feat(infra): standard storage service

packages/common/infra/package.json

@@ -9,6 +9,7 @@
     "./app-config-storage": "./src/app-config-storage.ts",
     "./di": "./src/di/index.ts",
     "./livedata": "./src/livedata/index.ts",
+    "./storage": "./src/storage/index.ts",
     ".": "./src/index.ts"
   },
   "dependencies": {

packages/common/infra/src/index.ts

@@ -2,3 +2,6 @@ export * from './app-config-storage';
 export * from './atom';
 export * from './blocksuite';
 export * from './command';
+export * from './di';
+export * from './livedata';
+export * from './storage';

packages/common/infra/src/storage/__tests__/memento.spec.ts

@@ -0,0 +1,40 @@
+import { describe, expect, test } from 'vitest';
+
+import { ServiceCollection } from '../../di';
+import { GlobalCache, GlobalState, MemoryMemento } from '..';
+
+describe('memento', () => {
+  test('memory', () => {
+    const memento = new MemoryMemento();
+
+    expect(memento.get('foo')).toBeNull();
+    memento.set('foo', 'bar');
+    expect(memento.get('foo')).toEqual('bar');
+
+    let subscribed = null;
+    const subscription = memento.watch('foo').subscribe(v => {
+      subscribed = v;
+    });
+    expect(subscribed).toEqual('bar');
+    memento.set('foo', 'baz');
+    expect(subscribed).toEqual('baz');
+
+    subscription.unsubscribe();
+    memento.set('foo', 'hello');
+    expect(subscribed).toEqual('baz');
+  });
+
+  test('service', () => {
+    const services = new ServiceCollection();
+
+    services
+      .addImpl(GlobalCache, MemoryMemento)
+      .addImpl(GlobalState, MemoryMemento);
+
+    const provider = services.provider();
+    const cache = provider.get(GlobalCache);
+    expect(cache).toBeInstanceOf(MemoryMemento);
+    const state = provider.get(GlobalState);
+    expect(state).toBeInstanceOf(MemoryMemento);
+  });
+});

packages/common/infra/src/storage/index.ts

@@ -0,0 +1 @@
+export * from './memento';

packages/common/infra/src/storage/memento.ts

@@ -0,0 +1,57 @@
+import type { Observable } from 'rxjs';
+
+import { createIdentifier } from '../di';
+import { LiveData } from '../livedata';
+
+/**
+ * A memento represents a storage utility. It can store and retrieve values, and observe changes.
+ */
+export interface Memento {
+  get<T>(key: string): T | null;
+  watch<T>(key: string): Observable<T | null>;
+  set<T>(key: string, value: T | null): void;
+}
+
+/**
+ * A memento object that stores the entire application state.
+ *
+ * State is persisted, even the application is closed.
+ */
+export interface GlobalState extends Memento {}
+
+export const GlobalState = createIdentifier<GlobalState>('GlobalState');
+
+/**
+ * A memento object that stores the entire application cache.
+ *
+ * Cache may be deleted from time to time, business logic should not rely on cache.
+ */
+export interface GlobalCache extends Memento {}
+
+export const GlobalCache = createIdentifier<GlobalCache>('GlobalCache');
+
+/**
+ * A simple implementation of Memento. Used for testing.
+ */
+export class MemoryMemento implements Memento {
+  private readonly data = new Map<string, LiveData<any>>();
+
+  private getLiveData(key: string): LiveData<any> {
+    let data = this.data.get(key);
+    if (!data) {
+      data = new LiveData<any>(null);
+      this.data.set(key, data);
+    }
+    return data;
+  }
+
+  get<T>(key: string): T | null {
+    return this.getLiveData(key).value;
+  }
+  watch<T>(key: string): Observable<T | null> {
+    return this.getLiveData(key).asObservable();
+  }
+  set<T>(key: string, value: T | null): void {
+    this.getLiveData(key).next(value);
+  }
+}