--- JSON-XS/XS.pm	2009/07/13 22:13:17	1.121
+++ JSON-XS/XS.pm	2014/03/02 22:09:38	1.154
@@ -66,10 +66,10 @@
 =item * 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 I<are> exceptions to this, read the MAPPING
-section below to learn about those.
+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 I<are> minor exceptions to this, read the
+MAPPING section below to learn about those.
 
 =item * strict checking of JSON correctness
 
@@ -85,7 +85,7 @@
 =item * simple to use
 
 This module has both a simple functional interface as well as an object
-oriented interface interface.
+oriented interface.
 
 =item * reasonably versatile output formats
 
@@ -103,24 +103,16 @@
 
 use common::sense;
 
-our $VERSION = '2.24';
+our $VERSION = 3.01;
 our @ISA = qw(Exporter);
 
-our @EXPORT = qw(encode_json decode_json to_json from_json);
-
-sub to_json($) {
-   require Carp;
-   Carp::croak ("JSON::XS::to_json has been renamed to encode_json, either downgrade to pre-2.0 versions of JSON::XS or rename the call");
-}
-
-sub from_json($) {
-   require Carp;
-   Carp::croak ("JSON::XS::from_json has been renamed to decode_json, either downgrade to pre-2.0 versions of JSON::XS or rename the call");
-}
+our @EXPORT = qw(encode_json decode_json);
 
 use Exporter;
 use XSLoader;
 
+use Types::Serialiser ();
+
 =head1 FUNCTIONAL INTERFACE
 
 The following convenience methods are provided by this module. They are
@@ -151,15 +143,6 @@
 
 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<true> and C<false> values in Perl.
-
-See MAPPING, below, for more information on how JSON values are mapped to
-Perl.
-
 =back
 
 
@@ -434,7 +417,8 @@
 
 If C<$enable> is false, then the C<encode> method will output key-value
 pairs in the order Perl stores them (which will likely change between runs
-of the same script).
+of the same script, and can change even within the same run from 5.18
+onwards).
 
 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,
@@ -443,6 +427,8 @@
 
 This setting has no effect when decoding JSON texts.
 
+This setting has currently no effect on tied hashes.
+
 =item $json = $json->allow_nonref ([$enable])
 
 =item $enabled = $json->get_allow_nonref
@@ -483,26 +469,28 @@
 
 =item $enabled = $json->get_allow_blessed
 
+See L<OBJECT SERIALISATION> for details.
+
 If C<$enable> is true (or missing), then the C<encode> method will not
-barf when it encounters a blessed reference. Instead, the value of the
-B<convert_blessed> option will decide whether C<null> (C<convert_blessed>
-disabled or no C<TO_JSON> method found) or a representation of the
-object (C<convert_blessed> enabled and C<TO_JSON> method found) is being
-encoded. Has no effect on C<decode>.
+barf when it encounters a blessed reference that it cannot convert
+otherwise. Instead, a JSON C<null> value is encoded instead of the object.
 
 If C<$enable> is false (the default), then C<encode> will throw an
-exception when it encounters a blessed object.
+exception when it encounters a blessed object that it cannot convert
+otherwise.
+
+This setting has no effect on C<decode>.
 
 =item $json = $json->convert_blessed ([$enable])
 
 =item $enabled = $json->get_convert_blessed
 
+See L<OBJECT SERIALISATION> for details.
+
 If C<$enable> is true (or missing), then C<encode>, upon encountering a
 blessed object, will check for the availability of the C<TO_JSON> 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<TO_JSON> method is found, the value of C<allow_blessed> will decide what
-to do.
+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.
 
 The C<TO_JSON> method may safely call die if it wants. If C<TO_JSON>
 returns other blessed objects, those will be handled in the same
@@ -512,12 +500,28 @@
 usually in upper case letters and to avoid collisions with any C<to_json>
 function or method.
 
-This setting does not yet influence C<decode> in any way, but in the
-future, global hooks might get installed that influence C<decode> and are
-enabled by this setting.
+If C<$enable> is false (the default), then C<encode> will not consider
+this type of conversion.
 
-If C<$enable> is false, then the C<allow_blessed> setting will decide what
-to do when a blessed object is found.
+This setting has no effect on C<decode>.
+
+=item $json = $json->allow_tags ([$enable])
+
+=item $enabled = $json->allow_tags
+
+See L<OBJECT SERIALISATION> for details.
+
+If C<$enable> is true (or missing), then C<encode>, upon encountering a
+blessed object, will check for the availability of the C<FREEZE> method on
+the object's class. If found, it will be used to serialise the object into
+a nonstandard tagged JSON value (that JSON decoders cannot decode).
+
+It also causes C<decode> to parse such tagged JSON values and deserialise
+them via a call to the C<THAW> method.
+
+If C<$enable> is false (the default), then C<encode> will not consider
+this type of conversion, and tagged JSON values will cause a parse error
+in C<decode>, as if tags were not part of the grammar.
 
 =item $json = $json->filter_json_object ([$coderef->($hashref)])
 
@@ -666,22 +670,14 @@
 
 =item $json_text = $json->encode ($perl_scalar)
 
-Converts the given Perl data structure (a simple scalar or a reference
-to a hash or array) to its JSON representation. Simple scalars will be
-converted into JSON string or number sequences, while references to arrays
-become JSON arrays and references to hashes become JSON objects. Undefined
-Perl values (e.g. C<undef>) become JSON C<null> values. Neither C<true>
-nor C<false> values will be generated.
+Converts the given Perl value or data structure to its JSON
+representation. Croaks on error.
 
 =item $perl_scalar = $json->decode ($json_text)
 
 The opposite of C<encode>: expects a JSON text and tries to parse it,
 returning the resulting simple scalar or reference. Croaks on error.
 
-JSON numbers and strings become simple Perl scalars. JSON arrays become
-Perl arrayrefs and JSON objects become Perl hashrefs. C<true> becomes
-C<1>, C<false> becomes C<0> and C<null> becomes C<undef>.
-
 =item ($perl_scalar, $characters) = $json->decode_prefix ($json_text)
 
 This works like the C<decode> method, but instead of raising an exception
@@ -690,8 +686,7 @@
 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.
+and you need to know where the JSON text ends.
 
    JSON::XS->new->decode_prefix ("[1] the tail")
    => ([], 3)
@@ -713,8 +708,8 @@
 JSON::XS will only attempt to parse the JSON text once it is sure it
 has enough text to get a decisive result, using a very simple but
 truly incremental parser. This means that it sometimes won't stop as
-early as the full parser, for example, it doesn't detect parenthese
-mismatches. The only thing it guarantees is that it starts decoding as
+early as the full parser, for example, it doesn't detect mismatched
+parentheses. The only thing it guarantees is that it starts decoding as
 soon as a syntactically valid JSON text has been seen. This means you need
 to set resource limits (e.g. C<max_size>) to ensure the parser will stop
 parsing in the presence if syntax errors.
@@ -740,7 +735,7 @@
 exactly I<one> JSON object. If that is successful, it will return this
 object, otherwise it will return C<undef>. If there is a parse error,
 this method will croak just as C<decode> would do (one can then use
-C<incr_skip> to skip the errornous part). This is the most common way of
+C<incr_skip> to skip the erroneous part). This is the most common way of
 using the method.
 
 And finally, in list context, it will try to extract as many objects
@@ -751,6 +746,11 @@
 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]");
+
 =item $lvalue_string = $json->incr_text
 
 This method returns the currently stored JSON fragment as an lvalue, that
@@ -774,7 +774,7 @@
 parse state.
 
 The difference to C<incr_reset> is that only text until the parse error
-occured is removed.
+occurred is removed.
 
 =item $json->incr_reset
 
@@ -790,10 +790,10 @@
 =head2 LIMITATIONS
 
 All options that affect decoding are supported, except
-C<allow_nonref>. The reason for this is that it cannot be made to
-work sensibly: JSON objects and arrays are self-delimited, i.e. you can concatenate
-them back to back and still decode them perfectly. This does not hold true
-for JSON numbers, however.
+C<allow_nonref>. The reason for this is that it cannot be made to work
+sensibly: JSON objects and arrays are self-delimited, i.e. you can
+concatenate them back to back and still decode them perfectly. This does
+not hold true for JSON numbers, however.
 
 For example, is the string C<1> a single JSON number, or is it simply the
 start of C<12>? Or is C<12> a single JSON number, or the concatenation
@@ -982,24 +982,45 @@
 a numeric (floating point) value if that is possible without loss of
 precision. Otherwise it will preserve the number as a string value (in
 which case you lose roundtripping ability, as the JSON number will be
-re-encoded toa JSON string).
+re-encoded to a JSON string).
 
 Numbers containing a fractional or exponential part will always be
 represented as numeric (floating point) values, possibly at a loss of
 precision (in which case you might lose perfect roundtripping 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 least significant bit.
+
 =item true, false
 
-These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
-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<JSON::XS::is_bool> function.
+These JSON atoms become C<Types::Serialiser::true> and
+C<Types::Serialiser::false>, 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<Types::Serialiser::is_bool>
+function (after C<use Types::Serialier>, of course).
 
 =item null
 
 A JSON null atom becomes C<undef> in Perl.
 
+=item shell-style comments (C<< # I<text> >>)
+
+As a nonstandard extension to the JSON syntax that is enabled by the
+C<relaxed> setting, shell-style comments are allowed. They can start
+anywhere outside strings and go till the end of the line.
+
+=item tagged values (C<< (I<tag>)I<value> >>).
+
+Another nonstandard extension to the JSON syntax, enabled with the
+C<allow_tags> setting, are tagged values. In this implementation, the
+I<tag> must be a perl package/class name encoded as a JSON string, and the
+I<value> must be a JSON array encoding optional constructor arguments.
+
+See L<OBJECT SERIALISATION>, below, for details.
+
 =back
 
 
@@ -1013,15 +1034,13 @@
 
 =item hash references
 
-Perl hash references become JSON objects. As there is no inherent ordering
-in hash keys (or JSON objects), they will usually be encoded in a
-pseudo-random order that can change between runs of the same program but
-stays generally the same within a single run of a program. JSON::XS can
-optionally sort the hash keys (determined by the I<canonical> flag), so
-the same datastructure will serialise to the same JSON text (given same
-settings and version of JSON::XS), but this incurs a runtime overhead
-and is only rarely useful, e.g. when you want to compare some JSON text
-against another for equality.
+Perl hash references become JSON objects. As there is no inherent
+ordering in hash keys (or JSON objects), they will usually be encoded
+in a pseudo-random order. JSON::XS can optionally sort the hash keys
+(determined by the I<canonical> flag), so the same datastructure will
+serialise to the same JSON text (given same settings and version of
+JSON::XS), but this incurs a runtime overhead and is only rarely useful,
+e.g. when you want to compare some JSON text against another for equality.
 
 =item array references
 
@@ -1031,23 +1050,26 @@
 
 Other unblessed references are generally not allowed and will cause an
 exception to be thrown, except for references to the integers C<0> and
-C<1>, which get turned into C<false> and C<true> atoms in JSON. You can
-also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
+C<1>, which get turned into C<false> and C<true> atoms in JSON.
+
+Since C<JSON::XS> uses the boolean model from L<Types::Serialiser>, you
+can also C<use Types::Serialiser> and then use C<Types::Serialiser::false>
+and C<Types::Serialiser::true> to improve readability.
 
-   encode_json [\0, JSON::XS::true]      # yields [false,true]
+   use Types::Serialiser;
+   encode_json [\0, Types::Serialiser::true]      # yields [false,true]
 
-=item JSON::XS::true, JSON::XS::false
+=item Types::Serialiser::true, Types::Serialiser::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.
+These special values from the L<Types::Serialiser> module 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 directly representable in JSON. See the
-C<allow_blessed> and C<convert_blessed> methods on various options on
-how to deal with this: basically, you can choose between throwing an
-exception, encoding the reference as if it weren't blessed, or provide
-your own serialiser method.
+Blessed objects are not directly representable in JSON, but C<JSON::XS>
+allows various ways of handling objects. See L<OBJECT SERIALISATION>,
+below, for details.
 
 =item simple scalars
 
@@ -1085,8 +1107,123 @@
 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.
+
 =back
 
+=head2 OBJECT SERIALISATION
+
+As JSON cannot directly represent Perl objects, you have to choose between
+a pure JSON representation (without the ability to deserialise the object
+automatically again), and a nonstandard extension to the JSON syntax,
+tagged values.
+
+=head3 SERIALISATION
+
+What happens when C<JSON::XS> encounters a Perl object depends on the
+C<allow_blessed>, C<convert_blessed> and C<allow_tags> settings, which are
+used in this order:
+
+=over 4
+
+=item 1. C<allow_tags> is enabled and the object has a C<FREEZE> method.
+
+In this case, C<JSON::XS> uses the L<Types::Serialiser> object
+serialisation protocol to create a tagged JSON value, using a nonstandard
+extension to the JSON syntax.
+
+This works by invoking the C<FREEZE> method on the object, with the first
+argument being the object to serialise, and the second argument being the
+constant string C<JSON> to distinguish it from other serialisers.
+
+The C<FREEZE> method can return any number of values (i.e. zero or
+more). These values and the paclkage/classname of the object will then be
+encoded as a tagged JSON value in the following format:
+
+   ("classname")[FREEZE return values...]
+
+e.g.:
+
+   ("URI")["http://www.google.com/"]
+   ("MyDate")[2013,10,29]
+   ("ImageData::JPEG")["Z3...VlCg=="]
+
+For example, the hypothetical C<My::Object> C<FREEZE> method might use the
+objects C<type> and C<id> members to encode the object:
+
+   sub My::Object::FREEZE {
+      my ($self, $serialiser) = @_;
+
+      ($self->{type}, $self->{id})
+   }
+
+=item 2. C<convert_blessed> is enabled and the object has a C<TO_JSON> method.
+
+In this case, the C<TO_JSON> method of the object is invoked in scalar
+context. It must return a single scalar that can be directly encoded into
+JSON. This scalar replaces the object in the JSON text.
+
+For example, the following C<TO_JSON> method will convert all L<URI>
+objects to JSON strings when serialised. The fatc that these values
+originally were L<URI> objects is lost.
+
+   sub URI::TO_JSON {
+      my ($uri) = @_;
+      $uri->as_string
+   }
+
+=item 3. C<allow_blessed> is enabled.
+
+The object will be serialised as a JSON null value.
+
+=item 4. none of the above
+
+If none of the settings are enabled or the respective methods are missing,
+C<JSON::XS> throws an exception.
+
+=back
+
+=head3 DESERIALISATION
+
+For deserialisation there are only two cases to consider: either
+nonstandard tagging was used, in which case C<allow_tags> decides,
+or objects cannot be automatically be deserialised, in which
+case you can use postprocessing or the C<filter_json_object> or
+C<filter_json_single_key_object> callbacks to get some real objects our of
+your JSON.
+
+This section only considers the tagged value case: I a tagged JSON object
+is encountered during decoding and C<allow_tags> is disabled, a parse
+error will result (as if tagged values were not part of the grammar).
+
+If C<allow_tags> is enabled, C<JSON::XS> will look up the C<THAW> method
+of the package/classname used during serialisation (it will not attempt
+to load the package as a Perl module). If there is no such method, the
+decoding will fail with an error.
+
+Otherwise, the C<THAW> method is invoked with the classname as first
+argument, the constant string C<JSON> as second argument, and all the
+values from the JSON array (the values originally returned by the
+C<FREEZE> method) as remaining arguments.
+
+The method must then return the object. While technically you can return
+any Perl scalar, you might have to enable the C<enable_nonref> setting to
+make that work in all cases, so better return an actual blessed reference.
+
+As an example, let's implement a C<THAW> function that regenerates the
+C<My::Object> from the C<FREEZE> example earlier:
+
+   sub My::Object::THAW {
+      my ($class, $serialiser, $type, $id) = @_;
+
+      $class->new (type => $type, id => $id)
+   }
+
 
 =head1 ENCODING/CODESET FLAG NOTES
 
@@ -1120,7 +1257,7 @@
 When C<utf8> is disabled (the default), then C<encode>/C<decode> generate
 and expect Unicode strings, that is, characters with high ordinal Unicode
 values (> 255) will be encoded as such characters, and likewise such
-characters are decoded as-is, no canges to them will be done, except
+characters are decoded as-is, no changes to them will be done, except
 "(re-)interpreting" them as Unicode codepoints or Unicode characters,
 respectively (to Perl, these are the same thing in strings unless you do
 funny/weird/dumb stuff).
@@ -1238,7 +1375,7 @@
 Another problem is that some javascript implementations reserve
 some property names for their own purposes (which probably makes
 them non-ECMAscript-compliant). For example, Iceweasel reserves the
-C<__proto__> property name for it's own purposes.
+C<__proto__> property name for its own purposes.
 
 If that is a problem, you could parse try to filter the resulting JSON
 output for these property strings, e.g.:
@@ -1246,7 +1383,7 @@
    $json =~ s/"__proto__"\s*:/"__proto__renamed":/g;
 
 This works because C<__proto__> is not valid outside of strings, so every
-occurence of C<"__proto__"\s*:> must be a string used as property name.
+occurrence of C<"__proto__"\s*:> must be a string used as property name.
 
 If you know of other incompatibilities, please let me know.
 
@@ -1268,12 +1405,12 @@
 This will I<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 and also has different and incompatible
-unicode handling, so you should make sure that your hash keys are
-noticeably shorter than the 1024 "stream characters" YAML allows and that
-you do not have characters with codepoint values outside the Unicode BMP
-(basic multilingual page). YAML also does not allow C<\/> sequences in
-strings (which JSON::XS does not I<currently> generate, but other JSON
-generators might).
+unicode character escape syntax, so you should make sure that your hash
+keys are noticeably shorter than the 1024 "stream characters" YAML allows
+and that you do not have characters with codepoint values outside the
+Unicode BMP (basic multilingual page). YAML also does not allow C<\/>
+sequences in strings (which JSON::XS does not I<currently> generate, but
+other JSON generators might).
 
 There might be other incompatibilities that I am not aware of (or the YAML
 specification has been changed yet again - it does so quite often). In
@@ -1302,6 +1439,12 @@
 real compatibility for many I<years> and trying to silence people who
 point out that it isn't true.
 
+Addendum/2009: the YAML 1.2 spec is still incompatible with JSON, even
+though the incompatibilities have been documented (and are known to Brian)
+for many years and the spec makes explicit claims that YAML is a superset
+of JSON. It would be so easy to fix, but apparently, bullying people and
+corrupting userdata is so much easier.
+
 =back
 
 
@@ -1318,49 +1461,48 @@
 
    {"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:
+shrink. JSON::DWIW/DS uses the deserialise function, while JSON::DWIW::FJ
+uses the from_json method). 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 compares
-favourably to Storable for small amounts of data.
+   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 (L<http://dist.schmorp.de/misc/json/long.json>).
 
-   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 result
@@ -1406,11 +1548,96 @@
 
 If you are using JSON::XS to return packets to consumption
 by JavaScript scripts in a browser you should have a look at
-L<http://jpsykes.com/47/practical-csrf-and-json-security> 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).
+L<http://blog.archive.jpsykes.com/47/practical-csrf-and-json-security/> 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).
+
+
+=head1 INTEROPERABILITY WITH OTHER MODULES
+
+C<JSON::XS> uses the L<Types::Serialiser> module to provide boolean
+constants. That means that the JSON true and false values will be
+comaptible to true and false values of iother modules that do the same,
+such as L<JSON::PP> and L<CBOR::XS>.
+
+
+=head1 INTEROPERABILITY WITH OTHER JSON DECODERS
+
+As long as you only serialise data that can be directly expressed in JSON,
+C<JSON::XS> is incapable of generating invalid JSON output (modulo bugs,
+but C<JSON::XS> has found more bugs in the official JSON testsuite (1)
+than the official JSON testsuite has found in C<JSON::XS> (0)).
+
+When you have trouble decoding JSON generated by this module using other
+decoders, then it is very likely that you have an encoding mismatch or the
+other decoder is broken.
+
+When decoding, C<JSON::XS> is strict by default and will likely catch all
+errors. There are currently two settings that change this: C<relaxed>
+makes C<JSON::XS> accept (but not generate) some non-standard extensions,
+and C<allow_tags> will allow you to encode and decode Perl objects, at the
+cost of not outputting valid JSON anymore.
+
+=head2 TAGGED VALUE SYNTAX AND STANDARD JSON EN/DECODERS
+
+When you use C<allow_tags> to use the extended (and also nonstandard and
+invalid) JSON syntax for serialised objects, and you still want to decode
+the generated When you want to serialise objects, you can run a regex
+to replace the tagged syntax by standard JSON arrays (it only works for
+"normal" packagesnames without comma, newlines or single colons). First,
+the readable Perl version:
+
+   # if your FREEZE methods return no values, you need this replace first:
+   $json =~ s/\( \s* (" (?: [^\\":,]+|\\.|::)* ") \s* \) \s* \[\s*\]/[$1]/gx;
+
+   # this works for non-empty constructor arg lists:
+   $json =~ s/\( \s* (" (?: [^\\":,]+|\\.|::)* ") \s* \) \s* \[/[$1,/gx;
+
+And here is a less readable version that is easy to adapt to other
+languages:
+
+   $json =~ s/\(\s*("([^\\":,]+|\\.|::)*")\s*\)\s*\[/[$1,/g;
+
+Here is an ECMAScript version (same regex):
+
+   json = json.replace (/\(\s*("([^\\":,]+|\\.|::)*")\s*\)\s*\[/g, "[$1,");
+
+Since this syntax converts to standard JSON arrays, it might be hard to
+distinguish serialised objects from normal arrays. You can prepend a
+"magic number" as first array element to reduce chances of a collision:
+
+   $json =~ s/\(\s*("([^\\":,]+|\\.|::)*")\s*\)\s*\[/["XU1peReLzT4ggEllLanBYq4G9VzliwKF",$1,/g;
+
+And after decoding the JSON text, you could walk the data
+structure looking for arrays with a first element of
+C<XU1peReLzT4ggEllLanBYq4G9VzliwKF>.
+
+The same approach can be used to create the tagged format with another
+encoder. First, you create an array with the magic string as first member,
+the classname as second, and constructor arguments last, encode it as part
+of your JSON structure, and then:
+
+   $json =~ s/\[\s*"XU1peReLzT4ggEllLanBYq4G9VzliwKF"\s*,\s*("([^\\":,]+|\\.|::)*")\s*,/($1)[/g;
+
+Again, this has some limitations - the magic string must not be encoded
+with character escapes, and the constructor arguments must be non-empty.
+
+
+=head1 RFC7158
+
+Since this module was written, Google has written a new JSON RFC, RFC
+7158. Unfortunately, this RFC breaks compatibility with both the original
+JSON specification on www.json.org and RFC4627.
+
+As far as I can see, you can get partial compatibility when parsing by
+using C<< ->allow_nonref >>. However, consider thew security implications
+of doing so.
+
+I haven't decided yet whether to break compatibility with RFC4627 by
+default (and potentially leave applications insecure), or change the
+default to follow RFC7158.
 
 
 =head1 THREADS
@@ -1423,6 +1650,24 @@
 (It might actually work, but you have been warned).
 
 
+=head1 THE PERILS OF SETLOCALE
+
+Sometimes people avoid the Perl locale support and directly call the
+system's setlocale function with C<LC_ALL>.
+
+This breaks both perl and modules such as JSON::XS, as stringification of
+numbers no longer works correctly (e.g. C<$x = 0.1; print "$x"+1> might
+print C<1>, and JSON::XS might output illegal JSON as JSON::XS relies on
+perl to stringify numbers).
+
+The solution is simple: don't call C<setlocale>, or use it for only those
+categories you need, such as C<LC_MESSAGES> or C<LC_CTYPE>.
+
+If you need C<LC_NUMERIC>, you should enable it only around the code that
+actually needs it (avoiding stringification of numbers), and restore it
+afterwards.
+
+
 =head1 BUGS
 
 While the goal of this module is to be correct, that unfortunately does
@@ -1434,29 +1679,18 @@
 
 =cut
 
-our $true  = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
-our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
+BEGIN {
+   *true    = \$Types::Serialiser::true;
+   *true    = \&Types::Serialiser::true;
+   *false   = \$Types::Serialiser::false;
+   *false   = \&Types::Serialiser::false;
+   *is_bool = \&Types::Serialiser::is_bool;
 
-sub true()  { $true  }
-sub false() { $false }
-
-sub is_bool($) {
-   UNIVERSAL::isa $_[0], "JSON::XS::Boolean"
-#      or UNIVERSAL::isa $_[0], "JSON::Literal"
+   *JSON::XS::Boolean:: = *Types::Serialiser::Boolean::;
 }
 
 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;
-
 =head1 SEE ALSO
 
 The F<json_xs> command line utility for quick experiments.
@@ -1468,3 +1702,5 @@
 
 =cut
 
+1
+