ECS2/class/fficlass.lua

--[[
    FFIClass system
    @author : Siapran Candoris
    For LuaJIT's FFI struct-based classes.
]]--

local class = require("class")
local ffi = require("ffi")
local rawget = rawget

local c_id = 0
local function make_C_identifier( )
    local res = "id" .. c_id
    c_id = c_id + 1
    return res
end

local function ffi_make_meta( self )
    local c_id = make_C_identifier()
    ffi.cdef("typedef struct {" .. self.__cdef .. "} " .. c_id ..";")
    self.__ctype = ffi.metatype(c_id, self)
    self.__c_id = c_id
end

local function ffi_new(self, ...)
    if not rawget(self, "__ctype") then
        ffi_make_meta(self)
    end
    local res = self.__ctype()
    if self.init then
        res:init(...)
    end
    return res
end

local function ffi_new_array(self, nb_elem, ...)
    if not rawget(self, "__ctype") then
        ffi_make_meta(self)
    end
    local res = ffi.new(self.__c_id .. "[?]", nb_elem)
    if self.init then
        for i = 0, nb_elem - 1 do
            res[i]:init(...)
        end
    end
    return res
end

local function make_ffi_class(structdef, ...)
    local res = class(...)
    res.new = ffi_new
    res.new_array = ffi_new_array
    res.__cdef = structdef
    res.is_ffi_class = true
    return res
end

return make_ffi_class