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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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