Source: \memoize.js
import MapCache from './.internal/MapCache.js'
/**
* Creates a function that memoizes the result of `func`. If `resolver` is
* provided, it determines the cache key for storing the result based on the
* arguments provided to the memoized function. By default, the first argument
* provided to the memoized function is used as the map cache key. The `func`
* is invoked with the `this` binding of the memoized function.
*
* **Note:** The cache is exposed as the `cache` property on the memoized
* function. Its creation may be customized by replacing the `memoize.Cache`
* constructor with one whose instances implement the
* [`Map`](http://ecma-international.org/ecma-262/7.0/#sec-properties-of-the-map-prototype-object)
* method interface of `clear`, `delete`, `get`, `has`, and `set`.
*
* @since 0.1.0
* @category Function
* @param {Function} func The function to have its output memoized.
* @param {Function} [resolver] The function to resolve the cache key.
* @returns {Function} Returns the new memoized function.
* @example
*
* const object = { 'a': 1, 'b': 2 }
* const other = { 'c': 3, 'd': 4 }
*
* const values = memoize(values)
* values(object)
* // => [1, 2]
*
* values(other)
* // => [3, 4]
*
* object.a = 2
* values(object)
* // => [1, 2]
*
* // Modify the result cache.
* values.cache.set(object, ['a', 'b'])
* values(object)
* // => ['a', 'b']
*
* // Replace `memoize.Cache`.
* memoize.Cache = WeakMap
*/
function memoize(func, resolver) {
if (typeof func != 'function' || (resolver != null && typeof resolver != 'function')) {
throw new TypeError('Expected a function')
}
const memoized = function(...args) {
const key = resolver ? resolver.apply(this, args) : args[0]
const cache = memoized.cache
if (cache.has(key)) {
return cache.get(key)
}
const result = func.apply(this, args)
memoized.cache = cache.set(key, result) || cache
return result
}
memoized.cache = new (memoize.Cache || MapCache)
return memoized
}
memoize.Cache = MapCache
export default memoize