ut2/lib/memoize.js

一个现代 JavaScript 实用工具库。[点击查看在线文档]。

'use strict';

var shallowEqual = require('./shallowEqual.js');
var native = require('./internals/native.js');

function memoize(func, options) {
    var opts = options || {};
    var max = native.mathCeil(opts.max || 0);
    var isEqual = typeof opts.isEqual === 'function' ? opts.isEqual : shallowEqual;
    var cache = [];
    function memoized() {
        var _this = this;
        var newArgs = [];
        for (var _i = 0; _i < arguments.length; _i++) {
            newArgs[_i] = arguments[_i];
        }
        var cacheValue = cache.find(function (item) { return item.lastThis === _this && isEqual(item.lastArgs, newArgs); });
        if (cacheValue) {
            return cacheValue.lastReturn;
        }
        var lastReturn = func.apply(this, newArgs);
        if (max > 0 && cache.length >= max) {
            cache.shift();
        }
        cache.push({
            lastArgs: newArgs,
            lastThis: this,
            lastReturn: lastReturn
        });
        return lastReturn;
    }
    memoized.clear = function () {
        cache.length = 0;
    };
    return memoized;
}

module.exports = memoize;