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import type {Read, Value} from './store';
export const deleteSentinel = Symbol();export type DeleteSentinel = typeof deleteSentinel;
export class WriteImplBase {  protected readonly _pending: Map<string, Value | DeleteSentinel> = new Map();  private readonly _read: Read;
  constructor(read: Read) {    this._read = read;  }
  async has(key: string): Promise<boolean> {    switch (this._pending.get(key)) {      case undefined:        return this._read.has(key);      case deleteSentinel:        return false;      default:        return true;    }  }
  async get(key: string): Promise<Value | undefined> {    const v = this._pending.get(key);    switch (v) {      case deleteSentinel:        return undefined;      case undefined:        return this._read.get(key);      default:        return v;    }  }
  async put(key: string, value: Value): Promise<void> {    this._pending.set(key, value);  }
  async del(key: string): Promise<void> {    this._pending.set(key, deleteSentinel);  }
  release(): void {    this._read.release();  }
  get closed(): boolean {    return this._read.closed;  }}