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- 'use strict';
- const mimicFn = require('mimic-fn');
- const isPromise = require('p-is-promise');
- const mapAgeCleaner = require('map-age-cleaner');
-
- const cacheStore = new WeakMap();
-
- const defaultCacheKey = (...arguments_) => {
- if (arguments_.length === 0) {
- return '__defaultKey';
- }
-
- if (arguments_.length === 1) {
- const [firstArgument] = arguments_;
- if (
- firstArgument === null ||
- firstArgument === undefined ||
- (typeof firstArgument !== 'function' && typeof firstArgument !== 'object')
- ) {
- return firstArgument;
- }
- }
-
- return JSON.stringify(arguments_);
- };
-
- const mem = (fn, options) => {
- options = Object.assign({
- cacheKey: defaultCacheKey,
- cache: new Map(),
- cachePromiseRejection: false
- }, options);
-
- if (typeof options.maxAge === 'number') {
- mapAgeCleaner(options.cache);
- }
-
- const {cache} = options;
- options.maxAge = options.maxAge || 0;
-
- const setData = (key, data) => {
- cache.set(key, {
- data,
- maxAge: Date.now() + options.maxAge
- });
- };
-
- const memoized = function (...arguments_) {
- const key = options.cacheKey(...arguments_);
-
- if (cache.has(key)) {
- return cache.get(key).data;
- }
-
- const cacheItem = fn.call(this, ...arguments_);
-
- setData(key, cacheItem);
-
- if (isPromise(cacheItem) && options.cachePromiseRejection === false) {
- // Remove rejected promises from cache unless `cachePromiseRejection` is set to `true`
- cacheItem.catch(() => cache.delete(key));
- }
-
- return cacheItem;
- };
-
- try {
- // The below call will throw in some host environments
- // See https://github.com/sindresorhus/mimic-fn/issues/10
- mimicFn(memoized, fn);
- } catch (_) {}
-
- cacheStore.set(memoized, options.cache);
-
- return memoized;
- };
-
- module.exports = mem;
- // TODO: Remove this for the next major release
- module.exports.default = mem;
-
- module.exports.clear = fn => {
- const cache = cacheStore.get(fn);
-
- if (cache && typeof cache.clear === 'function') {
- cache.clear();
- }
- };
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