A basic task queue

TaskQueue.swift

actor TaskQueue {
    private var queuedOperations: [() async -> Void] = [] // should probably be an actual `Queue`/`Deque` type
    private var currentTask: Task<Void, Never>?
    private var iterationTask: Task<Void, Never>?

    init() {}

    func addOperation(_ operation: @escaping () async -> Void) {
        if currentTask == nil {
            currentTask = Task {
                await operation()
                self.currentTask = nil
            }
        } else {
            queuedOperations.append(operation)
            if iterationTask == nil {
                iterationTask = Task {
                    await self.iterateThroughOperations()
                    self.iterationTask = nil
                }
            }
        }
    }

    private func iterateThroughOperations() async {
        while !queuedOperations.isEmpty {
            if let currentTask = currentTask {
                await currentTask.value
            }
            let next = queuedOperations.removeFirst()
            currentTask = Task {
                await next()
                self.currentTask = nil
            }
        }
    }
}