ryzom/client/data/gamedev/interfaces_v3/json.lua

   1 --
   2 -- json.lua
   3 --
   4 -- Copyright (c) 2015 rxi
   5 --
   6 -- This library is free software; you can redistribute it and/or modify it
   7 -- under the terms of the MIT license. See LICENSE for details.
   8 --
   9
  10 Json = { _version = "0.1.0" }
  11
  12 -------------------------------------------------------------------------------
  13 -- Encode
  14 -------------------------------------------------------------------------------
  15
  16 local encode
  17
  18 local escape_char_map = {
  19   [ "\\" ] = "\\\\",
  20   [ "\"" ] = "\\\"",
  21   [ "\b" ] = "\\b",
  22   [ "\f" ] = "\\f",
  23   [ "\n" ] = "\\n",
  24   [ "\r" ] = "\\r",
  25   [ "\t" ] = "\\t",
  26 }
  27
  28 local escape_char_map_inv = { [ "\\/" ] = "/" }
  29 for k, v in pairs(escape_char_map) do
  30   escape_char_map_inv[v] = k
  31 end
  32
  33
  34 local function escape_char(c)
  35   return escape_char_map[c] or string.format("\\u%04x", c:byte())
  36 end
  37
  38
  39 local function encode_nil(val)
  40   return "null"
  41 end
  42
  43
  44 local function encode_table(val, stack)
  45   local res = {}
  46   stack = stack or {}
  47
  48   -- Circular reference?
  49   if stack[val] then error("circular reference") end
  50
  51   stack[val] = true
  52
  53   if val[1] ~= nil or next(val) == nil then
  54     -- Treat as array -- check keys are valid and it is not sparse
  55     local n = 0
  56     for k in pairs(val) do
  57       if type(k) ~= "number" then
  58         error("invalid table: mixed or invalid key types")
  59       end
  60       n = n + 1
  61     end
  62     if n ~= #val then
  63       error("invalid table: sparse array")
  64     end
  65     -- Encode
  66     for i, v in ipairs(val) do
  67       table.insert(res, encode(v, stack))
  68     end
  69     stack[val] = nil
  70     return "[" .. table.concat(res, ",") .. "]"
  71
  72   else
  73     -- Treat as an object
  74     for k, v in pairs(val) do
  75       if type(k) ~= "string" then
  76         error("invalid table: mixed or invalid key types")
  77       end
  78       table.insert(res, encode(k, stack) .. ":" .. encode(v, stack))
  79     end
  80     stack[val] = nil
  81     return "{" .. table.concat(res, ",") .. "}"
  82   end
  83 end
  84
  85
  86 local function encode_string(val)
  87   return '"' .. val:gsub('[%z\1-\31\\"]', escape_char) .. '"'
  88 end
  89
  90
  91 local function encode_number(val)
  92   -- Check for NaN, -inf and inf
  93   if val ~= val or val <= -math.huge or val >= math.huge then
  94     error("unexpected number value '" .. tostring(val) .. "'")
  95   end
  96   return string.format("%.3f", val)
  97 end
  98
  99 local type_func_map = {
 100   [ "nil"     ] = encode_nil,
 101   [ "table"   ] = encode_table,
 102   [ "string"  ] = encode_string,
 103   [ "number"  ] = encode_number,
 104   [ "boolean" ] = tostring,
 105 }
 106
 107
 108 encode = function(val, stack)
 109   local t = type(val)
 110   local f = type_func_map[t]
 111   if f then
 112     return f(val, stack)
 113   end
 114   error("unexpected type '" .. t .. "'")
 115 end
 116
 117
 118 function Json.encode(val)
 119   return ( encode(val) )
 120 end
 121
 122
 123 -------------------------------------------------------------------------------
 124 -- Decode
 125 -------------------------------------------------------------------------------
 126
 127 local parse
 128
 129 local function create_set(...)
 130   local res = {}
 131   for i = 1, select("#", ...) do
 132     res[ select(i, ...) ] = true
 133   end
 134   return res
 135 end
 136
 137 local space_chars   = create_set(" ", "\t", "\r", "\n")
 138 local delim_chars   = create_set(" ", "\t", "\r", "\n", "]", "}", ",")
 139 local escape_chars  = create_set("\\", "/", '"', "b", "f", "n", "r", "t", "u")
 140 local literals      = create_set("true", "false", "null")
 141
 142 local literal_map = {
 143   [ "true"  ] = true,
 144   [ "false" ] = false,
 145   [ "null"  ] = nil,
 146 }
 147
 148
 149 local function next_char(str, idx, set, negate)
 150   for i = idx, #str do
 151     if set[str:sub(i, i)] ~= negate then
 152       return i
 153     end
 154   end
 155   return #str + 1
 156 end
 157
 158
 159 local function decode_error(str, idx, msg)
 160   local line_count = 1
 161   local col_count = 1
 162   for i = 1, idx - 1 do
 163     col_count = col_count + 1
 164     if str:sub(i, i) == "\n" then
 165       line_count = line_count + 1
 166       col_count = 1
 167     end
 168   end
 169   error( string.format("%s at line %d col %d", msg, line_count, col_count) )
 170 end
 171
 172
 173 local function codepoint_to_utf8(n)
 174   -- http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&id=iws-appendixa
 175   local f = math.floor
 176   if n <= 0x7f then
 177     return string.char(n)
 178   elseif n <= 0x7ff then
 179     return string.char(f(n / 64) + 192, n % 64 + 128)
 180   elseif n <= 0xffff then
 181     return string.char(f(n / 4096) + 224, f(n % 4096 / 64) + 128, n % 64 + 128)
 182   elseif n <= 0x10ffff then
 183     return string.char(f(n / 262144) + 240, f(n % 262144 / 4096) + 128,
 184                        f(n % 4096 / 64) + 128, n % 64 + 128)
 185   end
 186   error( string.format("invalid unicode codepoint '%x'", n) )
 187 end
 188
 189
 190 local function parse_unicode_escape(s)
 191   local n1 = tonumber( s:sub(3, 6),  16 )
 192   local n2 = tonumber( s:sub(9, 12), 16 )
 193   -- Surrogate pair?
 194   if n2 then
 195     return codepoint_to_utf8((n1 - 0xd800) * 0x400 + (n2 - 0xdc00) + 0x10000)
 196   else
 197     return codepoint_to_utf8(n1)
 198   end
 199 end
 200
 201
 202 local function parse_string(str, i)
 203   local has_unicode_escape = false
 204   local has_surrogate_escape = false
 205   local has_escape = false
 206   local last
 207   for j = i + 1, #str do
 208     local x = str:byte(j)
 209
 210     if x < 32 then
 211       decode_error(str, j, "control character in string")
 212     end
 213
 214     if last == 92 then -- "\\" (escape char)
 215       if x == 117 then -- "u" (unicode escape sequence)
 216         local hex = str:sub(j + 1, j + 5)
 217         if not hex:find("%x%x%x%x") then
 218           decode_error(str, j, "invalid unicode escape in string")
 219         end
 220         if hex:find("^[dD][89aAbB]") then
 221           has_surrogate_escape = true
 222         else
 223           has_unicode_escape = true
 224         end
 225       else
 226         local c = string.char(x)
 227         if not escape_chars[c] then
 228           decode_error(str, j, "invalid escape char '" .. c .. "' in string")
 229         end
 230         has_escape = true
 231       end
 232       last = nil
 233
 234     elseif x == 34 then -- '"' (end of string)
 235       local s = str:sub(i + 1, j - 1)
 236       if has_surrogate_escape then
 237         s = s:gsub("\\u[dD][89aAbB]..\\u....", parse_unicode_escape)
 238       end
 239       if has_unicode_escape then
 240         s = s:gsub("\\u....", parse_unicode_escape)
 241       end
 242       if has_escape then
 243         s = s:gsub("\\.", escape_char_map_inv)
 244       end
 245       return s, j + 1
 246
 247     else
 248       last = x
 249     end
 250   end
 251   decode_error(str, i, "expected closing quote for string")
 252 end
 253
 254
 255 local function parse_number(str, i)
 256   local x = next_char(str, i, delim_chars)
 257   local s = str:sub(i, x - 1)
 258   local n = tonumber(s)
 259   if not n then
 260     decode_error(str, i, "invalid number '" .. s .. "'")
 261   end
 262   return n, x
 263 end
 264
 265
 266 local function parse_literal(str, i)
 267   local x = next_char(str, i, delim_chars)
 268   local word = str:sub(i, x - 1)
 269   if not literals[word] then
 270     decode_error(str, i, "invalid literal '" .. word .. "'")
 271   end
 272   return literal_map[word], x
 273 end
 274
 275
 276 local function parse_array(str, i)
 277   local res = {}
 278   local n = 1
 279   i = i + 1
 280   while 1 do
 281     local x
 282     i = next_char(str, i, space_chars, true)
 283     -- Empty / end of array?
 284     if str:sub(i, i) == "]" then
 285       i = i + 1
 286       break
 287     end
 288     -- Read token
 289     x, i = parse(str, i)
 290     res[n] = x
 291     n = n + 1
 292     -- Next token
 293     i = next_char(str, i, space_chars, true)
 294     local chr = str:sub(i, i)
 295     i = i + 1
 296     if chr == "]" then break end
 297     if chr ~= "," then decode_error(str, i, "expected ']' or ','") end
 298   end
 299   return res, i
 300 end
 301
 302
 303 local function parse_object(str, i)
 304   local res = {}
 305   i = i + 1
 306   while 1 do
 307     local key, val
 308     i = next_char(str, i, space_chars, true)
 309     -- Empty / end of object?
 310     if str:sub(i, i) == "}" then
 311       i = i + 1
 312       break
 313     end
 314     -- Read key
 315     if str:sub(i, i) ~= '"' then
 316       decode_error(str, i, "expected string for key")
 317     end
 318     key, i = parse(str, i)
 319     -- Read ':' delimiter
 320     i = next_char(str, i, space_chars, true)
 321     if str:sub(i, i) ~= ":" then
 322       decode_error(str, i, "expected ':' after key")
 323     end
 324     i = next_char(str, i + 1, space_chars, true)
 325     -- Read value
 326     val, i = parse(str, i)
 327     -- Set
 328     res[key] = val
 329     -- Next token
 330     i = next_char(str, i, space_chars, true)
 331     local chr = str:sub(i, i)
 332     i = i + 1
 333     if chr == "}" then break end
 334     if chr ~= "," then decode_error(str, i, "expected '}' or ','") end
 335   end
 336   return res, i
 337 end
 338
 339
 340 local char_func_map = {
 341   [ '"' ] = parse_string,
 342   [ "0" ] = parse_number,
 343   [ "1" ] = parse_number,
 344   [ "2" ] = parse_number,
 345   [ "3" ] = parse_number,
 346   [ "4" ] = parse_number,
 347   [ "5" ] = parse_number,
 348   [ "6" ] = parse_number,
 349   [ "7" ] = parse_number,
 350   [ "8" ] = parse_number,
 351   [ "9" ] = parse_number,
 352   [ "-" ] = parse_number,
 353   [ "t" ] = parse_literal,
 354   [ "f" ] = parse_literal,
 355   [ "n" ] = parse_literal,
 356   [ "[" ] = parse_array,
 357   [ "{" ] = parse_object,
 358 }
 359
 360
 361 parse = function(str, idx)
 362   local chr = str:sub(idx, idx)
 363   local f = char_func_map[chr]
 364   if f then
 365     return f(str, idx)
 366   end
 367   decode_error(str, idx, "unexpected character '" .. chr .. "'")
 368 end
 369
 370
 371 function Json.decode(str)
 372   if type(str) ~= "string" then
 373     error("expected argument of type string, got " .. type(str))
 374   end
 375   return ( parse(str, next_char(str, 1, space_chars, true)) )
 376 end
 377
 378 -- VERSION --
 379 RYZOM_JSON_VERSION = 324