feat: [project-sequencer-statemachine] 初期ステートの設定周りを変更 (#2518)

Co-authored-by: Hiroshiba <[email protected]>

src/composables/useSequencerStateMachine.ts

@@ -1,13 +1,17 @@
 import { computed, ref } from "vue";
 import {
   ComputedRefs,
+  IdleStateId,
   PartialStore,
   Refs,
 } from "@/sing/sequencerStateMachine/common";
 import { getNoteDuration } from "@/sing/domain";
 import { createSequencerStateMachine } from "@/sing/sequencerStateMachine";
 
-export const useSequencerStateMachine = (store: PartialStore) => {
+export const useSequencerStateMachine = (
+  store: PartialStore,
+  initialStateId: IdleStateId,
+) => {
   const computedRefs: ComputedRefs = {
     snapTicks: computed(() =>
       getNoteDuration(store.state.sequencerSnapType, store.state.tpqn),
@@ -25,11 +29,14 @@ export const useSequencerStateMachine = (store: PartialStore) => {
     previewPitchEdit: ref(undefined),
     guideLineTicks: ref(0),
   };
-  const stateMachine = createSequencerStateMachine({
-    ...computedRefs,
-    ...refs,
-    store,
-  });
+  const stateMachine = createSequencerStateMachine(
+    {
+      ...computedRefs,
+      ...refs,
+      store,
+    },
+    initialStateId,
+  );
   return {
     stateMachine,
     nowPreviewing: computed(() => refs.nowPreviewing.value),

src/sing/sequencerStateMachine/index.ts

@@ -1,5 +1,6 @@
 import {
   Context,
+  IdleStateId,
   Input,
   SequencerStateDefinitions,
 } from "@/sing/sequencerStateMachine/common";
@@ -17,7 +18,10 @@ import { SelectNotesWithRectState } from "@/sing/sequencerStateMachine/states/se
 import { DrawPitchState } from "@/sing/sequencerStateMachine/states/drawPitchState";
 import { ErasePitchState } from "@/sing/sequencerStateMachine/states/erasePitchState";
 
-export const createSequencerStateMachine = (context: Context) => {
+export const createSequencerStateMachine = (
+  context: Context,
+  initialStateId: IdleStateId,
+) => {
   return new StateMachine<SequencerStateDefinitions, Input, Context>(
     {
       selectNotesToolIdle: () => new SelectNotesToolIdleState(),
@@ -32,7 +36,7 @@ export const createSequencerStateMachine = (context: Context) => {
       drawPitch: (args) => new DrawPitchState(args),
       erasePitch: (args) => new ErasePitchState(args),
     },
-    new SelectNotesToolIdleState(),
     context,
+    initialStateId,
   );
 };

src/sing/stateMachine.ts

@@ -91,6 +91,15 @@ type StateFactories<T extends StateDefinition[], Input, Context> = {
   ) => State<T, Input, Context> & { readonly id: U };
 };
 
+/**
+ * 初期ステートとして設定可能なステートのIDを表す型。
+ */
+type InitialStateId<T extends StateDefinition[]> = T[number] extends infer U
+  ? U extends { id: string; factoryArgs: undefined }
+    ? U["id"]
+    : never
+  : never;
+
 /**
  * ステートマシンを表すクラス。
  *
@@ -111,6 +120,7 @@ export class StateMachine<
   private readonly context: Context;
 
   private currentState: State<StateDefinitions, Input, Context>;
+  private isDisposed = false;
 
   /**
    * ステートマシンの現在のステートのID。
@@ -120,19 +130,36 @@ export class StateMachine<
   }
 
   /**
-   * @param initialState ステートマシンの初期ステート。
-   * @param context ステート間で共有されるコンテキスト。
+   * @param stateFactories ステートのファクトリー関数。
+   * @param context ステートマシンのコンテキスト。
+   * @param initialStateId ステートマシンの初期ステートのID。
    */
   constructor(
     stateFactories: StateFactories<StateDefinitions, Input, Context>,
-    initialState: State<StateDefinitions, Input, Context>,
     context: Context,
+    initialStateId: InitialStateId<StateDefinitions>,
   ) {
     this.stateFactories = stateFactories;
     this.context = context;
 
-    this.currentState = initialState;
+    this.currentState = stateFactories[initialStateId](undefined);
+  }
 
+  /**
+   * ステートを遷移し、ライフサイクルイベントを実行する。
+   *
+   * @param id 遷移先のステートのID。
+   * @param factoryArgs 遷移先のステートのファクトリー関数の引数。
+   */
+  transitionTo<T extends StateId<StateDefinitions>>(
+    id: T,
+    factoryArgs: FactoryArgs<StateDefinitions, T>,
+  ) {
+    if (this.isDisposed) {
+      throw new Error("This state machine is already disposed.");
+    }
+    this.currentState.onExit(this.context);
+    this.currentState = this.stateFactories[id](factoryArgs);
     this.currentState.onEnter(this.context);
   }
 
@@ -142,19 +169,36 @@ export class StateMachine<
    * @param input 処理する入力。
    */
   process(input: Input) {
+    if (this.isDisposed) {
+      throw new Error("This state machine is already disposed.");
+    }
+
     let nextState: State<StateDefinitions, Input, Context> | undefined =
       undefined;
+
     this.currentState.process({
       input,
       context: this.context,
       setNextState: (id, factoryArgs) => {
         nextState = this.stateFactories[id](factoryArgs);
       },
     });
+
     if (nextState != undefined) {
       this.currentState.onExit(this.context);
       this.currentState = nextState;
       this.currentState.onEnter(this.context);
     }
   }
+
+  /**
+   * ステートマシンを破棄する。
+   */
+  dispose() {
+    if (this.isDisposed) {
+      throw new Error("Already disposed.");
+    }
+    this.isDisposed = true;
+    this.currentState.onExit(this.context);
+  }
 }