123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118 |
- declare type AnyFunction = (...arguments_: any) => any;
- interface CacheStorageContent<ValueType> {
- data: ValueType;
- maxAge: number;
- }
- interface CacheStorage<KeyType, ValueType> {
- has: (key: KeyType) => boolean;
- get: (key: KeyType) => CacheStorageContent<ValueType> | undefined;
- set: (key: KeyType, value: CacheStorageContent<ValueType>) => void;
- delete: (key: KeyType) => void;
- clear?: () => void;
- }
- interface Options<FunctionToMemoize extends AnyFunction, CacheKeyType> {
- /**
- 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, __only the first argument is considered__ and it only works with [primitives](https://developer.mozilla.org/en-US/docs/Glossary/Primitive).
- A `cacheKey` function can return any type supported by `Map` (or whatever structure you use in the `cache` option).
- You can have it cache **all** the arguments by value with `JSON.stringify`, if they are compatible:
- ```
- import mem = require('mem');
- mem(function_, {cacheKey: JSON.stringify});
- ```
- Or you can use a more full-featured serializer like [serialize-javascript](https://github.com/yahoo/serialize-javascript) to add support for `RegExp`, `Date` and so on.
- ```
- import mem = require('mem');
- import serializeJavascript = require('serialize-javascript');
- mem(function_, {cacheKey: serializeJavascript});
- ```
- @default arguments_ => arguments_[0]
- @example arguments_ => JSON.stringify(arguments_)
- */
- readonly cacheKey?: (arguments_: Parameters<FunctionToMemoize>) => CacheKeyType;
- /**
- Use a different cache storage. Must implement the following methods: `.has(key)`, `.get(key)`, `.set(key, value)`, `.delete(key)`, and optionally `.clear()`. You could for example use a `WeakMap` instead or [`quick-lru`](https://github.com/sindresorhus/quick-lru) for a LRU cache.
- @default new Map()
- @example new WeakMap()
- */
- readonly cache?: CacheStorage<CacheKeyType, ReturnType<FunctionToMemoize>>;
- }
- /**
- [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
- ```
- */
- declare const mem: {
- <FunctionToMemoize extends AnyFunction, CacheKeyType>(fn: FunctionToMemoize, { cacheKey, cache, maxAge }?: Options<FunctionToMemoize, CacheKeyType>): FunctionToMemoize;
- /**
- @returns A [decorator](https://github.com/tc39/proposal-decorators) to memoize class methods or static class methods.
-
- @example
- ```
- import mem = require('mem');
-
- class Example {
- index = 0
-
- @mem.decorator()
- counter() {
- return ++this.index;
- }
- }
-
- class ExampleWithOptions {
- index = 0
-
- @mem.decorator({maxAge: 1000})
- counter() {
- return ++this.index;
- }
- }
- ```
- */
- decorator<FunctionToMemoize_1 extends AnyFunction, CacheKeyType_1>(options?: Options<FunctionToMemoize_1, CacheKeyType_1>): (target: any, propertyKey: string, descriptor: PropertyDescriptor) => void;
- /**
- Clear all cached data of a memoized function.
-
- @param fn - Memoized function.
- */
- clear(fn: AnyFunction): void;
- };
- export = mem;
|