162 lines
4.3 KiB
Lua
162 lines
4.3 KiB
Lua
--[[
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Licensed according to the included 'LICENSE' document
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Author: Thomas Harning Jr <harningt@gmail.com>
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]]
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local type = type
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local assert, error = assert, error
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local getmetatable, setmetatable = getmetatable, setmetatable
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local ipairs, pairs = ipairs, pairs
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local require = require
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local output = require("json.encode.output")
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local util = require("json.util")
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local util_merge, isCall = util.merge, util.isCall
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local _ENV = nil
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--[[
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List of encoding modules to load.
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Loaded in sequence such that earlier encoders get priority when
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duplicate type-handlers exist.
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]]
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local modulesToLoad = {
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"strings",
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"number",
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"calls",
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"others",
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"array",
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"object"
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}
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-- Modules that have been loaded
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local loadedModules = {}
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local json_encode = {}
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-- Configuration bases for client apps
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local modes_defined = { "default", "strict" }
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json_encode.default = {}
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json_encode.strict = {
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initialObject = true -- Require an object at the root
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}
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-- For each module, load it and its defaults
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for _,name in ipairs(modulesToLoad) do
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local mod = require("json.encode." .. name)
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if mod.mergeOptions then
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for _, mode in pairs(modes_defined) do
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mod.mergeOptions(json_encode[mode], mode)
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end
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end
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loadedModules[name] = mod
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end
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-- NOTE: Nested not found, so assume unsupported until use case arises
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local function flattenOutput(out, value)
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assert(type(value) ~= 'table')
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out = out or {}
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out[#out + 1] = value
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return out
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end
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-- Prepares the encoding map from the already provided modules and new config
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local function prepareEncodeMap(options)
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local map = {}
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for _, name in ipairs(modulesToLoad) do
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local encodermap = loadedModules[name].getEncoder(options[name])
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for valueType, encoderSet in pairs(encodermap) do
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map[valueType] = flattenOutput(map[valueType], encoderSet)
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end
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end
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return map
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end
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--[[
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Encode a value with a given encoding map and state
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]]
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local function encodeWithMap(value, map, state, isObjectKey)
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local t = type(value)
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local encoderList = assert(map[t], "Failed to encode value, unhandled type: " .. t)
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for _, encoder in ipairs(encoderList) do
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local ret = encoder(value, state, isObjectKey)
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if false ~= ret then
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return ret
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end
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end
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error("Failed to encode value, encoders for " .. t .. " deny encoding")
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end
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local function getBaseEncoder(options)
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local encoderMap = prepareEncodeMap(options)
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if options.preProcess then
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local preProcess = options.preProcess
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return function(value, state, isObjectKey)
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local ret = preProcess(value, isObjectKey or false)
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if nil ~= ret then
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value = ret
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end
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return encodeWithMap(value, encoderMap, state)
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end
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end
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return function(value, state, isObjectKey)
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return encodeWithMap(value, encoderMap, state)
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end
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end
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--[[
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Retreive an initial encoder instance based on provided options
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the initial encoder is responsible for initializing state
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State has at least these values configured: encode, check_unique, already_encoded
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]]
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function json_encode.getEncoder(options)
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options = options and util_merge({}, json_encode.default, options) or json_encode.default
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local encode = getBaseEncoder(options)
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local function initialEncode(value)
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if options.initialObject then
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local errorMessage = "Invalid arguments: expects a JSON Object or Array at the root"
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assert(type(value) == 'table' and not isCall(value, options), errorMessage)
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end
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local alreadyEncoded = {}
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local function check_unique(value)
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assert(not alreadyEncoded[value], "Recursive encoding of value")
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alreadyEncoded[value] = true
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end
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local outputEncoder = options.output and options.output() or output.getDefault()
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local state = {
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encode = encode,
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check_unique = check_unique,
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already_encoded = alreadyEncoded, -- To unmark encoding when moving up stack
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outputEncoder = outputEncoder
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}
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local ret = encode(value, state)
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if nil ~= ret then
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return outputEncoder.simple and outputEncoder.simple(ret) or ret
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end
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end
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return initialEncode
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end
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-- CONSTRUCT STATE WITH FOLLOWING (at least)
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--[[
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encoder
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check_unique -- used by inner encoders to make sure value is unique
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already_encoded -- used to unmark a value as unique
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]]
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function json_encode.encode(data, options)
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return json_encode.getEncoder(options)(data)
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end
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local mt = {}
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mt.__call = function(self, ...)
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return json_encode.encode(...)
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end
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setmetatable(json_encode, mt)
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return json_encode
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