package JSON; use strict; use Carp (); use base qw(Exporter); @JSON::EXPORT = qw(from_json to_json jsonToObj objToJson encode_json decode_json); BEGIN { $JSON::VERSION = '2.90'; $JSON::DEBUG = 0 unless (defined $JSON::DEBUG); $JSON::DEBUG = $ENV{ PERL_JSON_DEBUG } if exists $ENV{ PERL_JSON_DEBUG }; } my $Module_XS = 'JSON::XS'; my $Module_PP = 'JSON::PP'; my $Module_bp = 'JSON::backportPP'; # included in JSON distribution my $PP_Version = '2.27203'; my $XS_Version = '2.34'; # XS and PP common methods my @PublicMethods = qw/ ascii latin1 utf8 pretty indent space_before space_after relaxed canonical allow_nonref allow_blessed convert_blessed filter_json_object filter_json_single_key_object shrink max_depth max_size encode decode decode_prefix allow_unknown /; my @Properties = qw/ ascii latin1 utf8 indent space_before space_after relaxed canonical allow_nonref allow_blessed convert_blessed shrink max_depth max_size allow_unknown /; my @XSOnlyMethods = qw/allow_tags/; # Currently nothing my @PPOnlyMethods = qw/ indent_length sort_by allow_singlequote allow_bignum loose allow_barekey escape_slash as_nonblessed /; # JSON::PP specific # used in _load_xs and _load_pp ($INSTALL_ONLY is not used currently) my $_INSTALL_DONT_DIE = 1; # When _load_xs fails to load XS, don't die. my $_INSTALL_ONLY = 2; # Don't call _set_methods() my $_ALLOW_UNSUPPORTED = 0; my $_UNIV_CONV_BLESSED = 0; my $_USSING_bpPP = 0; # Check the environment variable to decide worker module. unless ($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' or $backend =~ /JSON::XS\s*,\s*JSON::PP/) { _load_xs($_INSTALL_DONT_DIE) or _load_pp(); } elsif ($backend eq '0' or $backend eq 'JSON::PP') { _load_pp(); } elsif ($backend eq '2' or $backend eq 'JSON::XS') { _load_xs(); } elsif ($backend eq 'JSON::backportPP') { $_USSING_bpPP = 1; _load_pp(); } else { Carp::croak "The value of environmental variable 'PERL_JSON_BACKEND' is invalid."; } } 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 eq $Module_XS); } next; } elsif ($tag eq '-no_export') { $no_export++, next; } elsif ( $tag eq '-convert_blessed_universally' ) { eval q| require B; *UNIVERSAL::TO_JSON = sub { my $b_obj = B::svref_2object( $_[0] ); return $b_obj->isa('B::HV') ? { %{ $_[0] } } : $b_obj->isa('B::AV') ? [ @{ $_[0] } ] : undef ; } | if ( !$_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 { $XS_Version; } sub backend { my $proto = shift; $JSON::Backend; } #*module = *backend; sub is_xs { return $_[0]->backend eq $Module_XS; } sub is_pp { return not $_[0]->is_xs; } sub pureperl_only_methods { @PPOnlyMethods; } sub property { my ($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 $opt = shift; $JSON::DEBUG and Carp::carp "Load $Module_XS."; # if called after install module, overload is disable.... why? JSON::Boolean::_overrride_overload($Module_XS); JSON::Boolean::_overrride_overload($Module_PP); eval qq| use $Module_XS $XS_Version (); |; if ($@) { if (defined $opt and $opt & $_INSTALL_DONT_DIE) { $JSON::DEBUG and Carp::carp "Can't load $Module_XS...($@)"; return 0; } Carp::croak $@; } unless (defined $opt and $opt & $_INSTALL_ONLY) { _set_module( $JSON::Backend = $Module_XS ); my $data = join("", ); # this code is from Jcode 2.xx. close(DATA); eval $data; JSON::Backend::XS->init; } return 1; }; sub _load_pp { my $opt = shift; my $backend = $_USSING_bpPP ? $Module_bp : $Module_PP; $JSON::DEBUG and Carp::carp "Load $backend."; # if called after install module, overload is disable.... why? JSON::Boolean::_overrride_overload($Module_XS); JSON::Boolean::_overrride_overload($backend); if ( $_USSING_bpPP ) { eval qq| require $backend |; } else { eval qq| use $backend $PP_Version () |; } if ($@) { if ( $backend eq $Module_PP ) { $JSON::DEBUG and Carp::carp "Can't load $Module_PP ($@), so try to load $Module_bp"; $_USSING_bpPP++; $backend = $Module_bp; JSON::Boolean::_overrride_overload($backend); local $^W; # if PP installed but invalid version, backportPP redefines methods. eval qq| require $Module_bp |; } Carp::croak $@ if $@; } unless (defined $opt and $opt & $_INSTALL_ONLY) { _set_module( $JSON::Backend = $Module_PP ); # even if backportPP, set $Backend with 'JSON::PP' JSON::Backend::PP->init; } }; sub _set_module { return if defined $JSON::true; my $module = shift; local $^W; no strict qw(refs); $JSON::true = ${"$module\::true"}; $JSON::false = ${"$module\::false"}; push @JSON::ISA, $module; if ( JSON->is_xs and JSON->backend->VERSION < 3 ) { eval 'package JSON::PP::Boolean'; push @{"$module\::Boolean::ISA"}, qw(JSON::PP::Boolean); } *{"JSON::is_bool"} = \&{"$module\::is_bool"}; for my $method ($module eq $Module_XS ? @PPOnlyMethods : @XSOnlyMethods) { *{"JSON::$method"} = sub { Carp::carp("$method is not supported in $module."); $_[0]; }; } return 1; } # # JSON Boolean # package JSON::Boolean; my %Installed; sub _overrride_overload { return; # this function is currently disable. return if ($Installed{ $_[0] }++); my $boolean = $_[0] . '::Boolean'; eval sprintf(q| package %s; use overload ( '""' => sub { ${$_[0]} == 1 ? 'true' : 'false' }, 'eq' => sub { my ($obj, $op) = ref ($_[0]) ? ($_[0], $_[1]) : ($_[1], $_[0]); if ($op eq 'true' or $op eq 'false') { return "$obj" eq 'true' ? 'true' eq $op : 'false' eq $op; } else { return $obj ? 1 == $op : 0 == $op; } }, ); |, $boolean); if ($@) { Carp::croak $@; } if ( exists $INC{'JSON/XS.pm'} and $boolean eq 'JSON::XS::Boolean' ) { local $^W; my $true = do { bless \(my $dummy = 1), $boolean }; my $false = do { bless \(my $dummy = 0), $boolean }; *JSON::XS::true = sub () { $true }; *JSON::XS::false = sub () { $false }; } elsif ( exists $INC{'JSON/PP.pm'} and $boolean eq 'JSON::PP::Boolean' ) { local $^W; my $true = do { bless \(my $dummy = 1), $boolean }; my $false = do { bless \(my $dummy = 0), $boolean }; *JSON::PP::true = sub { $true }; *JSON::PP::false = sub { $false }; } return 1; } # # Helper classes for Backend Module (PP) # package JSON::Backend::PP; sub init { 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::PP::is_xs"} = sub { 0 }; *{"JSON::PP::is_pp"} = sub { 1 }; return 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; use constant INDENT_LENGTH_FLAG => 15 << 12; use constant UNSUPPORTED_ENCODE_FLAG => { ESCAPE_SLASH => 0x00000010, ALLOW_BIGNUM => 0x00000020, AS_NONBLESSED => 0x00000040, EXPANDED => 0x10000000, # for developer's }; use constant UNSUPPORTED_DECODE_FLAG => { LOOSE => 0x00000001, ALLOW_BIGNUM => 0x00000002, ALLOW_BAREKEY => 0x00000004, ALLOW_SINGLEQUOTE => 0x00000008, EXPANDED => 0x20000000, # for developer's }; sub init { local $^W; no strict qw(refs); *{"JSON::decode_json"} = \&{"JSON::XS::decode_json"}; *{"JSON::encode_json"} = \&{"JSON::XS::encode_json"}; *{"JSON::XS::is_xs"} = sub { 1 }; *{"JSON::XS::is_pp"} = sub { 0 }; return 1; } sub support_by_pp { my ($class, @methods) = @_; local $^W; no strict qw(refs); my $JSON_XS_encode_orignal = \&JSON::XS::encode; my $JSON_XS_decode_orignal = \&JSON::XS::decode; my $JSON_XS_incr_parse_orignal = \&JSON::XS::incr_parse; *JSON::XS::decode = \&JSON::Backend::XS::Supportable::_decode; *JSON::XS::encode = \&JSON::Backend::XS::Supportable::_encode; *JSON::XS::incr_parse = \&JSON::Backend::XS::Supportable::_incr_parse; *{JSON::XS::_original_decode} = $JSON_XS_decode_orignal; *{JSON::XS::_original_encode} = $JSON_XS_encode_orignal; *{JSON::XS::_original_incr_parse} = $JSON_XS_incr_parse_orignal; push @JSON::Backend::XS::Supportable::ISA, 'JSON'; my $pkg = 'JSON::Backend::XS::Supportable'; *{JSON::new} = sub { my $proto = JSON::XS->new; $$proto = 0; bless $proto, $pkg; }; for my $method (@methods) { my $flag = uc($method); my $type |= (UNSUPPORTED_ENCODE_FLAG->{$flag} || 0); $type |= (UNSUPPORTED_DECODE_FLAG->{$flag} || 0); next unless($type); $pkg->_make_unsupported_method($method => $type); } # push @{"JSON::XS::Boolean::ISA"}, qw(JSON::PP::Boolean); # push @{"JSON::PP::Boolean::ISA"}, qw(JSON::Boolean); $JSON::DEBUG and Carp::carp("set -support_by_pp mode."); return 1; } # # Helper classes for XS # package JSON::Backend::XS::Supportable; $Carp::Internal{'JSON::Backend::XS::Supportable'} = 1; sub _make_unsupported_method { my ($pkg, $method, $type) = @_; local $^W; no strict qw(refs); *{"$pkg\::$method"} = sub { local $^W; if (defined $_[1] ? $_[1] : 1) { ${$_[0]} |= $type; } else { ${$_[0]} &= ~$type; } $_[0]; }; *{"$pkg\::get_$method"} = sub { ${$_[0]} & $type ? 1 : ''; }; } sub _set_for_pp { JSON::_load_pp( $_INSTALL_ONLY ); my $type = shift; my $pp = JSON::PP->new; my $prop = $_[0]->property; for my $name (keys %$prop) { $pp->$name( $prop->{$name} ? $prop->{$name} : 0 ); } my $unsupported = $type eq 'encode' ? JSON::Backend::XS::UNSUPPORTED_ENCODE_FLAG : JSON::Backend::XS::UNSUPPORTED_DECODE_FLAG; my $flags = ${$_[0]} || 0; for my $name (keys %$unsupported) { next if ($name eq 'EXPANDED'); # for developer's my $enable = ($flags & $unsupported->{$name}) ? 1 : 0; my $method = lc $name; $pp->$method($enable); } $pp->indent_length( $_[0]->get_indent_length ); return $pp; } sub _encode { # using with PP encode if (${$_[0]}) { _set_for_pp('encode' => @_)->encode($_[1]); } else { $_[0]->_original_encode( $_[1] ); } } sub _decode { # if unsupported-flag is set, use PP if (${$_[0]}) { _set_for_pp('decode' => @_)->decode($_[1]); } else { $_[0]->_original_decode( $_[1] ); } } sub decode_prefix { # if unsupported-flag is set, use PP _set_for_pp('decode' => @_)->decode_prefix($_[1]); } sub _incr_parse { if (${$_[0]}) { _set_for_pp('decode' => @_)->incr_parse($_[1]); } else { $_[0]->_original_incr_parse( $_[1] ); } } sub get_indent_length { ${$_[0]} << 4 >> 16; } sub indent_length { my $length = $_[1]; if (!defined $length or $length > 15 or $length < 0) { Carp::carp "The acceptable range of indent_length() is 0 to 15."; } else { local $^W; $length <<= 12; ${$_[0]} &= ~ JSON::Backend::XS::INDENT_LENGTH_FLAG; ${$_[0]} |= $length; *JSON::XS::encode = \&JSON::Backend::XS::Supportable::_encode; } $_[0]; } 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 # If you want to use PP only support features, call with '-support_by_pp' # When XS unsupported feature is enable, using PP (de|en)code instead of XS ones. use JSON -support_by_pp; # option-acceptable interfaces (expect/generate UNICODE by default) $json_text = to_json( $perl_scalar, { ascii => 1, pretty => 1 } ); $perl_scalar = from_json( $json_text, { utf8 => 1 } ); # Between (en|de)code_json and (to|from)_json, if you want to write # a code which communicates to an outer world (encoded in UTF-8), # recommend to use (en|de)code_json. =head1 VERSION 2.90 This version is compatible with JSON::XS B<2.34> and later. (Not yet compatble to JSON::XS B<3.0x>.) =head1 NOTE JSON::PP was earlier included in the C distribution, but has since Perl 5.14 been a core module. For this reason, L was removed from the JSON distribution and can now be found also in the Perl5 repository at =over =item * L =back (The newest JSON::PP version still exists in CPAN.) Instead, the C distribution will include JSON::backportPP for backwards computability. JSON.pm should thus work as it did before. =head1 DESCRIPTION *************************** CAUTION ************************************** * * * INCOMPATIBLE CHANGE (JSON::XS version 2.90) * * * * JSON.pm had patched JSON::XS::Boolean and JSON::PP::Boolean internally * * on loading time for making these modules inherit JSON::Boolean. * * But since JSON::XS v3.0 it use Types::Serialiser as boolean class. * * Then now JSON.pm breaks boolean classe overload features and * * -support_by_pp if JSON::XS v3.0 or later is installed. * * * * JSON::true and JSON::false returned JSON::Boolean objects. * * For workaround, they return JSON::PP::Boolean objects in this version. * * * * isa_ok(JSON::true, 'JSON::PP::Boolean'); * * * * And it discards a feature: * * * * ok(JSON::true eq 'true'); * * * * In other word, JSON::PP::Boolean overload numeric only. * * * * ok( JSON::true == 1 ); * * * ************************************************************************** ************************** CAUTION ******************************** * This is 'JSON module version 2' and there are many differences * * to version 1.xx * * Please check your applications using old version. * * See to 'INCOMPATIBLE CHANGES TO OLD VERSION' * ******************************************************************* JSON (JavaScript Object Notation) is a simple data format. See to L and C(L). This module converts Perl data structures to JSON and vice versa using either L or L. JSON::XS is the fastest and most proper JSON module on CPAN which must be compiled and installed in your environment. JSON::PP is a pure-Perl module which is bundled in this distribution and has a strong compatibility to JSON::XS. This module try to use JSON::XS by default and fail to it, use JSON::PP instead. So its features completely depend on JSON::XS or JSON::PP. See to L. To distinguish the module name 'JSON' and the format type JSON, the former is quoted by CEE (its results vary with your using media), and the latter is left just as it is. Module name : C Format type : JSON =head2 FEATURES =over =item * correct unicode handling This module (i.e. backend modules) knows how to handle Unicode, documents how and when it does so, and even documents what "correct" means. Even though there are limitations, this feature is available since Perl version 5.6. JSON::XS requires Perl 5.8.2 (but works correctly in 5.8.8 or later), so in older versions C should call JSON::PP as the backend which can be used since Perl 5.005. With Perl 5.8.x JSON::PP works, but from 5.8.0 to 5.8.2, because of a Perl side problem, JSON::PP works slower in the versions. And in 5.005, the Unicode handling is not available. See to L for more information. See also to L and L. =item * 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 I minor exceptions to this, read the L section below to learn about those. =item * 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). See to L and L. =item * fast This module returns a JSON::XS object itself if available. Compared to other JSON modules and other serialisers such as Storable, JSON::XS usually compares favorably in terms of speed, too. If not available, C returns a JSON::PP object instead of JSON::XS and it is very slow as pure-Perl. =item * simple to use This module has both a simple functional interface as well as an object oriented interface interface. =item * reasonably versatile output formats You can choose between the most compact guaranteed-single-line format possible (nice for simple line-based protocols), a pure-ASCII format (for when your transport is not 8-bit clean, still supports the whole Unicode range), or a pretty-printed format (for when you want to read that stuff). Or you can combine those features in whatever way you like. =back =head1 FUNCTIONAL INTERFACE Some documents are copied and modified from L. C and C are additional functions. =head2 encode_json $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: $json_text = JSON->new->utf8->encode($perl_scalar) =head2 decode_json $perl_scalar = decode_json $json_text The opposite of C: expects an UTF-8 (binary) string and tries to parse that as an UTF-8 encoded JSON text, returning the resulting reference. This function call is functionally identical to: $perl_scalar = JSON->new->utf8->decode($json_text) =head2 to_json $json_text = to_json($perl_scalar) Converts the given Perl data structure to a json string. This function call is functionally identical to: $json_text = JSON->new->encode($perl_scalar) Takes a hash reference as the second. $json_text = to_json($perl_scalar, $flag_hashref) So, $json_text = to_json($perl_scalar, {utf8 => 1, pretty => 1}) equivalent to: $json_text = JSON->new->utf8(1)->pretty(1)->encode($perl_scalar) If you want to write a modern perl code which communicates to outer world, you should use C (supposed that JSON data are encoded in UTF-8). =head2 from_json $perl_scalar = from_json($json_text) The opposite of C: expects a json string and tries to parse it, returning the resulting reference. This function call is functionally identical to: $perl_scalar = JSON->decode($json_text) Takes a hash reference as the second. $perl_scalar = from_json($json_text, $flag_hashref) So, $perl_scalar = from_json($json_text, {utf8 => 1}) equivalent to: $perl_scalar = JSON->new->utf8(1)->decode($json_text) If you want to write a modern perl code which communicates to outer world, you should use C (supposed that JSON data are encoded in UTF-8). =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 and C in Perl strings. =head2 JSON::true Returns JSON true value which is blessed object. It C JSON::Boolean object. =head2 JSON::false Returns JSON false value which is blessed object. It C JSON::Boolean object. =head2 JSON::null Returns C. See L, below, for more information on how JSON values are mapped to Perl. =head1 HOW DO I DECODE A DATA FROM OUTER AND ENCODE TO OUTER 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 C or C module object with C enable. And the decoded result will contain UNICODE characters. # from network my $json = JSON->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.data' ); $json_text = <$fh>; $perl_scalar = decode_json( $json_text ); If an outer data is not encoded in UTF-8, firstly you should C it. use Encode; local $/; open( my $fh, '<', 'json.data' ); my $encoding = 'cp932'; my $unicode_json_text = decode( $encoding, <$fh> ); # UNICODE # or you can write the below code. # # open( my $fh, "<:encoding($encoding)", 'json.data' ); # $unicode_json_text = <$fh>; In this case, C<$unicode_json_text> is of course UNICODE string. So you B use C nor C module object with C enable. Instead of them, you use C module object with C disable or C. $perl_scalar = $json->utf8(0)->decode( $unicode_json_text ); # or $perl_scalar = from_json( $unicode_json_text ); Or C and C: $perl_scalar = decode_json( encode( 'utf8', $unicode_json_text ) ); # this way is not efficient. And now, you want to convert your C<$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 C or C module object with C enable. print encode_json( $perl_scalar ); # to a network? file? or display? # or print $json->utf8->encode( $perl_scalar ); If C<$perl_scalar> does not contain UNICODE but C<$encoding>-encoded strings for some reason, then its characters are regarded as B for perl (because it does not concern with your $encoding). You B use C nor C module object with C enable. Instead of them, you use C module object with C disable or C. 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 ); # or $unicode_json_text = to_json( $perl_scalar ); # $unicode_json_text consists of characters less than 0x100 print $unicode_json_text; Or C all string values and C: $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 L, L. =head1 COMMON OBJECT-ORIENTED INTERFACE =head2 new $json = JSON->new Returns a new C object inherited from either JSON::XS or JSON::PP that can be used to de/encode JSON strings. All boolean flags described below are by default I. The mutators for flags all return the JSON 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 $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. 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 format. This feature depends on the used Perl version and environment. See to L if the backend is PP. JSON->new->ascii(1)->encode([chr 0x10401]) => ["\ud801\udc01"] =head2 latin1 $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->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 $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 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; $jsontext = encode "UTF-16BE", JSON::XS->new->encode ($object); Example, decode UTF-32LE-encoded JSON: use Encode; $object = JSON::XS->new->decode (decode "UTF-32LE", $jsontext); See to L if the backend is PP. =head2 pretty $json = $json->pretty([$enable]) This enables (or disables) all of the C, C and C (and in the future possibly more) flags in one call to generate the most readable (or most compact) form possible. Equivalent to: $json->indent->space_before->space_after The indent space length is three and JSON::XS cannot change the indent space length. =head2 indent $json = $json->indent([$enable]) $enabled = $json->get_indent If C<$enable> is true (or missing), then the C method will use a multiline format as output, putting every array member or object/hash key-value pair into its own line, identifying 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. This setting has no effect when decoding JSON texts. The indent space length is three. With JSON::PP, you can also access C to change indent space length. =head2 space_before $json = $json->space_before([$enable]) $enabled = $json->get_space_before If C<$enable> is true (or missing), then the C method will add an extra optional space before the C<:> separating keys from values in JSON objects. If C<$enable> is false, then the C method will not add any extra space at those places. This setting has no effect when decoding JSON texts. 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 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 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 will accept some extensions to normal JSON syntax (see below). C will not be affected in anyway. I. I suggest only to use this option to parse application-specific files written by humans (configuration files, resource files etc.) If C<$enable> is false (the default), then C will only accept valid JSON texts. Currently accepted extensions are: =over 4 =item * list items can have an end-comma JSON I array elements and key-value pairs with commas. This can be annoying if you write JSON texts manually and want to be able to quickly append elements, so this extension accepts comma at the end of such items not just between them: [ 1, 2, <- this comma not normally allowed ] { "k1": "v1", "k2": "v2", <- this comma not normally allowed } =item * shell-style '#'-comments Whenever JSON allows whitespace, shell-style comments are additionally allowed. They are terminated by the first carriage-return or line-feed character, after which more white-space and comments are allowed. [ 1, # this comment not allowed in JSON # neither this one... ] =back =head2 canonical $json = $json->canonical([$enable]) $enabled = $json->get_canonical If C<$enable> is true (or missing), then the C method will output JSON objects by sorting their keys. This is adding a comparatively high overhead. If C<$enable> is false, then the C 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. =head2 allow_nonref $json = $json->allow_nonref([$enable]) $enabled = $json->get_allow_nonref If C<$enable> is true (or missing), then the C method can convert a non-reference into its corresponding string, number or null JSON value, which is an extension to RFC4627. Likewise, C will accept those JSON values instead of croaking. If C<$enable> is false, then the C method will croak if it isn't passed an arrayref or hashref, as JSON texts must either be an object or array. Likewise, C will croak if given something that is not a JSON object or array. JSON->new->allow_nonref->encode ("Hello, World!") => "Hello, World!" =head2 allow_unknown $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. 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. =head2 allow_blessed $json = $json->allow_blessed([$enable]) $enabled = $json->get_allow_blessed If C<$enable> is true (or missing), then the C method will not barf when it encounters a blessed reference. Instead, the value of the B option will decide whether C (C disabled or no C method found) or a representation of the object (C enabled and C method found) is being encoded. Has no effect on C. If C<$enable> is false (the default), then C will throw an exception when it encounters a blessed object. =head2 convert_blessed $json = $json->convert_blessed([$enable]) $enabled = $json->get_convert_blessed If C<$enable> is true (or missing), then C, upon encountering a blessed object, will check for the availability of the C method on the object's class. If found, it will be called in scalar context and the resulting scalar will be encoded instead of the object. If no C method is found, the value of C will decide what to do. The C method may safely call die if it wants. If C returns other blessed objects, those will be handled in the same way. C must take care of not causing an endless recursion cycle (== crash) in this case. The name of C was chosen because other methods called by the Perl core (== not by the user of the object) are usually in upper case letters and to avoid collisions with the C function or method. This setting does not yet influence C in any way. If C<$enable> is false, then the C setting will decide what to do when a blessed object is found. =over =item convert_blessed_universally mode If use C with C<-convert_blessed_universally>, the C subroutine is defined as the below code: *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 ; } This will cause that C method converts simple blessed objects into JSON objects as non-blessed object. JSON -convert_blessed_universally; $json->allow_blessed->convert_blessed->encode( $blessed_object ) This feature is experimental and may be removed in the future. =back =head2 filter_json_object $json = $json->filter_json_object([$coderef]) When C<$coderef> is specified, it will be called from C each time it decodes a JSON object. The only argument passed to the coderef is a reference to the newly-created hash. If the code references returns a single scalar (which need not be a reference), this value (i.e. a copy of that scalar to avoid aliasing) is inserted into the deserialised data structure. If it returns an empty list (NOTE: I C, which is a valid scalar), the original deserialised hash will be inserted. This setting can slow down decoding considerably. When C<$coderef> is omitted or undefined, any existing callback will be removed and C will not change the deserialised hash in any way. Example, convert all JSON objects into the integer 5: my $js = JSON->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 [=> $coderef]) Works remotely similar to C, but is only called for JSON objects having a single key named C<$key>. This C<$coderef> is called before the one specified via C, if any. It gets passed the single value in the JSON object. If it returns a single value, it will be inserted into the data structure. If it returns nothing (not even C but the empty list), the callback from C will be called next, as if no single-key callback were specified. If C<$coderef> is omitted or undefined, the corresponding callback will be disabled. There can only ever be one callback for a given key. As this callback gets called less often then the C one, decoding speed will not usually suffer as much. Therefore, single-key objects make excellent targets to serialise Perl objects into, especially as single-key JSON objects are as close to the type-tagged value concept as JSON gets (it's basically an ID/VALUE tuple). Of course, JSON does not support this in any way, so you need to make sure your data never looks like a serialised Perl hash. Typical names for the single object key are C<__class_whatever__>, or C<$__dollars_are_rarely_used__$> or C<}ugly_brace_placement>, or even things like C<__class_md5sum(classname)__>, to reduce the risk of clashing with real hashes. Example, decode JSON objects of the form C<< { "__widget__" => } >> into the corresponding C<< $WIDGET{} >> object: # return whatever is in $WIDGET{5}: JSON ->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 shrink $json = $json->shrink([$enable]) $enabled = $json->get_shrink With JSON::XS, this flag resizes strings generated by either C or C to their minimum size possible. This can save memory when your JSON texts are either very very long or you have many short strings. It will also try to downgrade any strings to octet-form if possible: perl stores strings internally either in an encoding called UTF-X or in octet-form. The latter cannot store everything but uses less space in general (and some buggy Perl or C code might even rely on that internal representation being used). With JSON::PP, it is noop about resizing strings but tries C to the returned string by C. See to L. See to L and L. =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. If no argument is given, the highest possible setting will be used, which is rarely useful. Note that nesting is implemented by recursion in C. The default value has been chosen to be as large as typical operating systems allow without crashing. (JSON::XS) With JSON::PP as the backend, 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. See L for more info on why this is 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 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 (yet). If no argument is given, the limit check will be deactivated (same as when C<0> is specified). See L, below, for more info on why this is useful. =head2 encode $json_text = $json->encode($perl_scalar) Converts the given Perl data structure (a simple scalar or a reference to a hash or array) to its JSON representation. Simple scalars will be converted into JSON string or number sequences, while references to arrays become JSON arrays and references to hashes become JSON objects. Undefined Perl values (e.g. C) become JSON C values. References to the integers C<0> and C<1> are converted into C and C. =head2 decode $perl_scalar = $json->decode($json_text) The opposite of C: expects a JSON text and tries to parse it, returning the resulting simple scalar or reference. Croaks on error. JSON numbers and strings become simple Perl scalars. JSON arrays become Perl arrayrefs and JSON objects become Perl hashrefs. C becomes C<1> (C), C becomes C<0> (C) and C becomes C. =head2 decode_prefix ($perl_scalar, $characters) = $json->decode_prefix($json_text) This works like the C method, but instead of raising an exception when there is trailing garbage after the first JSON object, it will silently stop parsing there and return the number of characters consumed so far. JSON->new->decode_prefix ("[1] the tail") => ([], 3) See to L =head2 property $boolean = $json->property($property_name) Returns a boolean value about above some properties. The available properties are C, C, C, C,C, C, C, C, C, C, C, C, C, C and C. $boolean = $json->property('utf8'); => 0 $json->utf8; $boolean = $json->property('utf8'); => 1 Sets the property with a given boolean value. $json = $json->property($property_name => $boolean); With no argument, it returns all the above properties as a hash reference. $flag_hashref = $json->property(); =head1 INCREMENTAL PARSING Most of this section are copied and modified from L. 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 C to see if a full JSON object is available, but is much more efficient (and can be implemented with a minimum of method calls). The backend 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 parenthesis 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. C) 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 JSON object. If that is successful, it will return this object, otherwise it will return C. If there is a parse error, this method will croak just as C would do (one can then use C 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]"); =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 works when a preceding call to C in I 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 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, C attribute is not available. You must write codes like the below: $string = $json->incr_text; $string =~ s/\s*,\s*//; $json->incr_text( $string ); =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. This is useful after C 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. =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. See to L for examples. =head1 JSON::PP SUPPORT METHODS The below methods are JSON::PP own methods, so when C works with JSON::PP (i.e. the created object is a JSON::PP object), available. See to L in detail. If you use C with additional C<-support_by_pp>, some methods are available even with JSON::XS. See to L. BEING { $ENV{PERL_JSON_BACKEND} = 'JSON::XS' } use JSON -support_by_pp; my $json = JSON->new; $json->allow_nonref->escape_slash->encode("/"); # functional interfaces too. print to_json(["/"], {escape_slash => 1}); print from_json('["foo"]', {utf8 => 1}); If you do not want to all functions but C<-support_by_pp>, use C<-no_export>. use JSON -support_by_pp, -no_export; # functional interfaces are not exported. =head2 allow_singlequote $json = $json->allow_singlequote([$enable]) If C<$enable> is true (or missing), then C will accept any JSON strings quoted by single quotations that are invalid JSON format. $json->allow_singlequote->decode({"foo":'bar'}); $json->allow_singlequote->decode({'foo':"bar"}); $json->allow_singlequote->decode({'foo':'bar'}); As same as the C option, this option may be used to parse application-specific files written by humans. =head2 allow_barekey $json = $json->allow_barekey([$enable]) If C<$enable> is true (or missing), then C will accept bare keys of JSON object that are invalid JSON format. As same as the C option, this option may be used to parse application-specific files written by humans. $json->allow_barekey->decode('{foo:"bar"}'); =head2 allow_bignum $json = $json->allow_bignum([$enable]) If C<$enable> is true (or missing), then C will convert the big integer Perl cannot handle as integer into a L object and convert a floating number (any) into a L. On the contrary, C converts C objects and C objects into JSON numbers with C enable. $json->allow_nonref->allow_blessed->allow_bignum; $bigfloat = $json->decode('2.000000000000000000000000001'); print $json->encode($bigfloat); # => 2.000000000000000000000000001 See to L about the conversion of JSON number. =head2 loose $json = $json->loose([$enable]) The unescaped [\x00-\x1f\x22\x2f\x5c] strings are invalid in JSON strings and the module doesn't allow to C to these (except for \x2f). If C<$enable> is true (or missing), then C will accept these unescaped strings. $json->loose->decode(qq|["abc def"]|); See to L. =head2 escape_slash $json = $json->escape_slash([$enable]) According to JSON Grammar, I (U+002F) is escaped. But by default JSON backend modules encode strings without escaping slash. If C<$enable> is true (or missing), then C will escape slashes. =head2 indent_length $json = $json->indent_length($length) With JSON::XS, The indent space length is 3 and cannot be changed. With JSON::PP, it sets the indent space length with the given $length. The default is 3. The acceptable range is 0 to 15. =head2 sort_by $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. $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 $JSON::PP::b } As the sorting routine runs in the JSON::PP scope, the given subroutine name and the special variables C<$a>, C<$b> will begin with 'JSON::PP::'. If $integer is set, then the effect is same as C on. See to L. =head1 MAPPING This section is copied from JSON::XS and modified to C. JSON::XS and JSON::PP mapping mechanisms are almost equivalent. See to L. =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, C 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, C only guarantees precision up to but not including the least significant bit. If the backend is JSON::PP and C is enable, the big integers and the numeric can be optionally converted into L and L objects. =item true, false These JSON atoms become C and C, respectively. They are overloaded to act almost exactly like the numbers C<1> and C<0>. You can check whether a scalar is a JSON boolean by using the C function. print JSON::true + 1; => 1 ok(JSON::true eq '1'); ok(JSON::true == 1); C will install these missing overloading features to the backend modules. =item null A JSON null atom becomes C in Perl. C returns C. =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 that can change between runs of the same program but stays generally the same within a single run of a program. C optionally sort the hash keys (determined by the I flag), so the same data structure will serialise to the same JSON text (given same settings and version of JSON::XS), but this incurs a runtime overhead and is only rarely useful, e.g. when you want to compare some JSON text against another for equality. In future, the ordered object feature will be added to JSON::PP using C mechanism. =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 and C atoms in JSON. You can also use C and C to improve readability. to_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. JSON::null returns C. =item blessed objects Blessed objects are not directly representable in JSON. See the C and C 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. With C mode, C converts blessed hash references or blessed array references (contains other blessed references) into JSON members and arrays. use JSON -convert_blessed_universally; JSON->new->allow_blessed->convert_blessed->encode( $blessed_object ); See to L. =item 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 C 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. 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. =item Big Number If the backend is JSON::PP and C is enable, C converts C objects and C objects into JSON numbers. =back =head1 JSON and ECMAscript See to L. =head1 JSON and YAML JSON is not a subset of YAML. See to L. =head1 BACKEND MODULE DECISION When you use C, C tries to C JSON::XS. If this call failed, it will C JSON::PP. The required JSON::XS version is I<2.2> or later. The C constructor method returns an object inherited from the backend module, and JSON::XS object is a blessed scalar reference while JSON::PP is a blessed hash reference. So, your program should not depend on the backend module, especially returned objects should not be modified. my $json = JSON->new; # XS or PP? $json->{stash} = 'this is xs object'; # this code may raise an error! To check the backend module, there are some methods - C, C and C. JSON->backend; # 'JSON::XS' or 'JSON::PP' JSON->backend->is_pp: # 0 or 1 JSON->backend->is_xs: # 1 or 0 $json->is_xs; # 1 or 0 $json->is_pp; # 0 or 1 If you set an environment variable C, the calling action will be changed. =over =item PERL_JSON_BACKEND = 0 or PERL_JSON_BACKEND = 'JSON::PP' Always use JSON::PP =item PERL_JSON_BACKEND == 1 or PERL_JSON_BACKEND = 'JSON::XS,JSON::PP' (The default) Use compiled JSON::XS if it is properly compiled & installed, otherwise use JSON::PP. =item PERL_JSON_BACKEND == 2 or PERL_JSON_BACKEND = 'JSON::XS' Always use compiled JSON::XS, die if it isn't properly compiled & installed. =item PERL_JSON_BACKEND = 'JSON::backportPP' Always use JSON::backportPP. JSON::backportPP is JSON::PP back port module. C includes JSON::backportPP instead of JSON::PP. =back These ideas come from L mechanism. example: BEGIN { $ENV{PERL_JSON_BACKEND} = 'JSON::PP' } use JSON; # always uses JSON::PP In future, it may be able to specify another module. =head1 USE PP FEATURES EVEN THOUGH XS BACKEND Many methods are available with either JSON::XS or JSON::PP and when the backend module is JSON::XS, if any JSON::PP specific (i.e. JSON::XS unsupported) method is called, it will C and be noop. But If you C C passing the optional string C<-support_by_pp>, it makes a part of those unsupported methods available. This feature is achieved by using JSON::PP in C. BEGIN { $ENV{PERL_JSON_BACKEND} = 2 } # with JSON::XS use JSON -support_by_pp; my $json = JSON->new; $json->allow_nonref->escape_slash->encode("/"); At this time, the returned object is a C object (re-blessed XS object), and by checking JSON::XS unsupported flags in de/encoding, can support some unsupported methods - C, C, C, C, C and C. When any unsupported methods are not enable, C will be used as is. The switch is achieved by changing the symbolic tables. C<-support_by_pp> is effective only when the backend module is JSON::XS and it makes the de/encoding speed down a bit. See to L. =head1 INCOMPATIBLE CHANGES TO OLD VERSION There are big incompatibility between new version (2.00) and old (1.xx). If you use old C 1.xx in your code, please check it. See to L =over =item jsonToObj and objToJson are obsoleted. Non Perl-style name C and C are obsoleted (but not yet deleted from the source). If you use these functions in your code, please replace them with C and C. =item Global variables are no longer available. C class variables - C<$JSON::AUTOCONVERT>, C<$JSON::BareKey>, etc... - are not available any longer. Instead, various features can be used through object methods. =item Package JSON::Converter and JSON::Parser are deleted. Now C bundles with JSON::PP which can handle JSON more properly than them. =item Package JSON::NotString is deleted. There was C class which represents JSON value C, C, C and numbers. It was deleted and replaced by C. C represents C and C. C does not represent C. C returns C. C makes L and L is-a relation to L. =item function JSON::Number is obsoleted. C is now needless because JSON::XS and JSON::PP have round-trip integrity. =item JSONRPC modules are deleted. Perl implementation of JSON-RPC protocol - C, C and C are deleted in this distribution. Instead of them, there is L which supports JSON-RPC protocol version 1.1. =back =head2 Transition ways from 1.xx to 2.xx. You should set C mode firstly, because it is always successful for the below codes even with JSON::XS. use JSON -support_by_pp; =over =item Exported jsonToObj (simple) from_json($json_text); =item Exported objToJson (simple) to_json($perl_scalar); =item Exported jsonToObj (advanced) $flags = {allow_barekey => 1, allow_singlequote => 1}; from_json($json_text, $flags); equivalent to: $JSON::BareKey = 1; $JSON::QuotApos = 1; jsonToObj($json_text); =item Exported objToJson (advanced) $flags = {allow_blessed => 1, allow_barekey => 1}; to_json($perl_scalar, $flags); equivalent to: $JSON::BareKey = 1; objToJson($perl_scalar); =item jsonToObj as object method $json->decode($json_text); =item objToJson as object method $json->encode($perl_scalar); =item new method with parameters The C method in 2.x takes any parameters no longer. You can set parameters instead; $json = JSON->new->pretty; =item $JSON::Pretty, $JSON::Indent, $JSON::Delimiter If C is enable, that means C<$JSON::Pretty> flag set. And C<$JSON::Delimiter> was substituted by C and C. In conclusion: $json->indent->space_before->space_after; Equivalent to: $json->pretty; To change indent length, use C. (Only with JSON::PP, if C<-support_by_pp> is not used.) $json->pretty->indent_length(2)->encode($perl_scalar); =item $JSON::BareKey (Only with JSON::PP, if C<-support_by_pp> is not used.) $json->allow_barekey->decode($json_text) =item $JSON::ConvBlessed use C<-convert_blessed_universally>. See to L. =item $JSON::QuotApos (Only with JSON::PP, if C<-support_by_pp> is not used.) $json->allow_singlequote->decode($json_text) =item $JSON::SingleQuote Disable. C does not make such a invalid JSON string any longer. =item $JSON::KeySort $json->canonical->encode($perl_scalar) This is the ascii sort. If you want to use with your own sort routine, check the C method. (Only with JSON::PP, even if C<-support_by_pp> is used currently.) $json->sort_by($sort_routine_ref)->encode($perl_scalar) $json->sort_by(sub { $JSON::PP::a <=> $JSON::PP::b })->encode($perl_scalar) Can't access C<$a> and C<$b> but C<$JSON::PP::a> and C<$JSON::PP::b>. =item $JSON::SkipInvalid $json->allow_unknown =item $JSON::AUTOCONVERT Needless. C backend modules have the round-trip integrity. =item $JSON::UTF8 Needless because C (JSON::XS/JSON::PP) sets the UTF8 flag on properly. # With UTF8-flagged strings $json->allow_nonref; $str = chr(1000); # UTF8-flagged $json_text = $json->utf8(0)->encode($str); utf8::is_utf8($json_text); # true $json_text = $json->utf8(1)->encode($str); utf8::is_utf8($json_text); # false $str = '"' . chr(1000) . '"'; # UTF8-flagged $perl_scalar = $json->utf8(0)->decode($str); utf8::is_utf8($perl_scalar); # true $perl_scalar = $json->utf8(1)->decode($str); # died because of 'Wide character in subroutine' See to L. =item $JSON::UnMapping Disable. See to L. =item $JSON::SelfConvert This option was deleted. Instead of it, if a given blessed object has the C method, C will be executed with C. $json->convert_blessed->encode($blessed_hashref_or_arrayref) # if need, call allow_blessed Note that it was C in old version, but now not C but C. =back =head1 TODO =over =item example programs =back =head1 THREADS No test with JSON::PP. If with JSON::XS, See to L. =head1 BUGS Please report bugs relevant to C to Emakamaka[at]cpan.orgE. =head1 SEE ALSO Most of the document is copied and modified from JSON::XS doc. L, L C(L) =head1 AUTHOR Makamaka Hannyaharamitu, Emakamaka[at]cpan.orgE JSON::XS was written by Marc Lehmann 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