1 /* 2 * Copyright 2023 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.compose.ui.util 18 19 import kotlin.contracts.ExperimentalContracts 20 import kotlin.contracts.contract 21 22 /** 23 * Iterates through a [List] using the index and calls [action] for each item. This does not 24 * allocate an iterator like [Iterable.forEach]. 25 * 26 * **Do not use for collections that come from public APIs**, since they may not support random 27 * access in an efficient way, and this method may actually be a lot slower. Only use for 28 * collections that are created by code we control and are known to support random access. 29 */ 30 @Suppress("BanInlineOptIn") 31 @OptIn(ExperimentalContracts::class) fastForEachnull32internal inline fun <T> List<T>.fastForEach(action: (T) -> Unit) { 33 contract { callsInPlace(action) } 34 for (index in indices) { 35 val item = get(index) 36 action(item) 37 } 38 } 39 40 /** 41 * Returns a list containing the results of applying the given [transform] function to each element 42 * in the original collection. 43 * 44 * **Do not use for collections that come from public APIs**, since they may not support random 45 * access in an efficient way, and this method may actually be a lot slower. Only use for 46 * collections that are created by code we control and are known to support random access. 47 */ 48 @Suppress("BanInlineOptIn") 49 @OptIn(ExperimentalContracts::class) fastMapnull50internal inline fun <T, R> List<T>.fastMap(transform: (T) -> R): List<R> { 51 contract { callsInPlace(transform) } 52 val target = ArrayList<R>(size) 53 fastForEach { target += transform(it) } 54 return target 55 } 56