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- declare namespace mem {
- interface CacheStorage<KeyType extends unknown, ValueType extends unknown> {
- has(key: KeyType): boolean;
- get(key: KeyType): ValueType | undefined;
- set(key: KeyType, value: ValueType): void;
- delete(key: KeyType): void;
- clear?: () => void;
- }
-
- interface Options<
- ArgumentsType extends unknown[],
- CacheKeyType extends unknown,
- ReturnType extends unknown
- > {
- /**
- Milliseconds until the cache expires.
-
- @default Infinity
- */
- readonly maxAge?: number;
-
- /**
- Determines the cache key for storing the result based on the function arguments. By default, if there's only one argument and it's a [primitive](https://developer.mozilla.org/en-US/docs/Glossary/Primitive), it's used directly as a key, otherwise it's all the function arguments JSON stringified as an array.
-
- You could for example change it to only cache on the first argument `x => JSON.stringify(x)`.
- */
- readonly cacheKey?: (...arguments: ArgumentsType) => CacheKeyType;
-
- /**
- Use a different cache storage. You could for example use a `WeakMap` instead or [`quick-lru`](https://github.com/sindresorhus/quick-lru) for a LRU cache.
-
- @default new Map()
- */
- readonly cache?: CacheStorage<CacheKeyType, {data: ReturnType; maxAge: number}>;
-
- /**
- Cache rejected promises.
-
- @default false
- */
- readonly cachePromiseRejection?: boolean;
- }
- }
-
- declare const mem: {
- /**
- [Memoize](https://en.wikipedia.org/wiki/Memoization) functions - An optimization used to speed up consecutive function calls by caching the result of calls with identical input.
-
- @param fn - Function to be memoized.
-
- @example
- ```
- import mem = require('mem');
-
- let i = 0;
- const counter = () => ++i;
- const memoized = mem(counter);
-
- memoized('foo');
- //=> 1
-
- // Cached as it's the same arguments
- memoized('foo');
- //=> 1
-
- // Not cached anymore as the arguments changed
- memoized('bar');
- //=> 2
-
- memoized('bar');
- //=> 2
- ```
- */
- <
- ArgumentsType extends unknown[],
- ReturnType extends unknown,
- CacheKeyType extends unknown
- >(
- fn: (...arguments: ArgumentsType) => ReturnType,
- options?: mem.Options<ArgumentsType, CacheKeyType, ReturnType>
- ): (...arguments: ArgumentsType) => ReturnType;
-
- /**
- Clear all cached data of a memoized function.
-
- @param fn - Memoized function.
- */
- clear<ArgumentsType extends unknown[], ReturnType extends unknown>(
- fn: (...arguments: ArgumentsType) => ReturnType
- ): void;
-
- // TODO: Remove this for the next major release
- default: typeof mem;
- };
-
- export = mem;
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