lua/json/decode/object.lua

   1 --[[
   2         Licensed according to the included 'LICENSE' document
   3         Author: Thomas Harning Jr <harningt@gmail.com>
   4 ]]
   5 local lpeg = require("lpeg")
   6
   7 local util = require("json.decode.util")
   8 local merge = require("json.util").merge
   9
  10 local tonumber = tonumber
  11 local unpack = unpack
  12 local print = print
  13 local tostring = tostring
  14
  15 local rawset = rawset
  16
  17 module("json.decode.object")
  18
  19 -- BEGIN LPEG < 0.9 SUPPORT
  20 local initObject, applyObjectKey
  21 if not (lpeg.Cg and lpeg.Cf and lpeg.Ct) then
  22         function initObject()
  23                 return {}
  24         end
  25         function applyObjectKey(tab, key, val)
  26                 tab[key] = val
  27                 return tab
  28         end
  29 end
  30 -- END LPEG < 0.9 SUPPORT
  31
  32 local defaultOptions = {
  33         number = true,
  34         identifier = true,
  35         trailingComma = true
  36 }
  37
  38 default = nil -- Let the buildCapture optimization take place
  39
  40 strict = {
  41         number = false,
  42         identifier = false,
  43         trailingComma = false
  44 }
  45
  46 local function buildItemSequence(objectItem, ignored)
  47         return (objectItem * (ignored * lpeg.P(",") * ignored * objectItem)^0) + 0
  48 end
  49
  50 local function buildCapture(options, global_options, state)
  51         local ignored = global_options.ignored
  52         local string_type = lpeg.V(util.types.STRING)
  53         local integer_type = lpeg.V(util.types.INTEGER)
  54         local value_type = lpeg.V(util.types.VALUE)
  55         -- If match-time capture supported, use it to remove stack limit for JSON
  56         if lpeg.Cmt then
  57                 value_type = lpeg.Cmt(lpeg.Cp(), function(str, i)
  58                         -- Decode one value then return
  59                         local END_MARKER = {}
  60                         local pattern =
  61                                 -- Found empty segment
  62                                 #lpeg.P('}' * lpeg.Cc(END_MARKER) * lpeg.Cp())
  63                                 -- Found a value + captured, check for required , or } + capture next pos
  64                                 + state.VALUE_MATCH * #(lpeg.P(',') + lpeg.P('}')) * lpeg.Cp()
  65                         local capture, i = pattern:match(str, i)
  66                         if END_MARKER == capture then
  67                                 return i
  68                         elseif (i == nil and capture == nil) then
  69                                 return false
  70                         else
  71                                 return i, capture
  72                         end
  73                 end)
  74         end
  75
  76
  77         options = options and merge({}, defaultOptions, options) or defaultOptions
  78         local key = string_type
  79         if options.identifier then
  80                 key = key + lpeg.C(util.identifier)
  81         end
  82         if options.number then
  83                 key = key + integer_type
  84         end
  85         local objectItems
  86         local objectItem = (key * ignored * lpeg.P(":") * ignored * value_type)
  87         -- BEGIN LPEG < 0.9 SUPPORT
  88         if not (lpeg.Cg and lpeg.Cf and lpeg.Ct) then
  89                 objectItems = buildItemSequence(objectItem / applyObjectKey, ignored)
  90                 objectItems = lpeg.Ca(lpeg.Cc(false) / initObject * objectItems)
  91         -- END LPEG < 0.9 SUPPORT
  92         else
  93                 objectItems = buildItemSequence(lpeg.Cg(objectItem), ignored)
  94                 objectItems = lpeg.Cf(lpeg.Ct(0) * objectItems, rawset)
  95         end
  96
  97
  98         local capture = lpeg.P("{") * ignored
  99         capture = capture * objectItems * ignored
 100         if options.trailingComma then
 101                 capture = capture * (lpeg.P(",") + 0) * ignored
 102         end
 103         capture = capture * lpeg.P("}")
 104         return capture
 105 end
 106
 107 function register_types()
 108         util.register_type("OBJECT")
 109 end
 110
 111 function load_types(options, global_options, grammar, state)
 112         local capture = buildCapture(options, global_options, state)
 113         local object_id = util.types.OBJECT
 114         grammar[object_id] = capture
 115         util.append_grammar_item(grammar, "VALUE", lpeg.V(object_id))
 116 end