FlowAdapter.kt

/*
 * 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.compose.runtime

import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.collect
import kotlinx.coroutines.withContext
import kotlin.coroutines.CoroutineContext
import kotlin.coroutines.EmptyCoroutineContext

/**
 * Collects values from this [StateFlow] and represents its latest value via [State].
 * The [StateFlow.value] is used as an initial value. Every time there would be new value posted
 * into the [StateFlow] the returned [State] will be updated causing recomposition of every
 * [State.value] usage.
 *
 * @sample androidx.compose.runtime.samples.StateFlowSample
 *
 * @param context [CoroutineContext] to use for collecting.
 */
@ExperimentalCoroutinesApi
@Suppress("NOTHING_TO_INLINE")
@Composable
inline fun <T> StateFlow<T>.collectAsState(
    context: CoroutineContext = EmptyCoroutineContext
): State<T> = collectAsState(value, context)

/**
 * Collects values from this [Flow] and represents its latest value via [State]. Every time there
 * would be new value posted into the [Flow] the returned [State] will be updated causing
 * recomposition of every [State.value] usage.
 *
 * @sample androidx.compose.runtime.samples.FlowWithInitialSample
 *
 * @param context [CoroutineContext] to use for collecting.
 */
@Composable
fun <T : R, R> Flow<T>.collectAsState(
    initial: R,
    context: CoroutineContext = EmptyCoroutineContext
): State<R> {
    val state = remember { mutableStateOf(initial) }
    launchInComposition(this, context) {
        if (context == EmptyCoroutineContext) {
            collect {
                state.value = it
            }
        } else withContext(context) {
            collect {
                state.value = it
            }
        }
    }
    return state
}