@Includes / @Excludes

State guard decorators that restrict method calls to specific states.

@Includes

function Includes(...states: string[]): MethodDecorator

Only allows the call when the current state is in states, otherwise throws FSMError.

class Player extends FSM {
  @Includes('playing')
  pause() {
    // only callable in the playing state
  }
}

Error message:

{className} {action} failed: current state {state} not in {states}

this.state.toString() is used for comparison (so intermediate states’ toString() participates).

function Excludes(...states: string[]): MethodDecorator

Disallows the call when the current state is in states.

class Player extends FSM {
  @Excludes('disabled')
  play() {
    // callable in any state except disabled
  }
}

@Includes('playing', 'buffering')
pause() {}

@Excludes('disabled', 'errored')
play() {}

Decorators stack, applied bottom-up:

@Includes('idle')              // outer: validate first
@ChangeState('idle', 'done')   // inner: then transition
async fetch() {}

Usually you’ll use them alone — @ChangeState already includes from validation.