1 --[[--

2 json_string = -- JavaScript code representing the given datum (with quotes, if needed)

3 encode.json(

4 obj -- true, false, nil or a number or string

5 )

6

7 This function encodes any native datatype or atom in JavaScript object notation (JSON). It ensures that the returned string can be safely included in inline scripts both in HTML and XHTML (within CDATA section).

8

9 TODO: can't distinguish unambiguously between empty object and empty list!

10

11 --]]--

12

13 -- TODO: check if numeric representations are JSON compatible

14

15 function encode.json(obj)

16 if obj == nil then

17 return "null";

18 elseif atom.has_type(obj, atom.boolean) then

19 return tostring(obj)

20 elseif atom.has_type(obj, atom.number) then

21 return tostring(obj)

22 elseif type(obj) == "table" then

23 local parts = {}

24 local first = true

25 if #obj > 0 then

26 parts[#parts+1] = "["

27 for idx, value in ipairs(obj) do

28 if first then

29 first = false

30 else

31 parts[#parts+1] = ","

32 end

33 parts[#parts+1] = tostring(value)

34 end

35 parts[#parts+1] = "]"

36 else

37 parts[#parts+1] = "{"

38 for key, value in pairs(obj) do

39 if first then

40 first = false

41 else

42 parts[#parts+1] = ","

43 end

44 parts[#parts+1] = encode.json(key)

45 parts[#parts+1] = ":"

46 parts[#parts+1] = encode.json(value)

47 end

48 parts[#parts+1] = "}"

49 end

50 return table.concat(parts)

51 else

52 local str = atom.dump(obj)

53 str = string.gsub(str, ".",

54 function (char)

55 if char == '\r' then return '\\r' end

56 if char == '\n' then return '\\n' end

57 if char == '\\' then return '\\\\' end

58 if char == '"' then return '\\"' end

59 local byte = string.byte(char)

60 if byte < 32 then return string.format("\\u%04x", byte) end

61 end

62 )

63 str = string.gsub(str, "</", "<\\/")

64 str = string.gsub(str, "<!%[CDATA%[", "\\u003c![CDATA[")

65 str = string.gsub(str, "]]>", "]]\\u003e")

66 return '"' .. str .. '"'

67 end

68 end