src/json/encode.lua

   1 --[[
   2         Licensed according to the included 'LICENSE' document
   3         Author: Thomas Harning Jr <harningt@gmail.com>
   4 ]]
   5 local type = type
   6 local assert = assert
   7 local getmetatable, setmetatable = getmetatable, setmetatable
   8 local util = require("json.util")
   9 local null = util.null
  10
  11 local require = require
  12
  13 local strings = require("json.encode.strings")
  14 local others = require("json.encode.others")
  15
  16 module("json.encode")
  17
  18 -- Load these modules after defining that json.encode exists
  19 --  calls, object, and array need encodeValue and isEncodable
  20 local calls = require("json.encode.calls")
  21 local array = require("json.encode.array")
  22 local object = require("json.encode.object")
  23
  24
  25 local function encodeFunction(val, options)
  26         if val ~= null and calls.isCall(val, options) then
  27                 return calls.encode(val, options)
  28         end
  29         return 'null'
  30 end
  31
  32 local alreadyEncoded -- Table set at the beginning of every
  33         -- encoding operation to empty to detect recursiveness
  34 local function encodeTable(tab, options)
  35         assert(not alreadyEncoded[tab], "Recursive table detected")
  36         alreadyEncoded[tab] = true
  37         -- Pass off encoding to appropriate encoder
  38         if calls.isCall(tab, options) then
  39                 return calls.encode(tab, options)
  40         elseif array.isArray(tab, options) then
  41                 return array.encode(tab, options)
  42         else
  43                 return object.encode(tab, options)
  44         end
  45 end
  46
  47 local encodeMapping = {
  48         ['table'  ] = encodeTable,
  49         ['number' ] = others.encodeNumber,
  50         ['boolean'] = others.encodeBoolean,
  51         ['function'] = encodeFunction,
  52         ['string' ] = strings.encode,
  53         ['nil'] = others.encodeNil -- For the case that nils are encountered count them as nulls
  54 }
  55 function isEncodable(item, options)
  56         local isNotEncodableFunction = type(item) == 'function' and (item ~= null and not calls.isCall(item, options))
  57         return encodeMapping[type(item)] and not isNotEncodableFunction
  58 end
  59
  60 function encodeValue(item, options)
  61         local itemType = type(item)
  62         local encoder = encodeMapping[itemType]
  63         assert(encoder, "Invalid item to encode: " .. itemType)
  64         return encoder(item, options)
  65 end
  66
  67 local defaultOptions = {
  68         strings = {
  69                 preProcess = false
  70         },
  71         array = {
  72                 isArray = util.IsArray
  73         }
  74 }
  75
  76 function encode(data, options)
  77         options = options or defaultOptions
  78         alreadyEncoded = {}
  79         return encodeValue(data, options)
  80 end
  81
  82 local mt = getmetatable(_M) or {}
  83 mt.__call = function(self, ...)
  84         return encode(...)
  85 end
  86 setmetatable(_M, mt)