1// Copyright (C) 2023 The Android Open Source Project 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14 15// Return true if value is not nullish - i.e. not null or undefined 16// Allows doing the following 17// exists(val) && m('div', val) 18// Even if val is a non-nullish falsey value like 0 or '' 19export function exists<T>(value: T): value is NonNullable<T> { 20 return value !== undefined && value !== null; 21} 22 23// Generic result type - similar to Rust's Result<T, E> 24export type Result<T, E = {}> = 25 | {success: true; result: T} 26 | {success: false; error: E}; 27 28// Generic "optional" type 29export type Optional<T> = T | undefined; 30