You can not select more than 25 topics
			Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
		
		
		
		
		
			
		
			
				
					74 lines
				
				2.2 KiB
			
		
		
			
		
	
	
					74 lines
				
				2.2 KiB
			| 
											3 years ago
										 | var MapCache = require('./_MapCache'); | ||
|  | 
 | ||
|  | /** Error message constants. */ | ||
|  | var FUNC_ERROR_TEXT = 'Expected a function'; | ||
|  | 
 | ||
|  | /** | ||
|  |  * 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`. | ||
|  |  * | ||
|  |  * @static | ||
|  |  * @memberOf _ | ||
|  |  * @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 | ||
|  |  * | ||
|  |  * var object = { 'a': 1, 'b': 2 }; | ||
|  |  * var other = { 'c': 3, 'd': 4 }; | ||
|  |  * | ||
|  |  * var 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(FUNC_ERROR_TEXT); | ||
|  |   } | ||
|  |   var memoized = function() { | ||
|  |     var args = arguments, | ||
|  |         key = resolver ? resolver.apply(this, args) : args[0], | ||
|  |         cache = memoized.cache; | ||
|  | 
 | ||
|  |     if (cache.has(key)) { | ||
|  |       return cache.get(key); | ||
|  |     } | ||
|  |     var result = func.apply(this, args); | ||
|  |     memoized.cache = cache.set(key, result) || cache; | ||
|  |     return result; | ||
|  |   }; | ||
|  |   memoized.cache = new (memoize.Cache || MapCache); | ||
|  |   return memoized; | ||
|  | } | ||
|  | 
 | ||
|  | // Expose `MapCache`.
 | ||
|  | memoize.Cache = MapCache; | ||
|  | 
 | ||
|  | module.exports = memoize; |