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@ue-too/being / index / TemplateState

抽象 クラス: TemplateState<EventPayloadMapping, Context, States, EventOutputMapping> ​

定義: interface.ts:973

Abstract base class for state machine states.

Remarks ​

This abstract class provides the foundation for implementing individual states in a state machine. Each state defines how it responds to events through the eventReactions object.

Key Concepts ​

  • Event Reactions: Define handlers for events this state cares about. Unhandled events are ignored.
  • Guards: Conditional logic that determines which state to transition to based on context
  • Lifecycle Hooks: uponEnter and beforeExit callbacks for state transition side effects
  • Selective Handling: Only define reactions for events relevant to this state

Implementation Pattern ​

  1. Extend this class for each state in your state machine
  2. Implement the eventReactions property with handlers for relevant events
  3. Optionally override uponEnter and beforeExit for lifecycle logic
  4. Optionally define guards and eventGuards for conditional transitions

Examples ​

Simple state implementation

typescript
class IdleState extends TemplateState<MyEvents, MyContext, MyStates> {
  eventReactions = {
    start: {
      action: (context, event) => {
        console.log('Starting...');
        context.startTime = Date.now();
      },
      defaultTargetState: "ACTIVE"
    },
    reset: {
      action: (context, event) => {
        context.counter = 0;
      }
      // No state transition - stays in IDLE
    }
  };

  uponEnter(context, stateMachine, fromState) {
    console.log(`Entered IDLE from ${fromState}`);
  }
}

State with guards for conditional transitions

typescript
class PaymentState extends TemplateState<Events, VendingContext, States> {
  guards = {
    hasEnoughMoney: (context) => context.balance >= context.itemPrice,
    needsChange: (context) => context.balance > context.itemPrice
  };

  eventReactions = {
    selectItem: {
      action: (context, event) => {
        context.selectedItem = event.itemId;
        context.itemPrice = getPrice(event.itemId);
      },
      defaultTargetState: "IDLE" // Fallback if no guard matches
    }
  };

  eventGuards = {
    selectItem: [
      { guard: 'hasEnoughMoney', target: 'DISPENSING' },
      // If hasEnoughMoney is false, uses defaultTargetState (IDLE)
    ]
  };
}

参照 ​

によって拡張された ​

型パラメーター ​

EventPayloadMapping ​

EventPayloadMapping

Object mapping event names to their payload types

Context ​

Context extends BaseContext

Context type shared across all states

States ​

States extends string = "IDLE"

Union of all possible state names (string literals)

EventOutputMapping ​

EventOutputMapping extends Partial<Record<keyof EventPayloadMapping, unknown>> = DefaultOutputMapping<EventPayloadMapping>

Optional mapping of events to their output types

実装 ​

  • State<EventPayloadMapping, Context, States, EventOutputMapping>

コンストラクター ​

コンストラクター ​

new TemplateState<EventPayloadMapping, Context, States, EventOutputMapping>(): TemplateState<EventPayloadMapping, Context, States, EventOutputMapping>

戻り値 ​

TemplateState<EventPayloadMapping, Context, States, EventOutputMapping>

プロパティ ​

_defer ​

protected _defer: Defer<Context, EventPayloadMapping, States, EventOutputMapping> | undefined = undefined

定義: interface.ts:1007

_delay ​

protected _delay: Delay<Context, EventPayloadMapping, States, EventOutputMapping> | undefined = undefined

定義: interface.ts:1003

_eventGuards ​

protected _eventGuards: Partial<EventGuards<EventPayloadMapping, States, Context, Guard<Context>>>

定義: interface.ts:993

_eventPreconditions ​

protected _eventPreconditions: Partial<EventPreconditions<EventPayloadMapping, Context, Guard<Context>>>

定義: interface.ts:998

_eventReactions ​

protected _eventReactions: EventReactions<EventPayloadMapping, Context, States, EventOutputMapping>

定義: interface.ts:981

_guards ​

protected _guards: Guard<Context>

定義: interface.ts:992

アクセッサー ​

delay ​

署名を取得する ​

get delay(): Delay<Context, EventPayloadMapping, States, EventOutputMapping> | undefined

定義: interface.ts:1042

戻り値 ​

Delay<Context, EventPayloadMapping, States, EventOutputMapping> | undefined

の実装 ​

State.delay

eventGuards ​

署名を取得する ​

get eventGuards(): Partial<EventGuards<EventPayloadMapping, States, Context, Guard<Context>>>

定義: interface.ts:1021

戻り値 ​

Partial<EventGuards<EventPayloadMapping, States, Context, Guard<Context>>>

の実装 ​

State.eventGuards

eventPreconditions ​

署名を取得する ​

get eventPreconditions(): Partial<EventPreconditions<EventPayloadMapping, Context, Guard<Context>>>

定義: interface.ts:1027

Pre-action vetoes: named guards that must all pass before this state handles an event. Optional so existing State implementations remain valid; TemplateState always provides it.

戻り値 ​

Partial<EventPreconditions<EventPayloadMapping, Context, Guard<Context>>>

Pre-action vetoes: named guards that must all pass before this state handles an event. Optional so existing State implementations remain valid; TemplateState always provides it.

の実装 ​

State.eventPreconditions

eventReactions ​

署名を取得する ​

get eventReactions(): EventReactions<EventPayloadMapping, Context, States, EventOutputMapping>

定義: interface.ts:1033

戻り値 ​

EventReactions<EventPayloadMapping, Context, States, EventOutputMapping>

の実装 ​

State.eventReactions

guards ​

署名を取得する ​

get guards(): Guard<Context>

定義: interface.ts:1017

戻り値 ​

Guard<Context>

の実装 ​

State.guards

handlingEvents ​

署名を取得する ​

get handlingEvents(): keyof EventPayloadMapping[]

定義: interface.ts:1011

戻り値 ​

keyof EventPayloadMapping[]

メソッド ​

beforeExit() ​

beforeExit(context, stateMachine, to): void

定義: interface.ts:1061

パラメータ ​

context ​

Context

stateMachine ​

StateMachine<EventPayloadMapping, Context, States, EventOutputMapping>

to ​

"TERMINAL" | States

戻り値 ​

void

の実装 ​

State.beforeExit

handles() ​

handles<K>(args, context, stateMachine): EventResult<States, K extends keyof EventOutputMapping ? EventOutputMapping[K<K>] : void>

定義: interface.ts:1074

型パラメーター ​

K ​

K extends string | number | symbol

パラメータ ​

args ​

EventArgs<EventPayloadMapping, K>

context ​

Context

stateMachine ​

StateMachine<EventPayloadMapping, Context, States, EventOutputMapping>

戻り値 ​

EventResult<States, K extends keyof EventOutputMapping ? EventOutputMapping[K<K>] : void>

の実装 ​

State.handles

uponEnter() ​

uponEnter(context, stateMachine, from): void

定義: interface.ts:1048

パラメータ ​

context ​

Context

stateMachine ​

StateMachine<EventPayloadMapping, Context, States, EventOutputMapping>

from ​

"INITIAL" | States

戻り値 ​

void

の実装 ​

State.uponEnter