@naturalcycles/js-lib/dist/decorators/memo.decorator.d.ts

Standard library for universal (browser + Node.js) javascript

import type { CommonLogger } from '../log/commonLogger.js';
import type { AnyFunction, AnyObject, MaybeParameters } from '../types.js';
import type { MemoCache, MethodDecorator } from './memo.util.js';
export interface MemoOptions<FN> {
    /**
     * Provide a custom implementation of MemoCache.
     * Function that creates an instance of `MemoCache`.
     * e.g LRUMemoCache from `@naturalcycles/nodejs-lib`
     */
    cacheFactory?: () => MemoCache;
    /**
     * Provide a custom implementation of CacheKey function.
     */
    cacheKeyFn?: (args: MaybeParameters<FN>) => any;
    /**
     * Default to `console`
     */
    logger?: CommonLogger;
}
export interface MemoInstance {
    /**
     * Clears the cache.
     */
    clear: () => void;
    getInstanceCache: () => Map<AnyObject, MemoCache>;
    getCache: (instance: AnyFunction) => MemoCache | undefined;
}
/**
 * Memoizes the method of the class, so it caches the output and returns the cached version if the "key"
 * of the cache is the same. Key, by defaul, is calculated as `JSON.stringify(...args)`.
 * Cache is stored indefinitely in the internal Map.
 *
 * If origin function throws an Error - it is NOT cached.
 * So, error-throwing functions will be called multiple times.
 * Therefor, if the origin function can possibly throw - it should try to be idempotent.
 *
 * Cache is stored **per instance** - separate cache for separate instances of the class.
 * If you don't want it that way - you can use a static method, then there will be only one "instance".
 *
 * Supports dropping it's cache by calling .clear() method of decorated function (useful in unit testing).
 *
 * Based on:
 * https://github.com/mgechev/memo-decorator/blob/master/index.ts
 * http://decodize.com/blog/2012/08/27/javascript-memoization-caching-results-for-better-performance/
 * http://inlehmansterms.net/2015/03/01/javascript-memoization/
 * https://community.risingstack.com/the-worlds-fastest-javascript-memoization-library/
 */
export declare const _Memo: <FN>(opt?: MemoOptions<FN>) => MethodDecorator<FN>;
/**
 Call it on a method that is decorated with `@_Memo` to get access to additional functions,
 e.g `clear` to clear the cache, or get its underlying data.
 */
export declare function _getMemo(method: AnyFunction): MemoInstance;