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