ListSaver.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.compose.runtime.saveable
/**
* The [Saver] implementation which allows to represent your [Original] class as a list of
* [Saveable] values.
*
* What types can be saved is defined by [SaveableStateRegistry], by default everything which can
* be stored in the Bundle class can be saved.
*
* You can use it as a parameter for [rememberSaveable].
*
* @sample androidx.compose.runtime.saveable.samples.ListSaverSample
*/
fun <Original, Saveable> listSaver(
save: SaverScope.(value: Original) -> List<Saveable>,
restore: (list: List<Saveable>) -> Original?
): Saver<Original, Any> = @Suppress("UNCHECKED_CAST") Saver(
save = {
val list = save(it)
for (index in list.indices) {
val item = list[index]
if (item != null) {
require(canBeSaved(item))
}
}
if (list.isNotEmpty()) ArrayList(list) else null
},
restore = restore as (Any) -> Original?
)