Provided by: perl-doc_5.26.1-6_all bug


       JSON::PP - JSON::XS compatible pure-Perl module.


        use JSON::PP;

        # exported functions, they croak on error
        # and expect/generate UTF-8

        $utf8_encoded_json_text = encode_json $perl_hash_or_arrayref;
        $perl_hash_or_arrayref  = decode_json $utf8_encoded_json_text;

        # OO-interface

        $json = JSON::PP->new->ascii->pretty->allow_nonref;

        $json_text   = $json->encode( $perl_scalar );
        $perl_scalar = $json->decode( $json_text );

        $pretty_printed = $json->pretty->encode( $perl_scalar ); # pretty-printing

        # Note that JSON version 2.0 and above will automatically use
        # JSON::XS or JSON::PP, so you should be able to just:

        use JSON;



       JSON::XS 2.27 (~2.30) compatible.


       JSON::PP had been included in JSON distribution (CPAN module).  It was a perl core module
       in Perl 5.14.


       This module is JSON::XS compatible pure Perl module.  (Perl 5.8 or later is recommended)

       JSON::XS is the fastest and most proper JSON module on CPAN.  It is written by Marc
       Lehmann in C, so must be compiled and installed in the used environment.

       JSON::PP is a pure-Perl module and has compatibility to JSON::XS.

       ·   correct unicode handling

           This module knows how to handle Unicode (depending on Perl version).


       ·   round-trip integrity

           When you serialise a perl data structure using only data types 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

           There is no guessing, no generating of illegal JSON texts by default, and only JSON is
           accepted as input by default (the latter is a security feature).  But when some
           options are set, loose checking features are available.


       Some documents are copied and modified from "FUNCTIONAL INTERFACE" in JSON::XS.

           $json_text = encode_json $perl_scalar

       Converts the given Perl data structure to a UTF-8 encoded, binary string.

       This function call is functionally identical to:

           $json_text = JSON::PP->new->utf8->encode($perl_scalar)

           $perl_scalar = decode_json $json_text

       The opposite of "encode_json": expects an UTF-8 (binary) string and tries to parse that as
       an UTF-8 encoded JSON text, returning the resulting reference.

       This function call is functionally identical to:

           $perl_scalar = JSON::PP->new->utf8->decode($json_text)

           $is_boolean = JSON::PP::is_bool($scalar)

       Returns true if the passed scalar represents either JSON::PP::true or JSON::PP::false, two
       constants that act like 1 and 0 respectively and are also used to represent JSON "true"
       and "false" in Perl strings.

       Returns JSON true value which is blessed object.  It "isa" JSON::PP::Boolean object.

       Returns JSON false value which is blessed object.  It "isa" JSON::PP::Boolean object.

       Returns "undef".

       See MAPPING, below, for more information on how JSON values are mapped to Perl.


       This section supposes that your perl version is 5.8 or later.

       If you know a JSON text from an outer world - a network, a file content, and so on, is
       encoded in UTF-8, you should use "decode_json" or "JSON" module object with "utf8"
       enabled. And the decoded result will contain UNICODE characters.

         # from network
         my $json        = JSON::PP->new->utf8;
         my $json_text   = CGI->new->param( 'json_data' );
         my $perl_scalar = $json->decode( $json_text );

         # from file content
         local $/;
         open( my $fh, '<', '' );
         $json_text   = <$fh>;
         $perl_scalar = decode_json( $json_text );

       If an outer data is not encoded in UTF-8, firstly you should "decode" it.

         use Encode;
         local $/;
         open( my $fh, '<', '' );
         my $encoding = 'cp932';
         my $unicode_json_text = decode( $encoding, <$fh> ); # UNICODE

         # or you can write the below code.
         # open( my $fh, "<:encoding($encoding)", '' );
         # $unicode_json_text = <$fh>;

       In this case, $unicode_json_text is of course UNICODE string.  So you cannot use
       "decode_json" nor "JSON" module object with "utf8" enabled.  Instead of them, you use
       "JSON" module object with "utf8" disable.

         $perl_scalar = $json->utf8(0)->decode( $unicode_json_text );

       Or "encode 'utf8'" and "decode_json":

         $perl_scalar = decode_json( encode( 'utf8', $unicode_json_text ) );
         # this way is not efficient.

       And now, you want to convert your $perl_scalar into JSON data and send it to an outer
       world - a network or a file content, and so on.

       Your data usually contains UNICODE strings and you want the converted data to be encoded
       in UTF-8, you should use "encode_json" or "JSON" module object with "utf8" enabled.

         print encode_json( $perl_scalar ); # to a network? file? or display?
         # or
         print $json->utf8->encode( $perl_scalar );

       If $perl_scalar does not contain UNICODE but $encoding-encoded strings for some reason,
       then its characters are regarded as latin1 for perl (because it does not concern with your
       $encoding).  You cannot use "encode_json" nor "JSON" module object with "utf8" enabled.
       Instead of them, you use "JSON" module object with "utf8" disable.  Note that the resulted
       text is a UNICODE string but no problem to print it.

         # $perl_scalar contains $encoding encoded string values
         $unicode_json_text = $json->utf8(0)->encode( $perl_scalar );
         # $unicode_json_text consists of characters less than 0x100
         print $unicode_json_text;

       Or "decode $encoding" all string values and "encode_json":

         $perl_scalar->{ foo } = decode( $encoding, $perl_scalar->{ foo } );
         # ... do it to each string values, then encode_json
         $json_text = encode_json( $perl_scalar );

       This method is a proper way but probably not efficient.

       See to Encode, perluniintro.


       Basically, check to JSON or JSON::XS.

           $json = JSON::PP->new

       Returns a new JSON::PP object that can be used to de/encode JSON strings.

       All boolean flags described below are by default disabled.

       The mutators for flags all return the JSON object again and thus calls can be chained:

          my $json = JSON::PP->new->utf8->space_after->encode({a => [1,2]})
          => {"a": [1, 2]}

           $json = $json->ascii([$enable])

           $enabled = $json->get_ascii

       If $enable is true (or missing), then the encode method will not generate characters
       outside the code range 0..127. Any Unicode characters outside that range will be escaped
       using either a single \uXXXX or a double \uHHHH\uLLLLL escape sequence, as per RFC4627.

       In Perl 5.005, there is no character having high value (more than 255).  See to "UNICODE

       If $enable is false, then the encode method will not escape Unicode characters unless
       required by the JSON syntax or other flags. This results in a faster and more compact

         JSON::PP->new->ascii(1)->encode([chr 0x10401])
         => ["\ud801\udc01"]

           $json = $json->latin1([$enable])

           $enabled = $json->get_latin1

       If $enable is true (or missing), then the encode method will encode the resulting JSON
       text as latin1 (or iso-8859-1), escaping any characters outside the code range 0..255.

       If $enable is false, then the encode method will not escape Unicode characters unless
       required by the JSON syntax or other flags.

         JSON::XS->new->latin1->encode (["\x{89}\x{abc}"]
         => ["\x{89}\\u0abc"]    # (perl syntax, U+abc escaped, U+89 not)


           $json = $json->utf8([$enable])

           $enabled = $json->get_utf8

       If $enable is true (or missing), then the encode method will encode the JSON result into
       UTF-8, as required by many protocols, while the decode method expects to be handled an
       UTF-8-encoded string. Please note that UTF-8-encoded strings do not contain any characters
       outside the range 0..255, they are thus useful for bytewise/binary I/O.

       (In Perl 5.005, any character outside the range 0..255 does not exist.  See to "UNICODE

       In future versions, enabling this option might enable autodetection of the UTF-16 and
       UTF-32 encoding families, as described in RFC4627.

       If $enable is false, then the encode method will return the JSON string as a (non-encoded)
       Unicode string, while decode 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:

         use Encode;
         $jsontext = encode "UTF-16BE", JSON::PP->new->encode ($object);

       Example, decode UTF-32LE-encoded JSON:

         use Encode;
         $object = JSON::PP->new->decode (decode "UTF-32LE", $jsontext);

           $json = $json->pretty([$enable])

       This enables (or disables) all of the "indent", "space_before" and "space_after" flags in
       one call to generate the most readable (or most compact) form possible.

       Equivalent to:


           $json = $json->indent([$enable])

           $enabled = $json->get_indent

       The default indent space length is three.  You can use "indent_length" to change the

           $json = $json->space_before([$enable])

           $enabled = $json->get_space_before

       If $enable is true (or missing), then the "encode" method will add an extra optional space
       before the ":" separating keys from values in JSON objects.

       If $enable is false, then the "encode" method will not add any extra space at those

       This setting has no effect when decoding JSON texts.

       Example, space_before enabled, space_after and indent disabled:

          {"key" :"value"}

           $json = $json->space_after([$enable])

           $enabled = $json->get_space_after

       If $enable is true (or missing), then the "encode" method will add an extra optional space
       after the ":" separating keys from values in JSON objects and extra whitespace after the
       "," separating key-value pairs and array members.

       If $enable is false, then the "encode" method will not add any extra space at those

       This setting has no effect when decoding JSON texts.

       Example, space_before and indent disabled, space_after enabled:

          {"key": "value"}

           $json = $json->relaxed([$enable])

           $enabled = $json->get_relaxed

       If $enable is true (or missing), then "decode" will accept some extensions to normal JSON
       syntax (see below). "encode" will not be affected in anyway. Be aware that this option
       makes you accept invalid JSON texts as if they were valid!. I suggest only to use this
       option to parse application-specific files written by humans (configuration files,
       resource files etc.)

       If $enable is false (the default), then "decode" will only accept valid JSON texts.

       Currently accepted extensions are:

       ·   list items can have an end-comma

           JSON separates 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:

                 2, <- this comma not normally allowed
                 "k1": "v1",
                 "k2": "v2", <- this comma not normally allowed

       ·   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...

           $json = $json->canonical([$enable])

           $enabled = $json->get_canonical

       If $enable is true (or missing), then the "encode" method will output JSON objects by
       sorting their keys. This is adding a comparatively high overhead.

       If $enable is false, then the "encode" method will output key-value pairs in the order
       Perl stores them (which will likely change between runs of the same script).

       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 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.

       If you want your own sorting routine, you can give a code reference or a subroutine name
       to "sort_by". See to "JSON::PP OWN METHODS".

           $json = $json->allow_nonref([$enable])

           $enabled = $json->get_allow_nonref

       If $enable is true (or missing), then the "encode" method can convert a non-reference into
       its corresponding string, number or null JSON value, which is an extension to RFC4627.
       Likewise, "decode" will accept those JSON values instead of croaking.

       If $enable is false, then the "encode" method will croak if it isn't passed an arrayref or
       hashref, as JSON texts must either be an object or array. Likewise, "decode" will croak if
       given something that is not a JSON object or array.

          JSON::PP->new->allow_nonref->encode ("Hello, World!")
          => "Hello, World!"

           $json = $json->allow_unknown ([$enable])

           $enabled = $json->get_allow_unknown

       If $enable is true (or missing), then "encode" will *not* throw an exception when it
       encounters values it cannot represent in JSON (for example, filehandles) but instead will
       encode a JSON "null" value.  Note that blessed objects are not included here and are
       handled separately by c<allow_nonref>.

       If $enable is false (the default), then "encode" will throw an exception when it
       encounters anything it cannot encode as JSON.

       This option does not affect "decode" in any way, and it is recommended to leave it off
       unless you know your communications partner.

           $json = $json->allow_blessed([$enable])

           $enabled = $json->get_allow_blessed

       If $enable is true (or missing), then the "encode" method will not barf when it encounters
       a blessed reference. Instead, the value of the convert_blessed option will decide whether
       "null" ("convert_blessed" disabled or no "TO_JSON" method found) or a representation of
       the object ("convert_blessed" enabled and "TO_JSON" method found) is being encoded. Has no
       effect on "decode".

       If $enable is false (the default), then "encode" will throw an exception when it
       encounters a blessed object.

           $json = $json->convert_blessed([$enable])

           $enabled = $json->get_convert_blessed

       If $enable is true (or missing), then "encode", upon encountering a blessed object, will
       check for the availability of the "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 "TO_JSON" method is found, the value of "allow_blessed" will decide what to

       The "TO_JSON" method may safely call die if it wants. If "TO_JSON" returns other blessed
       objects, those will be handled in the same way. "TO_JSON" must take care of not causing an
       endless recursion cycle (== crash) in this case. The name of "TO_JSON" 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 "to_json" function or method.

       This setting does not yet influence "decode" in any way.

       If $enable is false, then the "allow_blessed" setting will decide what to do when a
       blessed object is found.

           $json = $json->filter_json_object([$coderef])

       When $coderef is specified, it will be called from "decode" each time it decodes a JSON
       object. The only argument passed to the coderef 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: not "undef", which is a valid scalar), the
       original deserialised hash will be inserted. This setting can slow down decoding

       When $coderef is omitted or undefined, any existing callback will be removed and "decode"
       will not change the deserialised hash in any way.

       Example, convert all JSON objects into the integer 5:

          my $js = JSON::PP->new->filter_json_object (sub { 5 });
          # returns [5]
          $js->decode ('[{}]'); # the given subroutine takes a hash reference.
          # throw an exception because allow_nonref is not enabled
          # so a lone 5 is not allowed.
          $js->decode ('{"a":1, "b":2}');

           $json = $json->filter_json_single_key_object($key [=> $coderef])

       Works remotely similar to "filter_json_object", but is only called for JSON objects having
       a single key named $key.

       This $coderef is called before the one specified via "filter_json_object", 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 "undef" but the empty
       list), the callback from "filter_json_object" will be called next, as if no single-key
       callback were specified.

       If $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 "filter_json_object" 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 "__class_whatever__", or
       "$__dollars_are_rarely_used__$" or "}ugly_brace_placement", or even things like
       "__class_md5sum(classname)__", to reduce the risk of clashing with real hashes.

       Example, decode JSON objects of the form "{ "__widget__" => <id> }" into the corresponding
       $WIDGET{<id>} object:

          # return whatever is in $WIDGET{5}:
             ->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} =;
                $WIDGET{$self->{id}} = $self;

             { __widget__ => $self->{id} }

           $json = $json->shrink([$enable])

           $enabled = $json->get_shrink

       In JSON::XS, this flag resizes strings generated by either "encode" or "decode" to their
       minimum size possible.  It will also try to downgrade any strings to octet-form if

       In JSON::PP, it is noop about resizing strings but tries "utf8::downgrade" to the returned
       string by "encode".  See to utf8.


           $json = $json->max_depth([$maximum_nesting_depth])

           $max_depth = $json->get_max_depth

       Sets the maximum nesting level (default 512) accepted while encoding or decoding. If a
       higher nesting level is detected in JSON text or a Perl data structure, then the encoder
       and decoder will stop and croak at that point.

       Nesting level is defined by number of hash- or arrayrefs that the encoder needs to
       traverse to reach a given point or the number of "{" or "[" characters without their
       matching closing parenthesis crossed to reach a given character in a string.

       If no argument is given, the highest possible setting will be used, which is rarely

       See "SECURITY CONSIDERATIONS" in JSON::XS for more info on why this is useful.

       When a large value (100 or more) was set and it de/encodes a deep nested object/text, it
       may raise a warning 'Deep recursion on subroutine' at the perl runtime phase.

           $json = $json->max_size([$maximum_string_size])

           $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 0, meaning no limit. When "decode" is called on a string that is longer
       then this many bytes, it will not attempt to decode the string but throw an exception.
       This setting has no effect on "encode" (yet).

       If no argument is given, the limit check will be deactivated (same as when 0 is

       See "SECURITY CONSIDERATIONS" in JSON::XS for more info on why this is useful.

           $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. "undef") become JSON "null" values.  References
       to the integers 0 and 1 are converted into "true" and "false".

           $perl_scalar = $json->decode($json_text)

       The opposite of "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. "true" becomes 1 ("JSON::true"), "false" becomes 0
       ("JSON::false") and "null" becomes "undef".

           ($perl_scalar, $characters) = $json->decode_prefix($json_text)

       This works like the "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.

          JSON->new->decode_prefix ("[1] the tail")
          => ([], 3)


       Most of this section are copied and modified from "INCREMENTAL PARSING" in JSON::XS.

       In some cases, there is the need for incremental parsing of JSON texts.  This module does
       allow you to parse a JSON stream incrementally.  It does so by accumulating text until it
       has a full JSON object, which it then can decode. This process is similar to using
       "decode_prefix" to see if a full JSON object is available, but is much more efficient (and
       can be implemented with a minimum of method calls).

       This module 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
       parentheses mismatches. 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. "max_size") to ensure the parser will stop parsing in the presence if syntax errors.

       The following methods implement this incremental parser.

           $json->incr_parse( [$string] ) # void context

           $obj_or_undef = $json->incr_parse( [$string] ) # scalar context

           @obj_or_empty = $json->incr_parse( [$string] ) # list context

       This is the central parsing function. It can both append new text and extract objects from
       the stream accumulated so far (both of these functions are optional).

       If $string is given, then this string is appended to the already existing JSON fragment
       stored in the $json object.

       After that, if the function is called in void context, it will simply return without doing
       anything further. This can be used to add more text in as many chunks as you want.

       If the method is called in scalar context, then it will try to extract exactly one JSON
       object. If that is successful, it will return this object, otherwise it will return
       "undef". If there is a parse error, this method will croak just as "decode" would do (one
       can then use "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 objects or arrays, instead they must be concatenated back-to-
       back. If an error occurs, an exception will be raised as in 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->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 call to "incr_parse" in scalar context
       successfully returned an object. Under all other circumstances you must not call this
       function (I mean it.  although in simple tests it might actually work, it will fail under
       real world conditions). As a special exception, you can also call this method before
       having parsed anything.

       This function is useful in two cases: a) finding the trailing text after a JSON object or
       b) parsing multiple JSON objects separated by non-JSON text (such as commas).

           $json->incr_text =~ s/\s*,\s*//;

       In Perl 5.005, "lvalue" attribute is not available.  You must write codes like the below:

           $string = $json->incr_text;
           $string =~ s/\s*,\s*//;
           $json->incr_text( $string );


       This will reset the state of the incremental parser and will remove the parsed text from
       the input buffer. This is useful after "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.


       This completely resets the incremental parser, that is, after this call, it will be as if
       the parser had never parsed anything.

       This is useful if you want to repeatedly parse JSON objects and want to ignore any
       trailing data, which means you have to reset the parser after each successful decode.

       See to "INCREMENTAL PARSING" in JSON::XS for examples.


           $json = $json->allow_singlequote([$enable])

       If $enable is true (or missing), then "decode" will accept JSON strings quoted by single
       quotations that are invalid JSON format.


       As same as the "relaxed" option, this option may be used to parse application-specific
       files written by humans.

           $json = $json->allow_barekey([$enable])

       If $enable is true (or missing), then "decode" will accept bare keys of JSON object that
       are invalid JSON format.

       As same as the "relaxed" option, this option may be used to parse application-specific
       files written by humans.


           $json = $json->allow_bignum([$enable])

       If $enable is true (or missing), then "decode" will convert the big integer Perl cannot
       handle as integer into a Math::BigInt object and convert a floating number (any) into a

       On the contrary, "encode" converts "Math::BigInt" objects and "Math::BigFloat" objects
       into JSON numbers with "allow_blessed" enabled.

          $bigfloat = $json->decode('2.000000000000000000000000001');
          print $json->encode($bigfloat);
          # => 2.000000000000000000000000001

       See to "MAPPING" in JSON::XS about the normal conversion of JSON number.

           $json = $json->loose([$enable])

       The unescaped [\x00-\x1f\x22\x2f\x5c] strings are invalid in JSON strings and the module
       doesn't allow you to "decode" to these (except for \x2f).  If $enable is true (or
       missing), then "decode"  will accept these unescaped strings.



           $json = $json->escape_slash([$enable])

       According to JSON Grammar, slash (U+002F) is escaped. But default JSON::PP (as same as
       JSON::XS) encodes strings without escaping slash.

       If $enable is true (or missing), then "encode" will escape slashes.

           $json = $json->indent_length($length)

       JSON::XS indent space length is 3 and cannot be changed.  JSON::PP set the indent space
       length with the given $length.  The default is 3. The acceptable range is 0 to 15.

           $json = $json->sort_by($function_name)
           $json = $json->sort_by($subroutine_ref)

       If $function_name or $subroutine_ref are set, its sort routine are used in encoding JSON

          $js = $pc->sort_by(sub { $JSON::PP::a cmp $JSON::PP::b })->encode($obj);
          # is($js, q|{"a":1,"b":2,"c":3,"d":4,"e":5,"f":6,"g":7,"h":8,"i":9}|);

          $js = $pc->sort_by('own_sort')->encode($obj);
          # is($js, q|{"a":1,"b":2,"c":3,"d":4,"e":5,"f":6,"g":7,"h":8,"i":9}|);

          sub JSON::PP::own_sort { $JSON::PP::a cmp $JSON::PP::b }

       As the sorting routine runs in the JSON::PP scope, the given subroutine name and the
       special variables $a, $b will begin 'JSON::PP::'.

       If $integer is set, then the effect is same as "canonical" on.


       For developers.


                       depth        => $depth,
                       indent_count => $indent_count,


                       text    => $text,
                       at      => $at,
                       ch      => $ch,
                       len     => $len,
                       depth   => $depth,
                       encoding      => $encoding,
                       is_valid_utf8 => $is_valid_utf8,


       This section is copied from JSON::XS and modified to "JSON::PP".  JSON::XS and JSON::PP
       mapping mechanisms are almost equivalent.

       See to "MAPPING" in JSON::XS.

           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).

           A JSON array becomes a reference to an array in Perl.

           A JSON string becomes a string scalar in Perl - Unicode codepoints in JSON are
           represented by the same codepoints in the Perl string, so no manual decoding is

           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" 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 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"
           only guarantees precision up to but not including the least significant bit.

           When "allow_bignum" is enabled, the big integers and the numeric can be optionally
           converted into Math::BigInt and Math::BigFloat objects.

       true, false
           These JSON atoms become "JSON::PP::true" and "JSON::PP::false", respectively. They are
           overloaded to act almost exactly like the numbers 1 and 0. You can check whether a
           scalar is a JSON boolean by using the "JSON::is_bool" function.

              print JSON::PP::true . "\n";
               => true
              print JSON::PP::true + 1;
               => 1

              ok(JSON::true eq  '1');
              ok(JSON::true == 1);

           "JSON" will install these missing overloading features to the backend modules.

           A JSON null atom becomes "undef" in Perl.

           "JSON::PP::null" returns "undef".

       The mapping from Perl to JSON is slightly more difficult, as Perl is a truly typeless
       language, so we can only guess which JSON type is meant by a Perl value.

       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" optionally sort the hash keys (determined by the 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

       array references
           Perl array references become JSON arrays.

       other references
           Other unblessed references are generally not allowed and will cause an exception to be
           thrown, except for references to the integers 0 and 1, which get turned into "false"
           and "true" atoms in JSON. You can also use "JSON::false" and "JSON::true" to improve

              to_json [\0,JSON::PP::true]      # yields [false,true]

       JSON::PP::true, JSON::PP::false, JSON::PP::null
           These special values become JSON true and JSON false values, respectively. You can
           also use "\1" and "\0" directly if you want.

           JSON::PP::null returns "undef".

       blessed objects
           Blessed objects are not directly representable in JSON. See the "allow_blessed" and
           "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.

           See to convert_blessed.

       simple scalars
           Simple Perl scalars (any scalar that is not a reference) are the most difficult
           objects to encode: JSON::XS and JSON::PP will encode undefined scalars as JSON "null"
           values, scalars that have last been used in a string context before encoding as JSON
           strings, and anything else as number value:

              # dump as number
              encode_json [2]                      # yields [2]
              encode_json [-3.0e17]                # yields [-3e+17]
              my $value = 5; encode_json [$value]  # yields [5]

              # used as string, so dump as string
              print $value;
              encode_json [$value]                 # yields ["5"]

              # undef becomes null
              encode_json [undef]                  # yields [null]

           You can force the type to be a 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:

              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 choice is yours.

           You cannot currently force the type in other, less obscure, ways.

           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.

       Big Number
           When "allow_bignum" is enabled, "encode" converts "Math::BigInt" objects and
           "Math::BigFloat" objects into JSON numbers.


       If you do not know about Unicode on Perl well, please check "A FEW NOTES ON UNICODE AND
       PERL" in JSON::XS.

   Perl 5.8 and later
       Perl can handle Unicode and the JSON::PP de/encode methods also work properly.

           $json->allow_nonref->encode(chr hex 3042);
           $json->allow_nonref->encode(chr hex 12345);

       Returns "\u3042" and "\ud808\udf45" respectively.


       Returns UTF-8 encoded strings with UTF8 flag, regarded as "U+3042" and "U+12345".

       Note that the versions from Perl 5.8.0 to 5.8.2, Perl built-in "join" was broken, so
       JSON::PP wraps the "join" with a subroutine. Thus JSON::PP works slow in the versions.

   Perl 5.6
       Perl can handle Unicode and the JSON::PP de/encode methods also work.

   Perl 5.005
       Perl 5.005 is a byte semantics world -- all strings are sequences of bytes.  That means
       the unicode handling is not available.

       In encoding,

           $json->allow_nonref->encode(chr hex 3042);  # hex 3042 is 12354.
           $json->allow_nonref->encode(chr hex 12345); # hex 12345 is 74565.

       Returns "B" and "E", as "chr" takes a value more than 255, it treats as "$value % 256", so
       the above codes are equivalent to :

           $json->allow_nonref->encode(chr 66);
           $json->allow_nonref->encode(chr 69);

       In decoding,


       The returned is a byte sequence "0xE3 0x81 0x82" for UTF-8 encoded Japanese character
       ("HIRAGANA LETTER A").  And if it is represented in Unicode code point, "U+3042".



       We ordinary expect the returned value is a Unicode character "U+3042".  But here is 5.005
       world. This is "0xE3 0x81 0x82".


       This is not a character "U+12345" but bytes - "0xf0 0x92 0x8d 0x85".


       memory saving


       Most of the document are copied and modified from JSON::XS doc.


       RFC4627 (<>)


       Makamaka Hannyaharamitu, <makamaka[at]>


       Copyright 2007-2016 by Makamaka Hannyaharamitu

       This library is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.