RequestFactoryAdapter.kt

private abstract class RequestFactoryAdapter<T> {

  lateinit var paginator: Paginator<T>

  abstract fun loadPage(page: Int)

  protected fun onSuccess(data: List<T>) {
    paginator.currentState.newData(data)
  }

  protected fun onError(error: Throwable) {
    Timber.e("strange error")
    Timber.e(error)
    paginator.currentState.fail(error)
  }
}

RxJava2Adapter.kt

private class RxJava2Adapter<T>(
    val requestFactory: (Int) -> io.reactivex.Single<List<T>>
) : RequestFactoryAdapter<T>() {

  var disposable: Disposable? = null

  override fun loadPage(page: Int) {
    disposable?.dispose()
    disposable = requestFactory.invoke(page)
        .subscribe(
            { onSuccess(it) },
            { onError(it) }
        )
  }
}

RxJavaAdapter.kt

private class RxJavaAdapter<T>(
    val requestFactory: (Int) -> Single<List<T>>
) : RequestFactoryAdapter<T>() {

  var subscription: Subscription? = null

  override fun loadPage(page: Int) {
    subscription?.unsubscribe()
    subscription = requestFactory.invoke(page)
        .subscribe(
            { onSuccess(it) },
            { onError(it) }
        )
  }
}