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index.js
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index.js
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'use strict';
const mimicFn = require('mimic-fn');
const cacheStore = new WeakMap();
const defaultCacheKey = function (x) {
if (arguments.length === 1 && (x === null || x === undefined || (typeof x !== 'function' && typeof x !== 'object'))) {
return x;
}
return JSON.stringify(arguments); // eslint-disable-line prefer-rest-params
};
module.exports = (fn, opts) => {
opts = Object.assign({
cacheKey: defaultCacheKey,
cache: new Map()
}, opts);
const memoized = function () {
const cache = cacheStore.get(memoized);
const key = opts.cacheKey.apply(null, arguments); // eslint-disable-line prefer-rest-params
const maxAgeDefined = typeof opts.maxAge === 'number';
if (cache.has(key)) {
const c = cache.get(key);
if (!maxAgeDefined || Date.now() < c.maxAge) {
return c.data;
}
if (typeof c.maxAgeTimeout !== 'undefined') {
clearTimeout(c.maxAgeTimeout);
}
cache.delete(key);
}
const ret = fn.apply(null, arguments); // eslint-disable-line prefer-spread, prefer-rest-params
cache.set(key, {
data: ret,
maxAge: maxAgeDefined ? Date.now() + opts.maxAge : Infinity,
maxAgeTimeout: maxAgeDefined ? setTimeout(() => {
cache.delete(key);
}, opts.maxAge).unref() : undefined
});
return ret;
};
mimicFn(memoized, fn);
cacheStore.set(memoized, opts.cache);
return memoized;
};
module.exports.clear = fn => {
const cache = cacheStore.get(fn);
if (cache && typeof cache.clear === 'function') {
cache.forEach(c => {
if (typeof c.maxAgeTimeout !== 'undefined') {
clearTimeout(c.maxAgeTimeout);
}
});
cache.clear();
}
};