--- JSON-XS/XS.pm 2007/04/11 12:23:02 1.31 +++ JSON-XS/XS.pm 2007/11/25 19:11:07 1.72 @@ -2,6 +2,9 @@ JSON::XS - JSON serialising/deserialising, done correctly and fast +JSON::XS - 正しくて高速な JSON シリアライザ/デシリアライザ + (http://fleur.hio.jp/perldoc/mix/lib/JSON/XS.html) + =head1 SYNOPSIS use JSON::XS; @@ -12,10 +15,6 @@ $utf8_encoded_json_text = to_json $perl_hash_or_arrayref; $perl_hash_or_arrayref = from_json $utf8_encoded_json_text; - # objToJson and jsonToObj aliases to to_json and from_json - # are exported for compatibility to the JSON module, - # but should not be used in new code. - # OO-interface $coder = JSON::XS->new->ascii->pretty->allow_nonref; @@ -43,7 +42,7 @@ =over 4 -=item * correct unicode handling +=item * correct Unicode handling This module knows how to handle Unicode, and even documents how and when it does so. @@ -73,10 +72,10 @@ =item * reasonably versatile output formats -You can choose between the most compact guarenteed single-line format +You can choose between the most compact guaranteed single-line format possible (nice for simple line-based protocols), a pure-ascii format (for when your transport is not 8-bit clean, still supports the whole -unicode range), or a pretty-printed format (for when you want to read that +Unicode range), or a pretty-printed format (for when you want to read that stuff). Or you can combine those features in whatever way you like. =back @@ -87,29 +86,25 @@ use strict; -BEGIN { - our $VERSION = '1.12'; - our @ISA = qw(Exporter); +our $VERSION = '1.53'; +our @ISA = qw(Exporter); - our @EXPORT = qw(to_json from_json objToJson jsonToObj); - require Exporter; +our @EXPORT = qw(to_json from_json); - require XSLoader; - XSLoader::load JSON::XS::, $VERSION; -} +use Exporter; +use XSLoader; =head1 FUNCTIONAL INTERFACE -The following convinience methods are provided by this module. They are +The following convenience methods are provided by this module. They are exported by default: =over 4 =item $json_text = to_json $perl_scalar -Converts the given Perl data structure (a simple scalar or a reference to -a hash or array) to a UTF-8 encoded, binary string (that is, the string contains -octets only). Croaks on error. +Converts the given Perl data structure to a UTF-8 encoded, binary string +(that is, the string contains octets only). Croaks on error. This function call is functionally identical to: @@ -119,9 +114,9 @@ =item $perl_scalar = from_json $json_text -The opposite of C: expects an UTF-8 (binary) string and tries to -parse that as an UTF-8 encoded JSON text, returning the resulting simple -scalar or reference. Croaks on error. +The opposite of C: expects an UTF-8 (binary) string and tries +to parse that as an UTF-8 encoded JSON text, returning the resulting +reference. Croaks on error. This function call is functionally identical to: @@ -129,9 +124,66 @@ except being faster. +=item $is_boolean = JSON::XS::is_bool $scalar + +Returns true if the passed scalar represents either JSON::XS::true or +JSON::XS::false, two constants that act like C<1> and C<0>, respectively +and are used to represent JSON C and C values in Perl. + +See MAPPING, below, for more information on how JSON values are mapped to +Perl. + =back +=head1 A FEW NOTES ON UNICODE AND PERL + +Since this often leads to confusion, here are a few very clear words on +how Unicode works in Perl, modulo bugs. + +=over 4 + +=item 1. Perl strings can store characters with ordinal values > 255. + +This enables you to store Unicode characters as single characters in a +Perl string - very natural. + +=item 2. Perl does I associate an encoding with your strings. + +Unless you force it to, e.g. when matching it against a regex, or printing +the scalar to a file, in which case Perl either interprets your string as +locale-encoded text, octets/binary, or as Unicode, depending on various +settings. In no case is an encoding stored together with your data, it is +I that decides encoding, not any magical metadata. + +=item 3. The internal utf-8 flag has no meaning with regards to the +encoding of your string. + +Just ignore that flag unless you debug a Perl bug, a module written in +XS or want to dive into the internals of perl. Otherwise it will only +confuse you, as, despite the name, it says nothing about how your string +is encoded. You can have Unicode strings with that flag set, with that +flag clear, and you can have binary data with that flag set and that flag +clear. Other possibilities exist, too. + +If you didn't know about that flag, just the better, pretend it doesn't +exist. + +=item 4. A "Unicode String" is simply a string where each character can be +validly interpreted as a Unicode codepoint. + +If you have UTF-8 encoded data, it is no longer a Unicode string, but a +Unicode string encoded in UTF-8, giving you a binary string. + +=item 5. A string containing "high" (> 255) character values is I a UTF-8 string. + +It's a fact. Learn to live with it. + +=back + +I hope this helps :) + + =head1 OBJECT-ORIENTED INTERFACE The object oriented interface lets you configure your own encoding or @@ -152,21 +204,56 @@ =item $json = $json->ascii ([$enable]) +=item $enabled = $json->get_ascii + If C<$enable> is true (or missing), then the C method will not generate characters outside the code range C<0..127> (which is ASCII). Any -unicode characters outside that range will be escaped using either a +Unicode characters outside that range will be escaped using either a single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence, -as per RFC4627. +as per RFC4627. The resulting encoded JSON text can be treated as a native +Unicode string, an ascii-encoded, latin1-encoded or UTF-8 encoded string, +or any other superset of ASCII. If C<$enable> is false, then the C method will not escape Unicode -characters unless required by the JSON syntax. This results in a faster -and more compact format. +characters unless required by the JSON syntax or other flags. This results +in a faster and more compact format. + +The main use for this flag is to produce JSON texts that can be +transmitted over a 7-bit channel, as the encoded JSON texts will not +contain any 8 bit characters. JSON::XS->new->ascii (1)->encode ([chr 0x10401]) => ["\ud801\udc01"] +=item $json = $json->latin1 ([$enable]) + +=item $enabled = $json->get_latin1 + +If C<$enable> is true (or missing), then the C method will encode +the resulting JSON text as latin1 (or iso-8859-1), escaping any characters +outside the code range C<0..255>. The resulting string can be treated as a +latin1-encoded JSON text or a native Unicode string. The C method +will not be affected in any way by this flag, as C by default +expects Unicode, which is a strict superset of latin1. + +If C<$enable> is false, then the C method will not escape Unicode +characters unless required by the JSON syntax or other flags. + +The main use for this flag is efficiently encoding binary data as JSON +text, as most octets will not be escaped, resulting in a smaller encoded +size. The disadvantage is that the resulting JSON text is encoded +in latin1 (and must correctly be treated as such when storing and +transferring), a rare encoding for JSON. It is therefore most useful when +you want to store data structures known to contain binary data efficiently +in files or databases, not when talking to other JSON encoders/decoders. + + JSON::XS->new->latin1->encode (["\x{89}\x{abc}"] + => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not) + =item $json = $json->utf8 ([$enable]) +=item $enabled = $json->get_utf8 + If C<$enable> is true (or missing), then the C method will encode the JSON result into UTF-8, as required by many protocols, while the C method expects to be handled an UTF-8-encoded string. Please @@ -176,8 +263,8 @@ and UTF-32 encoding families, as described in RFC4627. If C<$enable> is false, then the C method will return the JSON -string as a (non-encoded) unicode string, while C expects thus a -unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs +string as a (non-encoded) Unicode string, while C expects thus a +Unicode string. Any decoding or encoding (e.g. to UTF-8 or UTF-16) needs to be done yourself, e.g. using the Encode module. Example, output UTF-16BE-encoded JSON: @@ -192,6 +279,8 @@ =item $json = $json->pretty ([$enable]) +=item $enabled = $json->get_pretty + This enables (or disables) all of the C, C and C (and in the future possibly more) flags in one call to generate the most readable (or most compact) form possible. @@ -209,17 +298,21 @@ =item $json = $json->indent ([$enable]) +=item $enabled = $json->get_indent + If C<$enable> is true (or missing), then the C method will use a multiline format as output, putting every array member or object/hash key-value pair -into its own line, identing them properly. +into its own line, indenting them properly. If C<$enable> is false, no newlines or indenting will be produced, and the -resulting JSON text is guarenteed not to contain any C. +resulting JSON text is guaranteed not to contain any C. This setting has no effect when decoding JSON texts. =item $json = $json->space_before ([$enable]) +=item $enabled = $json->get_space_before + If C<$enable> is true (or missing), then the C method will add an extra optional space before the C<:> separating keys from values in JSON objects. @@ -235,6 +328,8 @@ =item $json = $json->space_after ([$enable]) +=item $enabled = $json->get_space_after + If C<$enable> is true (or missing), then the C method will add an extra optional space after the C<:> separating keys from values in JSON objects and extra whitespace after the C<,> separating key-value pairs and array @@ -249,8 +344,57 @@ {"key": "value"} +=item $json = $json->relaxed ([$enable]) + +=item $enabled = $json->get_relaxed + +If C<$enable> is true (or missing), then C will accept some +extensions to normal JSON syntax (see below). C will not be +affected in anyway. I. I suggest only to use this option to +parse application-specific files written by humans (configuration files, +resource files etc.) + +If C<$enable> is false (the default), then C will only accept +valid JSON texts. + +Currently accepted extensions are: + +=over 4 + +=item * list items can have an end-comma + +JSON I array elements and key-value pairs with commas. This +can be annoying if you write JSON texts manually and want to be able to +quickly append elements, so this extension accepts comma at the end of +such items not just between them: + + [ + 1, + 2, <- this comma not normally allowed + ] + { + "k1": "v1", + "k2": "v2", <- this comma not normally allowed + } + +=item * shell-style '#'-comments + +Whenever JSON allows whitespace, shell-style comments are additionally +allowed. They are terminated by the first carriage-return or line-feed +character, after which more white-space and comments are allowed. + + [ + 1, # this comment not allowed in JSON + # neither this one... + ] + +=back + =item $json = $json->canonical ([$enable]) +=item $enabled = $json->get_canonical + If C<$enable> is true (or missing), then the C method will output JSON objects by sorting their keys. This is adding a comparatively high overhead. @@ -260,13 +404,15 @@ This option is useful if you want the same data structure to be encoded as the same JSON text (given the same overall settings). If it is disabled, -the same hash migh be encoded differently even if contains the same data, +the same hash might be encoded differently even if contains the same data, as key-value pairs have no inherent ordering in Perl. This setting has no effect when decoding JSON texts. =item $json = $json->allow_nonref ([$enable]) +=item $enabled = $json->get_allow_nonref + If C<$enable> is true (or missing), then the C method can convert a non-reference into its corresponding string, number or null JSON value, which is an extension to RFC4627. Likewise, C will accept those JSON @@ -283,8 +429,126 @@ JSON::XS->new->allow_nonref->encode ("Hello, World!") => "Hello, World!" +=item $json = $json->allow_blessed ([$enable]) + +=item $enabled = $json->get_allow_bless + +If C<$enable> is true (or missing), then the C method will not +barf when it encounters a blessed reference. Instead, the value of the +B option will decide whether C (C +disabled or no C method found) or a representation of the +object (C enabled and C method found) is being +encoded. Has no effect on C. + +If C<$enable> is false (the default), then C will throw an +exception when it encounters a blessed object. + +=item $json = $json->convert_blessed ([$enable]) + +=item $enabled = $json->get_convert_blessed + +If C<$enable> is true (or missing), then C, upon encountering a +blessed object, will check for the availability of the C method +on the object's class. If found, it will be called in scalar context +and the resulting scalar will be encoded instead of the object. If no +C method is found, the value of C will decide what +to do. + +The C method may safely call die if it wants. If C +returns other blessed objects, those will be handled in the same +way. C must take care of not causing an endless recursion cycle +(== crash) in this case. The name of C was chosen because other +methods called by the Perl core (== not by the user of the object) are +usually in upper case letters and to avoid collisions with the C +function. + +This setting does not yet influence C in any way, but in the +future, global hooks might get installed that influence C and are +enabled by this setting. + +If C<$enable> is false, then the C setting will decide what +to do when a blessed object is found. + +=item $json = $json->filter_json_object ([$coderef->($hashref)]) + +When C<$coderef> is specified, it will be called from C each +time it decodes a JSON object. The only argument is a reference to the +newly-created hash. If the code references returns a single scalar (which +need not be a reference), this value (i.e. a copy of that scalar to avoid +aliasing) is inserted into the deserialised data structure. If it returns +an empty list (NOTE: I C, which is a valid scalar), the +original deserialised hash will be inserted. This setting can slow down +decoding considerably. + +When C<$coderef> is omitted or undefined, any existing callback will +be removed and C will not change the deserialised hash in any +way. + +Example, convert all JSON objects into the integer 5: + + my $js = JSON::XS->new->filter_json_object (sub { 5 }); + # returns [5] + $js->decode ('[{}]') + # throw an exception because allow_nonref is not enabled + # so a lone 5 is not allowed. + $js->decode ('{"a":1, "b":2}'); + +=item $json = $json->filter_json_single_key_object ($key [=> $coderef->($value)]) + +Works remotely similar to C, but is only called for +JSON objects having a single key named C<$key>. + +This C<$coderef> is called before the one specified via +C, if any. It gets passed the single value in the JSON +object. If it returns a single value, it will be inserted into the data +structure. If it returns nothing (not even C but the empty list), +the callback from C will be called next, as if no +single-key callback were specified. + +If C<$coderef> is omitted or undefined, the corresponding callback will be +disabled. There can only ever be one callback for a given key. + +As this callback gets called less often then the C +one, decoding speed will not usually suffer as much. Therefore, single-key +objects make excellent targets to serialise Perl objects into, especially +as single-key JSON objects are as close to the type-tagged value concept +as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not +support this in any way, so you need to make sure your data never looks +like a serialised Perl hash. + +Typical names for the single object key are C<__class_whatever__>, or +C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even +things like C<__class_md5sum(classname)__>, to reduce the risk of clashing +with real hashes. + +Example, decode JSON objects of the form C<< { "__widget__" => } >> +into the corresponding C<< $WIDGET{} >> object: + + # return whatever is in $WIDGET{5}: + JSON::XS + ->new + ->filter_json_single_key_object (__widget__ => sub { + $WIDGET{ $_[0] } + }) + ->decode ('{"__widget__": 5') + + # this can be used with a TO_JSON method in some "widget" class + # for serialisation to json: + sub WidgetBase::TO_JSON { + my ($self) = @_; + + unless ($self->{id}) { + $self->{id} = ..get..some..id..; + $WIDGET{$self->{id}} = $self; + } + + { __widget__ => $self->{id} } + } + =item $json = $json->shrink ([$enable]) +=item $enabled = $json->get_shrink + Perl usually over-allocates memory a bit when allocating space for strings. This flag optionally resizes strings generated by either C or C to their minimum size possible. This can save @@ -311,6 +575,8 @@ =item $json = $json->max_depth ([$maximum_nesting_depth]) +=item $max_depth = $json->get_max_depth + Sets the maximum nesting level (default C<512>) accepted while encoding or decoding. If the JSON text or Perl data structure has an equal or higher nesting level then this limit, then the encoder and decoder will @@ -324,8 +590,25 @@ Setting the maximum depth to one disallows any nesting, so that ensures that the object is only a single hash/object or array. -The argument to C will be rounded up to the next nearest power -of two. +The argument to C will be rounded up to the next highest power +of two. If no argument is given, the highest possible setting will be +used, which is rarely useful. + +See SECURITY CONSIDERATIONS, below, for more info on why this is useful. + +=item $json = $json->max_size ([$maximum_string_size]) + +=item $max_size = $json->get_max_size + +Set the maximum length a JSON text may have (in bytes) where decoding is +being attempted. The default is C<0>, meaning no limit. When C +is called on a string longer then this number of characters it will not +attempt to decode the string but throw an exception. This setting has no +effect on C (yet). + +The argument to C will be rounded up to the next B +power of two (so may be more than requested). If no argument is given, the +limit check will be deactivated (same as when C<0> is specified). See SECURITY CONSIDERATIONS, below, for more info on why this is useful. @@ -347,6 +630,20 @@ Perl arrayrefs and JSON objects become Perl hashrefs. C becomes C<1>, C becomes C<0> and C becomes C. +=item ($perl_scalar, $characters) = $json->decode_prefix ($json_text) + +This works like the C method, but instead of raising an exception +when there is trailing garbage after the first JSON object, it will +silently stop parsing there and return the number of characters consumed +so far. + +This is useful if your JSON texts are not delimited by an outer protocol +(which is not the brightest thing to do in the first place) and you need +to know where the JSON text ends. + + JSON::XS->new->decode_prefix ("[1] the tail") + => ([], 3) + =back @@ -358,9 +655,10 @@ (what you put in comes out as something equivalent). For the more enlightened: note that in the following descriptions, -lowercase I refers to the Perl interpreter, while uppcercase I +lowercase I refers to the Perl interpreter, while uppercase I refers to the abstract Perl language itself. + =head2 JSON -> PERL =over 4 @@ -368,7 +666,7 @@ =item object A JSON object becomes a reference to a hash in Perl. No ordering of object -keys is preserved (JSON does not preserver object key ordering itself). +keys is preserved (JSON does not preserve object key ordering itself). =item array @@ -382,18 +680,30 @@ =item number -A JSON number becomes either an integer or numeric (floating point) -scalar in perl, depending on its range and any fractional parts. On the -Perl level, there is no difference between those as Perl handles all the -conversion details, but an integer may take slightly less memory and might -represent more values exactly than (floating point) numbers. +A JSON number becomes either an integer, numeric (floating point) or +string scalar in perl, depending on its range and any fractional parts. On +the Perl level, there is no difference between those as Perl handles all +the conversion details, but an integer may take slightly less memory and +might represent more values exactly than (floating point) numbers. + +If the number consists of digits only, JSON::XS will try to represent +it as an integer value. If that fails, it will try to represent it as +a numeric (floating point) value if that is possible without loss of +precision. Otherwise it will preserve the number as a string value. + +Numbers containing a fractional or exponential part will always be +represented as numeric (floating point) values, possibly at a loss of +precision. + +This might create round-tripping problems as numbers might become strings, +but as Perl is typeless there is no other way to do it. =item true, false -These JSON atoms become C<0>, C<1>, respectively. Information is lost in -this process. Future versions might represent those values differently, -but they will be guarenteed to act like these integers would normally in -Perl. +These JSON atoms become C and C, +respectively. They are overloaded to act almost exactly like the numbers +C<1> and C<0>. You can check whether a scalar is a JSON boolean by using +the C function. =item null @@ -401,6 +711,7 @@ =back + =head2 PERL -> JSON The mapping from Perl to JSON is slightly more difficult, as Perl is a @@ -434,6 +745,11 @@ to_json [\0,JSON::XS::true] # yields [false,true] +=item JSON::XS::true, JSON::XS::false + +These special values become JSON true and JSON false values, +respectively. You can also use C<\1> and C<\0> directly if you want. + =item blessed objects Blessed objects are not allowed. JSON::XS currently tries to encode their @@ -459,21 +775,21 @@ # undef becomes null to_json [undef] # yields [null] -You can force the type to be a string by stringifying it: +You can force the type to be a JSON string by stringifying it: my $x = 3.1; # some variable containing a number "$x"; # stringified $x .= ""; # another, more awkward way to stringify print $x; # perl does it for you, too, quite often -You can force the type to be a number by numifying it: +You can force the type to be a JSON number by numifying it: my $x = "3"; # some variable containing a string $x += 0; # numify it, ensuring it will be dumped as a number - $x *= 1; # same thing, the choise is yours. + $x *= 1; # same thing, the choice is yours. -You can not currently output JSON booleans or force the type in other, -less obscure, ways. Tell me if you need this capability. +You can not currently force the type in other, less obscure, ways. Tell me +if you need this capability. =back @@ -492,11 +808,11 @@ Slow (but very portable, as it is written in pure Perl). -Undocumented/buggy Unicode handling (how JSON handles unicode values is -undocumented. One can get far by feeding it unicode strings and doing -en-/decoding oneself, but unicode escapes are not working properly). +Undocumented/buggy Unicode handling (how JSON handles Unicode values is +undocumented. One can get far by feeding it Unicode strings and doing +en-/decoding oneself, but Unicode escapes are not working properly). -No roundtripping (strings get clobbered if they look like numbers, e.g. +No round-tripping (strings get clobbered if they look like numbers, e.g. the string C<2.0> will encode to C<2.0> instead of C<"2.0">, and that will decode into the number 2. @@ -506,7 +822,7 @@ Undocumented/buggy Unicode handling. -No roundtripping. +No round-tripping. Has problems handling many Perl values (e.g. regex results and other magic values will make it croak). @@ -526,11 +842,11 @@ single-line compact format for use in a protocol, and preferably a way to generate ASCII-only JSON texts). -Completely broken (and confusingly documented) Unicode handling (unicode +Completely broken (and confusingly documented) Unicode handling (Unicode escapes are not working properly, you need to set ImplicitUnicode to I values on en- and decoding to get symmetric behaviour). -No roundtripping (simple cases work, but this depends on wether the scalar +No round-tripping (simple cases work, but this depends on whether the scalar value was used in a numeric context or not). Dumping hashes may skip hash values depending on iterator state. @@ -540,7 +856,7 @@ Does not check input for validity (i.e. will accept non-JSON input and return "something" instead of raising an exception. This is a security -issue: imagine two banks transfering money between each other using +issue: imagine two banks transferring money between each other using JSON. One bank might parse a given non-JSON request and deduct money, while the other might reject the transaction with a syntax error. While a good protocol will at least recover, that is extra unnecessary work and @@ -550,12 +866,12 @@ Very fast. Very natural. Very nice. -Undocumented unicode handling (but the best of the pack. Unicode escapes +Undocumented Unicode handling (but the best of the pack. Unicode escapes still don't get parsed properly). Very inflexible. -No roundtripping. +No round-tripping. Does not generate valid JSON texts (key strings are often unquoted, empty keys result in nothing being output) @@ -564,6 +880,30 @@ =back + +=head2 JSON and YAML + +You often hear that JSON is a subset (or a close subset) of YAML. This is, +however, a mass hysteria and very far from the truth. In general, there is +no way to configure JSON::XS to output a data structure as valid YAML. + +If you really must use JSON::XS to generate YAML, you should use this +algorithm (subject to change in future versions): + + my $to_yaml = JSON::XS->new->utf8->space_after (1); + my $yaml = $to_yaml->encode ($ref) . "\n"; + +This will usually generate JSON texts that also parse as valid +YAML. Please note that YAML has hardcoded limits on (simple) object key +lengths that JSON doesn't have, so you should make sure that your hash +keys are noticeably shorter than the 1024 characters YAML allows. + +There might be other incompatibilities that I am not aware of. In general +you should not try to generate YAML with a JSON generator or vice versa, +or try to parse JSON with a YAML parser or vice versa: chances are high +that you will run into severe interoperability problems. + + =head2 SPEED It seems that JSON::XS is surprisingly fast, as shown in the following @@ -571,47 +911,57 @@ in the JSON::XS distribution, to make it easy to compare on your own system. -First comes a comparison between various modules using a very short JSON -string: +First comes a comparison between various modules using a very short +single-line JSON string: - {"method": "handleMessage", "params": ["user1", "we were just talking"], "id": null} + {"method": "handleMessage", "params": ["user1", "we were just talking"], \ + "id": null, "array":[1,11,234,-5,1e5,1e7, true, false]} -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). Higher is better: +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 | 11488.516 | 7823.035 | - JSON::DWIW | 94708.054 | 129094.260 | - JSON::PC | 63884.157 | 128528.212 | - JSON::Syck | 34898.677 | 42096.911 | - JSON::XS | 654027.064 | 396423.669 | - JSON::XS/2 | 371564.190 | 371725.613 | + 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 more than six times faster than JSON::DWIW on -encoding, more than three times faster on decoding, and about thirty times -faster than JSON, even with pretty-printing and key sorting. +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 compares +favourably to Storable for small amounts of data. Using a longer test string (roughly 18KB, generated from Yahoo! Locals search API (http://nanoref.com/yahooapis/mgPdGg): module | encode | decode | -----------|------------|------------| - JSON | 273.023 | 44.674 | - JSON::DWIW | 1089.383 | 1145.704 | - JSON::PC | 3097.419 | 2393.921 | - JSON::Syck | 514.060 | 843.053 | - JSON::XS | 6479.668 | 3636.364 | - JSON::XS/2 | 3774.221 | 3599.124 | + 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 | -----------+------------+------------+ -Again, JSON::XS leads by far. +Again, JSON::XS leads by far (except for Storable which non-surprisingly +decodes faster). -On large strings containing lots of high unicode characters, some modules +On large strings containing lots of high Unicode characters, some modules (such as JSON::PC) seem to decode faster than JSON::XS, but the result -will be broken due to missing (or wrong) unicode handling. Others refuse +will be broken due to missing (or wrong) Unicode handling. Others refuse to decode or encode properly, so it was impossible to prepare a fair comparison table for that case. @@ -627,10 +977,12 @@ Second, you need to avoid resource-starving attacks. That means you should limit the size of JSON texts you accept, or make sure then when your -resources run out, thats just fine (e.g. by using a separate process that +resources run out, that's just fine (e.g. by using a separate process that can crash safely). The size of a JSON text in octets or characters is usually a good indication of the size of the resources required to decode -it into a Perl structure. +it into a Perl structure. While JSON::XS can check the size of the JSON +text, it might be too late when you already have it in memory, so you +might want to check the size before you accept the string. Third, JSON::XS recurses using the C stack when decoding objects and arrays. The C stack is a limited resource: for instance, on my amd64 @@ -645,6 +997,24 @@ of. In that case, you get to keep the pieces. I am always open for hints, though... +If you are using JSON::XS to return packets to consumption +by JavaScript scripts in a browser you should have a look at +L 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 doing security +right). + + +=head1 THREADS + +This module is I guaranteed to be thread safe and there are no +plans to change this until Perl gets thread support (as opposed to the +horribly slow so-called "threads" which are simply slow and bloated +process simulations - use fork, its I faster, cheaper, better). + +(It might actually work, but you have been warned). + =head1 BUGS @@ -653,10 +1023,31 @@ still relatively early in its development. If you keep reporting bugs they will be fixed swiftly, though. +Please refrain from using rt.cpan.org or any other bug reporting +service. I put the contact address into my modules for a reason. + =cut -sub true() { \1 } -sub false() { \0 } +our $true = do { bless \(my $dummy = 1), "JSON::XS::Boolean" }; +our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" }; + +sub true() { $true } +sub false() { $false } + +sub is_bool($) { + UNIVERSAL::isa $_[0], "JSON::XS::Boolean" +# or UNIVERSAL::isa $_[0], "JSON::Literal" +} + +XSLoader::load "JSON::XS", $VERSION; + +package JSON::XS::Boolean; + +use overload + "0+" => sub { ${$_[0]} }, + "++" => sub { $_[0] = ${$_[0]} + 1 }, + "--" => sub { $_[0] = ${$_[0]} - 1 }, + fallback => 1; 1;