jsone

jsone (0.2.3)

An Erlang library for encoding, decoding JSON data.

Features

• Provides simple encode/decode function only
• RFC4627-compliant
• Supports UTF-8 encoded binary
• Pure Erlang
• Highly Efficient
  • Maybe one of the fastest JSON library (except those which are implemented in NIF)
    • TODO: benchmark result
  • Decode function is written in continuation-passing style(CPS)
    • CPS facilitates application of 'creation of sub binary delayed' optimization
    • See also Erlang Efficiency Guide

QuickStart

# clone
$ git clone git://github.com/sile/jsone.git
$ cd jsone

# If you want to use HiPE enabled version, please execute following command.
# $ git checkout hipe

# compile
$ make compile

# run tests
$ make eunit

# dialyze
$ make dialyze

# Erlang shell
$ make start
1> jsone:decode(<<"[1,2,3]">>).
[1,2,3]

Usage Example

%% Decode
> jsone:decode(<<"[1,2,3]">>).
[1,2,3]

> jsone:decode(<<"{\"1\":2}">>).
{[{<<"1">>,2}]}

> jsone:try_decode(<<"[1,2,3] \"next value\"">>). % try_decode/1 returns remaining (unconsumed binary)
{ok,[1,2,3],<<" \"next value\"">>}

% error: raises exception
> jsone:decode(<<"1.x">>).
** exception error: bad argument
     in function  jsone_decode:number_fraction_part_rest/6
        called as jsone_decode:number_fraction_part_rest(<<"x">>,1,1,0,[],<<>>)
     in call from jsone:decode/1 (src/jsone.erl, line 71)

% error: returns {error, Reason}
> jsone:try_decode(<<"1.x">>).
{error,{badarg,[{jsone_decode,number_fraction_part_rest,
                              [<<"x">>,1,1,0,[],<<>>],
                              [{line,228}]}]}}


%% Encode
> jsone:encode([1,2,3]).
<<"[1,2,3]">>

> jsone:encode({[{<<"key">>, <<"value">>}]}).
<<"{\"key\":\"value\"}">>

% error: raises exception
> jsone:encode({[{key, <<"value">>}]}). % non binary key is not allowed
** exception error: bad argument
     in function  jsone_encode:object_members/3
        called as jsone_encode:object_members([{key,<<"value">>}],[],<<"{">>)
     in call from jsone:encode/1 (src/jsone.erl, line 97)

% error: returns {error, Reason}
> jsone:try_encode({[{key, <<"value">>}]}).
{error,{badarg,[{jsone_encode,object_members,
                              [[{key,<<"value">>}],[],<<"{">>],
                              [{line,138}]}]}}

Data Mapping (Erlang <=> JSON)

	Erlang	JSON
number	123	123
null	null	null
boolean	true	true
string	<<"abc">>	"abc"
array	[1,2,3]	[1,2,3]
object	{[{<<"key">>, <<"value">>}]}	{"key":"value"}

API

See EDoc Document