lua/json/decode/array.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 jsonutil = require("json.util")
   9
  10 local ipairs = ipairs
  11 local unpack = unpack
  12
  13 module("json.decode.array")
  14
  15 -- Utility function to help manage slighly sparse arrays
  16 local function processArray(array)
  17         array.n = #array
  18         for i,v in ipairs(array) do
  19                 if v == jsonutil.null then
  20                         array[i] = nil
  21                 end
  22         end
  23         if #array == array.n then
  24                 array.n = nil
  25         end
  26         if jsonutil.InitArray then
  27                 array = jsonutil.InitArray(array) or array
  28         end
  29         return array
  30 end
  31
  32 local defaultOptions = {
  33         trailingComma = true
  34 }
  35
  36 default = nil -- Let the buildCapture optimization take place
  37 strict = {
  38         trailingComma = false
  39 }
  40
  41 local function buildCapture(options, global_options, state)
  42         local ignored = global_options.ignored
  43         -- arrayItem == element
  44         local arrayItem = lpeg.V(util.types.VALUE)
  45         -- If match-time capture supported, use it to remove stack limit for JSON
  46         if lpeg.Cmt then
  47                 arrayItem = lpeg.Cmt(lpeg.Cp(), function(str, i)
  48                         -- Decode one value then return
  49                         local END_MARKER = {}
  50                         local pattern =
  51                                 -- Found empty segment
  52                                 #lpeg.P(']' * lpeg.Cc(END_MARKER) * lpeg.Cp())
  53                                 -- Found a value + captured, check for required , or ] + capture next pos
  54                                 + state.VALUE_MATCH * #(lpeg.P(',') + lpeg.P(']')) * lpeg.Cp()
  55                         local capture, i = pattern:match(str, i)
  56                         if END_MARKER == capture then
  57                                 return i
  58                         elseif (i == nil and capture == nil) then
  59                                 return false
  60                         else
  61                                 return i, capture
  62                         end
  63                 end)
  64         end
  65         local arrayElements = lpeg.Ct(arrayItem * (ignored * lpeg.P(',') * ignored * arrayItem)^0 + 0) / processArray
  66
  67         options = options and jsonutil.merge({}, defaultOptions, options) or defaultOptions
  68         local capture = lpeg.P("[")
  69         capture = capture * ignored
  70                 * arrayElements * ignored
  71         if options.trailingComma then
  72                 capture = capture * (lpeg.P(",") + 0) * ignored
  73         end
  74         capture = capture * lpeg.P("]")
  75         return capture
  76 end
  77
  78 function register_types()
  79         util.register_type("ARRAY")
  80 end
  81
  82 function load_types(options, global_options, grammar, state)
  83         local capture = buildCapture(options, global_options, state)
  84         local array_id = util.types.ARRAY
  85         grammar[array_id] = capture
  86         util.append_grammar_item(grammar, "VALUE", lpeg.V(array_id))
  87 end