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 TODO: replace with JSON library

12

13 --]]--

14

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

16

17 function encode.json(obj)

18 if obj == nil then

19 return "null";

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

21 return tostring(obj)

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

23 return tostring(obj)

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

25 local parts = {}

26 local first = true

27 if #obj > 0 then

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

29 for idx, value in ipairs(obj) do

30 if first then

31 first = false

32 else

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

34 end

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

36 end

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

38 else

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

40 for key, value in pairs(obj) do

41 if first then

42 first = false

43 else

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

45 end

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

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

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

49 end

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

51 end

52 return table.concat(parts)

53 else

54 local str = atom.dump(obj)

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

56 function (char)

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

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

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

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

61 local byte = string.byte(char)

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

63 end

64 )

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

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

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

68 return '"' .. str .. '"'

69 end

70 end