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// A function similar to Python's `range`. 16export function range(n: number): number[] { 17 if (n < 0) { 18 throw new Error('range size should be non-negative!'); 19 } 20 21 const result = new Array<number>(n); 22 23 for (let i = 0; i < n; i++) { 24 result[i] = i; 25 } 26 27 return result; 28} 29 30// Checks whether all the strings in the array are unique. 31export function allUnique(x: string[]): boolean { 32 return x.length == new Set(x).size; 33} 34 35// Check whether two arrays are identical. 36export function arrayEquals<T>(a: ArrayLike<T>, b: ArrayLike<T>): boolean { 37 if (a.length !== b.length) return false; 38 for (let i = 0; i < a.length; i++) { 39 if (a[i] !== b[i]) return false; 40 } 41 return true; 42} 43 44export function isArrayOf<P, Q>( 45 predicate: (x: P | Q) => x is P, 46 xs: (P | Q)[], 47): xs is P[] { 48 return xs.every(predicate); 49} 50 51// Filter out falsy values from an array, leaving only the truthy ones 52export function removeFalsyValues<T>( 53 array: (T | false | null | undefined)[], 54): T[] { 55 return array.filter(Boolean) as T[]; 56} 57