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index.js
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index.js
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'use strict';
const mimicFn = require('mimic-fn');
const isPromise = require('p-is-promise');
const cacheStore = new WeakMap();
const defaultCacheKey = (...args) => {
if (args.length === 1) {
const [firstArgument] = args;
if (
firstArgument === null ||
firstArgument === undefined ||
(typeof firstArgument !== 'function' && typeof firstArgument !== 'object')
) {
return firstArgument;
}
}
return JSON.stringify(args);
};
module.exports = (fn, options) => {
options = Object.assign({
cacheKey: defaultCacheKey,
cache: new Map(),
cachePromiseRejection: false
}, options);
const memoized = function (...args) {
const cache = cacheStore.get(memoized);
const key = options.cacheKey(...args);
if (cache.has(key)) {
const c = cache.get(key);
if (typeof options.maxAge !== 'number' || Date.now() < c.maxAge) {
return c.data;
}
cache.delete(key);
}
const ret = fn.call(this, ...args);
const setData = (key, data) => {
cache.set(key, {
data,
maxAge: Date.now() + (options.maxAge || 0)
});
};
setData(key, ret);
if (isPromise(ret) && options.cachePromiseRejection === false) {
// Remove rejected promises from cache unless `cachePromiseRejection` is set to `true`
ret.catch(() => cache.delete(key));
}
return ret;
};
mimicFn(memoized, fn);
cacheStore.set(memoized, options.cache);
return memoized;
};
module.exports.clear = fn => {
const cache = cacheStore.get(fn);
if (cache && typeof cache.clear === 'function') {
cache.clear();
}
};