graphql/jsutils/memoize3.js.flow

A Query Language and Runtime which can target any service.

/**
 * Copyright (c) 2017-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow strict
 */

/**
 * Memoizes the provided three-argument function.
 */
export default function memoize3<T: (a1: any, a2: any, a3: any) => any>(
  fn: T,
): T {
  let cache0;
  function memoized(a1, a2, a3) {
    if (!cache0) {
      cache0 = new WeakMap();
    }
    let cache1 = cache0.get(a1);
    let cache2;
    if (cache1) {
      cache2 = cache1.get(a2);
      if (cache2) {
        const cachedValue = cache2.get(a3);
        if (cachedValue !== undefined) {
          return cachedValue;
        }
      }
    } else {
      cache1 = new WeakMap();
      cache0.set(a1, cache1);
    }
    if (!cache2) {
      cache2 = new WeakMap();
      cache1.set(a2, cache2);
    }
    const newValue = fn.apply(this, arguments);
    cache2.set(a3, newValue);
    return newValue;
  }
  return (memoized: any);
}