six times faster than JSON::DWIW on + encoding, about five times faster on decoding, and over thirty to + seventy times faster than JSON's pure perl implementation. It also compares favourably to Storable for small amounts of data. Using a longer test string (roughly 18KB, generated from Yahoo! Locals search API (). - module | encode | decode | - -----------|------------|------------| - JSON 1.x | 55.260 | 34.971 | - JSON::DWIW | 825.228 | 1082.513 | - JSON::PC | 3571.444 | 2394.829 | - JSON::PP | 210.987 | 32.574 | - JSON::Syck | 552.551 | 787.544 | - JSON::XS | 5780.463 | 4854.519 | - JSON::XS/2 | 3869.998 | 4798.975 | - JSON::XS/3 | 5862.880 | 4798.975 | - Storable | 4445.002 | 5235.027 | - -----------+------------+------------+ + module | encode | decode | + --------------|------------|------------| + JSON::DWIW/DS | 1647.927 | 2673.916 | + JSON::DWIW/FJ | 1630.249 | 2596.128 | + JSON::PP | 400.640 | 62.311 | + JSON::Syck | 1481.040 | 1524.869 | + JSON::XS | 20661.596 | 9541.183 | + JSON::XS/2 | 10683.403 | 9416.938 | + JSON::XS/3 | 20661.596 | 9400.054 | + Storable | 19765.806 | 10000.725 | + --------------+------------+------------+ Again, JSON::XS leads by far (except for Storable which non-surprisingly - decodes faster). + decodes a bit faster). On large strings containing lots of high Unicode characters, some modules (such as JSON::PC) seem to decode faster than JSON::XS, but the @@ -1290,11 +1307,11 @@ If you are using JSON::XS to return packets to consumption by JavaScript scripts in a browser you should have a look at - to see whether - you are vulnerable to some common attack vectors (which really are - browser design bugs, but it is still you who will have to deal with it, - as major browser developers care only for features, not about getting - security right). + + to see whether you are vulnerable to some common attack vectors (which + really are browser design bugs, but it is still you who will have to + deal with it, as major browser developers care only for features, not + about getting security right). THREADS This module is *not* guaranteed to be thread safe and there are no plans