src/core: add an option system with core options that'll be used

sonic-radiance.love/core/init.lua

@@ -27,12 +27,20 @@ local CoreSystem = Object:extend()
 
 local DebugSystem = require "core.debug"
 
+local Options     = require "core.options"
+
 function CoreSystem:new()
-  self.debug = DebugSystem(self)
+  self.debug    = DebugSystem(self)
+  self.options  = Options(self)
 end
 
 function CoreSystem:update(dt)
   self.debug:update(dt)
 end
 
+function CoreSystem:exit()
+  self.options:save()
+  love.event.quit()
+end
+
 return CoreSystem

sonic-radiance.love/core/options.lua

@@ -0,0 +1,96 @@
+-- core/options.lua :: The options loading/saving system. Is used by the other
+-- modules to save their settings.
+
+--[[
+  Copyright © 2019 Kazhnuz
+
+  Permission is hereby granted, free of charge, to any person obtaining a copy of
+  this software and associated documentation files (the "Software"), to deal in
+  the Software without restriction, including without limitation the rights to
+  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+  the Software, and to permit persons to whom the Software is furnished to do so,
+  subject to the following conditions:
+
+  The above copyright notice and this permission notice shall be included in all
+  copies or substantial portions of the Software.
+
+  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+  FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+  COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+  IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+]]
+
+local OptionsManager = Object:extend()
+
+local binser = require "libs.binser"
+
+function OptionsManager:new()
+  -- We begin by creating an empty data table before reading the data.
+  self.data = {}
+  self:read()
+end
+
+function OptionsManager:reset()
+  -- Reset the option to the game defaults.
+  self.data.video = {}
+  self.data.video.crtfilter   = false
+  self.data.video.resolution  = 1
+  self.data.video.border      = true
+  self.data.video.vsync       = false
+  self.data.video.fullscreen  = false
+
+  -- We load the default files
+  self.data.input     = require "datas.input"
+
+  -- TODO: have a way to auto-load a language according to the OS ?
+  self.data.language  = "en"
+
+  self.data.audio = {}
+  self.data.audio.music = 100
+  self.data.audio.sfx   = 100
+end
+
+function OptionsManager:getFile(absolute)
+  local dir = ""
+  if absolute then
+    dir = love.filesystem.getSaveDirectory() .. "/"
+    if not utils.filesystem.exists(dir) then
+      love.filesystem.createDirectory( "" )
+    end
+  end
+
+  local filepath = dir .. "options.data"
+
+  return filepath
+end
+
+function OptionsManager:write()
+  local data = self:getData()
+
+  filepath = self:getFile(true)
+  binser.writeFile(filepath, data)
+end
+
+function OptionsManager:read()
+  filepath = self:getFile(true)
+  if utils.filesystem.exists("options.data") then
+    local loadedDatas = binser.readFile(filepath)
+    print("data file found, loading it")
+    self:setData(loadedDatas[1])
+  else
+    self:reset()
+    print("no data file found, reseting data it")
+  end
+end
+
+function OptionsManager:getData(data)
+  return self.data
+end
+
+function OptionsManager:setData(data)
+  self.data = data
+end
+
+return OptionsManager

sonic-radiance.love/libs/binser.lua

@@ -0,0 +1,687 @@
+-- binser.lua
+
+--[[
+Copyright (c) 2016 Calvin Rose
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+]]
+
+local assert = assert
+local error = error
+local select = select
+local pairs = pairs
+local getmetatable = getmetatable
+local setmetatable = setmetatable
+local tonumber = tonumber
+local type = type
+local loadstring = loadstring or load
+local concat = table.concat
+local char = string.char
+local byte = string.byte
+local format = string.format
+local sub = string.sub
+local dump = string.dump
+local floor = math.floor
+local frexp = math.frexp
+local unpack = unpack or table.unpack
+
+-- Lua 5.3 frexp polyfill
+-- From https://github.com/excessive/cpml/blob/master/modules/utils.lua
+if not frexp then
+    local log, abs, floor = math.log, math.abs, math.floor
+    local log2 = log(2)
+    frexp = function(x)
+        if x == 0 then return 0, 0 end
+        local e = floor(log(abs(x)) / log2 + 1)
+        return x / 2 ^ e, e
+    end
+end
+
+-- NIL = 202
+-- FLOAT = 203
+-- TRUE = 204
+-- FALSE = 205
+-- STRING = 206
+-- TABLE = 207
+-- REFERENCE = 208
+-- CONSTRUCTOR = 209
+-- FUNCTION = 210
+-- RESOURCE = 211
+-- INT64 = 212
+
+local mts = {}
+local ids = {}
+local serializers = {}
+local deserializers = {}
+local resources = {}
+local resources_by_name = {}
+
+local function pack(...)
+    return {...}, select("#", ...)
+end
+
+local function not_array_index(x, len)
+    return type(x) ~= "number" or x < 1 or x > len or x ~= floor(x)
+end
+
+local function type_check(x, tp, name)
+    assert(type(x) == tp,
+        format("Expected parameter %q to be of type %q.", name, tp))
+end
+
+local bigIntSupport = false
+local isInteger
+if math.type then -- Detect Lua 5.3
+    local mtype = math.type
+    bigIntSupport = loadstring[[
+    local char = string.char
+    return function(n)
+        local nn = n < 0 and -(n + 1) or n
+        local b1 = nn // 0x100000000000000
+        local b2 = nn // 0x1000000000000 % 0x100
+        local b3 = nn // 0x10000000000 % 0x100
+        local b4 = nn // 0x100000000 % 0x100
+        local b5 = nn // 0x1000000 % 0x100
+        local b6 = nn // 0x10000 % 0x100
+        local b7 = nn // 0x100 % 0x100
+        local b8 = nn % 0x100
+        if n < 0 then
+            b1, b2, b3, b4 = 0xFF - b1, 0xFF - b2, 0xFF - b3, 0xFF - b4
+            b5, b6, b7, b8 = 0xFF - b5, 0xFF - b6, 0xFF - b7, 0xFF - b8
+        end
+        return char(212, b1, b2, b3, b4, b5, b6, b7, b8)
+    end]]()
+    isInteger = function(x)
+        return mtype(x) == 'integer'
+    end
+else
+    isInteger = function(x)
+        return floor(x) == x
+    end
+end
+
+-- Copyright (C) 2012-2015 Francois Perrad.
+-- number serialization code modified from https://github.com/fperrad/lua-MessagePack
+-- Encode a number as a big-endian ieee-754 double, big-endian signed 64 bit integer, or a small integer
+local function number_to_str(n)
+    if isInteger(n) then -- int
+        if n <= 100 and n >= -27 then -- 1 byte, 7 bits of data
+            return char(n + 27)
+        elseif n <= 8191 and n >= -8192 then -- 2 bytes, 14 bits of data
+            n = n + 8192
+            return char(128 + (floor(n / 0x100) % 0x100), n % 0x100)
+        elseif bigIntSupport then
+            return bigIntSupport(n)
+        end
+    end
+    local sign = 0
+    if n < 0.0 then
+        sign = 0x80
+        n = -n
+    end
+    local m, e = frexp(n) -- mantissa, exponent
+    if m ~= m then
+        return char(203, 0xFF, 0xF8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
+    elseif m == 1/0 then
+        if sign == 0 then
+            return char(203, 0x7F, 0xF0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
+        else
+            return char(203, 0xFF, 0xF0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
+        end
+    end
+    e = e + 0x3FE
+    if e < 1 then -- denormalized numbers
+        m = m * 2 ^ (52 + e)
+        e = 0
+    else
+        m = (m * 2 - 1) * 2 ^ 52
+    end
+    return char(203,
+                sign + floor(e / 0x10),
+                (e % 0x10) * 0x10 + floor(m / 0x1000000000000),
+                floor(m / 0x10000000000) % 0x100,
+                floor(m / 0x100000000) % 0x100,
+                floor(m / 0x1000000) % 0x100,
+                floor(m / 0x10000) % 0x100,
+                floor(m / 0x100) % 0x100,
+                m % 0x100)
+end
+
+-- Copyright (C) 2012-2015 Francois Perrad.
+-- number deserialization code also modified from https://github.com/fperrad/lua-MessagePack
+local function number_from_str(str, index)
+    local b = byte(str, index)
+    if b < 128 then
+        return b - 27, index + 1
+    elseif b < 192 then
+        return byte(str, index + 1) + 0x100 * (b - 128) - 8192, index + 2
+    end
+    local b1, b2, b3, b4, b5, b6, b7, b8 = byte(str, index + 1, index + 8)
+    if b == 212 then
+        local flip = b1 >= 128
+        if flip then -- negative
+            b1, b2, b3, b4 = 0xFF - b1, 0xFF - b2, 0xFF - b3, 0xFF - b4
+            b5, b6, b7, b8 = 0xFF - b5, 0xFF - b6, 0xFF - b7, 0xFF - b8
+        end
+        local n = ((((((b1 * 0x100 + b2) * 0x100 + b3) * 0x100 + b4) * 0x100 + b5) * 0x100 + b6) * 0x100 + b7) * 0x100 + b8
+        if flip then
+            return (-n) - 1, index + 9
+        else
+            return n, index + 9
+        end
+    end
+    local sign = b1 > 0x7F and -1 or 1
+    local e = (b1 % 0x80) * 0x10 + floor(b2 / 0x10)
+    local m = ((((((b2 % 0x10) * 0x100 + b3) * 0x100 + b4) * 0x100 + b5) * 0x100 + b6) * 0x100 + b7) * 0x100 + b8
+    local n
+    if e == 0 then
+        if m == 0 then
+            n = sign * 0.0
+        else
+            n = sign * (m / 2 ^ 52) * 2 ^ -1022
+        end
+    elseif e == 0x7FF then
+        if m == 0 then
+            n = sign * (1/0)
+        else
+            n = 0.0/0.0
+        end
+    else
+        n = sign * (1.0 + m / 2 ^ 52) * 2 ^ (e - 0x3FF)
+    end
+    return n, index + 9
+end
+
+local types = {}
+
+types["nil"] = function(x, visited, accum)
+    accum[#accum + 1] = "\202"
+end
+
+function types.number(x, visited, accum)
+    accum[#accum + 1] = number_to_str(x)
+end
+
+function types.boolean(x, visited, accum)
+    accum[#accum + 1] = x and "\204" or "\205"
+end
+
+function types.string(x, visited, accum)
+    local alen = #accum
+    if visited[x] then
+        accum[alen + 1] = "\208"
+        accum[alen + 2] = number_to_str(visited[x])
+    else
+        visited[x] = visited.next
+        visited.next =  visited.next + 1
+        accum[alen + 1] = "\206"
+        accum[alen + 2] = number_to_str(#x)
+        accum[alen + 3] = x
+    end
+end
+
+local function check_custom_type(x, visited, accum)
+    local res = resources[x]
+    if res then
+        accum[#accum + 1] = "\211"
+        types[type(res)](res, visited, accum)
+        return true
+    end
+    local mt = getmetatable(x)
+    local id = mt and ids[mt]
+    if id then
+        if x == visited.temp then
+            error("Infinite loop in constructor.")
+        end
+        visited.temp = x
+        accum[#accum + 1] = "\209"
+        types[type(id)](id, visited, accum)
+        local args, len = pack(serializers[id](x))
+        accum[#accum + 1] = number_to_str(len)
+        for i = 1, len do
+            local arg = args[i]
+            types[type(arg)](arg, visited, accum)
+        end
+        visited[x] = visited.next
+        visited.next = visited.next + 1
+        return true
+    end
+end
+
+function types.userdata(x, visited, accum)
+    if visited[x] then
+        accum[#accum + 1] = "\208"
+        accum[#accum + 1] = number_to_str(visited[x])
+    else
+        if check_custom_type(x, visited, accum) then return end
+        error("Cannot serialize this userdata.")
+    end
+end
+
+function types.table(x, visited, accum)
+    if visited[x] then
+        accum[#accum + 1] = "\208"
+        accum[#accum + 1] = number_to_str(visited[x])
+    else
+        if check_custom_type(x, visited, accum) then return end
+        visited[x] = visited.next
+        visited.next =  visited.next + 1
+        local xlen = #x
+        accum[#accum + 1] = "\207"
+        accum[#accum + 1] = number_to_str(xlen)
+        for i = 1, xlen do
+            local v = x[i]
+            types[type(v)](v, visited, accum)
+        end
+        local key_count = 0
+        for k in pairs(x) do
+            if not_array_index(k, xlen) then
+                key_count = key_count + 1
+            end
+        end
+        accum[#accum + 1] = number_to_str(key_count)
+        for k, v in pairs(x) do
+            if not_array_index(k, xlen) then
+                types[type(k)](k, visited, accum)
+                types[type(v)](v, visited, accum)
+            end
+        end
+    end
+end
+
+types["function"] = function(x, visited, accum)
+    if visited[x] then
+        accum[#accum + 1] = "\208"
+        accum[#accum + 1] = number_to_str(visited[x])
+    else
+        if check_custom_type(x, visited, accum) then return end
+        visited[x] = visited.next
+        visited.next =  visited.next + 1
+        local str = dump(x)
+        accum[#accum + 1] = "\210"
+        accum[#accum + 1] = number_to_str(#str)
+        accum[#accum + 1] = str
+    end
+end
+
+types.cdata = function(x, visited, accum)
+    if visited[x] then
+        accum[#accum + 1] = "\208"
+        accum[#accum + 1] = number_to_str(visited[x])
+    else
+        if check_custom_type(x, visited, #accum) then return end
+        error("Cannot serialize this cdata.")
+    end
+end
+
+types.thread = function() error("Cannot serialize threads.") end
+
+local function deserialize_value(str, index, visited)
+    local t = byte(str, index)
+    if not t then return end
+    if t < 128 then
+        return t - 27, index + 1
+    elseif t < 192 then
+        return byte(str, index + 1) + 0x100 * (t - 128) - 8192, index + 2
+    elseif t == 202 then
+        return nil, index + 1
+    elseif t == 203 then
+        return number_from_str(str, index)
+    elseif t == 204 then
+        return true, index + 1
+    elseif t == 205 then
+        return false, index + 1
+    elseif t == 206 then
+        local length, dataindex = deserialize_value(str, index + 1, visited)
+        local nextindex = dataindex + length
+        local substr = sub(str, dataindex, nextindex - 1)
+        visited[#visited + 1] = substr
+        return substr, nextindex
+    elseif t == 207 then
+        local count, nextindex = number_from_str(str, index + 1)
+        local ret = {}
+        visited[#visited + 1] = ret
+        for i = 1, count do
+            ret[i], nextindex = deserialize_value(str, nextindex, visited)
+        end
+        count, nextindex = number_from_str(str, nextindex)
+        for i = 1, count do
+            local k, v
+            k, nextindex = deserialize_value(str, nextindex, visited)
+            v, nextindex = deserialize_value(str, nextindex, visited)
+            ret[k] = v
+        end
+        return ret, nextindex
+    elseif t == 208 then
+        local ref, nextindex = number_from_str(str, index + 1)
+        return visited[ref], nextindex
+    elseif t == 209 then
+        local count
+        local name, nextindex = deserialize_value(str, index + 1, visited)
+        count, nextindex = number_from_str(str, nextindex)
+        local args = {}
+        for i = 1, count do
+            args[i], nextindex = deserialize_value(str, nextindex, visited)
+        end
+        local ret = deserializers[name](unpack(args))
+        visited[#visited + 1] = ret
+        return ret, nextindex
+    elseif t == 210 then
+        local length, dataindex = deserialize_value(str, index + 1, visited)
+        local nextindex = dataindex + length
+        local ret = loadstring(sub(str, dataindex, nextindex - 1))
+        visited[#visited + 1] = ret
+        return ret, nextindex
+    elseif t == 211 then
+        local res, nextindex = deserialize_value(str, index + 1, visited)
+        return resources_by_name[res], nextindex
+    elseif t == 212 then
+        return number_from_str(str, index)
+    else
+        error("Could not deserialize type byte " .. t .. ".")
+    end
+end
+
+local function serialize(...)
+    local visited = {next = 1}
+    local accum = {}
+    for i = 1, select("#", ...) do
+        local x = select(i, ...)
+        types[type(x)](x, visited, accum)
+    end
+    return concat(accum)
+end
+
+local function make_file_writer(file)
+    return setmetatable({}, {
+        __newindex = function(_, _, v)
+            file:write(v)
+        end
+    })
+end
+
+local function serialize_to_file(path, mode, ...)
+    local file, err = io.open(path, mode)
+    assert(file, err)
+    local visited = {next = 1}
+    local accum = make_file_writer(file)
+    for i = 1, select("#", ...) do
+        local x = select(i, ...)
+        types[type(x)](x, visited, accum)
+    end
+    -- flush the writer
+    file:flush()
+    file:close()
+end
+
+local function writeFile(path, ...)
+    return serialize_to_file(path, "wb", ...)
+end
+
+local function appendFile(path, ...)
+    return serialize_to_file(path, "ab", ...)
+end
+
+local function deserialize(str, index)
+    assert(type(str) == "string", "Expected string to deserialize.")
+    local vals = {}
+    index = index or 1
+    local visited = {}
+    local len = 0
+    local val
+    while index do
+        val, index = deserialize_value(str, index, visited)
+        if index then
+            len = len + 1
+            vals[len] = val
+        end
+    end
+    return vals, len
+end
+
+local function deserializeN(str, n, index)
+    assert(type(str) == "string", "Expected string to deserialize.")
+    n = n or 1
+    assert(type(n) == "number", "Expected a number for parameter n.")
+    assert(n > 0 and floor(n) == n, "N must be a poitive integer.")
+    local vals = {}
+    index = index or 1
+    local visited = {}
+    local len = 0
+    local val
+    while index and len < n do
+        val, index = deserialize_value(str, index, visited)
+        if index then
+            len = len + 1
+            vals[len] = val
+        end
+    end
+    vals[len + 1] = index
+    return unpack(vals, 1, n + 1)
+end
+
+local function readFile(path)
+    local file, err = io.open(path, "rb")
+    assert(file, err)
+    local str = file:read("*all")
+    file:close()
+    return deserialize(str)
+end
+
+local function default_deserialize(metatable)
+    return function(...)
+        local ret = {}
+        for i = 1, select("#", ...), 2 do
+            ret[select(i, ...)] = select(i + 1, ...)
+        end
+        return setmetatable(ret, metatable)
+    end
+end
+
+local function default_serialize(x)
+    assert(type(x) == "table",
+        "Default serialization for custom types only works for tables.")
+    local args = {}
+    local len = 0
+    for k, v in pairs(x) do
+        args[len + 1], args[len + 2] = k, v
+        len = len + 2
+    end
+    return unpack(args, 1, len)
+end
+
+-- Templating
+
+local function normalize_template(template)
+    local ret = {}
+    for i = 1, #template do
+        ret[i] = template[i]
+    end
+    local non_array_part = {}
+    -- The non-array part of the template (nested templates) have to be deterministic, so they are sorted.
+    -- This means that inherently non deterministicly sortable keys (tables, functions) should NOT be used
+    -- in templates. Looking for way around this.
+    for k in pairs(template) do
+        if not_array_index(k, #template) then
+            non_array_part[#non_array_part + 1] = k
+        end
+    end
+    table.sort(non_array_part)
+    for i = 1, #non_array_part do
+        local name = non_array_part[i]
+        ret[#ret + 1] = {name, normalize_template(template[name])}
+    end
+    return ret
+end
+
+local function templatepart_serialize(part, argaccum, x, len)
+    local extras = {}
+    local extracount = 0
+    for k, v in pairs(x) do
+        extras[k] = v
+        extracount = extracount + 1
+    end
+    for i = 1, #part do
+        extracount = extracount - 1
+        if type(part[i]) == "table" then
+            extras[part[i][1]] = nil
+            len = templatepart_serialize(part[i][2], argaccum, x[part[i][1]], len)
+        else
+            extras[part[i]] = nil
+            len = len + 1
+            argaccum[len] = x[part[i]]
+        end
+    end
+    if extracount > 0 then
+        argaccum[len + 1] = extras
+    else
+        argaccum[len + 1] = nil
+    end
+    return len + 1
+end
+
+local function templatepart_deserialize(ret, part, values, vindex)
+    for i = 1, #part do
+        local name = part[i]
+        if type(name) == "table" then
+            local newret = {}
+            ret[name[1]] = newret
+            vindex = templatepart_deserialize(newret, name[2], values, vindex)
+        else
+            ret[name] = values[vindex]
+            vindex = vindex + 1
+        end
+    end
+    local extras = values[vindex]
+    if extras then
+        for k, v in pairs(extras) do
+            ret[k] = v
+        end
+    end
+    return vindex + 1
+end
+
+local function template_serializer_and_deserializer(metatable, template)
+    return function(x)
+        argaccum = {}
+        local len = templatepart_serialize(template, argaccum, x, 0)
+        return unpack(argaccum, 1, len)
+    end, function(...)
+        local ret = {}
+        local len = select("#", ...)
+        local args = {...}
+        templatepart_deserialize(ret, template, args, 1)
+        return setmetatable(ret, metatable)
+    end
+end
+
+local function register(metatable, name, serialize, deserialize)
+    name = name or metatable.name
+    serialize = serialize or metatable._serialize
+    deserialize = deserialize or metatable._deserialize
+    if not serialize then
+        if metatable._template then
+            local t = normalize_template(metatable._template)
+            serialize, deserialize = template_serializer_and_deserializer(metatable, t)
+        elseif not deserialize then
+            serialize = default_serialize
+            deserialize = default_deserialize(metatable)
+        else
+            serialize = metatable
+        end
+    end
+    type_check(metatable, "table", "metatable")
+    type_check(name, "string", "name")
+    type_check(serialize, "function", "serialize")
+    type_check(deserialize, "function", "deserialize")
+    assert(not ids[metatable], "Metatable already registered.")
+    assert(not mts[name], ("Name %q already registered."):format(name))
+    mts[name] = metatable
+    ids[metatable] = name
+    serializers[name] = serialize
+    deserializers[name] = deserialize
+    return metatable
+end
+
+local function unregister(item)
+    local name, metatable
+    if type(item) == "string" then -- assume name
+        name, metatable = item, mts[item]
+    else -- assume metatable
+        name, metatable = ids[item], item
+    end
+    type_check(name, "string", "name")
+    type_check(metatable, "table", "metatable")
+    mts[name] = nil
+    ids[metatable] = nil
+    serializers[name] = nil
+    deserializers[name] = nil
+    return metatable
+end
+
+local function registerClass(class, name)
+    name = name or class.name
+    if class.__instanceDict then -- middleclass
+        register(class.__instanceDict, name)
+    else -- assume 30log or similar library
+        register(class, name)
+    end
+    return class
+end
+
+local function registerResource(resource, name)
+    type_check(name, "string", "name")
+    assert(not resources[resource],
+        "Resource already registered.")
+    assert(not resources_by_name[name],
+        format("Resource %q already exists.", name))
+    resources_by_name[name] = resource
+    resources[resource] = name
+    return resource
+end
+
+local function unregisterResource(name)
+    type_check(name, "string", "name")
+    assert(resources_by_name[name], format("Resource %q does not exist.", name))
+    local resource = resources_by_name[name]
+    resources_by_name[name] = nil
+    resources[resource] = nil
+    return resource
+end
+
+return {
+    -- aliases
+    s = serialize,
+    d = deserialize,
+    dn = deserializeN,
+    r = readFile,
+    w = writeFile,
+    a = appendFile,
+
+    serialize = serialize,
+    deserialize = deserialize,
+    deserializeN = deserializeN,
+    readFile = readFile,
+    writeFile = writeFile,
+    appendFile = appendFile,
+    register = register,
+    unregister = unregister,
+    registerResource = registerResource,
+    unregisterResource = unregisterResource,
+    registerClass = registerClass
+}