@nestia/core/src/utils/Singleton.ts

Super-fast validation decorators of NestJS

/** @internal */
export class Singleton<T> {
  private value_: T | object;

  public constructor(private readonly closure_: () => T) {
    this.value_ = NOT_MOUNTED_YET;
  }

  public get(): T {
    if (this.value_ === NOT_MOUNTED_YET) this.value_ = this.closure_();
    return this.value_ as T;
  }
}

/** @internal */
const NOT_MOUNTED_YET = {};