recursive-memoize

recursive-memoize.js

import faker from "faker";
import { isUndefined, times, shuffle} from "lodash";

// const data = shuffle(
//   times(10, x => ({
//     order: x,
//     id: faker.internet.email(),
//     name: faker.name.findName()
//   }))
// );

// const indexByKey = memoize((collection, key, isDictionary = true) => {
//   console.log('indexByKey');
//   return Object.values(collection).reduce((acc, value) => {
//     acc[value[key]] = value;
//     return acc;
//   }, isDictionary ? {} : []);
// });

// console.log(indexByKey(data, "id"));

// console.log(indexByKey(data, "order", false));

const cache = new Map();

const getCacheResult = (cache, currentKey, ...nestedKeys) => {
    if(!cache.has(currentKey)){
        return undefined;
    } else if(nestedKeys.length === 0){
        return cache.get(currentKey).result;
    } else {
        return getCacheResult(cache.get(currentKey).cache, ...nestedKeys)
    }
}

const setCacheResult = (result, cache, currentKey, ...nestedKeys) => {
    let cacheLevel;
    if(!cache.has(currentKey)){
        cacheLevel = {
            cache: new Map()
        };
        cache.set(currentKey, cacheLevel);
    } else {
        cacheLevel = cache.get(currentKey);
    }

    if(nestedKeys.length){
        setCacheResult(result, cacheLevel.cache, ...nestedKeys);
    } else {
        cacheLevel.result = result;
    }
}


const memoizeR = (fn) => (...args) => {
    const cachedResult = getCacheResult(cache, ...args);
    if(cachedResult !== undefined){
        return cachedResult;
    }
    const result = fn(...args);
    setCacheResult(result, cache, ...args);
    return result;
}

let uuid = 1;
const fakeFunction = (x,y) => `${uuid++} -- ${Math.random()}`;
const betterFakeFunction = memoizeR(fakeFunction)

console.log(betterFakeFunction(1,2));
console.log(betterFakeFunction(1,2));
console.log(betterFakeFunction(1,3));
console.log(betterFakeFunction(2,2));
console.log(betterFakeFunction(2,3));
console.log(betterFakeFunction(2,3,4));
console.log(betterFakeFunction(2,3,4));