InitialDataSource.kt
/*
* Copyright 2021 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
/**
* [InitialDataSource] is a placeholder [DataSource] implementation that only returns empty
* pages and `null` keys.
*
* It should be used exclusively in [InitialPagedList] since it is required to be supplied
* synchronously, but [DataSource.Factory] should run on background thread.
*/
@Suppress("DEPRECATION")
internal class InitialDataSource<K : Any, V : Any> : PageKeyedDataSource<K, V>() {
override fun loadInitial(params: LoadInitialParams<K>, callback: LoadInitialCallback<K, V>) {
callback.onResult(listOf(), 0, 0, null, null)
}
override fun loadBefore(params: LoadParams<K>, callback: LoadCallback<K, V>) {
callback.onResult(listOf(), null)
}
override fun loadAfter(params: LoadParams<K>, callback: LoadCallback<K, V>) {
callback.onResult(listOf(), null)
}
}