| /* |
| * Copyright 2020 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| @file:JvmName("PagingLiveData") |
| |
| package androidx.paging |
| |
| import androidx.lifecycle.Lifecycle |
| import androidx.lifecycle.LiveData |
| import androidx.lifecycle.asFlow |
| import androidx.lifecycle.asLiveData |
| import androidx.lifecycle.coroutineScope |
| import kotlinx.coroutines.CoroutineScope |
| |
| /** |
| * A [LiveData] of [PagingData], which mirrors the stream provided by [Pager.flow], but exposes it |
| * as a [LiveData]. |
| */ |
| val <Key : Any, Value : Any> Pager<Key, Value>.liveData: LiveData<PagingData<Value>> |
| get() = flow.asLiveData() |
| |
| /** |
| * Operator which caches a [LiveData] of [PagingData] within the scope of a [Lifecycle]. |
| * |
| * [cachedIn] multicasts pages loaded and transformed by a [PagingData], allowing multiple |
| * observers on the same instance of [PagingData] to receive the same events, avoiding redundant |
| * work, but comes at the cost of buffering those events in memory. |
| * |
| * Calling [cachedIn] is required to allow calling |
| * [submitData][androidx.paging.AsyncPagingDataAdapter] on the same instance of [PagingData] |
| * emitted by [Pager] or any of its transformed derivatives, as reloading data from scratch on the |
| * same generation of [PagingData] is an unsupported operation. |
| * |
| * @param lifecycle The [Lifecycle] where the page cache will be kept alive. |
| */ |
| fun <T : Any> LiveData<PagingData<T>>.cachedIn(lifecycle: Lifecycle) = asFlow() |
| .cachedIn(lifecycle.coroutineScope) |
| .asLiveData() |
| |
| /** |
| * Operator which caches a [LiveData] of [PagingData] within a [CoroutineScope]. |
| * |
| * [cachedIn] multicasts pages loaded and transformed by a [PagingData], allowing multiple |
| * observers on the same instance of [PagingData] to receive the same events, avoiding redundant |
| * work, but comes at the cost of buffering those events in memory. |
| * |
| * Calling [cachedIn] is required to allow calling |
| * [submitData][androidx.paging.AsyncPagingDataAdapter] on the same instance of [PagingData] |
| * emitted by [Pager] or any of its transformed derivatives, as reloading data from scratch on the |
| * same generation of [PagingData] is an unsupported operation. |
| * |
| * @param scope The [CoroutineScope] where the page cache will be kept alive. Typically this |
| * would be a managed scope such as `ViewModel.viewModelScope`, which automatically cancels after |
| * the [PagingData] stream is no longer needed. Otherwise, the provided [CoroutineScope] must be |
| * manually cancelled to avoid memory leaks. |
| */ |
| fun <T : Any> LiveData<PagingData<T>>.cachedIn(scope: CoroutineScope) = asFlow() |
| .cachedIn(scope) |
| .asLiveData() |