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JSON::PP(3pm) User Contributed Perl Documentation JSON::PP(3pm)
NAME
JSON::PP - JSON::XS compatible pure-Perl module.
SYNOPSIS
use JSON::PP;
# exported functions, they croak on error
# and expect/generate UTF-8
$utf8_encoded_json_text = encode_json $perl_hash_or_arrayref;
$perl_hash_or_arrayref = decode_json $utf8_encoded_json_text;
# OO-interface
$coder = JSON::PP->new->ascii->pretty->allow_nonref;
$pretty_printed_unencoded = $coder->encode ($perl_scalar);
$perl_scalar = $coder->decode ($unicode_json_text);
# Note that JSON version 2.0 and above will automatically use
# JSON::XS or JSON::PP, so you should be able to just:
use JSON;
DESCRIPTION
This module is JSON::XS compatible pure Perl module. (Perl 5.8 or later is recommended)
JSON::XS is the fastest and most proper JSON module on CPAN. It is written by Marc
Lehmann in C, so must be compiled and installed in the used environment.
JSON::PP is a pure-Perl module and has compatibility to JSON::XS.
FEATURES
o correct unicode handling
This module knows how to handle Unicode (depending on Perl version).
See to "A FEW NOTES ON UNICODE AND PERL" in JSON::XS and "UNICODE HANDLING ON PERLS".
o round-trip integrity
When you serialise a perl data structure using only datatypes supported by JSON, the
deserialised data structure is identical on the Perl level. (e.g. the string "2.0"
doesn't suddenly become "2" just because it looks like a number).
o strict checking of JSON correctness
There is no guessing, no generating of illegal JSON texts by default, and only JSON is
accepted as input by default (the latter is a security feature). But when some
options are set, loose chcking features are available.
FUNCTIONS
Basically, check to JSON or JSON::XS.
encode_json
$json_text = encode_json $perl_scalar
decode_json
$perl_scalar = decode_json $json_text
JSON::PP::true
Returns JSON true value which is blessed object. It "isa" JSON::PP::Boolean object.
JSON::PP::false
Returns JSON false value which is blessed object. It "isa" JSON::PP::Boolean object.
JSON::PP::null
Returns "undef".
METHODS
Basically, check to JSON or JSON::XS.
new
$json = new JSON::PP
Rturns a new JSON::PP object that can be used to de/encode JSON strings.
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.
(See to "OBJECT-ORIENTED INTERFACE" in JSON::XS).
In Perl 5.005, there is no character having high value (more than 255). See to "UNICODE
HANDLING ON PERLS".
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.
JSON::PP->new->ascii(1)->encode([chr 0x10401])
=> ["\ud801\udc01"]
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::XS->new->latin1->encode (["\x{89}\x{abc}"]
=> ["\x{89}\\u0abc"] # (perl syntax, U+abc escaped, U+89 not)
See to "UNICODE HANDLING ON PERLS".
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 Perl 5.005, any character outside the range 0..255 does not exist. See to "UNICODE
HANDLING ON PERLS".)
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);
pretty
$json = $json->pretty([$enable])
This enables (or disables) all of the "indent", "space_before" and "space_after" flags in
one call to generate the most readable (or most compact) form possible.
indent
$json = $json->indent([$enable])
$enabled = $json->get_indent
The default indent space lenght is three. You can use "indent_length" to change the
length.
space_before
$json = $json->space_before([$enable])
$enabled = $json->get_space_before
space_after
$json = $json->space_after([$enable])
$enabled = $json->get_space_after
relaxed
$json = $json->relaxed([$enable])
$enabled = $json->get_relaxed
canonical
$json = $json->canonical([$enable])
$enabled = $json->get_canonical
If you want your own sorting routine, you can give a code referece or a subroutine name to
"sort_by". See to "JSON::PP OWN METHODS".
allow_nonref
$json = $json->allow_nonref([$enable])
$enabled = $json->get_allow_nonref
allow_unknown
$json = $json->allow_unknown ([$enable])
$enabled = $json->get_allow_unknown
allow_blessed
$json = $json->allow_blessed([$enable])
$enabled = $json->get_allow_blessed
convert_blessed
$json = $json->convert_blessed([$enable])
$enabled = $json->get_convert_blessed
filter_json_object
$json = $json->filter_json_object([$coderef])
filter_json_single_key_object
$json = $json->filter_json_single_key_object($key [=> $coderef])
shrink
$json = $json->shrink([$enable])
$enabled = $json->get_shrink
In JSON::XS, this flag resizes strings generated by either "encode" or "decode" to their
minimum size possible. It will also try to downgrade any strings to octet-form if
possible.
In JSON::PP, it is noop about resizing strings but tries "utf8::downgrade" to the returned
string by "encode". See to utf8.
See to "OBJECT-ORIENTED INTERFACE" in JSON::XS
max_depth
$json = $json->max_depth([$maximum_nesting_depth])
$max_depth = $json->get_max_depth
Sets the maximum nesting level (default 512) accepted while encoding or decoding. If a
higher nesting level is detected in JSON text or a Perl data structure, then the encoder
and decoder will stop and croak at that point.
Nesting level is defined by number of hash- or arrayrefs that the encoder needs to
traverse to reach a given point or the number of "{" or "[" characters without their
matching closing parenthesis crossed to reach a given character in a string.
If no argument is given, the highest possible setting will be used, which is rarely
useful.
See "SSECURITY CONSIDERATIONS" in JSON::XS for more info on why this is useful.
When a large value (100 or more) was set and it de/encodes a deep nested object/text, it
may raise a warning 'Deep recursion on subroutin' at the perl runtime phase.
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 0, meaning no limit. When "decode" is called on a string that is longer
then this many bytes, it will not attempt to decode the string but throw an exception.
This setting has no effect on "encode" (yet).
If no argument is given, the limit check will be deactivated (same as when 0 is
specified).
See "SSECURITY CONSIDERATIONS" in JSON::XS for more info on why this is useful.
encode
$json_text = $json->encode($perl_scalar)
decode
$perl_scalar = $json->decode($json_text)
decode_prefix
($perl_scalar, $characters) = $json->decode_prefix($json_text)
INCREMENTAL PARSING
In JSON::XS 2.2, incremental parsing feature of JSON texts was experimentally implemented.
Please check to "INCREMENTAL PARSING" in JSON::XS.
[void, scalar or list context] = $json->incr_parse ([$string])
This is the central parsing function. It can both append new text and extract objects
from the stream accumulated so far (both of these functions are optional).
If $string is given, then this string is appended to the already existing JSON
fragment stored in the $json object.
After that, if the function is called in void context, it will simply return without
doing anything further. This can be used to add more text in as many chunks as you
want.
If the method is called in scalar context, then it will try to extract exactly one
JSON object. If that is successful, it will return this object, otherwise it will
return "undef". If there is a parse error, this method will croak just as "decode"
would do (one can then use "incr_skip" to skip the errornous 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.
$lvalue_string = $json->incr_text
This method returns the currently stored JSON fragment as an lvalue, that is, you can
manipulate it. This only works when a preceding call to "incr_parse" in scalar context
successfully returned an object. Under all other circumstances you must not call this
function (I mean it. although in simple tests it might actually work, it will fail
under real world conditions). As a special exception, you can also call this method
before having parsed anything.
This function is useful in two cases: a) finding the trailing text after a JSON object
or b) parsing multiple JSON objects separated by non-JSON text (such as commas).
In Perl 5.005, "lvalue" attribute is not available. You must write codes like the
below:
$string = $json->incr_text;
$string =~ s/\s*,\s*//;
$json->incr_text( $string );
$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 "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.
JSON::PP OWN METHODS
allow_singlequote
$json = $json->allow_singlequote([$enable])
If $enable is true (or missing), then "decode" will accept JSON strings quoted by single
quotations that are invalid JSON format.
$json->allow_singlequote->decode({"foo":'bar'});
$json->allow_singlequote->decode({'foo':"bar"});
$json->allow_singlequote->decode({'foo':'bar'});
As same as the "relaxed" option, this option may be used to parse application-specific
files written by humans.
allow_barekey
$json = $json->allow_barekey([$enable])
If $enable is true (or missing), then "decode" will accept bare keys of JSON object that
are invalid JSON format.
As same as the "relaxed" option, this option may be used to parse application-specific
files written by humans.
$json->allow_barekey->decode('{foo:"bar"}');
allow_bignum
$json = $json->allow_bignum([$enable])
If $enable is true (or missing), then "decode" will convert the big integer Perl cannot
handle as integer into a Math::BigInt object and convert a floating number (any) into a
Math::BigFloat.
On the contary, "encode" converts "Math::BigInt" objects and "Math::BigFloat" objects into
JSON numbers with "allow_blessed" enable.
$json->allow_nonref->allow_blessed->allow_bignum;
$bigfloat = $json->decode('2.000000000000000000000000001');
print $json->encode($bigfloat);
# => 2.000000000000000000000000001
See to "MAPPING" in JSON::XS aboout the normal conversion of JSON number.
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 "decode" to these (except for \x2f). If $enable is true (or missing),
then "decode" will accept these unescaped strings.
$json->loose->decode(qq|["abc
def"]|);
See "SSECURITY CONSIDERATIONS" in JSON::XS.
escape_slash
$json = $json->escape_slash([$enable])
According to JSON Grammar, slash (U+002F) is escaped. But default JSON::PP (as same as
JSON::XS) encodes strings without escaping slash.
If $enable is true (or missing), then "encode" will escape slashes.
(OBSOLETED)as_nonblessed
$json = $json->as_nonblessed
(OBSOLETED) If $enable is true (or missing), then "encode" will convert a blessed hash
reference or a blessed array reference (contains other blessed references) into JSON
members and arrays.
This feature is effective only when "allow_blessed" is enable.
indent_length
$json = $json->indent_length($length)
JSON::XS indent space length is 3 and cannot be changed. JSON::PP set the indent space
length with the given $length. The default is 3. The acceptable range is 0 to 15.
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 in encoding JSON
objects.
$js = $pc->sort_by(sub { $JSON::PP::a cmp $JSON::PP::b })->encode($obj);
# is($js, q|{"a":1,"b":2,"c":3,"d":4,"e":5,"f":6,"g":7,"h":8,"i":9}|);
$js = $pc->sort_by('own_sort')->encode($obj);
# is($js, q|{"a":1,"b":2,"c":3,"d":4,"e":5,"f":6,"g":7,"h":8,"i":9}|);
sub JSON::PP::own_sort { $JSON::PP::a cmp $JSON::PP::b }
As the sorting routine runs in the JSON::PP scope, the given subroutine name and the
special variables $a, $b will begin 'JSON::PP::'.
If $integer is set, then the effect is same as "canonical" on.
INTERNAL
For developers.
PP_encode_box
Returns
{
depth => $depth,
indent_count => $indent_count,
}
PP_decode_box
Returns
{
text => $text,
at => $at,
ch => $ch,
len => $len,
depth => $depth,
encoding => $encoding,
is_valid_utf8 => $is_valid_utf8,
};
MAPPING
See to "MAPPING" in JSON::XS.
UNICODE HANDLING ON PERLS
If you do not know about Unicode on Perl well, please check "A FEW NOTES ON UNICODE AND
PERL" in JSON::XS.
Perl 5.8 and later
Perl can handle Unicode and the JSON::PP de/encode methods also work properly.
$json->allow_nonref->encode(chr hex 3042);
$json->allow_nonref->encode(chr hex 12345);
Reuturns "\u3042" and "\ud808\udf45" respectively.
$json->allow_nonref->decode('"\u3042"');
$json->allow_nonref->decode('"\ud808\udf45"');
Returns UTF-8 encoded strings with UTF8 flag, regarded as "U+3042" and "U+12345".
Note that the versions from Perl 5.8.0 to 5.8.2, Perl built-in "join" was broken, so
JSON::PP wraps the "join" with a subroutine. Thus JSON::PP works slow in the versions.
Perl 5.6
Perl can handle Unicode and the JSON::PP de/encode methods also work.
Perl 5.005
Perl 5.005 is a byte sementics world -- all strings are sequences of bytes. That means
the unicode handling is not available.
In encoding,
$json->allow_nonref->encode(chr hex 3042); # hex 3042 is 12354.
$json->allow_nonref->encode(chr hex 12345); # hex 12345 is 74565.
Returns "B" and "E", as "chr" takes a value more than 255, it treats as "$value % 256", so
the above codes are equivalent to :
$json->allow_nonref->encode(chr 66);
$json->allow_nonref->encode(chr 69);
In decoding,
$json->decode('"\u00e3\u0081\u0082"');
The returned is a byte sequence "0xE3 0x81 0x82" for UTF-8 encoded japanese character
("HIRAGANA LETTER A"). And if it is represented in Unicode code point, "U+3042".
Next,
$json->decode('"\u3042"');
We ordinary expect the returned value is a Unicode character "U+3042". But here is 5.005
world. This is "0xE3 0x81 0x82".
$json->decode('"\ud808\udf45"');
This is not a character "U+12345" but bytes - "0xf0 0x92 0x8d 0x85".
TODO
speed
memory saving
SEE ALSO
Most of the document are copied and modified from JSON::XS doc.
JSON::XS
RFC4627 (<http://www.ietf.org/rfc/rfc4627.txt>)
AUTHOR
Makamaka Hannyaharamitu, <makamaka[at]cpan.org>
COPYRIGHT AND LICENSE
Copyright 2007-2009 by Makamaka Hannyaharamitu
This library is free software; you can redistribute it and/or modify it under the same
terms as Perl itself.
perl v5.10.0 2009-06-02 JSON::PP(3pm)
Generated by $Id: phpMan.php,v 4.49 2006/02/26 13:18:18 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
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