.

node_modules/mem/index.js

@@ -0,0 +1,88 @@
+'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();
+	}
+};