src/json/encode/strings.lua

   1 local string_char = string.char
   2
   3 module("json.encode.strings")
   4
   5 local encodingMap = {
   6         ['\\'] = '\\\\',
   7         ['"'] = '\\"',
   8         ['\n'] = '\\n',
   9         ['\t'] = '\\t',
  10         ['\b'] = '\\b',
  11         ['\f'] = '\\f',
  12         ['\r'] = '\\r',
  13         ['/'] = '\\/'
  14 }
  15
  16 -- Pre-encode the control characters to speed up encoding...
  17 -- NOTE: UTF-8 may not work out right w/ JavaScript
  18 -- JavaScript uses 2 bytes after a \u... yet UTF-8 is a
  19 -- byte-stream encoding, not pairs of bytes (it does encode
  20 -- some letters > 1 byte, but base case is 1)
  21 for i = 1, 255 do
  22         local c = string_char(i)
  23         if c:match('%c') and not encodingMap[c] then
  24                 encodingMap[c] = ('\\u%.4X'):format(i)
  25         end
  26 end
  27
  28 function encode(s, options)
  29         local stringPreprocess = options and options.strings and options.strings.preProcess
  30         if stringPreprocess then
  31                 s = stringPreprocess(s)
  32         end
  33         return '"' .. s:gsub('[\\"/%c%z]', encodingMap) .. '"'
  34 end