LoginUser suspend fun (compiler generated code) - complete

LoginUserCompiled.java

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
fun loginUser(userId: String?, password: String?, completion: Continuation<Any?>) {

    class LoginUserStateMachine(
        // completion parameter is the callback to the function that called loginUser
        completion: Continuation<Any?>
    ): CoroutineImpl(completion) {
        // objects to store across the suspend function
        var user: User? = null
        var userDb: UserDb? = null

        // Common objects for all CoroutineImpl
        var result: Any? = null
        var label: Int = 0

        // this function calls the loginUser again to trigger the 
        // state machine (label will be already in the next state) and 
        // result will be the result of the previous state's computation
        override fun invokeSuspend(result: Any?) {
            this.result = result
            loginUser(null, null, this)
        }
    }

    val continuation = completion as? LoginUserStateMachine ?: LoginUserStateMachine(completion)

    when(continuation.label) {
        0 -> {
            // Checks for failures
            throwOnFailure(continuation.result)
            // Next time this continuation is called, it should go to state 1
            continuation.label = 1
            // The continuation object is passed to logUserIn to resume 
            // this state machine's execution when it finishes
            userRemoteDataSource.logUserIn(userId!!, password!!, continuation)
        }
        1 -> {
            // Checks for failures
            throwOnFailure(continuation.result)
            // Gets the result of the previous state
            continuation.user = continuation.result as User
            // Next time this continuation is called, it should go to state 2
            continuation.label = 2
            // The continuation object is passed to logUserIn to resume 
            // this state machine's execution when it finishes
            userLocalDataSource.logUserIn(continuation.user, continuation)
        }
        2 -> {
            // Checks for failures
            throwOnFailure(continuation.result)
            // Gets the result of the previous state
            continuation.userDb = continuation.result as UserDb
            // Resumes the execution of the function that called this one
            continuation.cont.resume(continuation.userDb)
        }
        else -> throw IllegalStateException(...)
    }
}