lua/json/decode/number.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 local tonumber = tonumber
   7 local merge = require("json.util").merge
   8 local util = require("json.decode.util")
   9
  10 module("json.decode.number")
  11
  12 local digit  = lpeg.R("09")
  13 local digits = digit^1
  14
  15 int = (lpeg.P('-') + 0) * (lpeg.R("19") * digits + digit)
  16 local int = int
  17
  18 local frac = lpeg.P('.') * digits
  19
  20 local exp = lpeg.S("Ee") * (lpeg.S("-+") + 0) * digits
  21
  22 local nan = lpeg.S("Nn") * lpeg.S("Aa") * lpeg.S("Nn")
  23 local inf = lpeg.S("Ii") * lpeg.P("nfinity")
  24 local ninf = lpeg.P('-') * lpeg.S("Ii") * lpeg.P("nfinity")
  25 local hex = (lpeg.P("0x") + lpeg.P("0X")) * lpeg.R("09","AF","af")^1
  26
  27 local defaultOptions = {
  28         nan = true,
  29         inf = true,
  30         frac = true,
  31         exp = true,
  32         hex = false
  33 }
  34
  35 default = nil -- Let the buildCapture optimization take place
  36 strict = {
  37         nan = false,
  38         inf = false
  39 }
  40
  41 local nan_value = 0/0
  42 local inf_value = 1/0
  43 local ninf_value = -1/0
  44
  45 --[[
  46         Options: configuration options for number rules
  47                 nan: match NaN
  48                 inf: match Infinity
  49            frac: match fraction portion (.0)
  50             exp: match exponent portion  (e1)
  51         DEFAULT: nan, inf, frac, exp
  52 ]]
  53 local function buildCapture(options)
  54         options = options and merge({}, defaultOptions, options) or defaultOptions
  55         local ret = int
  56         if options.frac then
  57                 ret = ret * (frac + 0)
  58         end
  59         if options.exp then
  60                 ret = ret * (exp + 0)
  61         end
  62         if options.hex then
  63                 ret = hex + ret
  64         end
  65         -- Capture number now
  66         ret = ret / tonumber
  67         if options.nan then
  68                 ret = ret + nan / function() return nan_value end
  69         end
  70         if options.inf then
  71                 ret = ret + ninf / function() return ninf_value end + inf / function() return inf_value end
  72         end
  73         return ret
  74 end
  75
  76 function register_types()
  77         util.register_type("INTEGER")
  78 end
  79
  80 function load_types(options, global_options, grammar)
  81         local integer_id = util.types.INTEGER
  82         local capture = buildCapture(options)
  83         util.append_grammar_item(grammar, "VALUE", capture)
  84         grammar[integer_id] = int / tonumber
  85 end