summaryrefslogtreecommitdiff
path: root/src/mochiweb/mochijson2.erl
blob: 592b4790ebead03ec32c7ad57e8202e2f18e9fec (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
%% @author Bob Ippolito <bob@mochimedia.com>
%% @copyright 2007 Mochi Media, Inc.

%% @doc Yet another JSON (RFC 4627) library for Erlang. mochijson2 works
%%      with binaries as strings, arrays as lists (without an {array, _})
%%      wrapper and it only knows how to decode UTF-8 (and ASCII).

-module(mochijson2).
-author('bob@mochimedia.com').
-export([encoder/1, encode/1]).
-export([decoder/1, decode/1]).
-export([test/0]).

% This is a macro to placate syntax highlighters..
-define(Q, $\").
-define(ADV_COL(S, N), S#decoder{offset=N+S#decoder.offset,
                                 column=N+S#decoder.column}).
-define(INC_COL(S), S#decoder{offset=1+S#decoder.offset,
                              column=1+S#decoder.column}).
-define(INC_LINE(S), S#decoder{offset=1+S#decoder.offset,
                               column=1,
                               line=1+S#decoder.line}).
-define(INC_CHAR(S, C),
        case C of
            $\n ->
                S#decoder{column=1,
                          line=1+S#decoder.line,
                          offset=1+S#decoder.offset};
            _ ->
                S#decoder{column=1+S#decoder.column,
                          offset=1+S#decoder.offset}
        end).
-define(IS_WHITESPACE(C),
        (C =:= $\s orelse C =:= $\t orelse C =:= $\r orelse C =:= $\n)).

%% @type iolist() = [char() | binary() | iolist()]
%% @type iodata() = iolist() | binary()
%% @type json_string() = atom | binary()
%% @type json_number() = integer() | float()
%% @type json_array() = [json_term()]
%% @type json_object() = {struct, [{json_string(), json_term()}]}
%% @type json_term() = json_string() | json_number() | json_array() |
%%                     json_object()

-record(encoder, {handler=null}).

-record(decoder, {object_hook=null,
                  offset=0,
                  line=1,
                  column=1,
                  state=null}).

%% @spec encoder([encoder_option()]) -> function()
%% @doc Create an encoder/1 with the given options.
encoder(Options) ->
    State = parse_encoder_options(Options, #encoder{}),
    fun (O) -> json_encode(O, State) end.

%% @spec encode(json_term()) -> iolist()
%% @doc Encode the given as JSON to an iolist.
encode(Any) ->
    json_encode(Any, #encoder{}).

%% @spec decoder([decoder_option()]) -> function()
%% @doc Create a decoder/1 with the given options.
decoder(Options) ->
    State = parse_decoder_options(Options, #decoder{}),
    fun (O) -> json_decode(O, State) end.

%% @spec decode(iolist()) -> json_term()
%% @doc Decode the given iolist to Erlang terms.
decode(S) ->
    json_decode(S, #decoder{}).

test() ->
    test_all().

%% Internal API

parse_encoder_options([], State) ->
    State;
parse_encoder_options([{handler, Handler} | Rest], State) ->
    parse_encoder_options(Rest, State#encoder{handler=Handler}).

parse_decoder_options([], State) ->
    State;
parse_decoder_options([{object_hook, Hook} | Rest], State) ->
    parse_decoder_options(Rest, State#decoder{object_hook=Hook}).

json_encode(true, _State) ->
    <<"true">>;
json_encode(false, _State) ->
    <<"false">>;
json_encode(null, _State) ->
    <<"null">>;
json_encode(I, _State) when is_integer(I) andalso I >= -2147483648 andalso I =< 2147483647 ->
    %% Anything outside of 32-bit integers should be encoded as a float
    integer_to_list(I);
json_encode(I, _State) when is_integer(I) ->
    mochinum:digits(float(I));
json_encode(F, _State) when is_float(F) ->
    mochinum:digits(F);
json_encode(S, State) when is_binary(S); is_atom(S) ->
    json_encode_string(S, State);
json_encode(Array, State) when is_list(Array) ->
    json_encode_array(Array, State);
json_encode({struct, Props}, State) when is_list(Props) ->
    json_encode_proplist(Props, State);
json_encode(Bad, #encoder{handler=null}) ->
    exit({json_encode, {bad_term, Bad}});
json_encode(Bad, State=#encoder{handler=Handler}) ->
    json_encode(Handler(Bad), State).

json_encode_array([], _State) ->
    <<"[]">>;
json_encode_array(L, State) ->
    F = fun (O, Acc) ->
                [$,, json_encode(O, State) | Acc]
        end,
    [$, | Acc1] = lists:foldl(F, "[", L),
    lists:reverse([$\] | Acc1]).

json_encode_proplist([], _State) ->
    <<"{}">>;
json_encode_proplist(Props, State) ->
    F = fun ({K, V}, Acc) ->
                KS = json_encode_string(K, State),
                VS = json_encode(V, State),
                [$,, VS, $:, KS | Acc]
        end,
    [$, | Acc1] = lists:foldl(F, "{", Props),
    lists:reverse([$\} | Acc1]).

json_encode_string(A, _State) when is_atom(A) ->
    json_encode_string_unicode(xmerl_ucs:from_utf8(atom_to_list(A)), [?Q]);
json_encode_string(B, _State) when is_binary(B) ->
    json_encode_string_unicode(xmerl_ucs:from_utf8(B), [?Q]);
json_encode_string(I, _State) when is_integer(I) ->
    json_encode_string_unicode(integer_to_list(I), [?Q]);
json_encode_string(L, _State) when is_list(L) ->
    json_encode_string_unicode(L, [?Q]).

json_encode_string_unicode([], Acc) ->
    lists:reverse([$\" | Acc]);
json_encode_string_unicode([C | Cs], Acc) ->
    Acc1 = case C of
               ?Q ->
                   [?Q, $\\ | Acc];
               %% Escaping solidus is only useful when trying to protect
               %% against "</script>" injection attacks which are only
               %% possible when JSON is inserted into a HTML document
               %% in-line. mochijson2 does not protect you from this, so
               %% if you do insert directly into HTML then you need to
               %% uncomment the following case or escape the output of encode.
               %%
               %% $/ ->
               %%    [$/, $\\ | Acc];
               %%
               $\\ ->
                   [$\\, $\\ | Acc];
               $\b ->
                   [$b, $\\ | Acc];
               $\f ->
                   [$f, $\\ | Acc];
               $\n ->
                   [$n, $\\ | Acc];
               $\r ->
                   [$r, $\\ | Acc];
               $\t ->
                   [$t, $\\ | Acc];
               C when C >= 0, C < $\s; C >= 16#7f, C =< 16#10FFFF ->
                   [unihex(C) | Acc];
               C when C < 16#7f ->
                   [C | Acc];
               _ ->
                   exit({json_encode, {bad_char, C}})
           end,
    json_encode_string_unicode(Cs, Acc1).

hexdigit(C) when C >= 0, C =< 9 ->
    C + $0;
hexdigit(C) when C =< 15 ->
    C + $a - 10.

unihex(C) when C < 16#10000 ->
    <<D3:4, D2:4, D1:4, D0:4>> = <<C:16>>,
    Digits = [hexdigit(D) || D <- [D3, D2, D1, D0]],
    [$\\, $u | Digits];
unihex(C) when C =< 16#10FFFF ->
    N = C - 16#10000,
    S1 = 16#d800 bor ((N bsr 10) band 16#3ff),
    S2 = 16#dc00 bor (N band 16#3ff),
    [unihex(S1), unihex(S2)].

json_decode(L, S) when is_list(L) ->
    json_decode(iolist_to_binary(L), S);
json_decode(B, S) ->
    {Res, S1} = decode1(B, S),
    {eof, _} = tokenize(B, S1#decoder{state=trim}),
    Res.

decode1(B, S=#decoder{state=null}) ->
    case tokenize(B, S#decoder{state=any}) of
        {{const, C}, S1} ->
            {C, S1};
        {start_array, S1} ->
            decode_array(B, S1);
        {start_object, S1} ->
            decode_object(B, S1)
    end.

make_object(V, #decoder{object_hook=null}) ->
    V;
make_object(V, #decoder{object_hook=Hook}) ->
    Hook(V).

decode_object(B, S) ->
    decode_object(B, S#decoder{state=key}, []).

decode_object(B, S=#decoder{state=key}, Acc) ->
    case tokenize(B, S) of
        {end_object, S1} ->
            V = make_object({struct, lists:reverse(Acc)}, S1),
            {V, S1#decoder{state=null}};
        {{const, K}, S1} ->
            {colon, S2} = tokenize(B, S1),
            {V, S3} = decode1(B, S2#decoder{state=null}),
            decode_object(B, S3#decoder{state=comma}, [{K, V} | Acc])
    end;
decode_object(B, S=#decoder{state=comma}, Acc) ->
    case tokenize(B, S) of
        {end_object, S1} ->
            V = make_object({struct, lists:reverse(Acc)}, S1),
            {V, S1#decoder{state=null}};
        {comma, S1} ->
            decode_object(B, S1#decoder{state=key}, Acc)
    end.

decode_array(B, S) ->
    decode_array(B, S#decoder{state=any}, []).

decode_array(B, S=#decoder{state=any}, Acc) ->
    case tokenize(B, S) of
        {end_array, S1} ->
            {lists:reverse(Acc), S1#decoder{state=null}};
        {start_array, S1} ->
            {Array, S2} = decode_array(B, S1),
            decode_array(B, S2#decoder{state=comma}, [Array | Acc]);
        {start_object, S1} ->
            {Array, S2} = decode_object(B, S1),
            decode_array(B, S2#decoder{state=comma}, [Array | Acc]);
        {{const, Const}, S1} ->
            decode_array(B, S1#decoder{state=comma}, [Const | Acc])
    end;
decode_array(B, S=#decoder{state=comma}, Acc) ->
    case tokenize(B, S) of
        {end_array, S1} ->
            {lists:reverse(Acc), S1#decoder{state=null}};
        {comma, S1} ->
            decode_array(B, S1#decoder{state=any}, Acc)
    end.

tokenize_string(B, S) ->
    tokenize_string(B, S, []).

tokenize_string(B, S=#decoder{offset=O}, Acc) ->
    case B of
        <<_:O/binary, ?Q, _/binary>> ->
            {{const, iolist_to_binary(lists:reverse(Acc))}, ?INC_COL(S)};
        <<_:O/binary, "\\\"", _/binary>> ->
            tokenize_string(B, ?ADV_COL(S, 2), [$\" | Acc]);
        <<_:O/binary, "\\\\", _/binary>> ->
            tokenize_string(B, ?ADV_COL(S, 2), [$\\ | Acc]);
        <<_:O/binary, "\\/", _/binary>> ->
            tokenize_string(B, ?ADV_COL(S, 2), [$/ | Acc]);
        <<_:O/binary, "\\b", _/binary>> ->
            tokenize_string(B, ?ADV_COL(S, 2), [$\b | Acc]);
        <<_:O/binary, "\\f", _/binary>> ->
            tokenize_string(B, ?ADV_COL(S, 2), [$\f | Acc]);
        <<_:O/binary, "\\n", _/binary>> ->
            tokenize_string(B, ?ADV_COL(S, 2), [$\n | Acc]);
        <<_:O/binary, "\\r", _/binary>> ->
            tokenize_string(B, ?ADV_COL(S, 2), [$\r | Acc]);
        <<_:O/binary, "\\t", _/binary>> ->
            tokenize_string(B, ?ADV_COL(S, 2), [$\t | Acc]);
        <<_:O/binary, "\\u", C3, C2, C1, C0, _/binary>> ->
            %% coalesce UTF-16 surrogate pair?
            C = erlang:list_to_integer([C3, C2, C1, C0], 16),
            Acc1 = lists:reverse(xmerl_ucs:to_utf8(C), Acc),
            tokenize_string(B, ?ADV_COL(S, 6), Acc1);
        <<_:O/binary, C, _/binary>> ->
            tokenize_string(B, ?INC_CHAR(S, C), [C | Acc])
    end.

tokenize_number(B, S) ->
    case tokenize_number(B, sign, S, []) of
        {{int, Int}, S1} ->
            {{const, list_to_integer(Int)}, S1};
        {{float, Float}, S1} ->
            {{const, list_to_float(Float)}, S1}
    end.

tokenize_number(B, sign, S=#decoder{offset=O}, []) ->
    case B of
        <<_:O/binary, $-, _/binary>> ->
            tokenize_number(B, int, ?INC_COL(S), [$-]);
        _ ->
            tokenize_number(B, int, S, [])
    end;
tokenize_number(B, int, S=#decoder{offset=O}, Acc) ->
    case B of
        <<_:O/binary, $0, _/binary>> ->
            tokenize_number(B, frac, ?INC_COL(S), [$0 | Acc]);
        <<_:O/binary, C, _/binary>> when C >= $1 andalso C =< $9 ->
            tokenize_number(B, int1, ?INC_COL(S), [C | Acc])
    end;
tokenize_number(B, int1, S=#decoder{offset=O}, Acc) ->
    case B of
        <<_:O/binary, C, _/binary>> when C >= $0 andalso C =< $9 ->
            tokenize_number(B, int1, ?INC_COL(S), [C | Acc]);
        _ ->
            tokenize_number(B, frac, S, Acc)
    end;
tokenize_number(B, frac, S=#decoder{offset=O}, Acc) ->
    case B of
        <<_:O/binary, $., C, _/binary>> when C >= $0, C =< $9 ->
            tokenize_number(B, frac1, ?ADV_COL(S, 2), [C, $. | Acc]);
        <<_:O/binary, E, _/binary>> when E =:= $e orelse E =:= $E ->
            tokenize_number(B, esign, ?INC_COL(S), [$e, $0, $. | Acc]);
        _ ->
            {{int, lists:reverse(Acc)}, S}
    end;
tokenize_number(B, frac1, S=#decoder{offset=O}, Acc) ->
    case B of
        <<_:O/binary, C, _/binary>> when C >= $0 andalso C =< $9 ->
            tokenize_number(B, frac1, ?INC_COL(S), [C | Acc]);
        <<_:O/binary, E, _/binary>> when E =:= $e orelse E =:= $E ->
            tokenize_number(B, esign, ?INC_COL(S), [$e | Acc]);
        _ ->
            {{float, lists:reverse(Acc)}, S}
    end;
tokenize_number(B, esign, S=#decoder{offset=O}, Acc) ->
    case B of
        <<_:O/binary, C, _/binary>> when C =:= $- orelse C=:= $+ ->
            tokenize_number(B, eint, ?INC_COL(S), [C | Acc]);
        _ ->
            tokenize_number(B, eint, S, Acc)
    end;
tokenize_number(B, eint, S=#decoder{offset=O}, Acc) ->
    case B of
        <<_:O/binary, C, _/binary>> when C >= $0 andalso C =< $9 ->
            tokenize_number(B, eint1, ?INC_COL(S), [C | Acc])
    end;
tokenize_number(B, eint1, S=#decoder{offset=O}, Acc) ->
    case B of
        <<_:O/binary, C, _/binary>> when C >= $0 andalso C =< $9 ->
            tokenize_number(B, eint1, ?INC_COL(S), [C | Acc]);
        _ ->
            {{float, lists:reverse(Acc)}, S}
    end.

tokenize(B, S=#decoder{offset=O}) ->
    case B of
        <<_:O/binary, C, _/binary>> when ?IS_WHITESPACE(C) ->
            tokenize(B, ?INC_CHAR(S, C));
        <<_:O/binary, "{", _/binary>> ->
            {start_object, ?INC_COL(S)};
        <<_:O/binary, "}", _/binary>> ->
            {end_object, ?INC_COL(S)};
        <<_:O/binary, "[", _/binary>> ->
            {start_array, ?INC_COL(S)};
        <<_:O/binary, "]", _/binary>> ->
            {end_array, ?INC_COL(S)};
        <<_:O/binary, ",", _/binary>> ->
            {comma, ?INC_COL(S)};
        <<_:O/binary, ":", _/binary>> ->
            {colon, ?INC_COL(S)};
        <<_:O/binary, "null", _/binary>> ->
            {{const, null}, ?ADV_COL(S, 4)};
        <<_:O/binary, "true", _/binary>> ->
            {{const, true}, ?ADV_COL(S, 4)};
        <<_:O/binary, "false", _/binary>> ->
            {{const, false}, ?ADV_COL(S, 5)};
        <<_:O/binary, "\"", _/binary>> ->
            tokenize_string(B, ?INC_COL(S));
        <<_:O/binary, C, _/binary>> when (C >= $0 andalso C =< $9)
                                         orelse C =:= $- ->
            tokenize_number(B, S);
        <<_:O/binary>> ->
            trim = S#decoder.state,
            {eof, S}
    end.

%% testing constructs borrowed from the Yaws JSON implementation.

%% Create an object from a list of Key/Value pairs.

obj_new() ->
    {struct, []}.

is_obj({struct, Props}) ->
    F = fun ({K, _}) when is_binary(K) ->
                true;
            (_) ->
                false
        end,    
    lists:all(F, Props).

obj_from_list(Props) ->
    Obj = {struct, Props},
    case is_obj(Obj) of
        true -> Obj;
        false -> exit({json_bad_object, Obj})
    end.

%% Test for equivalence of Erlang terms.
%% Due to arbitrary order of construction, equivalent objects might
%% compare unequal as erlang terms, so we need to carefully recurse
%% through aggregates (tuples and objects).

equiv({struct, Props1}, {struct, Props2}) ->
    equiv_object(Props1, Props2);
equiv(L1, L2) when is_list(L1), is_list(L2) ->
    equiv_list(L1, L2);
equiv(N1, N2) when is_number(N1), is_number(N2) -> N1 == N2;
equiv(B1, B2) when is_binary(B1), is_binary(B2) -> B1 == B2;
equiv(true, true) -> true;
equiv(false, false) -> true;
equiv(null, null) -> true.

%% Object representation and traversal order is unknown.
%% Use the sledgehammer and sort property lists.

equiv_object(Props1, Props2) ->
    L1 = lists:keysort(1, Props1),
    L2 = lists:keysort(1, Props2),
    Pairs = lists:zip(L1, L2),
    true = lists:all(fun({{K1, V1}, {K2, V2}}) ->
                             equiv(K1, K2) and equiv(V1, V2)
                     end, Pairs).

%% Recursively compare tuple elements for equivalence.

equiv_list([], []) ->
    true;
equiv_list([V1 | L1], [V2 | L2]) ->
    case equiv(V1, V2) of
        true ->
            equiv_list(L1, L2);
        false ->
            false
    end.

test_all() ->
    [1199344435545.0, 1] = decode(<<"[1199344435545.0,1]">>),
    test_one(e2j_test_vec(utf8), 1).

test_one([], _N) ->
    %% io:format("~p tests passed~n", [N-1]),
    ok;
test_one([{E, J} | Rest], N) ->
    %% io:format("[~p] ~p ~p~n", [N, E, J]),
    true = equiv(E, decode(J)),
    true = equiv(E, decode(encode(E))),
    test_one(Rest, 1+N).

e2j_test_vec(utf8) ->
    [
     {1, "1"},
     {3.1416, "3.14160"}, %% text representation may truncate, trail zeroes
     {-1, "-1"},
     {-3.1416, "-3.14160"},
     {12.0e10, "1.20000e+11"},
     {1.234E+10, "1.23400e+10"},
     {-1.234E-10, "-1.23400e-10"},
     {10.0, "1.0e+01"},
     {123.456, "1.23456E+2"},
     {10.0, "1e1"},
     {<<"foo">>, "\"foo\""},
     {<<"foo", 5, "bar">>, "\"foo\\u0005bar\""},
     {<<"">>, "\"\""},
     {<<"\n\n\n">>, "\"\\n\\n\\n\""},
     {<<"\" \b\f\r\n\t\"">>, "\"\\\" \\b\\f\\r\\n\\t\\\"\""},
     {obj_new(), "{}"},
     {obj_from_list([{<<"foo">>, <<"bar">>}]), "{\"foo\":\"bar\"}"},
     {obj_from_list([{<<"foo">>, <<"bar">>}, {<<"baz">>, 123}]),
      "{\"foo\":\"bar\",\"baz\":123}"},
     {[], "[]"},
     {[[]], "[[]]"},
     {[1, <<"foo">>], "[1,\"foo\"]"},
     
     %% json array in a json object
     {obj_from_list([{<<"foo">>, [123]}]),
      "{\"foo\":[123]}"},
     
     %% json object in a json object
     {obj_from_list([{<<"foo">>, obj_from_list([{<<"bar">>, true}])}]),
      "{\"foo\":{\"bar\":true}}"},
     
     %% fold evaluation order
     {obj_from_list([{<<"foo">>, []},
                     {<<"bar">>, obj_from_list([{<<"baz">>, true}])},
                     {<<"alice">>, <<"bob">>}]),
      "{\"foo\":[],\"bar\":{\"baz\":true},\"alice\":\"bob\"}"},
     
     %% json object in a json array
     {[-123, <<"foo">>, obj_from_list([{<<"bar">>, []}]), null],
      "[-123,\"foo\",{\"bar\":[]},null]"}
    ].