mout/function/memoize.js

Modular Utilities

"use strict";
exports.__esModule = true;
var isFunction_1 = require("../lang/isFunction");
var hasOwn_1 = require("../object/hasOwn");
/**
 * Creates a function that memoizes the result of `fn`. 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 coerced to a string and used as the
 * cache key. The `fn` is invoked with the `this` binding of the memoized
 * function. Modified from lodash.
 *
 * @param {Function} fn Function to have its output memoized.
 * @param {Function} context Function to resolve the cache key.
 * @return {Function} Returns the new memoized function.
 */
function memoize(fn, resolver) {
    if (!isFunction_1["default"](fn) || (resolver && !isFunction_1["default"](resolver))) {
        throw new TypeError('Expected a function');
    }
    var memoized = function () {
        var cache = memoized.cache;
        var key = resolver ? resolver.apply(this, arguments) : arguments[0];
        if (hasOwn_1["default"](cache, key)) {
            return cache[key];
        }
        var result = fn.apply(this, arguments);
        cache[key] = result;
        return result;
    };
    memoized.cache = {};
    return memoized;
}
exports["default"] = memoize;