libs/json/luasrc/json.lua

   1 --[[
   2
   3  JSON Encoder and Parser for Lua 5.1
   4
   5  Copyright � 2007 Shaun Brown (http://www.chipmunkav.com).
   6  All Rights Reserved.
   7
   8  Permission is hereby granted, free of charge, to any person
   9  obtaining a copy of this software to deal in the Software without
  10  restriction, including without limitation the rights to use,
  11  copy, modify, merge, publish, distribute, sublicense, and/or
  12  sell copies of the Software, and to permit persons to whom the
  13  Software is furnished to do so, subject to the following conditions:
  14
  15  The above copyright notice and this permission notice shall be
  16  included in all copies or substantial portions of the Software.
  17  If you find this software useful please give www.chipmunkav.com a mention.
  18
  19  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  20  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  21  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  22  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
  23  ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
  24  CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  25  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  26
  27  Usage:
  28
  29  -- Lua script:
  30  local t = {
  31         ["name1"] = "value1",
  32         ["name2"] = {1, false, true, 23.54, "a \021 string"},
  33         name3 = Json.Null()
  34  }
  35
  36  local json = Json.Encode (t)
  37  print (json)
  38  --> {"name1":"value1","name3":null,"name2":[1,false,true,23.54,"a \u0015 string"]}
  39
  40  local t = Json.Decode(json)
  41  print(t.name2[4])
  42  --> 23.54
  43
  44  Notes:
  45  1) Encodable Lua types: string, number, boolean, table, nil
  46  2) Use Json.Null() to insert a null value into a Json object
  47  3) All control chars are encoded to \uXXXX format eg "\021" encodes to "\u0015"
  48  4) All Json \uXXXX chars are decoded to chars (0-255 byte range only)
  49  5) Json single line // and /* */ block comments are discarded during decoding
  50  6) Numerically indexed Lua arrays are encoded to Json Lists eg [1,2,3]
  51  7) Lua dictionary tables are converted to Json objects eg {"one":1,"two":2}
  52  8) Json nulls are decoded to Lua nil and treated by Lua in the normal way
  53
  54 --]]
  55
  56 local string = string
  57 local math = math
  58 local table = table
  59 local error = error
  60 local tonumber = tonumber
  61 local tostring = tostring
  62 local type = type
  63 local setmetatable = setmetatable
  64 local pairs = pairs
  65 local ipairs = ipairs
  66 local assert = assert
  67 local Chipmunk = Chipmunk
  68
  69 module("luci.json")
  70
  71 local StringBuilder = {
  72         buffer = {}
  73 }
  74
  75 function StringBuilder:New()
  76         local o = {}
  77         setmetatable(o, self)
  78         self.__index = self
  79         o.buffer = {}
  80         return o
  81 end
  82
  83 function StringBuilder:Append(s)
  84         self.buffer[#self.buffer+1] = s
  85 end
  86
  87 function StringBuilder:ToString()
  88         return table.concat(self.buffer)
  89 end
  90
  91 local JsonWriter = {
  92         backslashes = {
  93                 ['\b'] = "\\b",
  94                 ['\t'] = "\\t",
  95                 ['\n'] = "\\n",
  96                 ['\f'] = "\\f",
  97                 ['\r'] = "\\r",
  98                 ['"']  = "\\\"",
  99                 ['\\'] = "\\\\",
 100                 ['/']  = "\\/"
 101         }
 102 }
 103
 104 function JsonWriter:New()
 105         local o = {}
 106         o.writer = StringBuilder:New()
 107         setmetatable(o, self)
 108         self.__index = self
 109         return o
 110 end
 111
 112 function JsonWriter:Append(s)
 113         self.writer:Append(s)
 114 end
 115
 116 function JsonWriter:ToString()
 117         return self.writer:ToString()
 118 end
 119
 120 function JsonWriter:Write(o)
 121         local t = type(o)
 122         if t == "nil" then
 123                 self:WriteNil()
 124         elseif t == "boolean" then
 125                 self:WriteString(o)
 126         elseif t == "number" then
 127                 self:WriteString(o)
 128         elseif t == "string" then
 129                 self:ParseString(o)
 130         elseif t == "table" then
 131                 self:WriteTable(o)
 132         elseif t == "function" then
 133                 self:WriteFunction(o)
 134         elseif t == "thread" then
 135                 self:WriteError(o)
 136         elseif t == "userdata" then
 137                 self:WriteError(o)
 138         end
 139 end
 140
 141 function JsonWriter:WriteNil()
 142         self:Append("null")
 143 end
 144
 145 function JsonWriter:WriteString(o)
 146         self:Append(tostring(o))
 147 end
 148
 149 function JsonWriter:ParseString(s)
 150         self:Append('"')
 151         self:Append(string.gsub(s, "[%z%c\\\"/]", function(n)
 152                 local c = self.backslashes[n]
 153                 if c then return c end
 154                 return string.format("\\u%.4X", string.byte(n))
 155         end))
 156         self:Append('"')
 157 end
 158
 159 function JsonWriter:IsArray(t)
 160         local count = 0
 161         local isindex = function(k)
 162                 if type(k) == "number" and k > 0 then
 163                         if math.floor(k) == k then
 164                                 return true
 165                         end
 166                 end
 167                 return false
 168         end
 169         for k,v in pairs(t) do
 170                 if not isindex(k) then
 171                         return false, '{', '}'
 172                 else
 173                         count = math.max(count, k)
 174                 end
 175         end
 176         return true, '[', ']', count
 177 end
 178
 179 function JsonWriter:WriteTable(t)
 180         local ba, st, et, n = self:IsArray(t)
 181         self:Append(st)
 182         if ba then
 183                 for i = 1, n do
 184                         self:Write(t[i])
 185                         if i < n then
 186                                 self:Append(',')
 187                         end
 188                 end
 189         else
 190                 local first = true;
 191                 for k, v in pairs(t) do
 192                         if not first then
 193                                 self:Append(',')
 194                         end
 195                         first = false;
 196                         self:ParseString(k)
 197                         self:Append(':')
 198                         self:Write(v)
 199                 end
 200         end
 201         self:Append(et)
 202 end
 203
 204 function JsonWriter:WriteError(o)
 205         error(string.format(
 206                 "Encoding of %s unsupported",
 207                 tostring(o)))
 208 end
 209
 210 function JsonWriter:WriteFunction(o)
 211         if o == Null then
 212                 self:WriteNil()
 213         else
 214                 self:WriteError(o)
 215         end
 216 end
 217
 218 local StringReader = {
 219         s = "",
 220         i = 0
 221 }
 222
 223 function StringReader:New(s)
 224         local o = {}
 225         setmetatable(o, self)
 226         self.__index = self
 227         o.s = s or o.s
 228         return o
 229 end
 230
 231 function StringReader:Peek()
 232         local i = self.i + 1
 233         if i <= #self.s then
 234                 return string.sub(self.s, i, i)
 235         end
 236         return nil
 237 end
 238
 239 function StringReader:Next()
 240         self.i = self.i+1
 241         if self.i <= #self.s then
 242                 return string.sub(self.s, self.i, self.i)
 243         end
 244         return nil
 245 end
 246
 247 function StringReader:All()
 248         return self.s
 249 end
 250
 251 local JsonReader = {
 252         escapes = {
 253                 ['t'] = '\t',
 254                 ['n'] = '\n',
 255                 ['f'] = '\f',
 256                 ['r'] = '\r',
 257                 ['b'] = '\b',
 258         }
 259 }
 260
 261 function JsonReader:New(s)
 262         local o = {}
 263         o.reader = StringReader:New(s)
 264         setmetatable(o, self)
 265         self.__index = self
 266         return o;
 267 end
 268
 269 function JsonReader:Read()
 270         self:SkipWhiteSpace()
 271         local peek = self:Peek()
 272         if peek == nil then
 273                 error(string.format(
 274                         "Nil string: '%s'",
 275                         self:All()))
 276         elseif peek == '{' then
 277                 return self:ReadObject()
 278         elseif peek == '[' then
 279                 return self:ReadArray()
 280         elseif peek == '"' then
 281                 return self:ReadString()
 282         elseif string.find(peek, "[%+%-%d]") then
 283                 return self:ReadNumber()
 284         elseif peek == 't' then
 285                 return self:ReadTrue()
 286         elseif peek == 'f' then
 287                 return self:ReadFalse()
 288         elseif peek == 'n' then
 289                 return self:ReadNull()
 290         elseif peek == '/' then
 291                 self:ReadComment()
 292                 return self:Read()
 293         else
 294                 error(string.format(
 295                         "Invalid input: '%s'",
 296                         self:All()))
 297         end
 298 end
 299
 300 function JsonReader:ReadTrue()
 301         self:TestReservedWord{'t','r','u','e'}
 302         return true
 303 end
 304
 305 function JsonReader:ReadFalse()
 306         self:TestReservedWord{'f','a','l','s','e'}
 307         return false
 308 end
 309
 310 function JsonReader:ReadNull()
 311         self:TestReservedWord{'n','u','l','l'}
 312         return nil
 313 end
 314
 315 function JsonReader:TestReservedWord(t)
 316         for i, v in ipairs(t) do
 317                 if self:Next() ~= v then
 318                          error(string.format(
 319                                 "Error reading '%s': %s",
 320                                 table.concat(t),
 321                                 self:All()))
 322                 end
 323         end
 324 end
 325
 326 function JsonReader:ReadNumber()
 327         local result = self:Next()
 328         local peek = self:Peek()
 329         while peek ~= nil and string.find(
 330                 peek,
 331                 "[%+%-%d%.eE]") do
 332             result = result .. self:Next()
 333             peek = self:Peek()
 334         end
 335         result = tonumber(result)
 336         if result == nil then
 337                 error(string.format(
 338                         "Invalid number: '%s'",
 339                         result))
 340         else
 341                 return result
 342         end
 343 end
 344
 345 function JsonReader:ReadString()
 346         local result = ""
 347         assert(self:Next() == '"')
 348         while self:Peek() ~= '"' do
 349                 local ch = self:Next()
 350                 if ch == '\\' then
 351                         ch = self:Next()
 352                         if self.escapes[ch] then
 353                                 ch = self.escapes[ch]
 354                         end
 355                 end
 356                 result = result .. ch
 357         end
 358         assert(self:Next() == '"')
 359         local fromunicode = function(m)
 360                 return string.char(tonumber(m, 16))
 361         end
 362         return string.gsub(
 363                 result,
 364                 "u%x%x(%x%x)",
 365                 fromunicode)
 366 end
 367
 368 function JsonReader:ReadComment()
 369         assert(self:Next() == '/')
 370         local second = self:Next()
 371         if second == '/' then
 372             self:ReadSingleLineComment()
 373         elseif second == '*' then
 374             self:ReadBlockComment()
 375         else
 376             error(string.format(
 377                 "Invalid comment: %s",
 378                 self:All()))
 379         end
 380 end
 381
 382 function JsonReader:ReadBlockComment()
 383         local done = false
 384         while not done do
 385                 local ch = self:Next()
 386                 if ch == '*' and self:Peek() == '/' then
 387                         done = true
 388                 end
 389                 if not done and
 390                         ch == '/' and
 391                         self:Peek() == "*" then
 392                     error(string.format(
 393                         "Invalid comment: %s, '/*' illegal.",
 394                         self:All()))
 395                 end
 396         end
 397         self:Next()
 398 end
 399
 400 function JsonReader:ReadSingleLineComment()
 401         local ch = self:Next()
 402         while ch ~= '\r' and ch ~= '\n' do
 403                 ch = self:Next()
 404         end
 405 end
 406
 407 function JsonReader:ReadArray()
 408         local result = {}
 409         assert(self:Next() == '[')
 410         self:SkipWhiteSpace()
 411         local done = false
 412         if self:Peek() == ']' then
 413                 done = true;
 414         end
 415         while not done do
 416                 local item = self:Read()
 417                 result[#result+1] = item
 418                 self:SkipWhiteSpace()
 419                 if self:Peek() == ']' then
 420                         done = true
 421                 end
 422                 if not done then
 423                         local ch = self:Next()
 424                         if ch ~= ',' then
 425                                 error(string.format(
 426                                         "Invalid array: '%s' due to: '%s'",
 427                                         self:All(), ch))
 428                         end
 429                 end
 430         end
 431         assert(']' == self:Next())
 432         return result
 433 end
 434
 435 function JsonReader:ReadObject()
 436         local result = {}
 437         assert(self:Next() == '{')
 438         self:SkipWhiteSpace()
 439         local done = false
 440         if self:Peek() == '}' then
 441                 done = true
 442         end
 443         while not done do
 444                 local key = self:Read()
 445                 if type(key) ~= "string" then
 446                         error(string.format(
 447                                 "Invalid non-string object key: %s",
 448                                 key))
 449                 end
 450                 self:SkipWhiteSpace()
 451                 local ch = self:Next()
 452                 if ch ~= ':' then
 453                         error(string.format(
 454                                 "Invalid object: '%s' due to: '%s'",
 455                                 self:All(),
 456                                 ch))
 457                 end
 458                 self:SkipWhiteSpace()
 459                 local val = self:Read()
 460                 result[key] = val
 461                 self:SkipWhiteSpace()
 462                 if self:Peek() == '}' then
 463                         done = true
 464                 end
 465                 if not done then
 466                         ch = self:Next()
 467                         if ch ~= ',' then
 468                                 error(string.format(
 469                                         "Invalid array: '%s' near: '%s'",
 470                                         self:All(),
 471                                         ch))
 472                         end
 473                 end
 474         end
 475         assert(self:Next() == "}")
 476         return result
 477 end
 478
 479 function JsonReader:SkipWhiteSpace()
 480         local p = self:Peek()
 481         while p ~= nil and string.find(p, "[%s/]") do
 482                 if p == '/' then
 483                         self:ReadComment()
 484                 else
 485                         self:Next()
 486                 end
 487                 p = self:Peek()
 488         end
 489 end
 490
 491 function JsonReader:Peek()
 492         return self.reader:Peek()
 493 end
 494
 495 function JsonReader:Next()
 496         return self.reader:Next()
 497 end
 498
 499 function JsonReader:All()
 500         return self.reader:All()
 501 end
 502
 503 function Encode(o)
 504         local writer = JsonWriter:New()
 505         writer:Write(o)
 506         return writer:ToString()
 507 end
 508
 509 function Decode(s)
 510         local reader = JsonReader:New(s)
 511         local object = reader:Read()
 512         reader:SkipWhiteSpace()
 513         assert(reader:Peek() == nil, "Invalid characters after JSON body")
 514         return object
 515 end
 516
 517 function Null()
 518         return Null
 519 end