// Copyright © 2018 ChaiShushan <chaishushan{AT}gmail.com>.
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/

package main

import (
	"unsafe"
)

type FunTwiceClosure struct {
	F uintptr
	X int
}

func NewTwiceFunClosure(x int) func() int {
	var p = &FunTwiceClosure{
		F: asmFunTwiceClosureAddr(),
		X: x,
	}
	return ptrToFunc(unsafe.Pointer(p))
}

func ptrToFunc(p unsafe.Pointer) func() int

func asmFunTwiceClosureAddr() uintptr
func asmFunTwiceClosureBody() int

func main() {
	fnTwice := NewTwiceFunClosure(1)

	println(fnTwice()) // 1*2 => 2
	println(fnTwice()) // 2*2 => 4
	println(fnTwice()) // 4*2 => 8
}