2 -- Copyright (C) 2008-2010 Matthew Wild
3 -- Copyright (C) 2008-2010 Waqas Hussain
5 -- This project is MIT/X11 licensed. Please see the
6 -- COPYING file in the source package for more information.
10 local t_insert, t_concat, t_remove, t_sort = table.insert, table.concat, table.remove, table.sort;
11 local s_char = string.char;
12 local tostring, tonumber = tostring, tonumber;
13 local pairs, ipairs = pairs, ipairs;
16 local getmetatable, setmetatable = getmetatable, setmetatable;
19 local has_array, array = pcall(require, "util.array");
20 local array_mt = has_array and getmetatable(array()) or {};
25 local null = setmetatable({}, { __tostring = function() return "null"; end; });
29 ["\""] = "\\\"", ["\\"] = "\\\\", ["\b"] = "\\b",
30 ["\f"] = "\\f", ["\n"] = "\\n", ["\r"] = "\\r", ["\t"] = "\\t"};
32 ["\""] = "\"", ["\\"] = "\\", ["/"] = "/",
33 b = "\b", f = "\f", n = "\n", r = "\r", t = "\t"};
36 if not escapes[ch] then escapes[ch] = ("\\u%.4X"):format(i); end
39 local function codepoint_to_utf8(code)
40 if code < 0x80 then return s_char(code); end
41 local bits0_6 = code % 64;
43 local bits6_5 = (code - bits0_6) / 64;
44 return s_char(0x80 + 0x40 + bits6_5, 0x80 + bits0_6);
46 local bits0_12 = code % 4096;
47 local bits6_6 = (bits0_12 - bits0_6) / 64;
48 local bits12_4 = (code - bits0_12) / 4096;
49 return s_char(0x80 + 0x40 + 0x20 + bits12_4, 0x80 + bits6_6, 0x80 + bits0_6);
58 local special_keys = {
63 local simplesave, tablesave, arraysave, stringsave;
65 function stringsave(o, buffer)
66 -- FIXME do proper utf-8 and binary data detection
67 t_insert(buffer, "\""..(o:gsub(".", escapes)).."\"");
70 function arraysave(o, buffer)
71 t_insert(buffer, "[");
73 for i,v in ipairs(o) do
74 simplesave(v, buffer);
75 t_insert(buffer, ",");
79 t_insert(buffer, "]");
82 function tablesave(o, buffer)
86 for i,v in ipairs(o) do
89 for k,v in pairs(o) do
90 local ktype, vtype = type(k), type(v);
91 if valid_types[vtype] or v == null then
92 if ktype == "string" and not special_keys[k] then
94 elseif (valid_types[ktype] or k == null) and __array[k] == nil then
99 if next(__hash) ~= nil or next(hash) ~= nil or next(__array) == nil then
100 t_insert(buffer, "{");
101 local mark = #buffer;
102 if buffer.ordered then
104 for k in pairs(hash) do
108 for _,k in ipairs(keys) do
109 stringsave(k, buffer);
110 t_insert(buffer, ":");
111 simplesave(hash[k], buffer);
112 t_insert(buffer, ",");
115 for k,v in pairs(hash) do
116 stringsave(k, buffer);
117 t_insert(buffer, ":");
118 simplesave(v, buffer);
119 t_insert(buffer, ",");
122 if next(__hash) ~= nil then
123 t_insert(buffer, "\"__hash\":[");
124 for k,v in pairs(__hash) do
125 simplesave(k, buffer);
126 t_insert(buffer, ",");
127 simplesave(v, buffer);
128 t_insert(buffer, ",");
131 t_insert(buffer, "]");
132 t_insert(buffer, ",");
134 if next(__array) then
135 t_insert(buffer, "\"__array\":");
136 arraysave(__array, buffer);
137 t_insert(buffer, ",");
139 if mark ~= #buffer then t_remove(buffer); end
140 t_insert(buffer, "}");
142 arraysave(__array, buffer);
146 function simplesave(o, buffer)
148 if t == "number" then
149 t_insert(buffer, tostring(o));
150 elseif t == "string" then
151 stringsave(o, buffer);
152 elseif t == "table" then
153 local mt = getmetatable(o);
154 if mt == array_mt then
155 arraysave(o, buffer);
157 tablesave(o, buffer);
159 elseif t == "boolean" then
160 t_insert(buffer, (o and "true" or "false"));
162 t_insert(buffer, "null");
166 function json.encode(obj)
171 function json.encode_ordered(obj)
172 local t = { ordered = true };
176 function json.encode_array(obj)
182 -----------------------------------
185 local function _skip_whitespace(json, index)
186 return json:find("[^ \t\r\n]", index) or index; -- no need to check \r\n, we converted those to \t
188 local function _fixobject(obj)
189 local __array = obj.__array;
192 for i,v in ipairs(__array) do
196 local __hash = obj.__hash;
200 for i,v in ipairs(__hash) do
210 local _readvalue, _readstring;
211 local function _readobject(json, index)
215 index = _skip_whitespace(json, index + 1);
216 if json:byte(index) ~= 0x22 then -- "\""
217 if json:byte(index) == 0x7d then return o, index + 1; end -- "}"
218 return nil, "key expected";
220 key, index = _readstring(json, index);
221 if key == nil then return nil, index; end
222 index = _skip_whitespace(json, index);
223 if json:byte(index) ~= 0x3a then return nil, "colon expected"; end -- ":"
224 val, index = _readvalue(json, index + 1);
225 if val == nil then return nil, index; end
227 index = _skip_whitespace(json, index);
228 local b = json:byte(index);
229 if b == 0x7d then return _fixobject(o), index + 1; end -- "}"
230 if b ~= 0x2c then return nil, "object eof"; end -- ","
233 local function _readarray(json, index)
235 local oindex = index;
238 val, index = _readvalue(json, index + 1);
240 if json:byte(oindex + 1) == 0x5d then return setmetatable(a, array_mt), oindex + 2; end -- "]"
244 index = _skip_whitespace(json, index);
245 local b = json:byte(index);
246 if b == 0x5d then return setmetatable(a, array_mt), index + 1; end -- "]"
247 if b ~= 0x2c then return nil, "array eof"; end -- ","
250 local _unescape_error;
251 local function _unescape_surrogate_func(x)
252 local lead, trail = tonumber(x:sub(3, 6), 16), tonumber(x:sub(9, 12), 16);
253 local codepoint = lead * 0x400 + trail - 0x35FDC00;
254 local a = codepoint % 64;
255 codepoint = (codepoint - a) / 64;
256 local b = codepoint % 64;
257 codepoint = (codepoint - b) / 64;
258 local c = codepoint % 64;
259 codepoint = (codepoint - c) / 64;
260 return s_char(0xF0 + codepoint, 0x80 + c, 0x80 + b, 0x80 + a);
262 local function _unescape_func(x)
263 x = x:match("%x%x%x%x", 3);
265 --if x >= 0xD800 and x <= 0xDFFF then _unescape_error = true; end -- bad surrogate pair
266 return codepoint_to_utf8(tonumber(x, 16));
268 _unescape_error = true;
270 function _readstring(json, index)
272 local endindex = json:find("\"", index, true);
274 local s = json:sub(index, endindex - 1);
275 --if s:find("[%z-\31]") then return nil, "control char in string"; end
276 -- FIXME handle control characters
277 _unescape_error = nil;
278 --s = s:gsub("\\u[dD][89abAB]%x%x\\u[dD][cdefCDEF]%x%x", _unescape_surrogate_func);
279 -- FIXME handle escapes beyond BMP
280 s = s:gsub("\\u.?.?.?.?", _unescape_func);
281 if _unescape_error then return nil, "invalid escape"; end
282 return s, endindex + 1;
284 return nil, "string eof";
286 local function _readnumber(json, index)
287 local m = json:match("[0-9%.%-eE%+]+", index); -- FIXME do strict checking
288 return tonumber(m), index + #m;
290 local function _readnull(json, index)
291 local a, b, c = json:byte(index + 1, index + 3);
292 if a == 0x75 and b == 0x6c and c == 0x6c then
293 return null, index + 4;
295 return nil, "null parse failed";
297 local function _readtrue(json, index)
298 local a, b, c = json:byte(index + 1, index + 3);
299 if a == 0x72 and b == 0x75 and c == 0x65 then
300 return true, index + 4;
302 return nil, "true parse failed";
304 local function _readfalse(json, index)
305 local a, b, c, d = json:byte(index + 1, index + 4);
306 if a == 0x61 and b == 0x6c and c == 0x73 and d == 0x65 then
307 return false, index + 5;
309 return nil, "false parse failed";
311 function _readvalue(json, index)
312 index = _skip_whitespace(json, index);
313 local b = json:byte(index);
314 -- TODO try table lookup instead of if-else?
315 if b == 0x7B then -- "{"
316 return _readobject(json, index);
317 elseif b == 0x5B then -- "["
318 return _readarray(json, index);
319 elseif b == 0x22 then -- "\""
320 return _readstring(json, index);
321 elseif b ~= nil and b >= 0x30 and b <= 0x39 or b == 0x2d then -- "0"-"9" or "-"
322 return _readnumber(json, index);
323 elseif b == 0x6e then -- "n"
324 return _readnull(json, index);
325 elseif b == 0x74 then -- "t"
326 return _readtrue(json, index);
327 elseif b == 0x66 then -- "f"
328 return _readfalse(json, index);
330 return nil, "value expected";
333 local first_escape = {
334 ["\\\""] = "\\u0022";
335 ["\\\\"] = "\\u005c";
336 ["\\/" ] = "\\u002f";
337 ["\\b" ] = "\\u0008";
338 ["\\f" ] = "\\u000C";
339 ["\\n" ] = "\\u000A";
340 ["\\r" ] = "\\u000D";
341 ["\\t" ] = "\\u0009";
345 function json.decode(json)
346 json = json:gsub("\\.", first_escape) -- get rid of all escapes except \uXXXX, making string parsing much simpler
347 --:gsub("[\r\n]", "\t"); -- \r\n\t are equivalent, we care about none of them, and none of them can be in strings
349 -- TODO do encoding verification
351 local val, index = _readvalue(json, 1);
352 if val == nil then return val, index; end
353 if json:find("[^ \t\r\n]", index) then return nil, "garbage at eof"; end
358 function json.test(object)
359 local encoded = json.encode(object);
360 local decoded = json.decode(encoded);
361 local recoded = json.encode(decoded);
362 if encoded ~= recoded then
364 print("encoded:", encoded);
365 print("recoded:", recoded);
369 return encoded == recoded;