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+package JSON;
+
+
+use strict;
+use Carp ();
+use Exporter;
+BEGIN { @JSON::ISA = 'Exporter' }
+
+@JSON::EXPORT = qw(from_json to_json jsonToObj objToJson encode_json decode_json);
+
+BEGIN {
+ $JSON::VERSION = '2.94';
+ $JSON::DEBUG = 0 unless (defined $JSON::DEBUG);
+ $JSON::DEBUG = $ENV{ PERL_JSON_DEBUG } if exists $ENV{ PERL_JSON_DEBUG };
+}
+
+my %RequiredVersion = (
+ 'JSON::PP' => '2.27203',
+ 'JSON::XS' => '2.34',
+);
+
+# XS and PP common methods
+
+my @PublicMethods = qw/
+ ascii latin1 utf8 pretty indent space_before space_after relaxed canonical allow_nonref
+ allow_blessed convert_blessed filter_json_object filter_json_single_key_object
+ shrink max_depth max_size encode decode decode_prefix allow_unknown
+/;
+
+my @Properties = qw/
+ ascii latin1 utf8 indent space_before space_after relaxed canonical allow_nonref
+ allow_blessed convert_blessed shrink max_depth max_size allow_unknown
+/;
+
+my @XSOnlyMethods = qw/allow_tags/; # Currently nothing
+
+my @PPOnlyMethods = qw/
+ indent_length sort_by
+ allow_singlequote allow_bignum loose allow_barekey escape_slash as_nonblessed
+/; # JSON::PP specific
+
+
+# used in _load_xs and _load_pp ($INSTALL_ONLY is not used currently)
+my $_INSTALL_DONT_DIE = 1; # When _load_xs fails to load XS, don't die.
+my $_ALLOW_UNSUPPORTED = 0;
+my $_UNIV_CONV_BLESSED = 0;
+
+
+# Check the environment variable to decide worker module.
+
+unless ($JSON::Backend) {
+ $JSON::DEBUG and Carp::carp("Check used worker module...");
+
+ my $backend = exists $ENV{PERL_JSON_BACKEND} ? $ENV{PERL_JSON_BACKEND} : 1;
+
+ if ($backend eq '1') {
+ $backend = 'JSON::XS,JSON::PP';
+ }
+ elsif ($backend eq '0') {
+ $backend = 'JSON::PP';
+ }
+ elsif ($backend eq '2') {
+ $backend = 'JSON::XS';
+ }
+ $backend =~ s/\s+//g;
+
+ my @backend_modules = split /,/, $backend;
+ while(my $module = shift @backend_modules) {
+ if ($module =~ /JSON::XS/) {
+ _load_xs($module, @backend_modules ? $_INSTALL_DONT_DIE : 0);
+ }
+ elsif ($module =~ /JSON::PP/) {
+ _load_pp($module);
+ }
+ elsif ($module =~ /JSON::backportPP/) {
+ _load_pp($module);
+ }
+ else {
+ Carp::croak "The value of environmental variable 'PERL_JSON_BACKEND' is invalid.";
+ }
+ last if $JSON::Backend;
+ }
+}
+
+
+sub import {
+ my $pkg = shift;
+ my @what_to_export;
+ my $no_export;
+
+ for my $tag (@_) {
+ if ($tag eq '-support_by_pp') {
+ if (!$_ALLOW_UNSUPPORTED++) {
+ JSON::Backend::XS
+ ->support_by_pp(@PPOnlyMethods) if ($JSON::Backend->is_xs);
+ }
+ next;
+ }
+ elsif ($tag eq '-no_export') {
+ $no_export++, next;
+ }
+ elsif ( $tag eq '-convert_blessed_universally' ) {
+ my $org_encode = $JSON::Backend->can('encode');
+ eval q|
+ require B;
+ local $^W;
+ no strict 'refs';
+ *{"${JSON::Backend}\::encode"} = sub {
+ # only works with Perl 5.18+
+ local *UNIVERSAL::TO_JSON = sub {
+ my $b_obj = B::svref_2object( $_[0] );
+ return $b_obj->isa('B::HV') ? { %{ $_[0] } }
+ : $b_obj->isa('B::AV') ? [ @{ $_[0] } ]
+ : undef
+ ;
+ };
+ $org_encode->(@_);
+ };
+ | if ( !$_UNIV_CONV_BLESSED++ );
+ next;
+ }
+ push @what_to_export, $tag;
+ }
+
+ return if ($no_export);
+
+ __PACKAGE__->export_to_level(1, $pkg, @what_to_export);
+}
+
+
+# OBSOLETED
+
+sub jsonToObj {
+ my $alternative = 'from_json';
+ if (defined $_[0] and UNIVERSAL::isa($_[0], 'JSON')) {
+ shift @_; $alternative = 'decode';
+ }
+ Carp::carp "'jsonToObj' will be obsoleted. Please use '$alternative' instead.";
+ return JSON::from_json(@_);
+};
+
+sub objToJson {
+ my $alternative = 'to_json';
+ if (defined $_[0] and UNIVERSAL::isa($_[0], 'JSON')) {
+ shift @_; $alternative = 'encode';
+ }
+ Carp::carp "'objToJson' will be obsoleted. Please use '$alternative' instead.";
+ JSON::to_json(@_);
+};
+
+
+# INTERFACES
+
+sub to_json ($@) {
+ if (
+ ref($_[0]) eq 'JSON'
+ or (@_ > 2 and $_[0] eq 'JSON')
+ ) {
+ Carp::croak "to_json should not be called as a method.";
+ }
+ my $json = JSON->new;
+
+ if (@_ == 2 and ref $_[1] eq 'HASH') {
+ my $opt = $_[1];
+ for my $method (keys %$opt) {
+ $json->$method( $opt->{$method} );
+ }
+ }
+
+ $json->encode($_[0]);
+}
+
+
+sub from_json ($@) {
+ if ( ref($_[0]) eq 'JSON' or $_[0] eq 'JSON' ) {
+ Carp::croak "from_json should not be called as a method.";
+ }
+ my $json = JSON->new;
+
+ if (@_ == 2 and ref $_[1] eq 'HASH') {
+ my $opt = $_[1];
+ for my $method (keys %$opt) {
+ $json->$method( $opt->{$method} );
+ }
+ }
+
+ return $json->decode( $_[0] );
+}
+
+
+
+sub true { $JSON::true }
+
+sub false { $JSON::false }
+
+sub null { undef; }
+
+
+sub require_xs_version { $RequiredVersion{'JSON::XS'}; }
+
+sub backend {
+ my $proto = shift;
+ $JSON::Backend;
+}
+
+#*module = *backend;
+
+
+sub is_xs {
+ return $_[0]->backend->is_xs;
+}
+
+
+sub is_pp {
+ return $_[0]->backend->is_pp;
+}
+
+
+sub pureperl_only_methods { @PPOnlyMethods; }
+
+
+sub property {
+ my ($self, $name, $value) = @_;
+
+ if (@_ == 1) {
+ my %props;
+ for $name (@Properties) {
+ my $method = 'get_' . $name;
+ if ($name eq 'max_size') {
+ my $value = $self->$method();
+ $props{$name} = $value == 1 ? 0 : $value;
+ next;
+ }
+ $props{$name} = $self->$method();
+ }
+ return \%props;
+ }
+ elsif (@_ > 3) {
+ Carp::croak('property() can take only the option within 2 arguments.');
+ }
+ elsif (@_ == 2) {
+ if ( my $method = $self->can('get_' . $name) ) {
+ if ($name eq 'max_size') {
+ my $value = $self->$method();
+ return $value == 1 ? 0 : $value;
+ }
+ $self->$method();
+ }
+ }
+ else {
+ $self->$name($value);
+ }
+
+}
+
+
+
+# INTERNAL
+
+sub __load_xs {
+ my ($module, $opt) = @_;
+
+ $JSON::DEBUG and Carp::carp "Load $module.";
+ my $required_version = $RequiredVersion{$module} || '';
+
+ eval qq|
+ use $module $required_version ();
+ |;
+
+ if ($@) {
+ if (defined $opt and $opt & $_INSTALL_DONT_DIE) {
+ $JSON::DEBUG and Carp::carp "Can't load $module...($@)";
+ return 0;
+ }
+ Carp::croak $@;
+ }
+ $JSON::BackendModuleXS = $module;
+ return 1;
+}
+
+sub _load_xs {
+ my ($module, $opt) = @_;
+ __load_xs($module, $opt) or return;
+
+ my $data = join("", <DATA>); # this code is from Jcode 2.xx.
+ close(DATA);
+ eval $data;
+ JSON::Backend::XS->init($module);
+
+ return 1;
+};
+
+
+sub __load_pp {
+ my ($module, $opt) = @_;
+
+ $JSON::DEBUG and Carp::carp "Load $module.";
+ my $required_version = $RequiredVersion{$module} || '';
+
+ eval qq| use $module $required_version () |;
+
+ if ($@) {
+ if ( $module eq 'JSON::PP' ) {
+ $JSON::DEBUG and Carp::carp "Can't load $module ($@), so try to load JSON::backportPP";
+ $module = 'JSON::backportPP';
+ local $^W; # if PP installed but invalid version, backportPP redefines methods.
+ eval qq| require $module |;
+ }
+ Carp::croak $@ if $@;
+ }
+ $JSON::BackendModulePP = $module;
+ return 1;
+}
+
+sub _load_pp {
+ my ($module, $opt) = @_;
+ __load_pp($module, $opt);
+
+ JSON::Backend::PP->init($module);
+};
+
+#
+# Helper classes for Backend Module (PP)
+#
+
+package JSON::Backend::PP;
+
+sub init {
+ my ($class, $module) = @_;
+
+ # name may vary, but the module should (always) be a JSON::PP
+
+ local $^W;
+ no strict qw(refs); # this routine may be called after JSON::Backend::XS init was called.
+ *{"JSON::decode_json"} = \&{"JSON::PP::decode_json"};
+ *{"JSON::encode_json"} = \&{"JSON::PP::encode_json"};
+ *{"JSON::is_bool"} = \&{"JSON::PP::is_bool"};
+
+ $JSON::true = ${"JSON::PP::true"};
+ $JSON::false = ${"JSON::PP::false"};
+
+ push @JSON::Backend::PP::ISA, 'JSON::PP';
+ push @JSON::ISA, $class;
+ $JSON::Backend = $class;
+ $JSON::BackendModule = $module;
+ ${"$class\::VERSION"} = $module->VERSION;
+
+ for my $method (@XSOnlyMethods) {
+ *{"JSON::$method"} = sub {
+ Carp::carp("$method is not supported in $module.");
+ $_[0];
+ };
+ }
+
+ return 1;
+}
+
+sub is_xs { 0 };
+sub is_pp { 1 };
+
+#
+# To save memory, the below lines are read only when XS backend is used.
+#
+
+package JSON;
+
+1;
+__DATA__
+
+
+#
+# Helper classes for Backend Module (XS)
+#
+
+package JSON::Backend::XS;
+
+sub init {
+ my ($class, $module) = @_;
+
+ local $^W;
+ no strict qw(refs);
+ *{"JSON::decode_json"} = \&{"$module\::decode_json"};
+ *{"JSON::encode_json"} = \&{"$module\::encode_json"};
+ *{"JSON::is_bool"} = \&{"$module\::is_bool"};
+
+ $JSON::true = ${"$module\::true"};
+ $JSON::false = ${"$module\::false"};
+
+ push @JSON::Backend::XS::ISA, $module;
+ push @JSON::ISA, $class;
+ $JSON::Backend = $class;
+ $JSON::BackendModule = $module;
+ ${"$class\::VERSION"} = $module->VERSION;
+
+ if ( $module->VERSION < 3 ) {
+ eval 'package JSON::PP::Boolean';
+ push @{"$module\::Boolean::ISA"}, qw(JSON::PP::Boolean);
+ }
+
+ for my $method (@PPOnlyMethods) {
+ *{"JSON::$method"} = sub {
+ Carp::carp("$method is not supported in $module.");
+ $_[0];
+ };
+ }
+
+ return 1;
+}
+
+sub is_xs { 1 };
+sub is_pp { 0 };
+
+sub support_by_pp {
+ my ($class, @methods) = @_;
+
+ JSON::__load_pp('JSON::PP');
+
+ local $^W;
+ no strict qw(refs);
+
+ for my $method (@methods) {
+ my $pp_method = JSON::PP->can($method) or next;
+ *{"JSON::$method"} = sub {
+ if (!$_[0]->isa('JSON::PP')) {
+ my $xs_self = $_[0];
+ my $pp_self = JSON::PP->new;
+ for (@Properties) {
+ my $getter = "get_$_";
+ $pp_self->$_($xs_self->$getter);
+ }
+ $_[0] = $pp_self;
+ }
+ $pp_method->(@_);
+ };
+ }
+
+ $JSON::DEBUG and Carp::carp("set -support_by_pp mode.");
+}
+
+1;
+__END__
+
+=head1 NAME
+
+JSON - JSON (JavaScript Object Notation) encoder/decoder
+
+=head1 SYNOPSIS
+
+ use JSON; # imports encode_json, decode_json, to_json and from_json.
+
+ # simple and fast interfaces (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->new->allow_nonref;
+
+ $json_text = $json->encode( $perl_scalar );
+ $perl_scalar = $json->decode( $json_text );
+
+ $pretty_printed = $json->pretty->encode( $perl_scalar ); # pretty-printing
+
+=head1 VERSION
+
+ 2.93
+
+=head1 DESCRIPTION
+
+This module is a thin wrapper for L<JSON::XS>-compatible modules with a few
+additional features. All the backend modules convert a Perl data structure
+to a JSON text as of RFC4627 (which we know is obsolete but we still stick
+to; see below for an option to support part of RFC7159) and vice versa.
+This module uses L<JSON::XS> by default, and when JSON::XS is not available,
+this module falls back on L<JSON::PP>, which is in the Perl core since 5.14.
+If JSON::PP is not available either, this module then falls back on
+JSON::backportPP (which is actually JSON::PP in a different .pm file)
+bundled in the same distribution as this module. You can also explicitly
+specify to use L<Cpanel::JSON::XS>, a fork of JSON::XS by Reini Urban.
+
+All these backend modules have slight incompatibilities between them,
+including extra features that other modules don't support, but as long as you
+use only common features (most important ones are described below), migration
+from backend to backend should be reasonably easy. For details, see each
+backend module you use.
+
+=head1 CHOOSING BACKEND
+
+This module respects an environmental variable called C<PERL_JSON_BACKEND>
+when it decides a backend module to use. If this environmental variable is
+not set, it tries to load JSON::XS, and if JSON::XS is not available, it
+falls back on JSON::PP, and then JSON::backportPP if JSON::PP is not available
+either.
+
+If you always don't want it to fall back on pure perl modules, set the
+variable like this (C<export> may be C<setenv>, C<set> and the likes,
+depending on your environment):
+
+ > export PERL_JSON_BACKEND=JSON::XS
+
+If you prefer Cpanel::JSON::XS to JSON::XS, then:
+
+ > export PERL_JSON_BACKEND=Cpanel::JSON::XS,JSON::XS,JSON::PP
+
+You may also want to set this variable at the top of your test files, in order
+not to be bothered with incompatibilities between backends (you need to wrap
+this in C<BEGIN>, and set before actually C<use>-ing JSON module, as it decides
+its backend as soon as it's loaded):
+
+ BEGIN { $ENV{PERL_JSON_BACKEND}='JSON::backportPP'; }
+ use JSON;
+
+=head1 USING OPTIONAL FEATURES
+
+There are a few options you can set when you C<use> this module:
+
+=over
+
+=item -support_by_pp
+
+ BEGIN { $ENV{PERL_JSON_BACKEND} = 'JSON::XS' }
+
+ use JSON -support_by_pp;
+
+ my $json = JSON->new;
+ # escape_slash is for JSON::PP only.
+ $json->allow_nonref->escape_slash->encode("/");
+
+With this option, this module loads its pure perl backend along with
+its XS backend (if available), and lets the XS backend to watch if you set
+a flag only JSON::PP supports. When you do, the internal JSON::XS object
+is replaced with a newly created JSON::PP object with the setting copied
+from the XS object, so that you can use JSON::PP flags (and its slower
+C<decode>/C<encode> methods) from then on. In other words, this is not
+something that allows you to hook JSON::XS to change its behavior while
+keeping its speed. JSON::XS and JSON::PP objects are quite different
+(JSON::XS object is a blessed scalar reference, while JSON::PP object is
+a blessed hash reference), and can't share their internals.
+
+To avoid needless overhead (by copying settings), you are advised not
+to use this option and just to use JSON::PP explicitly when you need
+JSON::PP features.
+
+=item -convert_blessed_universally
+
+ use JSON -convert_blessed_universally;
+
+ my $json = JSON->new->allow_nonref->convert_blessed;
+ my $object = bless {foo => 'bar'}, 'Foo';
+ $json->encode($object); # => {"foo":"bar"}
+
+JSON::XS-compatible backend modules don't encode blessed objects by
+default (except for their boolean values, which are typically blessed
+JSON::PP::Boolean objects). If you need to encode a data structure
+that may contain objects, you usually need to look into the structure
+and replace objects with alternative non-blessed values, or enable
+C<convert_blessed> and provide a C<TO_JSON> method for each object's
+(base) class that may be found in the structure, in order to let the
+methods replace the objects with whatever scalar values the methods
+return.
+
+If you need to serialise data structures that may contain arbitrary
+objects, it's probably better to use other serialisers (such as
+L<Sereal> or L<Storable> for example), but if you do want to use
+this module for that purpose, C<-convert_blessed_universally> option
+may help, which tweaks C<encode> method of the backend to install
+C<UNIVERSAL::TO_JSON> method (locally) before encoding, so that
+all the objects that don't have their own C<TO_JSON> method can
+fall back on the method in the C<UNIVERSAL> namespace. Note that you
+still need to enable C<convert_blessed> flag to actually encode
+objects in a data structure, and C<UNIVERSAL::TO_JSON> method
+installed by this option only converts blessed hash/array references
+into their unblessed clone (including private keys/values that are
+not supposed to be exposed). Other blessed references will be
+converted into null.
+
+This feature is experimental and may be removed in the future.
+
+=item -no_export
+
+When you don't want to import functional interfaces from a module, you
+usually supply C<()> to its C<use> statement.
+
+ use JSON (); # no functional interfaces
+
+If you don't want to import functional interfaces, but you also want to
+use any of the above options, add C<-no_export> to the option list.
+
+ # no functional interfaces, while JSON::PP support is enabled.
+ use JSON -support_by_pp, -no_export;
+
+=back
+
+=head1 FUNCTIONAL INTERFACE
+
+This section is taken from JSON::XS. C<encode_json> and C<decode_json>
+are exported by default.
+
+This module also exports C<to_json> and C<from_json> for backward
+compatibility. These are slower, and may expect/generate different stuff
+from what C<encode_json> and C<decode_json> do, depending on their
+options. It's better just to use Object-Oriented interfaces than using
+these two functions.
+
+=head2 encode_json
+
+ $json_text = encode_json $perl_scalar
+
+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:
+
+ $json_text = JSON->new->utf8->encode($perl_scalar)
+
+Except being faster.
+
+=head2 decode_json
+
+ $perl_scalar = decode_json $json_text
+
+The opposite of C<encode_json>: 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:
+
+ $perl_scalar = JSON->new->utf8->decode($json_text)
+
+Except being faster.
+
+=head2 to_json
+
+ $json_text = to_json($perl_scalar[, $optional_hashref])
+
+Converts the given Perl data structure to a Unicode string by default.
+Croaks on error.
+
+Basically, this function call is functionally identical to:
+
+ $json_text = JSON->new->encode($perl_scalar)
+
+Except being slower.
+
+You can pass an optional hash reference to modify its behavior, but
+that may change what C<to_json> expects/generates (see
+C<ENCODING/CODESET FLAG NOTES> for details).
+
+ $json_text = to_json($perl_scalar, {utf8 => 1, pretty => 1})
+ # => JSON->new->utf8(1)->pretty(1)->encode($perl_scalar)
+
+=head2 from_json
+
+ $perl_scalar = from_json($json_text[, $optional_hashref])
+
+The opposite of C<to_json>: expects a Unicode string and tries
+to parse it, returning the resulting reference. Croaks on error.
+
+Basically, this function call is functionally identical to:
+
+ $perl_scalar = JSON->new->decode($json_text)
+
+You can pass an optional hash reference to modify its behavior, but
+that may change what C<from_json> expects/generates (see
+C<ENCODING/CODESET FLAG NOTES> for details).
+
+ $perl_scalar = from_json($json_text, {utf8 => 1})
+ # => JSON->new->utf8(1)->decode($json_text)
+
+=head2 JSON::is_bool
+
+ $is_boolean = JSON::is_bool($scalar)
+
+Returns true if the passed scalar represents either JSON::true or
+JSON::false, two constants that act like C<1> and C<0> respectively
+and are also used to represent JSON C<true> and C<false> in Perl strings.
+
+See L<MAPPING>, below, for more information on how JSON values are mapped to
+Perl.
+
+=head1 COMMON OBJECT-ORIENTED INTERFACE
+
+This section is also taken from JSON::XS.
+
+The object oriented interface lets you configure your own encoding or
+decoding style, within the limits of supported formats.
+
+=head2 new
+
+ $json = JSON->new
+
+Creates a new JSON::XS-compatible backend object that can be used to de/encode JSON
+strings. All boolean flags described below are by default I<disabled>.
+
+The mutators for flags all return the backend object again and thus calls can
+be chained:
+
+ my $json = JSON->new->utf8->space_after->encode({a => [1,2]})
+ => {"a": [1, 2]}
+
+=head2 ascii
+
+ $json = $json->ascii([$enable])
+
+ $enabled = $json->get_ascii
+
+If C<$enable> is true (or missing), then the C<encode> 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
+single \uXXXX (BMP characters) or a double \uHHHH\uLLLLL escape sequence,
+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<encode> method will not escape Unicode
+characters unless required by the JSON syntax or other flags. This results
+in a faster and more compact format.
+
+See also the section I<ENCODING/CODESET FLAG NOTES> later in this document.
+
+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->new->ascii(1)->encode([chr 0x10401])
+ => ["\ud801\udc01"]
+
+=head2 latin1
+
+ $json = $json->latin1([$enable])
+
+ $enabled = $json->get_latin1
+
+If C<$enable> is true (or missing), then the C<encode> 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<decode> method
+will not be affected in any way by this flag, as C<decode> by default
+expects Unicode, which is a strict superset of latin1.
+
+If C<$enable> is false, then the C<encode> method will not escape Unicode
+characters unless required by the JSON syntax or other flags.
+
+See also the section I<ENCODING/CODESET FLAG NOTES> later in this document.
+
+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->new->latin1->encode (["\x{89}\x{abc}"]
+ => ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
+
+=head2 utf8
+
+ $json = $json->utf8([$enable])
+
+ $enabled = $json->get_utf8
+
+If C<$enable> is true (or missing), then the C<encode> method will encode
+the JSON result into UTF-8, as required by many protocols, while the
+C<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 C<0..255>, they are thus useful for bytewise/binary I/O. In future
+versions, enabling this option might enable autodetection of the UTF-16
+and UTF-32 encoding families, as described in RFC4627.
+
+If C<$enable> is false, then the C<encode> method will return the JSON
+string as a (non-encoded) Unicode string, while C<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.
+
+See also the section I<ENCODING/CODESET FLAG NOTES> later in this document.
+
+Example, output UTF-16BE-encoded JSON:
+
+ use Encode;
+ $jsontext = encode "UTF-16BE", JSON->new->encode ($object);
+
+Example, decode UTF-32LE-encoded JSON:
+
+ use Encode;
+ $object = JSON->new->decode (decode "UTF-32LE", $jsontext);
+
+=head2 pretty
+
+ $json = $json->pretty([$enable])
+
+This enables (or disables) all of the C<indent>, C<space_before> and
+C<space_after> (and in the future possibly more) flags in one call to
+generate the most readable (or most compact) form possible.
+
+=head2 indent
+
+ $json = $json->indent([$enable])
+
+ $enabled = $json->get_indent
+
+If C<$enable> is true (or missing), then the C<encode> method will use a multiline
+format as output, putting every array member or object/hash key-value pair
+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 guaranteed not to contain any C<newlines>.
+
+This setting has no effect when decoding JSON texts.
+
+=head2 space_before
+
+ $json = $json->space_before([$enable])
+
+ $enabled = $json->get_space_before
+
+If C<$enable> is true (or missing), then the C<encode> method will add an extra
+optional space before the C<:> separating keys from values in JSON objects.
+
+If C<$enable> is false, then the C<encode> method will not add any extra
+space at those places.
+
+This setting has no effect when decoding JSON texts. You will also
+most likely combine this setting with C<space_after>.
+
+Example, space_before enabled, space_after and indent disabled:
+
+ {"key" :"value"}
+
+=head2 space_after
+
+ $json = $json->space_after([$enable])
+
+ $enabled = $json->get_space_after
+
+If C<$enable> is true (or missing), then the C<encode> 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
+members.
+
+If C<$enable> is false, then the C<encode> method will not add any extra
+space at those places.
+
+This setting has no effect when decoding JSON texts.
+
+Example, space_before and indent disabled, space_after enabled:
+
+ {"key": "value"}
+
+=head2 relaxed
+
+ $json = $json->relaxed([$enable])
+
+ $enabled = $json->get_relaxed
+
+If C<$enable> is true (or missing), then C<decode> will accept some
+extensions to normal JSON syntax (see below). C<encode> will not be
+affected in anyway. I<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 C<$enable> is false (the default), then C<decode> will only accept
+valid JSON texts.
+
+Currently accepted extensions are:
+
+=over 4
+
+=item * list items can have an end-comma
+
+JSON I<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:
+
+ [
+ 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
+
+=head2 canonical
+
+ $json = $json->canonical([$enable])
+
+ $enabled = $json->get_canonical
+
+If C<$enable> is true (or missing), then the C<encode> method will output JSON objects
+by sorting their keys. This is adding a comparatively high overhead.
+
+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, 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,
+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.
+
+This setting has currently no effect on tied hashes.
+
+=head2 allow_nonref
+
+ $json = $json->allow_nonref([$enable])
+
+ $enabled = $json->get_allow_nonref
+
+If C<$enable> is true (or missing), then the C<encode> method can convert a
+non-reference into its corresponding string, number or null JSON value,
+which is an extension to RFC4627. Likewise, C<decode> will accept those JSON
+values instead of croaking.
+
+If C<$enable> is false, then the C<encode> method will croak if it isn't
+passed an arrayref or hashref, as JSON texts must either be an object
+or array. Likewise, C<decode> will croak if given something that is not a
+JSON object or array.
+
+Example, encode a Perl scalar as JSON value with enabled C<allow_nonref>,
+resulting in an invalid JSON text:
+
+ JSON->new->allow_nonref->encode ("Hello, World!")
+ => "Hello, World!"
+
+=head2 allow_unknown
+
+ $json = $json->allow_unknown ([$enable])
+
+ $enabled = $json->get_allow_unknown
+
+If C<$enable> is true (or missing), then C<encode> will I<not> throw an
+exception when it encounters values it cannot represent in JSON (for
+example, filehandles) but instead will encode a JSON C<null> value. Note
+that blessed objects are not included here and are handled separately by
+c<allow_nonref>.
+
+If C<$enable> is false (the default), then C<encode> will throw an
+exception when it encounters anything it cannot encode as JSON.
+
+This option does not affect C<decode> in any way, and it is recommended to
+leave it off unless you know your communications partner.
+
+=head2 allow_blessed
+
+ $json = $json->allow_blessed([$enable])
+
+ $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 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 that it cannot convert
+otherwise.
+
+This setting has no effect on C<decode>.
+
+=head2 convert_blessed
+
+ $json = $json->convert_blessed([$enable])
+
+ $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.
+
+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
+way. C<TO_JSON> must take care of not causing an endless recursion cycle
+(== crash) in this case. The name of C<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 any C<to_json>
+function or method.
+
+If C<$enable> is false (the default), then C<encode> will not consider
+this type of conversion.
+
+This setting has no effect on C<decode>.
+
+=head2 filter_json_object
+
+ $json = $json->filter_json_object([$coderef])
+
+When C<$coderef> is specified, it will be called from C<decode> each
+time it decodes a JSON object. The only argument is a reference to the
+newly-created hash. If the code references returns a single scalar (which
+need not be a reference), this value (i.e. a copy of that scalar to avoid
+aliasing) is inserted into the deserialised data structure. If it returns
+an empty list (NOTE: I<not> C<undef>, which is a valid scalar), the
+original deserialised hash will be inserted. This setting can slow down
+decoding considerably.
+
+When C<$coderef> is omitted or undefined, any existing callback will
+be removed and C<decode> will not change the deserialised hash in any
+way.
+
+Example, convert all JSON objects into the integer 5:
+
+ my $js = JSON->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}');
+
+=head2 filter_json_single_key_object
+
+ $json = $json->filter_json_single_key_object($key [=> $coderef])
+
+Works remotely similar to C<filter_json_object>, but is only called for
+JSON objects having a single key named C<$key>.
+
+This C<$coderef> is called before the one specified via
+C<filter_json_object>, if any. It gets passed the single value in the JSON
+object. If it returns a single value, it will be inserted into the data
+structure. If it returns nothing (not even C<undef> but the empty list),
+the callback from C<filter_json_object> will be called next, as if no
+single-key callback were specified.
+
+If C<$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<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 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__" => <id> } >>
+into the corresponding C<< $WIDGET{<id>} >> object:
+
+ # return whatever is in $WIDGET{5}:
+ JSON
+ ->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} }
+ }
+
+=head2 max_depth
+
+ $json = $json->max_depth([$maximum_nesting_depth])
+
+ $max_depth = $json->get_max_depth
+
+Sets the maximum nesting level (default C<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 C<{> or C<[>
+characters without their matching closing parenthesis crossed to reach a
+given character in a string.
+
+Setting the maximum depth to one disallows any nesting, so that ensures
+that the object is only a single hash/object or array.
+
+If no argument is given, the highest possible setting will be used, which
+is rarely useful.
+
+=head2 max_size
+
+ $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 C<0>, meaning no limit. When C<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 C<encode> (yet).
+
+If no argument is given, the limit check will be deactivated (same as when
+C<0> is specified).
+
+=head2 encode
+
+ $json_text = $json->encode($perl_scalar)
+
+Converts the given Perl value or data structure to its JSON
+representation. Croaks on error.
+
+=head2 decode
+
+ $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.
+
+=head2 decode_prefix
+
+ ($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
+and you need to know where the JSON text ends.
+
+ JSON->new->decode_prefix ("[1] the tail")
+ => ([1], 3)
+
+=head1 ADDITIONAL METHODS
+
+The following methods are for this module only.
+
+=head2 backend
+
+ $backend = $json->backend
+
+Since 2.92, C<backend> method returns an abstract backend module used currently,
+which should be JSON::Backend::XS (which inherits JSON::XS or Cpanel::JSON::XS),
+or JSON::Backend::PP (which inherits JSON::PP), not to monkey-patch the actual
+backend module globally.
+
+If you need to know what is used actually, use C<isa>, instead of string comparison.
+
+=head2 is_xs
+
+ $boolean = $json->is_xs
+
+Returns true if the backend inherits JSON::XS or Cpanel::JSON::XS.
+
+=head2 is_pp
+
+ $boolean = $json->is_pp
+
+Returns true if the backend inherits JSON::PP.
+
+=head2 property
+
+ $settings = $json->property()
+
+Returns a reference to a hash that holds all the common flag settings.
+
+ $json = $json->property('utf8' => 1)
+ $value = $json->property('utf8') # 1
+
+You can use this to get/set a value of a particular flag.
+
+=head1 INCREMENTAL PARSING
+
+This section is also taken from JSON::XS.
+
+In some cases, there is the need for incremental parsing of JSON
+texts. While this module always has to keep both JSON text and resulting
+Perl data structure in memory at one time, it 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 C<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 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.
+
+The following methods implement this incremental parser.
+
+=head2 incr_parse
+
+ $json->incr_parse( [$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 C<$string> is given, then this string is appended to the already
+existing JSON fragment stored in the C<$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 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 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 (other than
+whitespace) 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]");
+
+=head2 incr_text
+
+ $lvalue_string = $json->incr_text
+
+This method returns the currently stored JSON fragment as an lvalue, that
+is, you can manipulate it. This I<only> works when a preceding call to
+C<incr_parse> in I<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 I<will> fail under
+real world conditions). As a special exception, you can also call this
+method before having parsed anything.
+
+That means you can only use this function to look at or manipulate text
+before or after complete JSON objects, not while the parser is in the
+middle of parsing a JSON object.
+
+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).
+
+=head2 incr_skip
+
+ $json->incr_skip
+
+This will reset the state of the incremental parser and will remove
+the parsed text from the input buffer so far. This is useful after
+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
+occurred is removed.
+
+=head2 incr_reset
+
+ $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.
+
+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.
+
+=head1 MAPPING
+
+Most of this section is also taken from JSON::XS.
+
+This section describes how the backend modules map Perl values to JSON values and
+vice versa. These mappings are designed to "do the right thing" in most
+circumstances automatically, preserving round-tripping characteristics
+(what you put in comes out as something equivalent).
+
+For the more enlightened: note that in the following descriptions,
+lowercase I<perl> refers to the Perl interpreter, while uppercase I<Perl>
+refers to the abstract Perl language itself.
+
+=head2 JSON -> PERL
+
+=over 4
+
+=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).
+
+=item array
+
+A JSON array becomes a reference to an array in Perl.
+
+=item string
+
+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 necessary.
+
+=item number
+
+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, this module 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, this module only guarantees precision up to but not including
+the least significant bit.
+
+=item true, false
+
+These JSON atoms become C<JSON::true> and C<JSON::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::is_bool> function.
+
+=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.
+
+=back
+
+
+=head2 PERL -> JSON
+
+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.
+
+=over 4
+
+=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. This module can optionally sort the hash keys
+(determined by the I<canonical> flag), so the same data structure will
+serialise to the same JSON text (given same settings and version of
+the same backend), 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
+
+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
+also use C<JSON::false> and C<JSON::true> to improve readability.
+
+ encode_json [\0,JSON::true] # yields [false,true]
+
+=item JSON::true, JSON::false, JSON::null
+
+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 directly representable in JSON, but C<JSON::XS>
+allows various ways of handling objects. See L<OBJECT SERIALISATION>,
+below, for details.
+
+=item simple scalars
+
+Simple Perl scalars (any scalar that is not a reference) are the most
+difficult objects to encode: this module will encode undefined scalars as
+JSON C<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
+ $x *= 1; # same thing, the choice is yours.
+
+You can not currently force the type in other, less obscure, ways. Tell me
+if you need this capability (but don't forget to explain why it's needed
+:).
+
+Note that numerical precision has the same meaning as under Perl (so
+binary to decimal conversion follows the same rules as in Perl, which
+can differ to other languages). Also, your perl interpreter might expose
+extensions to the floating point numbers of your platform, such as
+infinities or NaN's - these cannot be represented in JSON, and it is an
+error to pass those in.
+
+=back
+
+=head2 OBJECT SERIALISATION
+
+As for Perl objects, this module only supports a pure JSON representation
+(without the ability to deserialise the object automatically again).
+
+=head3 SERIALISATION
+
+What happens when this module encounters a Perl object depends on the
+C<allow_blessed> and C<convert_blessed> settings, which are used in
+this order:
+
+=over 4
+
+=item 1. C<convert_blessed> is enabled and the object has a C<TO_JSON> method.
+
+In this case, the C<TO_JSON> method of the object is invoked in scalar
+context. It must return a single scalar that can be directly encoded into
+JSON. This scalar replaces the object in the JSON text.
+
+For example, the following C<TO_JSON> method will convert all L<URI>
+objects to JSON strings when serialised. The fact that these values
+originally were L<URI> objects is lost.
+
+ sub URI::TO_JSON {
+ my ($uri) = @_;
+ $uri->as_string
+ }
+
+=item 2. C<allow_blessed> is enabled.
+
+The object will be serialised as a JSON null value.
+
+=item 3. none of the above
+
+If none of the settings are enabled or the respective methods are missing,
+this module throws an exception.
+
+=back
+
+=head1 ENCODING/CODESET FLAG NOTES
+
+This section is taken from JSON::XS.
+
+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
+some confusion on what these do, so here is a short comparison:
+
+C<utf8> controls whether the JSON text created by C<encode> (and expected
+by C<decode>) is UTF-8 encoded or not, while C<latin1> and C<ascii> only
+control whether C<encode> escapes character values outside their respective
+codeset range. Neither of these flags conflict with each other, although
+some combinations make less sense than others.
+
+Care has been taken to make all flags symmetrical with respect to
+C<encode> and C<decode>, that is, texts encoded with any combination of
+these flag values will be correctly decoded when the same flags are used
+- in general, if you use different flag settings while encoding vs. when
+decoding you likely have a bug somewhere.
+
+Below comes a verbose discussion of these flags. Note that a "codeset" is
+simply an abstract set of character-codepoint pairs, while an encoding
+takes those codepoint numbers and I<encodes> them, in our case into
+octets. Unicode is (among other things) a codeset, UTF-8 is an encoding,
+and ISO-8859-1 (= latin 1) and ASCII are both codesets I<and> encodings at
+the same time, which can be confusing.
+
+=over 4
+
+=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 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
+want to have UTF-16 encoded JSON texts) or when some other layer does
+the encoding for you (for example, when printing to a terminal using a
+filehandle that transparently encodes to UTF-8 you certainly do NOT want
+to UTF-8 encode your data first and have Perl encode it another time).
+
+=item C<utf8> flag enabled
+
+If the C<utf8>-flag is enabled, C<encode>/C<decode> will encode all
+characters using the corresponding UTF-8 multi-byte sequence, and will
+expect your input strings to be encoded as UTF-8, that is, no "character"
+of the input string must have any value > 255, as UTF-8 does not allow
+that.
+
+The C<utf8> flag therefore switches between two modes: disabled means you
+will get a Unicode string in Perl, enabled means you get an UTF-8 encoded
+octet/binary string in Perl.
+
+=item C<latin1> or C<ascii> flags enabled
+
+With C<latin1> (or C<ascii>) enabled, C<encode> will escape characters
+with ordinal values > 255 (> 127 with C<ascii>) and encode the remaining
+characters as specified by the C<utf8> flag.
+
+If C<utf8> is disabled, then the result is also correctly encoded in those
+character sets (as both are proper subsets of Unicode, meaning that a
+Unicode string with all character values < 256 is the same thing as a
+ISO-8859-1 string, and a Unicode string with all character values < 128 is
+the same thing as an ASCII string in Perl).
+
+If C<utf8> is enabled, you still get a correct UTF-8-encoded string,
+regardless of these flags, just some more characters will be escaped using
+C<\uXXXX> then before.
+
+Note that ISO-8859-1-I<encoded> strings are not compatible with UTF-8
+encoding, while ASCII-encoded strings are. That is because the ISO-8859-1
+encoding is NOT a subset of UTF-8 (despite the ISO-8859-1 I<codeset> being
+a subset of Unicode), while ASCII is.
+
+Surprisingly, C<decode> will ignore these flags and so treat all input
+values as governed by the C<utf8> flag. If it is disabled, this allows you
+to decode ISO-8859-1- and ASCII-encoded strings, as both strict subsets of
+Unicode. If it is enabled, you can correctly decode UTF-8 encoded strings.
+
+So neither C<latin1> nor C<ascii> are incompatible with the C<utf8> flag -
+they only govern when the JSON output engine escapes a character or not.
+
+The main use for C<latin1> is to relatively efficiently store binary data
+as JSON, at the expense of breaking compatibility with most JSON decoders.
+
+The main use for C<ascii> is to force the output to not contain characters
+with values > 127, which means you can interpret the resulting string
+as UTF-8, ISO-8859-1, ASCII, KOI8-R or most about any character set and
+8-bit-encoding, and still get the same data structure back. This is useful
+when your channel for JSON transfer is not 8-bit clean or the encoding
+might be mangled in between (e.g. in mail), and works because ASCII is a
+proper subset of most 8-bit and multibyte encodings in use in the world.
+
+=back
+
+=head1 BACKWARD INCOMPATIBILITY
+
+Since version 2.90, stringification (and string comparison) for
+C<JSON::true> and C<JSON::false> has not been overloaded. It shouldn't
+matter as long as you treat them as boolean values, but a code that
+expects they are stringified as "true" or "false" doesn't work as
+you have expected any more.
+
+ if (JSON::true eq 'true') { # now fails
+
+ print "The result is $JSON::true now."; # => The result is 1 now.
+
+And now these boolean values don't inherit JSON::Boolean, either.
+When you need to test a value is a JSON boolean value or not, use
+C<JSON::is_bool> function, instead of testing the value inherits
+a particular boolean class or not.
+
+=head1 BUGS
+
+Please report bugs on backend selection and additional features
+this module provides to RT or GitHub issues for this module:
+
+=over 4
+
+=item https://rt.cpan.org/Public/Dist/Display.html?Queue=JSON
+
+=item https://github.com/makamaka/JSON/issues
+
+=back
+
+Please report bugs and feature requests on decoding/encoding
+and boolean behaviors to the author of the backend module you
+are using.
+
+=head1 SEE ALSO
+
+L<JSON::XS>, L<Cpanel::JSON::XS>, L<JSON::PP> for backends.
+
+L<JSON::MaybeXS>, an alternative that prefers Cpanel::JSON::XS.
+
+C<RFC4627>(L<http://www.ietf.org/rfc/rfc4627.txt>)
+
+=head1 AUTHOR
+
+Makamaka Hannyaharamitu, E<lt>makamaka[at]cpan.orgE<gt>
+
+JSON::XS was written by Marc Lehmann <schmorp[at]schmorp.de>
+
+The release of this new version owes to the courtesy of Marc Lehmann.
+
+
+=head1 COPYRIGHT AND LICENSE
+
+Copyright 2005-2013 by Makamaka Hannyaharamitu
+
+This library is free software; you can redistribute it and/or modify
+it under the same terms as Perl itself.
+
+=cut
+