noita-mapcap/files/libraries/noita-api/json.lua

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-- Copyright (c) 2022 David Vogel
--
-- This software is released under the MIT License.
-- https://opensource.org/licenses/MIT
-- Simple library to marshal JSON values. Mainly for Noita.
local lib = {}
---Maps single characters to escaped strings.
---
---Copyright (c) 2020 rxi
---@see [github.com/rxi/json.lua](https://github.com/rxi/json.lua/blob/master/json.lua)
local escapeCharacters = {
["\\"] = "\\",
["\""] = "\"",
["\b"] = "b",
["\f"] = "f",
["\n"] = "n",
["\r"] = "r",
["\t"] = "t",
}
---escapeRune returns the escaped string for a given rune.
---
---Copyright (c) 2020 rxi
---@see [github.com/rxi/json.lua](https://github.com/rxi/json.lua/blob/master/json.lua)
---@param rune string
---@return string
local function escapeCharacter(rune)
return "\\" .. (escapeCharacters[rune] or string.format("u%04x", rune:byte()))
end
---escapeString returns the escaped version of the given string.
---
---Copyright (c) 2020 rxi
---@see [github.com/rxi/json.lua](https://github.com/rxi/json.lua/blob/master/json.lua)
---@param str string
---@return string
local function escapeString(str)
local result, count = str:gsub('[%z\1-\31\\"]', escapeCharacter)
return result
end
---MarshalString returns the JSON representation of a string value.
---@param val string
---@return string
function lib.MarshalString(val)
return string.format("%q", escapeString(val))
end
---MarshalNumber returns the JSON representation of a number value.
---@param val number
---@return string
function lib.MarshalNumber(val)
-- Edge cases, as there is no real solution to this.
-- JSON can't store special IEEE754 values, this is dumb as hell.
if val ~= val then
return "null" -- Alternatively we could output the string "NaN" (With quotes).
elseif val <= -math.huge then
return "-1E+600" -- Just output a stupidly large number.
elseif val >= math.huge then
return "1E+600" -- Just output a stupidly large number.
end
return tostring(val)
end
---MarshalBoolean returns the JSON representation of a boolean value.
---@param val boolean
---@return string
function lib.MarshalBoolean(val)
return tostring(val)
end
---MarshalObject returns the JSON representation of a table object.
---
---This only works with string keys. Number keys will be converted into strings.
---@param val table<string,any>
---@return string
function lib.MarshalObject(val)
local result = "{"
for k, v in pairs(val) do
result = result .. lib.MarshalString(k) .. ": " .. lib.Marshal(v)
-- Append character depending on whether this is the last element or not.
if next(val, k) == nil then
result = result .. "}"
else
result = result .. ", "
end
end
return result
end
---MarshalArray returns the JSON representation of an array object.
---
---@param val table<number,any>
---@param customMarshalFunction function|nil -- Custom function for marshalling the array values.
---@return string
function lib.MarshalArray(val, customMarshalFunction)
local result = "["
-- TODO: Check if the type of all array entries is the same.
local length = #val
for i, v in ipairs(val) do
if customMarshalFunction then
result = result .. customMarshalFunction(v)
else
result = result .. lib.Marshal(v)
end
-- Append character depending on whether this is the last element or not.
if i == length then
result = result .. "]"
else
result = result .. ", "
end
end
return result
end
---Marshal marshals any value into JSON representation.
---@param val any
---@return string
function lib.Marshal(val)
local t = type(val)
if t == "nil" then
return "null"
elseif t == "number" then
return lib.MarshalNumber(val)
elseif t == "string" then
return lib.MarshalString(val)
elseif t == "boolean" then
return lib.MarshalBoolean(val)
elseif t == "table" then
-- Check if object implements the JSON marshaler interface.
if val.MarshalJSON ~= nil and type(val.MarshalJSON) == "function" then
return val:MarshalJSON()
end
-- If not, fall back to array or object handling.
local commonKeyType, commonValueType
for k, v in pairs(val) do
local keyType, valueType = type(k), type(v)
commonKeyType = commonKeyType or keyType
if commonKeyType ~= keyType then
-- Different types detected, abort.
commonKeyType = "mixed"
break
end
commonValueType = commonValueType or valueType
if commonValueType ~= valueType then
-- Different types detected, abort.
commonValueType = "mixed"
break
end
end
-- Decide based on common types.
if commonKeyType == "number" and commonValueType ~= "mixed" then
return lib.MarshalArray(val) -- This will falsely detect sparse integer key maps as arrays. But meh.
elseif commonKeyType == "string" then
return lib.MarshalObject(val) -- This will not detect if there are number keys, which would work with MarshalObject.
elseif commonKeyType == nil and commonValueType == nil then
return "null" -- Fallback in case of empty table. There is no other way than using null, as we don't have type information without table elements.
end
error(string.format("unsupported table type. CommonKeyType = %s. CommonValueType = %s. MetaTable = %s", commonKeyType or "nil", commonValueType or "nil", getmetatable(val) or "nil"))
end
error(string.format("unsupported type %q", t))
end
return lib