/*
* 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:OptIn(ExperimentalTypeInference::class)
package androidx.compose.runtime
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.suspendCancellableCoroutine
import kotlin.coroutines.CoroutineContext
import kotlin.experimental.ExperimentalTypeInference
/**
* Receiver scope for use with [produceState].
*/
interface ProduceStateScope<T> : MutableState<T>, CoroutineScope {
/**
* Await the disposal of this producer whether it left the composition,
* the source changed, or an error occurred. Always runs [onDispose] before resuming.
*
* This method is useful when configuring callback-based state producers that do not suspend,
* for example:
*
* @sample androidx.compose.runtime.samples.ProduceStateAwaitDispose
*/
suspend fun awaitDispose(onDispose: () -> Unit): Nothing
}
private class ProduceStateScopeImpl<T>(
state: MutableState<T>,
override val coroutineContext: CoroutineContext
) : ProduceStateScope<T>, MutableState<T> by state {
override suspend fun awaitDispose(onDispose: () -> Unit): Nothing {
try {
suspendCancellableCoroutine<Nothing> { }
} finally {
onDispose()
}
}
}
/**
* Return an observable [snapshot][androidx.compose.runtime.snapshots.Snapshot] [State] that
* produces values over time without a defined data source.
*
* [producer] is launched when [produceState] enters the composition and is cancelled when
* [produceState] leaves the composition. [producer] should use [ProduceStateScope.value]
* to set new values on the returned [State].
*
* The returned [State] conflates values; no change will be observable if
* [ProduceStateScope.value] is used to set a value that is [equal][Any.equals] to its old value,
* and observers may only see the latest value if several values are set in rapid succession.
*
* [produceState] may be used to observe either suspending or non-suspending sources of external
* data, for example:
*
* @sample androidx.compose.runtime.samples.ProduceState
*
* @sample androidx.compose.runtime.samples.ProduceStateAwaitDispose
*/
@Composable
fun <T> produceState(
initialValue: T,
@BuilderInference producer: suspend ProduceStateScope<T>.() -> Unit
): State<T> {
val result = remember { mutableStateOf(initialValue) }
LaunchedEffect(Unit) {
ProduceStateScopeImpl(result, coroutineContext).producer()
}
return result
}
/**
* Return an observable [snapshot][androidx.compose.runtime.snapshots.Snapshot] [State] that
* produces values over time from [subject].
*
* [producer] is launched when [produceState] enters the composition and is cancelled when
* [produceState] leaves the composition. If [subject] changes, a running [producer] will be
* cancelled and re-launched for the new source. [producer] should use [ProduceStateScope.value]
* to set new values on the returned [State].
*
* The returned [State] conflates values; no change will be observable if
* [ProduceStateScope.value] is used to set a value that is [equal][Any.equals] to its old value,
* and observers may only see the latest value if several values are set in rapid succession.
*
* [produceState] may be used to observe either suspending or non-suspending sources of external
* data, for example:
*
* @sample androidx.compose.runtime.samples.ProduceState
*
* @sample androidx.compose.runtime.samples.ProduceStateAwaitDispose
*/
@Composable
fun <T> produceState(
initialValue: T,
subject: Any?,
@BuilderInference producer: suspend ProduceStateScope<T>.() -> Unit
): State<T> {
val result = remember { mutableStateOf(initialValue) }
LaunchedEffect(subject) {
ProduceStateScopeImpl(result, coroutineContext).producer()
}
return result
}
/**
* Return an observable [snapshot][androidx.compose.runtime.snapshots.Snapshot] [State] that
* produces values over time from [subject1] and [subject2].
*
* [producer] is launched when [produceState] enters the composition and is cancelled when
* [produceState] leaves the composition. If [subject1] or [subject2] change, a running [producer]
* will be cancelled and re-launched for the new source. [producer] should use
* [ProduceStateScope.value] to set new values on the returned [State].
*
* The returned [State] conflates values; no change will be observable if
* [ProduceStateScope.value] is used to set a value that is [equal][Any.equals] to its old value,
* and observers may only see the latest value if several values are set in rapid succession.
*
* [produceState] may be used to observe either suspending or non-suspending sources of external
* data, for example:
*
* @sample androidx.compose.runtime.samples.ProduceState
*
* @sample androidx.compose.runtime.samples.ProduceStateAwaitDispose
*/
@Composable
fun <T> produceState(
initialValue: T,
subject1: Any?,
subject2: Any?,
@BuilderInference producer: suspend ProduceStateScope<T>.() -> Unit
): State<T> {
val result = remember { mutableStateOf(initialValue) }
LaunchedEffect(subject1, subject2) {
ProduceStateScopeImpl(result, coroutineContext).producer()
}
return result
}
/**
* Return an observable [snapshot][androidx.compose.runtime.snapshots.Snapshot] [State] that
* produces values over time from [subject1], [subject2] and [subject3].
*
* [producer] is launched when [produceState] enters the composition and is cancelled when
* [produceState] leaves the composition. If [subject1], [subject2] or [subject3] change, a running
* [producer] will be cancelled and re-launched for the new source. [producer should use
* [ProduceStateScope.value] to set new values on the returned [State].
*
* The returned [State] conflates values; no change will be observable if
* [ProduceStateScope.value] is used to set a value that is [equal][Any.equals] to its old value,
* and observers may only see the latest value if several values are set in rapid succession.
*
* [produceState] may be used to observe either suspending or non-suspending sources of external
* data, for example:
*
* @sample androidx.compose.runtime.samples.ProduceState
*
* @sample androidx.compose.runtime.samples.ProduceStateAwaitDispose
*/
@Composable
fun <T> produceState(
initialValue: T,
subject1: Any?,
subject2: Any?,
subject3: Any?,
@BuilderInference producer: suspend ProduceStateScope<T>.() -> Unit
): State<T> {
val result = remember { mutableStateOf(initialValue) }
LaunchedEffect(subject1, subject2, subject3) {
ProduceStateScopeImpl(result, coroutineContext).producer()
}
return result
}
/**
* Return an observable [snapshot][androidx.compose.runtime.snapshots.Snapshot] [State] that
* produces values over time from [subjects].
*
* [producer] is launched when [produceState] enters the composition and is cancelled when
* [produceState] leaves the composition. If [subjects] change, a running [producer] will be
* cancelled and re-launched for the new source. [producer] should use [ProduceStateScope.value]
* to set new values on the returned [State].
*
* The returned [State] conflates values; no change will be observable if
* [ProduceStateScope.value] is used to set a value that is [equal][Any.equals] to its old value,
* and observers may only see the latest value if several values are set in rapid succession.
*
* [produceState] may be used to observe either suspending or non-suspending sources of external
* data, for example:
*
* @sample androidx.compose.runtime.samples.ProduceState
*
* @sample androidx.compose.runtime.samples.ProduceStateAwaitDispose
*/
@Composable
fun <T> produceState(
initialValue: T,
vararg subjects: Any?,
@BuilderInference producer: suspend ProduceStateScope<T>.() -> Unit
): State<T> {
val result = remember { mutableStateOf(initialValue) }
@Suppress("CHANGING_ARGUMENTS_EXECUTION_ORDER_FOR_NAMED_VARARGS")
LaunchedEffect(subjects = subjects) {
ProduceStateScopeImpl(result, coroutineContext).producer()
}
return result
}