robonen
96f4cba4a8
- Add array/async/etc. modules and type tests; migrate to eslint flat config and composite tsconfig (vitest typecheck enabled). - Fix PubSub.emit to snapshot listeners before iterating (stable EventEmitter semantics; avoids invoking listeners added during the same emit).
51 lines
1.5 KiB
TypeScript
51 lines
1.5 KiB
TypeScript
import type { AnyFunction } from '../../types';
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export type MemoizeResolver<T extends AnyFunction> = (...args: Parameters<T>) => unknown;
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export type MemoizedFunction<T extends AnyFunction> = T & {
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/** The underlying cache, keyed by the resolver (first argument by default). */
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cache: Map<unknown, ReturnType<T>>;
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/** Drop all cached results. */
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clear: () => void;
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};
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/**
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* @name memoize
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* @category Functions
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* @description Caches the result of a function by its arguments
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*
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* @param {Function} fn - The function to memoize
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* @param {Function} [resolver] - Maps the arguments to a cache key; defaults to the first argument
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* @returns {MemoizedFunction} The memoized function, exposing its `cache` and a `clear()` method
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*
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* @example
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* const slow = memoize((n: number) => expensive(n));
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* slow(2); // computed
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* slow(2); // cached
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*
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* @example
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* const sum = memoize((a: number, b: number) => a + b, (a, b) => `${a},${b}`);
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*
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* @since 0.0.10
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*/
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export function memoize<T extends AnyFunction>(fn: T, resolver?: MemoizeResolver<T>): MemoizedFunction<T> {
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const cache = new Map<unknown, ReturnType<T>>();
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const memoized = function (this: unknown, ...args: Parameters<T>): ReturnType<T> {
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const key = resolver ? resolver(...args) : args[0];
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if (cache.has(key))
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return cache.get(key)!;
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const result = fn.apply(this, args) as ReturnType<T>;
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cache.set(key, result);
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return result;
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} as MemoizedFunction<T>;
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memoized.cache = cache;
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memoized.clear = () => cache.clear();
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return memoized;
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}
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