memorize.decorator.ts

export const memorizeFn = <T extends () => void>(fn: T, size = 5, duration = 0): any => {
  const cache: Map<string, any> = new Map<string, any>();
  if (duration) {
    setInterval(() => cache.clear(), duration);
  }

  return (...args: any[]): any => {
    const key: string = JSON.stringify(args);
    if (!cache.has(key)) {
      cache.set(key, (fn as any)(...args));
    }

    try {
      return cache.get(key);
    } finally {
      if (cache.size > size) {
        cache.delete(cache.keys().next().value);
      }
    }
  };
};

export function Memorize(opts: { size?: number; duration?: number } = {}): any {
  return (target: object, name: string, descriptor: PropertyDescriptor): PropertyDescriptor => {
    descriptor.value = memorizeFn(target[name], opts.size, opts.duration);

    return descriptor;
  };
}