aboutsummaryrefslogtreecommitdiffstats
path: root/util/json.lua
blob: 2c598446bab233d05825b7926bd21a7bd29d7b19 (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
-- Prosody IM
-- Copyright (C) 2008-2010 Matthew Wild
-- Copyright (C) 2008-2010 Waqas Hussain
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

local type = type;
local t_insert, t_concat, t_remove, t_sort = table.insert, table.concat, table.remove, table.sort;
local s_char = string.char;
local tostring, tonumber = tostring, tonumber;
local pairs, ipairs = pairs, ipairs;
local next = next;
local error = error;
local getmetatable, setmetatable = getmetatable, setmetatable;
local print = print;

local has_array, array = pcall(require, "util.array");
local array_mt = has_array and getmetatable(array()) or {};

--module("json")
local json = {};

local null = setmetatable({}, { __tostring = function() return "null"; end; });
json.null = null;

local escapes = {
	["\""] = "\\\"", ["\\"] = "\\\\", ["\b"] = "\\b",
	["\f"] = "\\f", ["\n"] = "\\n", ["\r"] = "\\r", ["\t"] = "\\t"};
local unescapes = {
	["\""] = "\"", ["\\"] = "\\", ["/"] = "/",
	b = "\b", f = "\f", n = "\n", r = "\r", t = "\t"};
for i=0,31 do
	local ch = s_char(i);
	if not escapes[ch] then escapes[ch] = ("\\u%.4X"):format(i); end
end

local function codepoint_to_utf8(code)
	if code < 0x80 then return s_char(code); end
	local bits0_6 = code % 64;
	if code < 0x800 then
		local bits6_5 = (code - bits0_6) / 64;
		return s_char(0x80 + 0x40 + bits6_5, 0x80 + bits0_6);
	end
	local bits0_12 = code % 4096;
	local bits6_6 = (bits0_12 - bits0_6) / 64;
	local bits12_4 = (code - bits0_12) / 4096;
	return s_char(0x80 + 0x40 + 0x20 + bits12_4, 0x80 + bits6_6, 0x80 + bits0_6);
end

local valid_types = {
	number  = true,
	string  = true,
	table   = true,
	boolean = true
};
local special_keys = {
	__array = true;
	__hash  = true;
};

local simplesave, tablesave, arraysave, stringsave;

function stringsave(o, buffer)
	-- FIXME do proper utf-8 and binary data detection
	t_insert(buffer, "\""..(o:gsub(".", escapes)).."\"");
end

function arraysave(o, buffer)
	t_insert(buffer, "[");
	if next(o) then
		for i,v in ipairs(o) do
			simplesave(v, buffer);
			t_insert(buffer, ",");
		end
		t_remove(buffer);
	end
	t_insert(buffer, "]");
end

function tablesave(o, buffer)
	local __array = {};
	local __hash = {};
	local hash = {};
	for i,v in ipairs(o) do
		__array[i] = v;
	end
	for k,v in pairs(o) do
		local ktype, vtype = type(k), type(v);
		if valid_types[vtype] or v == null then
			if ktype == "string" and not special_keys[k] then
				hash[k] = v;
			elseif (valid_types[ktype] or k == null) and __array[k] == nil then
				__hash[k] = v;
			end
		end
	end
	if next(__hash) ~= nil or next(hash) ~= nil or next(__array) == nil then
		t_insert(buffer, "{");
		local mark = #buffer;
		if buffer.ordered then
			local keys = {};
			for k in pairs(hash) do
				t_insert(keys, k);
			end
			t_sort(keys);
			for _,k in ipairs(keys) do
				stringsave(k, buffer);
				t_insert(buffer, ":");
				simplesave(hash[k], buffer);
				t_insert(buffer, ",");
			end
		else
			for k,v in pairs(hash) do
				stringsave(k, buffer);
				t_insert(buffer, ":");
				simplesave(v, buffer);
				t_insert(buffer, ",");
			end
		end
		if next(__hash) ~= nil then
			t_insert(buffer, "\"__hash\":[");
			for k,v in pairs(__hash) do
				simplesave(k, buffer);
				t_insert(buffer, ",");
				simplesave(v, buffer);
				t_insert(buffer, ",");
			end
			t_remove(buffer);
			t_insert(buffer, "]");
			t_insert(buffer, ",");
		end
		if next(__array) then
			t_insert(buffer, "\"__array\":");
			arraysave(__array, buffer);
			t_insert(buffer, ",");
		end
		if mark ~= #buffer then t_remove(buffer); end
		t_insert(buffer, "}");
	else
		arraysave(__array, buffer);
	end
end

function simplesave(o, buffer)
	local t = type(o);
	if o == null then
		t_insert(buffer, "null");
	elseif t == "number" then
		t_insert(buffer, tostring(o));
	elseif t == "string" then
		stringsave(o, buffer);
	elseif t == "table" then
		local mt = getmetatable(o);
		if mt == array_mt then
			arraysave(o, buffer);
		else
			tablesave(o, buffer);
		end
	elseif t == "boolean" then
		t_insert(buffer, (o and "true" or "false"));
	else
		t_insert(buffer, "null");
	end
end

function json.encode(obj)
	local t = {};
	simplesave(obj, t);
	return t_concat(t);
end
function json.encode_ordered(obj)
	local t = { ordered = true };
	simplesave(obj, t);
	return t_concat(t);
end
function json.encode_array(obj)
	local t = {};
	arraysave(obj, t);
	return t_concat(t);
end

-----------------------------------


local function _skip_whitespace(json, index)
	return json:find("[^ \t\r\n]", index) or index; -- no need to check \r\n, we converted those to \t
end
local function _fixobject(obj)
	local __array = obj.__array;
	if __array then
		obj.__array = nil;
		for i,v in ipairs(__array) do
			t_insert(obj, v);
		end
	end
	local __hash = obj.__hash;
	if __hash then
		obj.__hash = nil;
		local k;
		for i,v in ipairs(__hash) do
			if k ~= nil then
				obj[k] = v; k = nil;
			else
				k = v;
			end
		end
	end
	return obj;
end
local _readvalue, _readstring;
local function _readobject(json, index)
	local o = {};
	while true do
		local key, val;
		index = _skip_whitespace(json, index + 1);
		if json:byte(index) ~= 0x22 then -- "\""
			if json:byte(index) == 0x7d then return o, index + 1; end -- "}"
			return nil, "key expected";
		end
		key, index = _readstring(json, index);
		if key == nil then return nil, index; end
		index = _skip_whitespace(json, index);
		if json:byte(index) ~= 0x3a then return nil, "colon expected"; end -- ":"
		val, index = _readvalue(json, index + 1);
		if val == nil then return nil, index; end
		o[key] = val;
		index = _skip_whitespace(json, index);
		local b = json:byte(index);
		if b == 0x7d then return _fixobject(o), index + 1; end -- "}"
		if b ~= 0x2c then return nil, "object eof"; end -- ","
	end
end
local function _readarray(json, index)
	local a = {};
	local oindex = index;
	while true do
		local val;
		val, index = _readvalue(json, index + 1);
		if val == nil then
			if json:byte(oindex + 1) == 0x5d then return setmetatable(a, array_mt), oindex + 2; end -- "]"
			return val, index;
		end
		t_insert(a, val);
		index = _skip_whitespace(json, index);
		local b = json:byte(index);
		if b == 0x5d then return setmetatable(a, array_mt), index + 1; end -- "]"
		if b ~= 0x2c then return nil, "array eof"; end -- ","
	end
end
local _unescape_error;
local function _unescape_surrogate_func(x)
	local lead, trail = tonumber(x:sub(3, 6), 16), tonumber(x:sub(9, 12), 16);
	local codepoint = lead * 0x400 + trail - 0x35FDC00;
	local a = codepoint % 64;
	codepoint = (codepoint - a) / 64;
	local b = codepoint % 64;
	codepoint = (codepoint - b) / 64;
	local c = codepoint % 64;
	codepoint = (codepoint - c) / 64;
	return s_char(0xF0 + codepoint, 0x80 + c, 0x80 + b, 0x80 + a);
end
local function _unescape_func(x)
	x = x:match("%x%x%x%x", 3);
	if x then
		--if x >= 0xD800 and x <= 0xDFFF then _unescape_error = true; end -- bad surrogate pair
		return codepoint_to_utf8(tonumber(x, 16));
	end
	_unescape_error = true;
end
function _readstring(json, index)
	index = index + 1;
	local endindex = json:find("\"", index, true);
	if endindex then
		local s = json:sub(index, endindex - 1);
		--if s:find("[%z-\31]") then return nil, "control char in string"; end
		-- FIXME handle control characters
		_unescape_error = nil;
		--s = s:gsub("\\u[dD][89abAB]%x%x\\u[dD][cdefCDEF]%x%x", _unescape_surrogate_func);
		-- FIXME handle escapes beyond BMP
		s = s:gsub("\\u.?.?.?.?", _unescape_func);
		if _unescape_error then return nil, "invalid escape"; end
		return s, endindex + 1;
	end
	return nil, "string eof";
end
local function _readnumber(json, index)
	local m = json:match("[0-9%.%-eE%+]+", index); -- FIXME do strict checking
	return tonumber(m), index + #m;
end
local function _readnull(json, index)
	local a, b, c = json:byte(index + 1, index + 3);
	if a == 0x75 and b == 0x6c and c == 0x6c then
		return null, index + 4;
	end
	return nil, "null parse failed";
end
local function _readtrue(json, index)
	local a, b, c = json:byte(index + 1, index + 3);
	if a == 0x72 and b == 0x75 and c == 0x65 then
		return true, index + 4;
	end
	return nil, "true parse failed";
end
local function _readfalse(json, index)
	local a, b, c, d = json:byte(index + 1, index + 4);
	if a == 0x61 and b == 0x6c and c == 0x73 and d == 0x65 then
		return false, index + 5;
	end
	return nil, "false parse failed";
end
function _readvalue(json, index)
	index = _skip_whitespace(json, index);
	local b = json:byte(index);
	-- TODO try table lookup instead of if-else?
	if b == 0x7B then -- "{"
		return _readobject(json, index);
	elseif b == 0x5B then -- "["
		return _readarray(json, index);
	elseif b == 0x22 then -- "\""
		return _readstring(json, index);
	elseif b ~= nil and b >= 0x30 and b <= 0x39 or b == 0x2d then -- "0"-"9" or "-"
		return _readnumber(json, index);
	elseif b == 0x6e then -- "n"
		return _readnull(json, index);
	elseif b == 0x74 then -- "t"
		return _readtrue(json, index);
	elseif b == 0x66 then -- "f"
		return _readfalse(json, index);
	else
		return nil, "value expected";
	end
end
local first_escape = {
	["\\\""] = "\\u0022";
	["\\\\"] = "\\u005c";
	["\\/" ] = "\\u002f";
	["\\b" ] = "\\u0008";
	["\\f" ] = "\\u000C";
	["\\n" ] = "\\u000A";
	["\\r" ] = "\\u000D";
	["\\t" ] = "\\u0009";
	["\\u" ] = "\\u";
};

function json.decode(json)
	json = json:gsub("\\.", first_escape) -- get rid of all escapes except \uXXXX, making string parsing much simpler
		--:gsub("[\r\n]", "\t"); -- \r\n\t are equivalent, we care about none of them, and none of them can be in strings

	-- TODO do encoding verification

	local val, index = _readvalue(json, 1);
	if val == nil then return val, index; end
	if json:find("[^ \t\r\n]", index) then return nil, "garbage at eof"; end

	return val;
end

function json.test(object)
	local encoded = json.encode(object);
	local decoded = json.decode(encoded);
	local recoded = json.encode(decoded);
	if encoded ~= recoded then
		print("FAILED");
		print("encoded:", encoded);
		print("recoded:", recoded);
	else
		print(encoded);
	end
	return encoded == recoded;
end

return json;