| 1 | /** |
| 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
| 3 | * |
| 4 | * This source code is licensed under the MIT license found in the |
| 5 | * LICENSE file in the root directory of this source tree. |
| 6 | */ |
| 7 | |
| 8 | import deepEqual from 'fast-deep-equal'; |
| 9 | |
| 10 | /** Try to reuse objects from `oldArray` for objects with the same key and deepEqual values. */ |
| 11 | export function reuseEqualObjects<T>( |
| 12 | oldArray: Array<T>, |
| 13 | newArray: Array<T>, |
| 14 | keyFunc: (value: T) => string, |
| 15 | equalFunc: (a: T, b: T) => boolean = deepEqual, |
| 16 | ): Array<T> { |
| 17 | const oldMap = new Map<string, T>(oldArray.map(v => [keyFunc(v), v])); |
| 18 | return newArray.map(value => { |
| 19 | const oldValue = oldMap.get(keyFunc(value)); |
| 20 | return oldValue && equalFunc(oldValue, value) ? oldValue : value; |
| 21 | }); |
| 22 | } |
| 23 | |