libs/luci-lib-json/luasrc/json.lua

   1 -- Copyright 2008 Steven Barth <steven@midlink.org>
   2 -- Copyright 2008 Jo-Philipp Wich <jow@openwrt.org>
   3 -- Licensed to the public under the Apache License 2.0.
   4
   5 local nixio     = require "nixio"
   6 local util      = require "luci.util"
   7 local table     = require "table"
   8 local string    = require "string"
   9 local coroutine = require "coroutine"
  10
  11 local assert    = assert
  12 local tonumber  = tonumber
  13 local tostring  = tostring
  14 local error     = error
  15 local type          = type
  16 local pairs         = pairs
  17 local ipairs    = ipairs
  18 local next      = next
  19 local pcall             = pcall
  20
  21 local band      = nixio.bit.band
  22 local bor       = nixio.bit.bor
  23 local rshift    = nixio.bit.rshift
  24 local char      = string.char
  25
  26 local getmetatable = getmetatable
  27
  28 module "luci.json"
  29
  30
  31 function decode(json, ...)
  32         local a = ActiveDecoder(function() return nil end, ...)
  33         a.chunk = json
  34         local s, obj = pcall(a.get, a)
  35         return s and obj or nil
  36 end
  37
  38
  39 function encode(obj, ...)
  40         local out = {}
  41         local e = Encoder(obj, 1, ...):source()
  42         local chnk, err
  43         repeat
  44                 chnk, err = e()
  45                 out[#out+1] = chnk
  46         until not chnk
  47         return not err and table.concat(out) or nil
  48 end
  49
  50
  51 function null()
  52         return null
  53 end
  54
  55 Encoder = util.class()
  56
  57 function Encoder.__init__(self, data, buffersize, fastescape)
  58         self.data = data
  59         self.buffersize = buffersize or 512
  60         self.buffer = ""
  61         self.fastescape = fastescape
  62
  63         getmetatable(self).__call = Encoder.source
  64 end
  65
  66 function Encoder.source(self)
  67         local source = coroutine.create(self.dispatch)
  68         return function()
  69                 local res, data = coroutine.resume(source, self, self.data, true)
  70                 if res then
  71                         return data
  72                 else
  73                         return nil, data
  74                 end
  75         end
  76 end
  77
  78 function Encoder.dispatch(self, data, start)
  79         local parser = self.parsers[type(data)]
  80
  81         parser(self, data)
  82
  83         if start then
  84                 if #self.buffer > 0 then
  85                         coroutine.yield(self.buffer)
  86                 end
  87
  88                 coroutine.yield()
  89         end
  90 end
  91
  92 function Encoder.put(self, chunk)
  93         if self.buffersize < 2 then
  94                 coroutine.yield(chunk)
  95         else
  96                 if #self.buffer + #chunk > self.buffersize then
  97                         local written = 0
  98                         local fbuffer = self.buffersize - #self.buffer
  99
 100                         coroutine.yield(self.buffer .. chunk:sub(written + 1, fbuffer))
 101                         written = fbuffer
 102
 103                         while #chunk - written > self.buffersize do
 104                                 fbuffer = written + self.buffersize
 105                                 coroutine.yield(chunk:sub(written + 1, fbuffer))
 106                                 written = fbuffer
 107                         end
 108
 109                         self.buffer = chunk:sub(written + 1)
 110                 else
 111                         self.buffer = self.buffer .. chunk
 112                 end
 113         end
 114 end
 115
 116 function Encoder.parse_nil(self)
 117         self:put("null")
 118 end
 119
 120 function Encoder.parse_bool(self, obj)
 121         self:put(obj and "true" or "false")
 122 end
 123
 124 function Encoder.parse_number(self, obj)
 125         self:put(tostring(obj))
 126 end
 127
 128 function Encoder.parse_string(self, obj)
 129         if self.fastescape then
 130                 self:put('"' .. obj:gsub('\\', '\\\\'):gsub('"', '\\"') .. '"')
 131         else
 132                 self:put('"' ..
 133                         obj:gsub('[%c\\"]',
 134                                 function(char)
 135                                         return '\\u00%02x' % char:byte()
 136                                 end
 137                         )
 138                 .. '"')
 139         end
 140 end
 141
 142 function Encoder.parse_iter(self, obj)
 143         if obj == null then
 144                 return self:put("null")
 145         end
 146
 147         if type(obj) == "table" and (#obj == 0 and next(obj)) then
 148                 self:put("{")
 149                 local first = true
 150
 151                 for key, entry in pairs(obj) do
 152                         if key ~= null then
 153                                 first = first or self:put(",")
 154                                 first = first and false
 155                                 self:parse_string(tostring(key))
 156                                 self:put(":")
 157                                 self:dispatch(entry)
 158                         end
 159                 end
 160
 161                 self:put("}")
 162         else
 163                 self:put("[")
 164                 local first = true
 165
 166                 if type(obj) == "table" then
 167                         for i=1, #obj do
 168                                 first = first or self:put(",")
 169                                 first = first and nil
 170                                 self:dispatch(obj[i])
 171                         end
 172                 else
 173                         for entry in obj do
 174                                 first = first or self:put(",")
 175                                 first = first and nil
 176                                 self:dispatch(entry)
 177                         end
 178                 end
 179
 180                 self:put("]")
 181         end
 182 end
 183
 184 Encoder.parsers = {
 185         ['nil']      = Encoder.parse_nil,
 186         ['table']    = Encoder.parse_iter,
 187         ['number']   = Encoder.parse_number,
 188         ['string']   = Encoder.parse_string,
 189         ['boolean']  = Encoder.parse_bool,
 190         ['function'] = Encoder.parse_iter
 191 }
 192
 193
 194 Decoder = util.class()
 195
 196 function Decoder.__init__(self, customnull)
 197         self.cnull = customnull
 198         getmetatable(self).__call = Decoder.sink
 199 end
 200
 201 function Decoder.sink(self)
 202         local sink = coroutine.create(self.dispatch)
 203         return function(...)
 204                 return coroutine.resume(sink, self, ...)
 205         end
 206 end
 207
 208
 209 function Decoder.get(self)
 210         return self.data
 211 end
 212
 213 function Decoder.dispatch(self, chunk, src_err, strict)
 214         local robject, object
 215         local oset = false
 216
 217         while chunk do
 218                 while chunk and #chunk < 1 do
 219                         chunk = self:fetch()
 220                 end
 221
 222                 assert(not strict or chunk, "Unexpected EOS")
 223                 if not chunk then break end
 224
 225                 local char   = chunk:sub(1, 1)
 226                 local parser = self.parsers[char]
 227                  or (char:match("%s")     and self.parse_space)
 228                  or (char:match("[0-9-]") and self.parse_number)
 229                  or error("Unexpected char '%s'" % char)
 230
 231                 chunk, robject = parser(self, chunk)
 232
 233                 if parser ~= self.parse_space then
 234                         assert(not oset, "Scope violation: Too many objects")
 235                         object = robject
 236                         oset = true
 237
 238                         if strict then
 239                                 return chunk, object
 240                         end
 241                 end
 242         end
 243
 244         assert(not src_err, src_err)
 245         assert(oset, "Unexpected EOS")
 246
 247         self.data = object
 248 end
 249
 250
 251 function Decoder.fetch(self)
 252         local tself, chunk, src_err = coroutine.yield()
 253         assert(chunk or not src_err, src_err)
 254         return chunk
 255 end
 256
 257
 258 function Decoder.fetch_atleast(self, chunk, bytes)
 259         while #chunk < bytes do
 260                 local nchunk = self:fetch()
 261                 assert(nchunk, "Unexpected EOS")
 262                 chunk = chunk .. nchunk
 263         end
 264
 265         return chunk
 266 end
 267
 268
 269 function Decoder.fetch_until(self, chunk, pattern)
 270         local start = chunk:find(pattern)
 271
 272         while not start do
 273                 local nchunk = self:fetch()
 274                 assert(nchunk, "Unexpected EOS")
 275                 chunk = chunk .. nchunk
 276                 start = chunk:find(pattern)
 277         end
 278
 279         return chunk, start
 280 end
 281
 282
 283 function Decoder.parse_space(self, chunk)
 284         local start = chunk:find("[^%s]")
 285
 286         while not start do
 287                 chunk = self:fetch()
 288                 if not chunk then
 289                         return nil
 290                 end
 291                 start = chunk:find("[^%s]")
 292         end
 293
 294         return chunk:sub(start)
 295 end
 296
 297
 298 function Decoder.parse_literal(self, chunk, literal, value)
 299         chunk = self:fetch_atleast(chunk, #literal)
 300         assert(chunk:sub(1, #literal) == literal, "Invalid character sequence")
 301         return chunk:sub(#literal + 1), value
 302 end
 303
 304
 305 function Decoder.parse_null(self, chunk)
 306         return self:parse_literal(chunk, "null", self.cnull and null)
 307 end
 308
 309
 310 function Decoder.parse_true(self, chunk)
 311         return self:parse_literal(chunk, "true", true)
 312 end
 313
 314
 315 function Decoder.parse_false(self, chunk)
 316         return self:parse_literal(chunk, "false", false)
 317 end
 318
 319
 320 function Decoder.parse_number(self, chunk)
 321         local chunk, start = self:fetch_until(chunk, "[^0-9eE.+-]")
 322         local number = tonumber(chunk:sub(1, start - 1))
 323         assert(number, "Invalid number specification")
 324         return chunk:sub(start), number
 325 end
 326
 327
 328 function Decoder.parse_string(self, chunk)
 329         local str = ""
 330         local object = nil
 331         assert(chunk:sub(1, 1) == '"', 'Expected "')
 332         chunk = chunk:sub(2)
 333
 334         while true do
 335                 local spos = chunk:find('[\\"]')
 336                 if spos then
 337                         str = str .. chunk:sub(1, spos - 1)
 338
 339                         local char = chunk:sub(spos, spos)
 340                         if char == '"' then                             -- String end
 341                                 chunk = chunk:sub(spos + 1)
 342                                 break
 343                         elseif char == "\\" then                -- Escape sequence
 344                                 chunk, object = self:parse_escape(chunk:sub(spos))
 345                                 str = str .. object
 346                         end
 347                 else
 348                         str = str .. chunk
 349                         chunk = self:fetch()
 350                         assert(chunk, "Unexpected EOS while parsing a string")
 351                 end
 352         end
 353
 354         return chunk, str
 355 end
 356
 357
 358 function Decoder.utf8_encode(self, s1, s2)
 359         local n = s1 * 256 + s2
 360
 361         if n >= 0 and n <= 0x7F then
 362                 return char(n)
 363         elseif n >= 0 and n <= 0x7FF then
 364                 return char(
 365                         bor(band(rshift(n,  6), 0x1F), 0xC0),
 366                         bor(band(n,             0x3F), 0x80)
 367                 )
 368         elseif n >= 0 and n <= 0xFFFF then
 369                 return char(
 370                         bor(band(rshift(n, 12), 0x0F), 0xE0),
 371                         bor(band(rshift(n,  6), 0x3F), 0x80),
 372                         bor(band(n,             0x3F), 0x80)
 373                 )
 374         elseif n >= 0 and n <= 0x10FFFF then
 375                 return char(
 376                         bor(band(rshift(n, 18), 0x07), 0xF0),
 377                         bor(band(rshift(n, 12), 0x3F), 0x80),
 378                         bor(band(rshift(n,  6), 0x3F), 0x80),
 379                         bor(band(n,             0x3F), 0x80)
 380                 )
 381         else
 382                 return "?"
 383         end
 384 end
 385
 386
 387 function Decoder.parse_escape(self, chunk)
 388         local str = ""
 389         chunk = self:fetch_atleast(chunk:sub(2), 1)
 390         local char = chunk:sub(1, 1)
 391         chunk = chunk:sub(2)
 392
 393         if char == '"' then
 394                 return chunk, '"'
 395         elseif char == "\\" then
 396                 return chunk, "\\"
 397         elseif char == "u" then
 398                 chunk = self:fetch_atleast(chunk, 4)
 399                 local s1, s2 = chunk:sub(1, 2), chunk:sub(3, 4)
 400                 s1, s2 = tonumber(s1, 16), tonumber(s2, 16)
 401                 assert(s1 and s2, "Invalid Unicode character")
 402
 403                 return chunk:sub(5), self:utf8_encode(s1, s2)
 404         elseif char == "/" then
 405                 return chunk, "/"
 406         elseif char == "b" then
 407                 return chunk, "\b"
 408         elseif char == "f" then
 409                 return chunk, "\f"
 410         elseif char == "n" then
 411                 return chunk, "\n"
 412         elseif char == "r" then
 413                 return chunk, "\r"
 414         elseif char == "t" then
 415                 return chunk, "\t"
 416         else
 417                 error("Unexpected escaping sequence '\\%s'" % char)
 418         end
 419 end
 420
 421
 422 function Decoder.parse_array(self, chunk)
 423         chunk = chunk:sub(2)
 424         local array = {}
 425         local nextp = 1
 426
 427         local chunk, object = self:parse_delimiter(chunk, "%]")
 428
 429         if object then
 430                 return chunk, array
 431         end
 432
 433         repeat
 434                 chunk, object = self:dispatch(chunk, nil, true)
 435                 table.insert(array, nextp, object)
 436                 nextp = nextp + 1
 437
 438                 chunk, object = self:parse_delimiter(chunk, ",%]")
 439                 assert(object, "Delimiter expected")
 440         until object == "]"
 441
 442         return chunk, array
 443 end
 444
 445
 446 function Decoder.parse_object(self, chunk)
 447         chunk = chunk:sub(2)
 448         local array = {}
 449         local name
 450
 451         local chunk, object = self:parse_delimiter(chunk, "}")
 452
 453         if object then
 454                 return chunk, array
 455         end
 456
 457         repeat
 458                 chunk = self:parse_space(chunk)
 459                 assert(chunk, "Unexpected EOS")
 460
 461                 chunk, name   = self:parse_string(chunk)
 462
 463                 chunk, object = self:parse_delimiter(chunk, ":")
 464                 assert(object, "Separator expected")
 465
 466                 chunk, object = self:dispatch(chunk, nil, true)
 467                 array[name] = object
 468
 469                 chunk, object = self:parse_delimiter(chunk, ",}")
 470                 assert(object, "Delimiter expected")
 471         until object == "}"
 472
 473         return chunk, array
 474 end
 475
 476
 477 function Decoder.parse_delimiter(self, chunk, delimiter)
 478         while true do
 479                 chunk = self:fetch_atleast(chunk, 1)
 480                 local char = chunk:sub(1, 1)
 481                 if char:match("%s") then
 482                         chunk = self:parse_space(chunk)
 483                         assert(chunk, "Unexpected EOS")
 484                 elseif char:match("[%s]" % delimiter) then
 485                         return chunk:sub(2), char
 486                 else
 487                         return chunk, nil
 488                 end
 489         end
 490 end
 491
 492
 493 Decoder.parsers = {
 494         ['"'] = Decoder.parse_string,
 495         ['t'] = Decoder.parse_true,
 496         ['f'] = Decoder.parse_false,
 497         ['n'] = Decoder.parse_null,
 498         ['['] = Decoder.parse_array,
 499         ['{'] = Decoder.parse_object
 500 }
 501
 502
 503 ActiveDecoder = util.class(Decoder)
 504
 505 function ActiveDecoder.__init__(self, source, customnull)
 506         Decoder.__init__(self, customnull)
 507         self.source = source
 508         self.chunk = nil
 509         getmetatable(self).__call = self.get
 510 end
 511
 512
 513 function ActiveDecoder.get(self)
 514         local chunk, src_err, object
 515         if not self.chunk then
 516                 chunk, src_err = self.source()
 517         else
 518                 chunk = self.chunk
 519         end
 520
 521         self.chunk, object = self:dispatch(chunk, src_err, true)
 522         return object
 523 end
 524
 525
 526 function ActiveDecoder.fetch(self)
 527         local chunk, src_err = self.source()
 528         assert(chunk or not src_err, src_err)
 529         return chunk
 530 end