[ViewVC] Diff of: cvs/JSON-XS/XS.pm

Comparing JSON-XS/XS.pm (file contents):
Revision 1.139 by root, Thu May 23 09:31:32 2013 UTC vs.
Revision 1.145 by root, Tue Oct 29 00:06:40 2013 UTC

 this module usually compares favourably in terms of speed, too.
 =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
 You can choose between the most compact guaranteed-single-line format
 possible (nice for simple line-based protocols), a pure-ASCII format
 package JSON::XS;
 use common::sense;
-our $VERSION = 2.34;
+our $VERSION = '3.0';
 our @ISA = qw(Exporter);
-our @EXPORT = qw(encode_json decode_json to_json from_json);
+our @EXPORT = qw(encode_json decode_json);
-sub to_json($) {
-   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");
-}
 use Exporter;
 use XSLoader;
+use Types::Serialiser ();
 =head1 FUNCTIONAL INTERFACE
 The following convenience methods are provided by this module. They are
 exported by default:
 This function call is functionally identical to:
    $perl_scalar = JSON::XS->new->utf8->decode ($json_text)
 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
 =head1 A FEW NOTES ON UNICODE AND PERL
 See SECURITY CONSIDERATIONS, below, for more info on why this is useful.
 =item $json_text = $json->encode ($perl_scalar)
-Converts the given Perl data structure (a simple scalar or a reference
+Converts the given Perl value or data structure to its JSON
-to a hash or array) to its JSON representation. Simple scalars will be
+representation. Croaks on error.
-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.
 =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
 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.
+and you need to know where the JSON text ends.
    JSON::XS->new->decode_prefix ("[1] the tail")
    => ([], 3)
 =back
 If the method is called in scalar context, then it will try to extract
 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
 from the stream as it can find and return them, or the empty list
 otherwise. For this to work, there must be no separators between the JSON
 C<incr_parse> died, in which case the input buffer and incremental parser
 state is left unchanged, to skip the text parsed so far and to reset the
 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
 This completely resets the incremental parser, that is, after this call,
 it will be as if the parser had never parsed anything.
 =back
 =head2 LIMITATIONS
 All options that affect decoding are supported, except
-C<allow_nonref>. The reason for this is that it cannot be made to
+C<allow_nonref>. The reason for this is that it cannot be made to work
-work sensibly: JSON objects and arrays are self-delimited, i.e. you can concatenate
+sensibly: JSON objects and arrays are self-delimited, i.e. you can
-them back to back and still decode them perfectly. This does not hold true
+concatenate them back to back and still decode them perfectly. This does
-for JSON numbers, however.
+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
 of C<1> and C<2>? In neither case you can tell, and this is why JSON::XS
 takes the conservative route and disallows this case.
 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 (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 leats significant bit.
+the least significant bit.
 =item true, false
-These JSON atoms become C<JSON::XS::true> and C<JSON::XS::false>,
+These JSON atoms become C<Types::Serialiser::true> and
-respectively. They are overloaded to act almost exactly like the numbers
+C<Types::Serialiser::false>, respectively. They are overloaded to act
-C<1> and C<0>. You can check whether a scalar is a JSON boolean by using
+almost exactly like the numbers C<1> and C<0>. You can check whether
-the C<JSON::XS::is_bool> function.
+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 "OBJECT SERIALISATION", below, for details.
 =back
 =head2 PERL -> JSON
 =over 4
 =item hash references
-Perl hash references become JSON objects. As there is no inherent ordering
+Perl hash references become JSON objects. As there is no inherent
-in hash keys (or JSON objects), they will usually be encoded in a
+ordering in hash keys (or JSON objects), they will usually be encoded
-pseudo-random order that can change between runs of the same program but
+in a pseudo-random order. JSON::XS can optionally sort the hash keys
-stays generally the same within a single run of a program. JSON::XS can
+(determined by the I<canonical> flag), so the same datastructure will
-optionally sort the hash keys (determined by the I<canonical> flag), so
+serialise to the same JSON text (given same settings and version of
-the same datastructure will serialise to the same JSON text (given same
+JSON::XS), but this incurs a runtime overhead and is only rarely useful,
-settings and version of JSON::XS), but this incurs a runtime overhead
+e.g. when you want to compare some JSON text against another for equality.
-and is only rarely useful, e.g. when you want to compare some JSON text
-against another for equality.
 =item array references
 Perl array references become JSON arrays.
 =item other references
 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
+C<1>, which get turned into C<false> and C<true> atoms in JSON.
-also use C<JSON::XS::false> and C<JSON::XS::true> to improve readability.
+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.
+   use Types::Serialiser;
-   encode_json [\0, JSON::XS::true]      # yields [false,true]
+   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,
+These special values from the L<Types::Serialiser> module become JSON true
-respectively. You can also use C<\1> and C<\0> directly if you want.
+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
+Blessed objects are not directly representable in JSON, but C<JSON::XS>
-C<allow_blessed> and C<convert_blessed> methods on various options on
+allows various ways of handling objects. See "OBJECT SERIALISATION",
-how to deal with this: basically, you can choose between throwing an
+below, for details.
-exception, encoding the reference as if it weren't blessed, or provide
-your own serialiser method.
 =item simple scalars
 Simple Perl scalars (any scalar that is not a reference) are the most
 difficult objects to encode: JSON::XS will encode undefined scalars 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 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...]
+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}, $self->{id})
+   }
+=item 2. C<convert_blessed> is enabled and object has a C<TO_JSON> method.
+In this case, the C<TO_JSON> method of the object is invoked in scalar
+context. It must return a single scalar that can be directly encoded into
+JSON. This scalar replaces the object in the JSON text.
+For example, the following C<TO_JSON> method will convert all L<URI>
+objects to JSON strings when serialised. The fatc that these values
+originally were L<URI> objects is lost.
+   sub URI::TO_JSON {
+      my ($uri) = @_;
+      $uri->as_string
+   }
+=item 3. C<allow_blessed> is enabled.
+The object will be serialised as a JSON null value.
+=item 4. none of the above
+If none of the settings are enabled or the respective methods are missing,
+C<JSON::XS> throws an exception.
+=back
+=head3 DESERIALISATION
+For deserialisation there are only two cases to consider: either
+nonstandard tagging was used, in which case C<allow_tags> decides,
+or objects cannot be automatically be deserialised, in which
+case you can use postprocessing or the C<filter_json_object> or
+C<filter_json_single_key_object> callbacks to get some real objects our of
+your JSON.
+This section only considers the tagged value case: I a tagged JSON object
+is encountered during decoding and C<allow_tags> is disabled, a parse
+error will result (as if tagged values were not part of the grammar).
+If C<allow_tags> is enabled, C<JSON::XS> will look up the C<THAW> method
+of the package/classname used during serialisation. If there is no such
+method, the decoding will fail with an error.
+Otherwise, the C<THAW> method is invoked with the classname as first
+argument, the constant string C<JSON> as second argument, and all the
+values from the JSON array (the values originally returned by the
+C<FREEZE> method) as remaining arguments.
+The method must then return the object. While technically you can return
+any Perl scalar, you might have to enable the C<enable_nonref> setting to
+make that work in all cases, so better return an actual blessed reference.
+As an example, let's implement a C<THAW> function that regenerates the
+C<My::Object> from the C<FREEZE> example earlier:
+   sub My::Object::THAW {
+      my ($class, $serialiser, $type, $id) = @_;
+      $class->new (type => $type, id => $id)
+   }
 =head1 ENCODING/CODESET FLAG NOTES
 The interested reader might have seen a number of flags that signify
 encodings or codesets - C<utf8>, C<latin1> and C<ascii>. There seems to be
 =item C<utf8> flag disabled
 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).
 This is useful when you want to do the encoding yourself (e.g. when you
 output for these property strings, e.g.:
    $json =~ s/"__proto__"\s*:/"__proto__renamed":/g;
 This works because C<__proto__> is not valid outside of strings, so every
-occurence of C<"__proto__"\s*:> must be a string used as property name.
+occurrence of C<"__proto__"\s*:> must be a string used as property name.
 If you know of other incompatibilities, please let me know.
 =head2 JSON and YAML
 are browser design bugs, but it is still you who will have to deal with
 it, as major browser developers care only for features, not about getting
 security right).
+=head1 INTEROPERABILITY WITH OTHER MODULES
+C<JSON::XS> uses the L<Types::Serialiser> module to provide boolean
+constants. That means that the JSON true and false values will be
+comaptible to true and false values of iother modules that do the same,
+such as L<JSON::PP> and L<CBOR::XS>.
 =head1 THREADS
 This module is I<not> guaranteed to be thread safe and there are no
 plans to change this until Perl gets thread support (as opposed to the
 horribly slow so-called "threads" which are simply slow and bloated
 Sometimes people avoid the Perl locale support and directly call the
 system's setlocale function with C<LC_ALL>.
 This breaks both perl and modules such as JSON::XS, as stringification of
-numbers no longer works correcly (e.g. C<$x = 0.1; print "$x"+1> might
+numbers no longer works correctly (e.g. C<$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>.
 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
-our $true  = do { bless \(my $dummy = 1), "JSON::XS::Boolean" };
+BEGIN {
-our $false = do { bless \(my $dummy = 0), "JSON::XS::Boolean" };
+   *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  }
+   *JSON::XS::Boolean:: = *Types::Serialiser::Boolean::;
-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;
 =head1 SEE ALSO
 The F<json_xs> command line utility for quick experiments.
  Marc Lehmann <schmorp@schmorp.de>
  http://home.schmorp.de/
 =cut
+1

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing JSON-XS/XS.pm (file contents): Revision 1.139 by root, Thu May 23 09:31:32 2013 UTC vs. Revision 1.145 by root, Tue Oct 29 00:06:40 2013 UTC

Diff Legend

Comparing JSON-XS/XS.pm (file contents):
Revision 1.139 by root, Thu May 23 09:31:32 2013 UTC vs.
Revision 1.145 by root, Tue Oct 29 00:06:40 2013 UTC