Class StateMachineWithEvents<V>

A state machine that fires events when state changes.

const transitions = StateMachine.fromList(`a`, `b`, `c`);
const m = new StateMachineWithEvents(transitions);
m.addEventListener(`change`, event => {
 console.log(`${event.priorState} -> ${event.newState}`);
});
m.addEventListener(`stop`, event => {
 console.log(`State machine has reached final state`);
});

Type Parameters

V extends Transitions

Hierarchy (View Summary)

SimpleEventEmitter<StateMachineEventMap<V>>
- StateMachineWithEvents

Index

Accessors

changedAt

get changedAt(): number
Returns timestamp when state was last changed. See also elapsed

Returns number
- Defined in flow/src/state-machine/with-events.ts:179

elapsed

get elapsed(): number
Returns milliseconds elapsed since last state change. See also changedAt

Returns number
- Defined in flow/src/state-machine/with-events.ts:187

isDisposed

get isDisposed(): boolean
Returns boolean
Inherited from SimpleEventEmitter.isDisposed
- Defined in events/src/simple-event-emitter.ts:13

isDone

get isDone(): boolean
Returns true if state machine is in its final state

Returns boolean
- Defined in flow/src/state-machine/with-events.ts:116

state

get state(): string
Returns string
- Defined in flow/src/state-machine/with-events.ts:171
set state(newState: StateNames<V>): void
Gets or sets state. Throws an error if an invalid transition is attempted. Use isValid() to check validity without changing.

If newState is the same as current state, the request is ignored silently.
Parameters
- newState: StateNames<V>
Returns void
- Defined in flow/src/state-machine/with-events.ts:154

statesDefined

get statesDefined(): readonly StateNames<V>[]
Return a list of all defined states

Returns readonly StateNames<V>[]
- Defined in flow/src/state-machine/with-events.ts:94

statesPossible

get statesPossible(): readonly (null | StateNames<V>)[]
Return a list of possible states from current state.

If list is empty, no states are possible. Otherwise lists possible states, including 'null' for terminal

Returns readonly (null | StateNames<V>)[]
- Defined in flow/src/state-machine/with-events.ts:87

Constructors

constructor

new StateMachineWithEvents<V extends Transitions>(
m: V,
opts?: StateMachineWithEventsOptions<V>,
): StateMachineWithEvents<V>
Create a state machine with initial state, description and options
Type Parameters
- V extends Transitions
Parameters
- m: V
  Machine description
- opts: StateMachineWithEventsOptions<V> = {}
  Options for machine (defaults to {debug:false})
Returns StateMachineWithEvents<V>
Overrides SimpleEventEmitter.constructor
- Defined in flow/src/state-machine/with-events.ts:55

Methods

addEventListener

addEventListener<K extends keyof StateMachineEventMap<V>>(
    name: K,
    listener: (
        event: StateMachineEventMap<V>[K],
        sender: SimpleEventEmitter<StateMachineEventMap<V>>,
    ) => void,
): void
Adds event listener.
Type Parameters
- K extends keyof StateMachineEventMap<V>
  Events
Parameters
- name: K
  Event name
- listener: (
  event: StateMachineEventMap<V>[K],
  sender: SimpleEventEmitter<StateMachineEventMap<V>>,
  ) => void
  Event handler
Returns void
Throws
Error if emitter is disposed
Inherited from SimpleEventEmitter.addEventListener
- Defined in events/src/simple-event-emitter.ts:39

dispose

dispose(): void
Returns void
Inherited from SimpleEventEmitter.dispose
- Defined in events/src/simple-event-emitter.ts:8

`Protected`fireEvent

fireEvent<K extends keyof StateMachineEventMap<V>>(
type: K,
args: StateMachineEventMap<V>[K],
): void
Fire event
Type Parameters
- K extends keyof StateMachineEventMap<V>
Parameters
- type: K
  Type of event
- args: StateMachineEventMap<V>[K]
  Arguments for event
Returns void
Inherited from SimpleEventEmitter.fireEvent
- Defined in events/src/simple-event-emitter.ts:23

isValid

isValid(newState: StateNames<V>): boolean
Returns true if newState is valid transition from current state. Use validateTransition if you want an explanation for the false results.
Parameters
- newState: StateNames<V>
Returns boolean
- Defined in flow/src/state-machine/with-events.ts:144

next(): null | string
Moves to the next state if possible. If multiple states are possible, it will use the first. If machine is finalised, no error is thrown and null is returned.

Returns null | string
Returns new state, or null if machine is finalised
- Defined in flow/src/state-machine/with-events.ts:104

removeEventListener

removeEventListener<K extends keyof StateMachineEventMap<V>>(
    type: K,
    listener: (
        event: StateMachineEventMap<V>[K],
        sender: SimpleEventEmitter<StateMachineEventMap<V>>,
    ) => void,
): void
Remove event listener
Type Parameters
- K extends keyof StateMachineEventMap<V>
Parameters
- type: K
- listener: (
  event: StateMachineEventMap<V>[K],
  sender: SimpleEventEmitter<StateMachineEventMap<V>>,
  ) => void
Returns void
Inherited from SimpleEventEmitter.removeEventListener
- Defined in events/src/simple-event-emitter.ts:55

reset

reset(): void
Resets machine to initial state

Returns void
- Defined in flow/src/state-machine/with-events.ts:123

validateTransition

validateTransition(newState: StateNames<V>): void
Throws if it's not valid to transition to newState
Parameters
- newState: StateNames<V>
Returns void
- Defined in flow/src/state-machine/with-events.ts:134

Class StateMachineWithEvents<V>

Type Parameters

Hierarchy (View Summary)

Index

Accessors

Constructors

Methods

Accessors

changedAt

Returns number

elapsed

Returns number

isDisposed

Returns boolean

isDone

Returns boolean

state

Returns string

Parameters

Returns void

statesDefined

Returns readonly StateNames<V>[]

statesPossible

Returns readonly (null | StateNames<V>)[]

Constructors

constructor

Type Parameters

Parameters

Returns StateMachineWithEvents<V>

Methods

addEventListener

Type Parameters

Parameters

Returns void

Throws

dispose

Returns void

ProtectedfireEvent

Type Parameters

Parameters

Returns void

isValid

Parameters

Returns boolean

next

Returns null | string

removeEventListener

Type Parameters

Parameters

Returns void

reset

Returns void

validateTransition

Parameters

Returns void

Settings

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`Protected`fireEvent