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Commit 0cb42cdc authored by Treehugger Robot's avatar Treehugger Robot Committed by Android (Google) Code Review
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Merge changes Ibb14d99a,Ia5852ccd,I064b1371 into main 

* changes:
  [kairos] fix MutableTFlow backpressure
  [kairos] Add TState.transitions utility
  [kairos] add Flow.scanTo utilities
parents 6e2d093d 60f5dd1b

packages/SystemUI/utils/kairos/src/com/android/systemui/kairos/Combinators.kt

+12 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
package com.android.systemui.kairos



import com.android.systemui.kairos.util.These

import com.android.systemui.kairos.util.WithPrev

import com.android.systemui.kairos.util.just

import com.android.systemui.kairos.util.none

import kotlinx.coroutines.flow.Flow
@@ -238,3 +239,14 @@ val <A> FrpStatefulMode<A>.compiledStateful: FrpStateful<TState<A>> 
 */

fun <A> FrpBuildScope.rebuildOn(rebuildSignal: TFlow<*>, spec: FrpSpec<A>): TState<A> =

    rebuildSignal.map { spec }.holdLatestSpec(spec)



/**

 * Like [stateChanges] but also includes the old value of this [TState].

 *

 * Shorthand for:

 * ``` kotlin

 *     stateChanges.map { WithPrev(previousValue = sample(), newValue = it) }

 * ```

 */

val <A> TState<A>.transitions: TFlow<WithPrev<A, A>>

    get() = stateChanges.map { WithPrev(previousValue = sample(), newValue = it) }

packages/SystemUI/utils/kairos/src/com/android/systemui/kairos/FrpBuildScope.kt

+21 −0
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ import kotlinx.coroutines.flow.MutableStateFlow 
import kotlinx.coroutines.flow.SharedFlow

import kotlinx.coroutines.flow.StateFlow

import kotlinx.coroutines.flow.dropWhile

import kotlinx.coroutines.flow.scan

import kotlinx.coroutines.launch



/** A function that modifies the FrpNetwork. */
@@ -595,6 +596,26 @@ interface FrpBuildScope : FrpStateScope { 
    @ExperimentalFrpApi

    fun <A> Flow<A>.toTState(initialValue: A): TState<A> = toTFlow().hold(initialValue)



    /**

     * Shorthand for:

     * ```kotlin

     * flow.scan(initialValue, operation).toTFlow().hold(initialValue)

     * ```

     */

    @ExperimentalFrpApi

    fun <A, B> Flow<A>.scanToTState(initialValue: B, operation: (B, A) -> B): TState<B> =

        scan(initialValue, operation).toTFlow().hold(initialValue)



    /**

     * Shorthand for:

     * ```kotlin

     * flow.scan(initialValue) { a, f -> f(a) }.toTFlow().hold(initialValue)

     * ```

     */

    @ExperimentalFrpApi

    fun <A> Flow<(A) -> A>.scanToTState(initialValue: A): TState<A> =

        scanToTState(initialValue) { a, f -> f(a) }



    /**

     * Invokes [block] whenever this [TFlow] emits a value. [block] receives an [FrpBuildScope] that

     * can be used to make further modifications to the FRP network, and/or perform side-effects via

packages/SystemUI/utils/kairos/src/com/android/systemui/kairos/TFlow.kt

+4 −6
Original line number Diff line number Diff line
@@ -520,16 +520,14 @@ internal constructor(internal val network: Network, internal val impl: InputNode 
    @ExperimentalFrpApi

    suspend fun emit(value: T) {

        coroutineScope {

            var jobOrNull: Job? = null

            val newEmit =

                async(start = CoroutineStart.LAZY) {

                    jobOrNull?.join()

                    network.transaction { impl.visit(this, value) }.await()

                }

            val jobOrNull = storage.getAndSet(newEmit)

            if (jobOrNull?.isActive != true) {

            jobOrNull = storage.getAndSet(newEmit)

            newEmit.await()

            } else {

                jobOrNull.join()

            }

        }

    }