@beenotung/tslib/memorize.js

utils library in Typescript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.MemorizePool = exports.memorize = void 0;
const map_map_1 = require("./map-map");
const reflection_1 = require("./reflection");
/* tslint:disable:ban-types */
/**
 * @description support any arguments length, any data type arguments
 *   do not works for self-recursive functions
 *   unless it is wrapped when being constructed
 *
 *   Example that works:
 *
 *       const q = memorize((n: number) => n < 2 ? 1 : q(n - 1) + q(n - 2));
 *
 *   Example that do not works:
 *
 *       let f = (n: number) => n < 2 ? 1 : f(n - 1) + f(n - 2);
 *       f = memorize(f);
 *
 * */
function memorize(f) {
    /* tslint:enable:ban-types */
    /* length => ...args */
    const cache = new map_map_1.MapMap();
    return Object.assign(reflection_1.wrapFunction(function () {
        let map = cache.getMap(arguments.length);
        for (let i = arguments.length - 1; i > 0; i--) {
            map = map.getMap(arguments[i]);
        }
        const last = arguments[0];
        if (map.has(last)) {
            return map.get(last);
        }
        const res = f.apply(null, arguments);
        map.set(last, res);
        return res;
    }, f.length, f.name), { clear: () => cache.clear() });
}
exports.memorize = memorize;
class MemorizePool {
    constructor() {
        this.cache = new map_map_1.MapMap();
    }
    get(args) {
        const map = this.getLastMap(args);
        const last = args[0];
        if (map.has(last)) {
            return [map.get(last)];
        }
        else {
            return undefined;
        }
    }
    set(args, res) {
        this.getLastMap(args).set(args[0], res);
    }
    getOrCalc(args, f) {
        const map = this.getLastMap(args);
        const last = args[0];
        if (map.has(last)) {
            return map.get(last);
        }
        const res = f();
        map.set(last, res);
        return res;
    }
    getLastMap(args) {
        let map = this.cache.getMap(args.length);
        for (let i = args.length - 1; i > 0; i--) {
            map = map.getMap(args[i]);
        }
        return map;
    }
}
exports.MemorizePool = MemorizePool;
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