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