memorize.js

/** @typedef {import("../index").EXPECTED_ANY} EXPECTED_ANY */

const cacheStore = new WeakMap();

/**
 * @template T
 * @typedef {(...args: EXPECTED_ANY) => T} FunctionReturning
 */

/**
 * @template T
 * @param {FunctionReturning<T>} fn memorized function
 * @param {({ cache?: Map<string, { data: T }> } | undefined)=} cache cache
 * @param {((value: T) => T)=} callback callback
 * @returns {FunctionReturning<T>} new function
 */
function memorize(fn, { cache = new Map() } = {}, callback = undefined) {
  /**
   * @param {EXPECTED_ANY[]} arguments_ args
   * @returns {EXPECTED_ANY} result
   */
  const memoized = (...arguments_) => {
    const [key] = arguments_;
    const cacheItem = cache.get(key);

    if (cacheItem) {
      return cacheItem.data;
    }

    // @ts-expect-error
    let result = fn.apply(this, arguments_);

    if (callback) {
      result = callback(result);
    }

    cache.set(key, {
      data: result,
    });

    return result;
  };

  cacheStore.set(memoized, cache);

  return memoized;
}

module.exports = memorize;