lua/json/encode/strings.lua

   1 --[[
   2         Licensed according to the included 'LICENSE' document
   3         Author: Thomas Harning Jr <harningt@gmail.com>
   4 ]]
   5 local string_char = require("string").char
   6 local pairs = pairs
   7
   8 local util_merge = require("json.util").merge
   9
  10 local is_52 = _VERSION == "Lua 5.2"
  11 local _G = _G
  12
  13 if is_52 then
  14         _ENV = nil
  15 end
  16
  17 local normalEncodingMap = {
  18         ['"'] = '\\"',
  19         ['\\'] = '\\\\',
  20         ['/'] = '\\/',
  21         ['\b'] = '\\b',
  22         ['\f'] = '\\f',
  23         ['\n'] = '\\n',
  24         ['\r'] = '\\r',
  25         ['\t'] = '\\t',
  26         ['\v'] = '\\v' -- not in official spec, on report, removing
  27 }
  28
  29 local xEncodingMap = {}
  30 for char, encoded in pairs(normalEncodingMap) do
  31         xEncodingMap[char] = encoded
  32 end
  33
  34 -- Pre-encode the control characters to speed up encoding...
  35 -- NOTE: UTF-8 may not work out right w/ JavaScript
  36 -- JavaScript uses 2 bytes after a \u... yet UTF-8 is a
  37 -- byte-stream encoding, not pairs of bytes (it does encode
  38 -- some letters > 1 byte, but base case is 1)
  39 for i = 0, 255 do
  40         local c = string_char(i)
  41         if c:match('[%z\1-\031\128-\255]') and not normalEncodingMap[c] then
  42                 -- WARN: UTF8 specializes values >= 0x80 as parts of sequences...
  43                 --       without \x encoding, do not allow encoding > 7F
  44                 normalEncodingMap[c] = ('\\u%.4X'):format(i)
  45                 xEncodingMap[c] = ('\\x%.2X'):format(i)
  46         end
  47 end
  48
  49 local defaultOptions = {
  50         xEncode = false, -- Encode single-bytes as \xXX
  51         processor = nil, -- Simple processor for the string prior to quoting
  52         -- / is not required to be quoted but it helps with certain decoding
  53         -- Required encoded characters, " \, and 00-1F  (0 - 31)
  54         encodeSet = '\\"/%z\1-\031',
  55         encodeSetAppend = nil -- Chars to append to the default set
  56 }
  57
  58 local default = nil
  59 local strict = nil
  60
  61 local function getEncoder(options)
  62         options = options and util_merge({}, defaultOptions, options) or defaultOptions
  63         local encodeSet = options.encodeSet
  64         if options.encodeSetAppend then
  65                 encodeSet = encodeSet .. options.encodeSetAppend
  66         end
  67         local encodingMap = options.xEncode and xEncodingMap or normalEncodingMap
  68         local encodeString
  69         if options.processor then
  70                 local processor = options.processor
  71                 encodeString = function(s, state)
  72                         return '"' .. processor(s:gsub('[' .. encodeSet .. ']', encodingMap)) .. '"'
  73                 end
  74         else
  75                 encodeString = function(s, state)
  76                         return '"' .. s:gsub('[' .. encodeSet .. ']', encodingMap) .. '"'
  77                 end
  78         end
  79         return {
  80                 string = encodeString
  81         }
  82 end
  83
  84 local strings = {
  85         default = default,
  86         strict = strict,
  87         getEncoder = getEncoder
  88 }
  89
  90 if not is_52 then
  91         _G.json = _G.json or {}
  92         _G.json.encode = _G.json.encode or {}
  93         _G.json.encode.strings = strings
  94 end
  95
  96 return strings