StateMachine

v0.0.8tested

Simple, performant, and type-safe finite state machine

Signature

class StateMachine<States extends string = string, Events extends string = string, Context = undefined> extends BaseStateMachine<States, Events, Context, SyncStateNodeConfig<Context>>

Type Parameters

Statesextends string= string

Eventsextends string= string

Context= undefined

Methods

send

Send an event to the machine, potentially causing a state transition

send(event: Events): States

Parameter	Type	Default	Description
`event`	`Events`	—	Event name

ReturnsStatesThe current state after processing the event

can

Check if an event can trigger a transition from the current state

can(event: Events): boolean

Parameter	Type	Default	Description
`event`	`Events`	—	Event to check

Returnsboolean

Related Types

TransitionConfig

Configuration for a state transition

interface TransitionConfig<Context, Guard = boolean, Action = void>

Property	Type	Default	Description
`target`	`string`	—	Target state to transition to
`guard`?	`((context: Context) => Guard) \| undefined`	—	Guard condition — transition only occurs if this returns true
`action`?	`((context: Context) => Action) \| undefined`	—	Side effect executed during transition (before entering target state)

StateNodeConfig

Configuration for a state node

interface StateNodeConfig<Context, Guard = boolean, Hook = void>

Property	Type	Default	Description
`on`?	`Record<string, Transition<Context, Guard, Hook>> \| undefined`	—	Map of event names to transitions
`entry`?	`((context: Context) => Hook) \| undefined`	—	Hook called when entering this state
`exit`?	`((context: Context) => Hook) \| undefined`	—	Hook called when exiting this state

Transition

A transition can be a target state name or a detailed configuration

export type Transition<
  Context,
  Guard = boolean,
  Action = void,
> = string | TransitionConfig<Context, Guard, Action>;

SyncStateNodeConfig

Sync state node config — guards return boolean, hooks return void

export type SyncStateNodeConfig<Context> = StateNodeConfig<Context, boolean, void>;

AsyncStateNodeConfig

Async state node config — guards return MaybePromise\<boolean\>, hooks return MaybePromise\<void\>

export type AsyncStateNodeConfig<Context> = StateNodeConfig<Context, MaybePromise<boolean>, MaybePromise<void>>;