/*
* 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.
*/
package androidx.paging
import kotlinx.coroutines.flow.Flow
/**
* Primary entry point into Paging; constructor for a reactive stream of [PagingData].
*
* Each [PagingData] represents a snapshot of the backing paginated data. Updates to the backing
* dataset should be represented by a new instance of [PagingData].
*
* [PagingSource.invalidate] and calls to [AsyncPagingDataDiffer.refresh] or
* [PagingDataAdapter.refresh] will notify [Pager] that the backing dataset has been updated and a
* new [PagingData] / [PagingSource] pair will be generated to represent an updated snapshot.
*
* [PagingData] can be transformed to alter data as it loads, and presented in a `RecyclerView` via
* `AsyncPagingDataDiffer` or `PagingDataAdapter`.
*
* LiveData support is available as an extension property provided by the
* `androidx.paging:paging-runtime` artifact.
*
* RxJava support is available as extension properties provided by the
* `androidx.paging:paging-rxjava2` artifact.
*/
class Pager<Key : Any, Value : Any>
@JvmOverloads constructor(
config: PagingConfig,
initialKey: Key? = null,
@OptIn(ExperimentalPagingApi::class)
remoteMediator: RemoteMediator<Key, Value>? = null,
pagingSourceFactory: () -> PagingSource<Key, Value>
) {
/**
* A cold [Flow] of [PagingData], which emits new instances of [PagingData] once they become
* invalidated by [PagingSource.invalidate] or calls to [AsyncPagingDataDiffer.refresh] or
* [PagingDataAdapter.refresh].
*/
val flow: Flow<PagingData<Value>> = PageFetcher(
pagingSourceFactory,
initialKey,
config,
remoteMediator
).flow
}