Transitions between functions when the value passed to each decrements to zero

bitwise_function_pointer_swap.swift

import Foundation

typealias PredicateFunction = (UInt) -> UInt
typealias PredicateFunctionPointer = UnsafeMutablePointer<PredicateFunction>

let swapPointers: () -> Void = {
	var funcA: PredicateFunction = { predicate in
		print("funcA returned", terminator: " ")
		return predicate
	}

	var funcB: PredicateFunction = { predicate in
		print("funcB returned", terminator: " ")
		return predicate
	}

	var current: PredicateFunctionPointer = UnsafeMutablePointer(&funcA)
	var swap: PredicateFunctionPointer = UnsafeMutablePointer(&funcB)

	print("Invoked current(11) and", terminator: " ")
	print(current.pointee(11))
	print("Swapped current with swap and then ", terminator: "")

	(current, swap) = (swap, current)

	print("invoked current again (with a value of 24):", terminator: " ")
	print(current.pointee(24))
}

swapPointers()