jsx/src/jsx_to_json.erl

%% The MIT License

%% Copyright (c) 2010-2013 alisdair sullivan <alisdairsullivan@yahoo.ca>

%% Permission is hereby granted, free of charge, to any person obtaining a copy
%% of this software and associated documentation files (the "Software"), to deal
%% in the Software without restriction, including without limitation the rights
%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
%% copies of the Software, and to permit persons to whom the Software is
%% furnished to do so, subject to the following conditions:

%% The above copyright notice and this permission notice shall be included in
%% all copies or substantial portions of the Software.

%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
%% THE SOFTWARE.


-module(jsx_to_json).

-export([to_json/2, format/2]).
-export([init/1, handle_event/2]).
-export([start_object/1, start_array/1, insert/2, insert/3, finish/1]).


-record(config, {
    space = 0,
    indent = 0,
    depth = 0
}).

-type config() :: list().


-spec to_json(Source::any(), Config::config()) -> binary().

to_json(Source, Config) when is_list(Config) ->
    (jsx:encoder(?MODULE, Config, jsx_config:extract_config(Config ++ [escaped_strings])))(Source).


-spec format(Source::binary(), Config::config()) -> binary().

format(Source, Config) when is_binary(Source) andalso is_list(Config) ->
    (jsx:decoder(?MODULE, Config, jsx_config:extract_config(Config ++ [escaped_strings])))(Source);
format(_, _) -> erlang:error(badarg).


parse_config(Config) -> parse_config(Config, #config{}).

parse_config([{space, Val}|Rest], Config) when is_integer(Val), Val > 0 ->
    parse_config(Rest, Config#config{space = Val});
parse_config([space|Rest], Config) ->
    parse_config(Rest, Config#config{space = 1});
parse_config([{indent, Val}|Rest], Config) when is_integer(Val), Val > 0 ->
    parse_config(Rest, Config#config{indent = Val});
parse_config([indent|Rest], Config) ->
    parse_config(Rest, Config#config{indent = 1});
parse_config([{K, _}|Rest] = Options, Config) ->
    case lists:member(K, jsx_config:valid_flags()) of
        true -> parse_config(Rest, Config)
        ; false -> erlang:error(badarg, [Options, Config])
    end;
parse_config([K|Rest] = Options, Config) ->
    case lists:member(K, jsx_config:valid_flags()) of
        true -> parse_config(Rest, Config)
        ; false -> erlang:error(badarg, [Options, Config])
    end;
parse_config([], Config) ->
    Config.


-define(start_object, <<"{">>).
-define(start_array, <<"[">>).
-define(end_object, <<"}">>).
-define(end_array, <<"]">>).
-define(colon, <<":">>).
-define(comma, <<",">>).
-define(quote, <<"\"">>).
-define(space, <<" ">>).
-define(newline, <<"\n">>).


init(Config) -> {[], parse_config(Config)}.


handle_event(end_json, {Term, _Config}) -> Term;

handle_event(start_object, State) -> start_object(State);
handle_event(end_object, State) -> finish(State);

handle_event(start_array, State) -> start_array(State);
handle_event(end_array, State) -> finish(State);

handle_event({Type, Event}, {_, Config} = State) -> insert(encode(Type, Event, Config), State).


encode(string, String, _Config) ->
    <<?quote/binary, String/binary, ?quote/binary>>;
encode(key, Key, _Config) ->
    <<?quote/binary, Key/binary, ?quote/binary>>;
encode(literal, Literal, _Config) ->
    unicode:characters_to_binary(erlang:atom_to_list(Literal));
encode(integer, Integer, _Config) ->
    unicode:characters_to_binary(erlang:integer_to_list(Integer));
encode(float, Float, _Config) ->
    [Output] = io_lib:format("~p", [Float]), unicode:characters_to_binary(Output).


space(Config) ->
    case Config#config.space of
        0 -> <<>>
        ; X when X > 0 -> binary:copy(?space, X)
    end.


indent(Config) ->
    case Config#config.indent of
        0 -> <<>>
        ; X when X > 0 -> <<?newline/binary, (binary:copy(?space, X * Config#config.depth))/binary>>
    end.


indent_or_space(Config) ->
    case Config#config.indent > 0 of
        true -> indent(Config)
        ; false -> space(Config)
    end.


%% internal state is a stack and a config object
%%  `{Stack, Config}`
%% the stack is a list of in progress objects/arrays
%%  `[Current, Parent, Grandparent,...OriginalAncestor]`
%% an object has the representation on the stack of
%%  `{object, Object}`
%% of if there's a key with a yet to be matched value
%%  `{object, Key, Object}`
%% an array looks like
%%  `{array, Array}`
%% `Object` and `Array` are utf8 encoded binaries

%% allocate a new object on top of the stack
start_object({Stack, Config}) -> {[{object, ?start_object}] ++ Stack, Config}.

%% allocate a new array on top of the stack
start_array({Stack, Config}) -> {[{array, ?start_array}] ++ Stack, Config}.

%% finish an object or array and insert it into the parent object if it exists
finish({[{object, Object}], Config}) ->
    {<<Object/binary, ?end_object/binary>>, Config};
finish({[{object, Object}|Rest], Config}) ->
    insert(<<Object/binary, ?end_object/binary>>, {Rest, Config});
finish({[{array, Array}], Config}) ->
    {<<Array/binary, ?end_array/binary>>, Config};
finish({[{array, Array}|Rest], Config}) ->
    insert(<<Array/binary, ?end_array/binary>>, {Rest, Config});
finish(_) -> erlang:error(badarg).

%% insert a value when there's no parent object or array
insert(Value, {[], Config}) when is_binary(Value) ->
    {Value, Config};
%% insert a key or value into an object or array, autodetects the 'right' thing
insert(Key, {[{object, Object}|Rest], Config}) when is_binary(Key) ->
    {[{object, Key, Object}] ++ Rest, Config};
insert(Value, {[{object, Key, ?start_object}|Rest], Config}) when is_binary(Value) ->
    {
        [{object, <<?start_object/binary,
            Key/binary,
            ?colon/binary,
            (space(Config))/binary,
            Value/binary
        >>}] ++ Rest,
        Config
    };
insert(Value, {[{object, Key, Object}|Rest], Config}) when is_binary(Value) ->
    {
        [{object, <<Object/binary,
            ?comma/binary,
            (indent_or_space(Config))/binary,
            Key/binary,
            ?colon/binary,
            (space(Config))/binary,
            Value/binary
        >>}] ++ Rest,
        Config
    };
insert(Value, {[{array, ?start_array}|Rest], Config}) when is_binary(Value) ->
    {[{array, <<?start_array/binary, Value/binary>>}] ++ Rest, Config};
insert(Value, {[{array, Array}|Rest], Config}) when is_binary(Value) ->
    {
        [{array, <<Array/binary,
            ?comma/binary,
            (indent_or_space(Config))/binary,
            Value/binary
        >>}] ++ Rest,
        Config
    };
insert(_, _) -> erlang:error(badarg).

%% insert a key/value pair into an object
insert(Key, Value, {[{object, ?start_object}|Rest], Config}) when is_binary(Key), is_binary(Value) ->
    {
        [{object, <<?start_object/binary,
            Key/binary,
            ?colon/binary,
            (space(Config))/binary,
            Value/binary
        >>}] ++ Rest,
        Config
    };
insert(Key, Value, {[{object, Object}|Rest], Config}) when is_binary(Key), is_binary(Value) ->
    {
        [{object, <<Object/binary,
            ?comma/binary,
            (indent_or_space(Config))/binary,
            Key/binary,
            ?colon/binary,
            (space(Config))/binary,
            Value/binary
        >>}] ++ Rest,
        Config
    };
insert(_, _, _) -> erlang:error(badarg).


%% eunit tests

-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").


config_test_() ->
    [
        {"empty config", ?_assertEqual(#config{}, parse_config([]))},
        {"unspecified indent/space", ?_assertEqual(
            #config{space=1, indent=1},
            parse_config([space, indent])
        )},
        {"specific indent", ?_assertEqual(
            #config{indent=4},
            parse_config([{indent, 4}])
        )},
        {"specific space", ?_assertEqual(
            #config{space=2},
            parse_config([{space, 2}])
        )},
        {"specific space and indent", ?_assertEqual(
            #config{space=2, indent=2},
            parse_config([{space, 2}, {indent, 2}])
        )},
        {"invalid opt flag", ?_assertError(badarg, parse_config([error]))},
        {"invalid opt tuple", ?_assertError(badarg, parse_config([{error, true}]))}
    ].


space_test_() ->
    [
        {"no space", ?_assertEqual(<<>>, space(#config{space=0}))},
        {"one space", ?_assertEqual(<<" ">>, space(#config{space=1}))},
        {"four spaces", ?_assertEqual(<<"    ">>, space(#config{space=4}))}
    ].


indent_test_() ->
    [
        {"no indent", ?_assertEqual(<<>>, indent(#config{indent=0, depth=1}))},
        {"indent 1 depth 1", ?_assertEqual(
            <<?newline/binary, <<" ">>/binary>>,
            indent(#config{indent=1, depth=1})
        )},
        {"indent 1 depth 2", ?_assertEqual(
            <<?newline/binary, <<"  ">>/binary>>,
            indent(#config{indent=1, depth=2})
        )},
        {"indent 4 depth 1", ?_assertEqual(
            <<?newline/binary, <<"    ">>/binary>>,
            indent(#config{indent=4, depth=1})
        )},
        {"indent 4 depth 2", ?_assertEqual(
            <<?newline/binary, <<"    ">>/binary, <<"    ">>/binary>>,
            indent(#config{indent=4, depth=2})
        )}
    ].


indent_or_space_test_() ->
    [
        {"no indent so space", ?_assertEqual(
            <<" ">>,
            indent_or_space(#config{space=1, indent=0, depth=1})
        )},
        {"indent so no space", ?_assertEqual(
            <<?newline/binary, <<" ">>/binary>>,
            indent_or_space(#config{space=1, indent=1, depth=1})
        )}
    ].


format_test_() ->
    [
        {"0.0", ?_assert(encode(float, 0.0, #config{}) =:= <<"0.0">>)},
        {"1.0", ?_assert(encode(float, 1.0, #config{}) =:= <<"1.0">>)},
        {"-1.0", ?_assert(encode(float, -1.0, #config{}) =:= <<"-1.0">>)},
        {"3.1234567890987654321", 
            ?_assert(
                encode(float, 3.1234567890987654321, #config{}) =:= <<"3.1234567890987655">>)
        },
        {"1.0e23", ?_assert(encode(float, 1.0e23, #config{}) =:= <<"1.0e23">>)},
        {"0.3", ?_assert(encode(float, 3.0/10.0, #config{}) =:= <<"0.3">>)},
        {"0.0001", ?_assert(encode(float, 0.0001, #config{}) =:= <<"0.0001">>)},
        {"0.00001", ?_assert(encode(float, 0.00001, #config{}) =:= <<"1.0e-5">>)},
        {"0.00000001", ?_assert(encode(float, 0.00000001, #config{}) =:= <<"1.0e-8">>)},
        {"1.0e-323", ?_assert(encode(float, 1.0e-323, #config{}) =:= <<"1.0e-323">>)},
        {"1.0e308", ?_assert(encode(float, 1.0e308, #config{}) =:= <<"1.0e308">>)},
        {"min normalized float", 
            ?_assert(
                encode(float, math:pow(2, -1022), #config{}) =:= <<"2.2250738585072014e-308">>
            )
        },
        {"max normalized float", 
            ?_assert(
                encode(float, (2 - math:pow(2, -52)) * math:pow(2, 1023), #config{}) 
                    =:= <<"1.7976931348623157e308">>
            )
        },
        {"min denormalized float", 
            ?_assert(encode(float, math:pow(2, -1074), #config{}) =:= <<"5.0e-324">>)
        },
        {"max denormalized float", 
            ?_assert(
                encode(float, (1 - math:pow(2, -52)) * math:pow(2, -1022), #config{}) 
                    =:= <<"2.225073858507201e-308">>
            )
        },
        {"hello world", ?_assert(encode(string, <<"hello world">>, #config{}) =:= <<"\"hello world\"">>)},
        {"key", ?_assert(encode(key, <<"key">>, #config{}) =:= <<"\"key\"">>)},
        {"1", ?_assert(encode(integer, 1, #config{}) =:= <<"1">>)},
        {"-1", ?_assert(encode(integer, -1, #config{}) =:= <<"-1">>)},
        {"true", ?_assert(encode(literal, true, #config{}) =:= <<"true">>)},
        {"false", ?_assert(encode(literal, false, #config{}) =:= <<"false">>)},
        {"null", ?_assert(encode(literal, null, #config{}) =:= <<"null">>)}      
    ].


rep_manipulation_test_() ->
    [
        {"allocate a new object on an empty stack", ?_assertEqual(
            {[{object, <<"{">>}], #config{}},
            start_object({[], #config{}})
        )},
        {"allocate a new object on a stack", ?_assertEqual(
            {[{object, <<"{">>}, {object, <<"{">>}], #config{}},
            start_object({[{object, <<"{">>}], #config{}})
        )},
        {"allocate a new array on an empty stack", ?_assertEqual(
            {[{array, <<"[">>}], #config{}},
            start_array({[], #config{}})
        )},
        {"allocate a new array on a stack", ?_assertEqual(
            {[{array, <<"[">>}, {object, <<"{">>}], #config{}},
            start_array({[{object, <<"{">>}], #config{}})
        )},
        {"insert a key into an object", ?_assertEqual(
            {[{object, <<"\"key\"">>, <<"{">>}], #config{}},
            insert(<<"\"key\"">>, {[{object, <<"{">>}], #config{}})
        )},
        {"insert a value into an object", ?_assertEqual(
            {[{object, <<"{\"key\":true">>}], #config{}},
            insert(<<"true">>, {[{object, <<"\"key\"">>, <<"{">>}], #config{}})
        )},
        {"insert a value into an array", ?_assertEqual(
            {[{array, <<"[true">>}], #config{}},
            insert(<<"true">>, {[{array, <<"[">>}], #config{}})
        )},
        {"insert a key/value pair into an object", ?_assertEqual(
            {[{object, <<"{\"x\":true,\"y\":false">>}], #config{}},
            insert(<<"\"y\"">>, <<"false">>, {[{object, <<"{\"x\":true">>}], #config{}})
        )},
        {"finish an object with no ancestor", ?_assertEqual(
            {<<"{\"x\":true,\"y\":false}">>, #config{}},
            finish({[{object, <<"{\"x\":true,\"y\":false">>}], #config{}})
        )},
        {"finish an empty object", ?_assertEqual(
            {<<"{}">>, #config{}},
            finish({[{object, <<"{">>}], #config{}})
        )},
        {"finish an object with an ancestor", ?_assertEqual(
            {[{object, <<"{\"a\":[],\"b\":{\"x\":true,\"y\":false}">>}], #config{}},
            finish({
                [{object, <<"{\"x\":true,\"y\":false">>}, {object, <<"\"b\"">>, <<"{\"a\":[]">>}],
                #config{}
            })
        )},
        {"finish an array with no ancestor", ?_assertEqual(
            {<<"[true,false,null]">>, #config{}},
            finish({[{array, <<"[true,false,null">>}], #config{}})
        )},
        {"finish an array with an ancestor", ?_assertEqual(
            {[{array, <<"[1,2,3,[true,false,null]">>}], #config{}},
            finish({[{array, <<"[true,false,null">>}, {array, <<"[1,2,3">>}], #config{}})
        )}
    ].


handle_event_test_() ->
    Data = jsx:test_cases(),
    [
        {
            Title, ?_assertEqual(
                JSON,
                lists:foldl(fun handle_event/2, init([]), Events ++ [end_json])
            )
        } || {Title, JSON, _, Events} <- Data
    ].


-endif.