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 jsonutil = require("json.util")
   8 local merge = jsonutil.merge
   9 local util = require("json.decode.util")
  10
  11 local _ENV = nil
  12
  13 local digit  = lpeg.R("09")
  14 local digits = digit^1
  15
  16 -- Illegal octal declaration
  17 local illegal_octal_detect = #(lpeg.P('0') * digits) * util.denied("Octal numbers")
  18
  19 local int = (lpeg.P('-') + 0) * (lpeg.R("19") * digits + illegal_octal_detect + digit)
  20
  21 local frac = lpeg.P('.') * digits
  22
  23 local exp = lpeg.S("Ee") * (lpeg.S("-+") + 0) * digits
  24
  25 local nan = lpeg.S("Nn") * lpeg.S("Aa") * lpeg.S("Nn")
  26 local inf = lpeg.S("Ii") * lpeg.P("nfinity")
  27 local ninf = lpeg.P('-') * lpeg.S("Ii") * lpeg.P("nfinity")
  28 local hex = (lpeg.P("0x") + lpeg.P("0X")) * lpeg.R("09","AF","af")^1
  29
  30 local defaultOptions = {
  31         nan = true,
  32         inf = true,
  33         frac = true,
  34         exp = true,
  35         hex = false
  36 }
  37
  38 local modeOptions = {}
  39
  40 modeOptions.strict = {
  41         nan = false,
  42         inf = false
  43 }
  44
  45 local nan_value = 0/0
  46 local inf_value = 1/0
  47 local ninf_value = -1/0
  48
  49 --[[
  50         Options: configuration options for number rules
  51                 nan: match NaN
  52                 inf: match Infinity
  53            frac: match fraction portion (.0)
  54             exp: match exponent portion  (e1)
  55         DEFAULT: nan, inf, frac, exp
  56 ]]
  57 local function mergeOptions(options, mode)
  58         jsonutil.doOptionMerge(options, false, 'number', defaultOptions, mode and modeOptions[mode])
  59 end
  60
  61 local function generateLexer(options)
  62         options = options.number
  63         local ret = int
  64         if options.frac then
  65                 ret = ret * (frac + 0)
  66         else
  67                 ret = ret * (#frac * util.denied("Fractions", "number.frac") + 0)
  68         end
  69         if options.exp then
  70                 ret = ret * (exp + 0)
  71         else
  72                 ret = ret * (#exp * util.denied("Exponents", "number.exp") + 0)
  73         end
  74         if options.hex then
  75                 ret = hex + ret
  76         else
  77                 ret = #hex * util.denied("Hexadecimal", "number.hex") + ret
  78         end
  79         -- Capture number now
  80         ret = ret / tonumber
  81         if options.nan then
  82                 ret = ret + nan / function() return nan_value end
  83         else
  84                 ret = ret + #nan * util.denied("NaN", "number.nan")
  85         end
  86         if options.inf then
  87                 ret = ret + ninf / function() return ninf_value end + inf / function() return inf_value end
  88         else
  89                 ret = ret + (#ninf + #inf) * util.denied("+/-Inf", "number.inf")
  90         end
  91         return ret
  92 end
  93
  94 local number = {
  95         int = int,
  96         mergeOptions = mergeOptions,
  97         generateLexer = generateLexer
  98 }
  99
 100 return number