FSM DSL in Kotlin

Transcript

1. FSM DSL in Kotlin tomoya0x00 Kotlin Developers Meetup
2. About me tomoya0x00 Twitter, GitHub, Qiita Android, Embedded system, BLE/BT, iOS DeNA Co., Ltd. Automotive Business Unit.
3. Everyone
4. You want to make DSL by yourself?
5. I want to FSM DSL in Kotlin FSM is nite state machine.
6. Why FSM? Avoid confusion caused by multiple ag management Easy to test
7. And, I want to support composite states
8. Example
9. Simple smart lock for bike sharing
10. I am developing a Proof-of-Concept
11. DSL Example val sm = stateMachine(initial = MyState.NotLoaned) { state(MyState.NotLoaned) { edge(MyEvent.PressRental, next = MyState.Lock) } state(MyState.OnLoan, entry = { println("turnOnRentalLed") }, exit = { println("turnOffRentalLed") }) { state(MyState.Lock) { edge(MyEvent.PressReturn, next = MyState.NotLoaned) edge(MyEvent.PressUnLock, next = MyState.UnLock) } state(MyState.UnLock) { edge(MyEvent.PressLock, next = MyState.Lock) } } }
12. Let's run! val next = sm.dispatch(MyEvent.PressRental) assert(next).isEqualTo(MyState.Lock) result: turnOnRentalLed next == MyState.Lock
13. Internal
14. Generate the tree of states DSL Tree of states
15. DSL internal fun stateMachine( initial: BaseState, init: StateMachine.() -> Unit ): StateMachine = StateMachine(initial = initial) .apply(init)
16. Problem
17. Search processing is executed for each dispatch
18. When press return in Lock state Find route to NotLoaned state from Lock state
19. When press return in Lock state Find route to NotLoaned state from Lock state
20. When press return in Lock state Find route to NotLoaned state from Lock state
21. When press return in Lock state Find route to NotLoaned state from Lock state
22. When press return in Lock state Find route to NotLoaned state from Lock state
23. When press return in Lock state Execute entry/exit on route
24. Solution
25. StateMachine.Builder fun stateMachine( initial: BaseState, init: StateMachine.Builder.() -> Unit ): StateMachine = StateMachine.Builder(initial = initial) .apply(init).build()
26. Generate transition map in build() state event actions next NotLoaned PressRental [OnLoan.entry] Lock Lock PressReturn [OnLoan.exit] NotLoaned Lock PressUnLock [] UnLock UnLock PressLock [] Lock
27. But, not implemented yet... to be available soon!
28. Any Idea? Tree search algorithm when creating transition map, if you have any good idea, please let me know!
29. Waiting for your suggestions︕ https://github.com/tomoya0x00/fsm-dsl- kotlin-poc
30. Thank you!