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Commit fb88b527 authored by Steve Elliott's avatar Steve Elliott
Browse files

[kairos] Add TState.transitions utility 

Flag: EXEMPT unused
Test: atest kairos-tests
Change-Id: Ia5852ccd630b968dd39b36ff97fe765f703c741c
parent 6943fa9e

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) }