prosody
bf223e6c2b4c
util/json.lua

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util/json.lua @ 3979:bf223e6c2b4c

util.json: Initial commit.
author Waqas Hussain <waqas20@gmail.com>
date Mon, 27 Dec 2010 19:37:04 +0500
child 4147:7f119ebcf55f
comparison
equal deleted inserted replaced
3978:13ee740b1f89 3979:bf223e6c2b4c
1
2 local type = type;
3 local t_insert, t_concat, t_remove = table.insert, table.concat, table.remove;
4 local s_char = string.char;
5 local tostring, tonumber = tostring, tonumber;
6 local pairs, ipairs = pairs, ipairs;
7 local next = next;
8 local error = error;
9 local newproxy, getmetatable = newproxy, getmetatable;
10 local print = print;
11
12 --module("json")
13 local json = {};
14
15 local null = newproxy and newproxy(true) or {};
16 if getmetatable and getmetatable(null) then
17 getmetatable(null).__tostring = function() return "null"; end;
18 end
19 json.null = null;
20
21 local escapes = {
22 ["\""] = "\\\"", ["\\"] = "\\\\", ["\b"] = "\\b",
23 ["\f"] = "\\f", ["\n"] = "\\n", ["\r"] = "\\r", ["\t"] = "\\t"};
24 local unescapes = {
25 ["\""] = "\"", ["\\"] = "\\", ["/"] = "/",
26 b = "\b", f = "\f", n = "\n", r = "\r", t = "\t"};
27 for i=0,31 do
28 local ch = s_char(i);
29 if not escapes[ch] then escapes[ch] = ("\\u%.4X"):format(i); end
30 end
31
32 local valid_types = {
33 number = true,
34 string = true,
35 table = true,
36 boolean = true
37 };
38 local special_keys = {
39 __array = true;
40 __hash = true;
41 };
42
43 local simplesave, tablesave, arraysave, stringsave;
44
45 function stringsave(o, buffer)
46 -- FIXME do proper utf-8 and binary data detection
47 t_insert(buffer, "\""..(o:gsub(".", escapes)).."\"");
48 end
49
50 function arraysave(o, buffer)
51 t_insert(buffer, "[");
52 if next(o) then
53 for i,v in ipairs(o) do
54 simplesave(v, buffer);
55 t_insert(buffer, ",");
56 end
57 t_remove(buffer);
58 end
59 t_insert(buffer, "]");
60 end
61
62 function tablesave(o, buffer)
63 local __array = {};
64 local __hash = {};
65 local hash = {};
66 for i,v in ipairs(o) do
67 __array[i] = v;
68 end
69 for k,v in pairs(o) do
70 local ktype, vtype = type(k), type(v);
71 if valid_types[vtype] or v == null then
72 if ktype == "string" and not special_keys[k] then
73 hash[k] = v;
74 elseif (valid_types[ktype] or k == null) and __array[k] == nil then
75 __hash[k] = v;
76 end
77 end
78 end
79 if next(__hash) ~= nil or next(hash) ~= nil or next(__array) == nil then
80 t_insert(buffer, "{");
81 local mark = #buffer;
82 for k,v in pairs(hash) do
83 stringsave(k, buffer);
84 t_insert(buffer, ":");
85 simplesave(v, buffer);
86 t_insert(buffer, ",");
87 end
88 if next(__hash) ~= nil then
89 t_insert(buffer, "\"__hash\":[");
90 for k,v in pairs(__hash) do
91 simplesave(k, buffer);
92 t_insert(buffer, ",");
93 simplesave(v, buffer);
94 t_insert(buffer, ",");
95 end
96 t_remove(buffer);
97 t_insert(buffer, "]");
98 t_insert(buffer, ",");
99 end
100 if next(__array) then
101 t_insert(buffer, "\"__array\":");
102 arraysave(__array, buffer);
103 t_insert(buffer, ",");
104 end
105 if mark ~= #buffer then t_remove(buffer); end
106 t_insert(buffer, "}");
107 else
108 arraysave(__array, buffer);
109 end
110 end
111
112 function simplesave(o, buffer)
113 local t = type(o);
114 if t == "number" then
115 t_insert(buffer, tostring(o));
116 elseif t == "string" then
117 stringsave(o, buffer);
118 elseif t == "table" then
119 tablesave(o, buffer);
120 elseif t == "boolean" then
121 t_insert(buffer, (o and "true" or "false"));
122 else
123 t_insert(buffer, "null");
124 end
125 end
126
127 function json.encode(obj)
128 local t = {};
129 simplesave(obj, t);
130 return t_concat(t);
131 end
132
133 -----------------------------------
134
135
136 function json.decode(json)
137 local pos = 1;
138 local current = {};
139 local stack = {};
140 local ch, peek;
141 local function next()
142 ch = json:sub(pos, pos);
143 pos = pos+1;
144 peek = json:sub(pos, pos);
145 return ch;
146 end
147
148 local function skipwhitespace()
149 while ch and (ch == "\r" or ch == "\n" or ch == "\t" or ch == " ") do
150 next();
151 end
152 end
153 local function skiplinecomment()
154 repeat next(); until not(ch) or ch == "\r" or ch == "\n";
155 skipwhitespace();
156 end
157 local function skipstarcomment()
158 next(); next(); -- skip '/', '*'
159 while peek and ch ~= "*" and peek ~= "/" do next(); end
160 if not peek then error("eof in star comment") end
161 next(); next(); -- skip '*', '/'
162 skipwhitespace();
163 end
164 local function skipstuff()
165 while true do
166 skipwhitespace();
167 if ch == "/" and peek == "*" then
168 skipstarcomment();
169 elseif ch == "/" and peek == "*" then
170 skiplinecomment();
171 else
172 return;
173 end
174 end
175 end
176
177 local readvalue;
178 local function readarray()
179 local t = {};
180 next(); -- skip '['
181 skipstuff();
182 if ch == "]" then next(); return t; end
183 t_insert(t, readvalue());
184 while true do
185 skipstuff();
186 if ch == "]" then next(); return t; end
187 if not ch then error("eof while reading array");
188 elseif ch == "," then next();
189 elseif ch then error("unexpected character in array, comma expected"); end
190 if not ch then error("eof while reading array"); end
191 t_insert(t, readvalue());
192 end
193 end
194
195 local function checkandskip(c)
196 local x = ch or "eof";
197 if x ~= c then error("unexpected "..x..", '"..c.."' expected"); end
198 next();
199 end
200 local function readliteral(lit, val)
201 for c in lit:gmatch(".") do
202 checkandskip(c);
203 end
204 return val;
205 end
206 local function readstring()
207 local s = "";
208 checkandskip("\"");
209 while ch do
210 while ch and ch ~= "\\" and ch ~= "\"" do
211 s = s..ch; next();
212 end
213 if ch == "\\" then
214 next();
215 if unescapes[ch] then
216 s = s..unescapes[ch];
217 next();
218 elseif ch == "u" then
219 local seq = "";
220 for i=1,4 do
221 next();
222 if not ch then error("unexpected eof in string"); end
223 if not ch:match("[0-9a-fA-F]") then error("invalid unicode escape sequence in string"); end
224 seq = seq..ch;
225 end
226 s = s..s.char(tonumber(seq, 16)); -- FIXME do proper utf-8
227 next();
228 else error("invalid escape sequence in string"); end
229 end
230 if ch == "\"" then
231 next();
232 return s;
233 end
234 end
235 error("eof while reading string");
236 end
237 local function readnumber()
238 local s = "";
239 if ch == "-" then
240 s = s..ch; next();
241 if not ch:match("[0-9]") then error("number format error"); end
242 end
243 if ch == "0" then
244 s = s..ch; next();
245 if ch:match("[0-9]") then error("number format error"); end
246 else
247 while ch and ch:match("[0-9]") do
248 s = s..ch; next();
249 end
250 end
251 if ch == "." then
252 s = s..ch; next();
253 if not ch:match("[0-9]") then error("number format error"); end
254 while ch and ch:match("[0-9]") do
255 s = s..ch; next();
256 end
257 if ch == "e" or ch == "E" then
258 s = s..ch; next();
259 if ch == "+" or ch == "-" then
260 s = s..ch; next();
261 if not ch:match("[0-9]") then error("number format error"); end
262 while ch and ch:match("[0-9]") do
263 s = s..ch; next();
264 end
265 end
266 end
267 end
268 return tonumber(s);
269 end
270 local function readmember(t)
271 local k = readstring();
272 checkandskip(":");
273 t[k] = readvalue();
274 end
275 local function fixobject(obj)
276 local __array = obj.__array;
277 if __array then
278 obj.__array = nil;
279 for i,v in ipairs(__array) do
280 t_insert(obj, v);
281 end
282 end
283 local __hash = obj.__hash;
284 if __hash then
285 obj.__hash = nil;
286 local k;
287 for i,v in ipairs(__hash) do
288 if k ~= nil then
289 obj[k] = v; k = nil;
290 else
291 k = v;
292 end
293 end
294 end
295 return obj;
296 end
297 local function readobject()
298 local t = {};
299 next(); -- skip '{'
300 skipstuff();
301 if ch == "}" then next(); return t; end
302 if not ch then error("eof while reading object"); end
303 readmember(t);
304 while true do
305 skipstuff();
306 if ch == "}" then next(); return fixobject(t); end
307 if not ch then error("eof while reading object");
308 elseif ch == "," then next();
309 elseif ch then error("unexpected character in object, comma expected"); end
310 if not ch then error("eof while reading object"); end
311 readmember(t);
312 end
313 end
314
315 function readvalue()
316 skipstuff();
317 while ch do
318 if ch == "{" then
319 return readobject();
320 elseif ch == "[" then
321 return readarray();
322 elseif ch == "\"" then
323 return readstring();
324 elseif ch:match("[%-0-9%.]") then
325 return readnumber();
326 elseif ch == "n" then
327 return readliteral("null", null);
328 elseif ch == "t" then
329 return readliteral("true", true);
330 elseif ch == "f" then
331 return readliteral("false", false);
332 else
333 error("invalid character at value start: "..ch);
334 end
335 end
336 error("eof while reading value");
337 end
338 next();
339 return readvalue();
340 end
341
342 function json.test(object)
343 local encoded = json.encode(object);
344 local decoded = json.decode(encoded);
345 local recoded = json.encode(decoded);
346 if encoded ~= recoded then
347 print("FAILED");
348 print("encoded:", encoded);
349 print("recoded:", recoded);
350 else
351 print(encoded);
352 end
353 return encoded == recoded;
354 end
355
356 return json;