AyeMinMyat

Create_By_Aye_Min_Myat

Oct 22nd, 2021
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  1. --
  2. -- json.lua
  3. --
  4. -- Copyright (c) 2020 rxi
  5. --
  6. -- Permission is hereby granted, free of charge, to any person obtaining a copy of
  7. -- this software and associated documentation files (the "Software"), to deal in
  8. -- the Software without restriction, including without limitation the rights to
  9. -- use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
  10. -- of the Software, and to permit persons to whom the Software is furnished to do
  11. -- so, subject to the following conditions:
  12. --
  13. -- The above copyright notice and this permission notice shall be included in all
  14. -- copies or substantial portions of the Software.
  15. --
  16. -- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17. -- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18. -- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19. -- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20. -- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21. -- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  22. -- SOFTWARE.
  23. --
  24.  
  25. local json = { _version = "0.1.2" }
  26.  
  27. -------------------------------------------------------------------------------
  28. -- Encode
  29. -------------------------------------------------------------------------------
  30.  
  31. local encode
  32.  
  33. local escape_char_map = {
  34.   [ "\\" ] = "\\",
  35.   [ "\"" ] = "\"",
  36.   [ "\b" ] = "b",
  37.   [ "\f" ] = "f",
  38.   [ "\n" ] = "n",
  39.   [ "\r" ] = "r",
  40.   [ "\t" ] = "t",
  41. }
  42.  
  43. local escape_char_map_inv = { [ "/" ] = "/" }
  44. for k, v in pairs(escape_char_map) do
  45.   escape_char_map_inv[v] = k
  46. end
  47.  
  48.  
  49. local function escape_char(c)
  50.   return "\\" .. (escape_char_map[c] or string.format("u%04x", c:byte()))
  51. end
  52.  
  53.  
  54. local function encode_nil(val)
  55.   return "null"
  56. end
  57.  
  58.  
  59. local function encode_table(val, stack)
  60.   local res = {}
  61.   stack = stack or {}
  62.  
  63.   -- Circular reference?
  64.   if stack[val] then error("circular reference") end
  65.  
  66.   stack[val] = true
  67.  
  68.   if rawget(val, 1) ~= nil or next(val) == nil then
  69.     -- Treat as array -- check keys are valid and it is not sparse
  70.     local n = 0
  71.     for k in pairs(val) do
  72.       if type(k) ~= "number" then
  73.         error("invalid table: mixed or invalid key types")
  74.       end
  75.       n = n + 1
  76.     end
  77.     if n ~= #val then
  78.       error("invalid table: sparse array")
  79.     end
  80.     -- Encode
  81.     for i, v in ipairs(val) do
  82.       table.insert(res, encode(v, stack))
  83.     end
  84.     stack[val] = nil
  85.     return "[" .. table.concat(res, ",") .. "]"
  86.  
  87.   else
  88.     -- Treat as an object
  89.     for k, v in pairs(val) do
  90.       if type(k) ~= "string" then
  91.         error("invalid table: mixed or invalid key types")
  92.       end
  93.       table.insert(res, encode(k, stack) .. ":" .. encode(v, stack))
  94.     end
  95.     stack[val] = nil
  96.     return "{" .. table.concat(res, ",") .. "}"
  97.   end
  98. end
  99.  
  100.  
  101. local function encode_string(val)
  102.   return '"' .. val:gsub('[%z\1-\31\\"]', escape_char) .. '"'
  103. end
  104.  
  105.  
  106. local function encode_number(val)
  107.   -- Check for NaN, -inf and inf
  108.   if val ~= val or val <= -math.huge or val >= math.huge then
  109.     error("unexpected number value '" .. tostring(val) .. "'")
  110.   end
  111.   return string.format("%.14g", val)
  112. end
  113.  
  114.  
  115. local type_func_map = {
  116.   [ "nil"     ] = encode_nil,
  117.   [ "table"   ] = encode_table,
  118.   [ "string"  ] = encode_string,
  119.   [ "number"  ] = encode_number,
  120.   [ "boolean" ] = tostring,
  121. }
  122.  
  123.  
  124. encode = function(val, stack)
  125.   local t = type(val)
  126.   local f = type_func_map[t]
  127.   if f then
  128.     return f(val, stack)
  129.   end
  130.   error("unexpected type '" .. t .. "'")
  131. end
  132.  
  133.  
  134. function json.encode(val)
  135.   return ( encode(val) )
  136. end
  137.  
  138.  
  139. -------------------------------------------------------------------------------
  140. -- Decode
  141. -------------------------------------------------------------------------------
  142.  
  143. local parse
  144.  
  145. local function create_set(...)
  146.   local res = {}
  147.   for i = 1, select("#", ...) do
  148.     res[ select(i, ...) ] = true
  149.   end
  150.   return res
  151. end
  152.  
  153. local space_chars   = create_set(" ", "\t", "\r", "\n")
  154. local delim_chars   = create_set(" ", "\t", "\r", "\n", "]", "}", ",")
  155. local escape_chars  = create_set("\\", "/", '"', "b", "f", "n", "r", "t", "u")
  156. local literals      = create_set("true", "false", "null")
  157.  
  158. local literal_map = {
  159.   [ "true"  ] = true,
  160.   [ "false" ] = false,
  161.   [ "null"  ] = nil,
  162. }
  163.  
  164.  
  165. local function next_char(str, idx, set, negate)
  166.   for i = idx, #str do
  167.     if set[str:sub(i, i)] ~= negate then
  168.       return i
  169.     end
  170.   end
  171.   return #str + 1
  172. end
  173.  
  174.  
  175. local function decode_error(str, idx, msg)
  176.   local line_count = 1
  177.   local col_count = 1
  178.   for i = 1, idx - 1 do
  179.     col_count = col_count + 1
  180.     if str:sub(i, i) == "\n" then
  181.       line_count = line_count + 1
  182.       col_count = 1
  183.     end
  184.   end
  185.   error( string.format("%s at line %d col %d", msg, line_count, col_count) )
  186. end
  187.  
  188.  
  189. local function codepoint_to_utf8(n)
  190.   -- http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&id=iws-appendixa
  191.   local f = math.floor
  192.   if n <= 0x7f then
  193.     return string.char(n)
  194.   elseif n <= 0x7ff then
  195.     return string.char(f(n / 64) + 192, n % 64 + 128)
  196.   elseif n <= 0xffff then
  197.     return string.char(f(n / 4096) + 224, f(n % 4096 / 64) + 128, n % 64 + 128)
  198.   elseif n <= 0x10ffff then
  199.     return string.char(f(n / 262144) + 240, f(n % 262144 / 4096) + 128,
  200.                        f(n % 4096 / 64) + 128, n % 64 + 128)
  201.   end
  202.   error( string.format("invalid unicode codepoint '%x'", n) )
  203. end
  204.  
  205.  
  206. local function parse_unicode_escape(s)
  207.   local n1 = tonumber( s:sub(1, 4),  16 )
  208.   local n2 = tonumber( s:sub(7, 10), 16 )
  209.    -- Surrogate pair?
  210.   if n2 then
  211.     return codepoint_to_utf8((n1 - 0xd800) * 0x400 + (n2 - 0xdc00) + 0x10000)
  212.   else
  213.     return codepoint_to_utf8(n1)
  214.   end
  215. end
  216.  
  217.  
  218. local function parse_string(str, i)
  219.   local res = ""
  220.   local j = i + 1
  221.   local k = j
  222.  
  223.   while j <= #str do
  224.     local x = str:byte(j)
  225.  
  226.     if x < 32 then
  227.       decode_error(str, j, "control character in string")
  228.  
  229.     elseif x == 92 then -- `\`: Escape
  230.       res = res .. str:sub(k, j - 1)
  231.       j = j + 1
  232.       local c = str:sub(j, j)
  233.       if c == "u" then
  234.         local hex = str:match("^[dD][89aAbB]%x%x\\u%x%x%x%x", j + 1)
  235.                  or str:match("^%x%x%x%x", j + 1)
  236.                  or decode_error(str, j - 1, "invalid unicode escape in string")
  237.         res = res .. parse_unicode_escape(hex)
  238.         j = j + #hex
  239.       else
  240.         if not escape_chars[c] then
  241.           decode_error(str, j - 1, "invalid escape char '" .. c .. "' in string")
  242.         end
  243.         res = res .. escape_char_map_inv[c]
  244.       end
  245.       k = j + 1
  246.  
  247.     elseif x == 34 then -- `"`: End of string
  248.      res = res .. str:sub(k, j - 1)
  249.      return res, j + 1
  250.    end
  251.  
  252.    j = j + 1
  253.  end
  254.  
  255.  decode_error(str, i, "expected closing quote for string")
  256. end
  257.  
  258.  
  259. local function parse_number(str, i)
  260.  local x = next_char(str, i, delim_chars)
  261.  local s = str:sub(i, x - 1)
  262.  local n = tonumber(s)
  263.  if not n then
  264.    decode_error(str, i, "invalid number '" .. s .. "'")
  265.  end
  266.  return n, x
  267. end
  268.  
  269.  
  270. local function parse_literal(str, i)
  271.  local x = next_char(str, i, delim_chars)
  272.  local word = str:sub(i, x - 1)
  273.  if not literals[word] then
  274.    decode_error(str, i, "invalid literal '" .. word .. "'")
  275.  end
  276.  return literal_map[word], x
  277. end
  278.  
  279.  
  280. local function parse_array(str, i)
  281.  local res = {}
  282.  local n = 1
  283.  i = i + 1
  284.  while 1 do
  285.    local x
  286.    i = next_char(str, i, space_chars, true)
  287.    -- Empty / end of array?
  288.    if str:sub(i, i) == "]" then
  289.      i = i + 1
  290.      break
  291.    end
  292.    -- Read token
  293.    x, i = parse(str, i)
  294.    res[n] = x
  295.    n = n + 1
  296.    -- Next token
  297.    i = next_char(str, i, space_chars, true)
  298.    local chr = str:sub(i, i)
  299.    i = i + 1
  300.    if chr == "]" then break end
  301.    if chr ~= "," then decode_error(str, i, "expected ']' or ','") end
  302.  end
  303.  return res, i
  304. end
  305.  
  306.  
  307. local function parse_object(str, i)
  308.  local res = {}
  309.  i = i + 1
  310.  while 1 do
  311.    local key, val
  312.    i = next_char(str, i, space_chars, true)
  313.    -- Empty / end of object?
  314.    if str:sub(i, i) == "}" then
  315.      i = i + 1
  316.      break
  317.    end
  318.    -- Read key
  319.    if str:sub(i, i) ~= '"' then
  320.      decode_error(str, i, "expected string for key")
  321.    end
  322.    key, i = parse(str, i)
  323.    -- Read ':' delimiter
  324.    i = next_char(str, i, space_chars, true)
  325.    if str:sub(i, i) ~= ":" then
  326.      decode_error(str, i, "expected ':' after key")
  327.    end
  328.    i = next_char(str, i + 1, space_chars, true)
  329.    -- Read value
  330.    val, i = parse(str, i)
  331.    -- Set
  332.    res[key] = val
  333.    -- Next token
  334.    i = next_char(str, i, space_chars, true)
  335.    local chr = str:sub(i, i)
  336.    i = i + 1
  337.    if chr == "}" then break end
  338.    if chr ~= "," then decode_error(str, i, "expected '}' or ','") end
  339.  end
  340.  return res, i
  341. end
  342.  
  343.  
  344. local char_func_map = {
  345.  [ '"' ] = parse_string,
  346.  [ "0" ] = parse_number,
  347.  [ "1" ] = parse_number,
  348.  [ "2" ] = parse_number,
  349.  [ "3" ] = parse_number,
  350.  [ "4" ] = parse_number,
  351.  [ "5" ] = parse_number,
  352.  [ "6" ] = parse_number,
  353.  [ "7" ] = parse_number,
  354.  [ "8" ] = parse_number,
  355.  [ "9" ] = parse_number,
  356.  [ "-" ] = parse_number,
  357.  [ "t" ] = parse_literal,
  358.  [ "f" ] = parse_literal,
  359.  [ "n" ] = parse_literal,
  360.  [ "[" ] = parse_array,
  361.  [ "{" ] = parse_object,
  362. }
  363.  
  364.  
  365. parse = function(str, idx)
  366.  local chr = str:sub(idx, idx)
  367.  local f = char_func_map[chr]
  368.  if f then
  369.    return f(str, idx)
  370.  end
  371.  decode_error(str, idx, "unexpected character '" .. chr .. "'")
  372. end
  373.  
  374.  
  375. function json.decode(str)
  376.  if type(str) ~= "string" then
  377.    error("expected argument of type string, got " .. type(str))
  378.  end
  379.  local res, idx = parse(str, next_char(str, 1, space_chars, true))
  380.  idx = next_char(str, idx, space_chars, true)
  381.  if idx <= #str then
  382.    decode_error(str, idx, "trailing garbage")
  383.  end
  384.  return res
  385. end
  386.  
  387.  
  388. return json
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