Use Children in Stack and Overlay

decompose/api/android/decompose.api

@@ -132,9 +132,7 @@ public final class com/arkivanov/decompose/router/overlay/OverlayNavigationFacto
 	public static final fun OverlayNavigation ()Lcom/arkivanov/decompose/router/overlay/OverlayNavigation;
 }
 
-public abstract interface class com/arkivanov/decompose/router/overlay/OverlayNavigationSource {
-	public abstract fun subscribe (Lkotlin/jvm/functions/Function1;)V
-	public abstract fun unsubscribe (Lkotlin/jvm/functions/Function1;)V
+public abstract interface class com/arkivanov/decompose/router/overlay/OverlayNavigationSource : com/arkivanov/decompose/router/children/NavigationSource {
 }
 
 public final class com/arkivanov/decompose/router/overlay/OverlayNavigationSource$Event {
@@ -188,9 +186,7 @@ public final class com/arkivanov/decompose/router/stack/StackNavigationFactoryKt
 	public static final fun StackNavigation ()Lcom/arkivanov/decompose/router/stack/StackNavigation;
 }
 
-public abstract interface class com/arkivanov/decompose/router/stack/StackNavigationSource {
-	public abstract fun subscribe (Lkotlin/jvm/functions/Function1;)V
-	public abstract fun unsubscribe (Lkotlin/jvm/functions/Function1;)V
+public abstract interface class com/arkivanov/decompose/router/stack/StackNavigationSource : com/arkivanov/decompose/router/children/NavigationSource {
 }
 
 public final class com/arkivanov/decompose/router/stack/StackNavigationSource$Event {
@@ -220,19 +216,11 @@ public final class com/arkivanov/decompose/router/stack/StackNavigatorExtKt {
 	public static synthetic fun replaceCurrent$default (Lcom/arkivanov/decompose/router/stack/StackNavigator;Ljava/lang/Object;Lkotlin/jvm/functions/Function0;ILjava/lang/Object;)V
 }
 
-public final class com/arkivanov/decompose/router/stack/StackSaverImpl$SavedEntry$Creator : android/os/Parcelable$Creator {
-	public fun <init> ()V
-	public final fun createFromParcel (Landroid/os/Parcel;)Lcom/arkivanov/decompose/router/stack/StackSaverImpl$SavedEntry;
-	public synthetic fun createFromParcel (Landroid/os/Parcel;)Ljava/lang/Object;
-	public final fun newArray (I)[Lcom/arkivanov/decompose/router/stack/StackSaverImpl$SavedEntry;
-	public synthetic fun newArray (I)[Ljava/lang/Object;
-}
-
-public final class com/arkivanov/decompose/router/stack/StackSaverImpl$SavedState$Creator : android/os/Parcelable$Creator {
+public final class com/arkivanov/decompose/router/stack/StackSavedNavState$Creator : android/os/Parcelable$Creator {
 	public fun <init> ()V
-	public final fun createFromParcel (Landroid/os/Parcel;)Lcom/arkivanov/decompose/router/stack/StackSaverImpl$SavedState;
+	public final fun createFromParcel (Landroid/os/Parcel;)Lcom/arkivanov/decompose/router/stack/StackSavedNavState;
 	public synthetic fun createFromParcel (Landroid/os/Parcel;)Ljava/lang/Object;
-	public final fun newArray (I)[Lcom/arkivanov/decompose/router/stack/StackSaverImpl$SavedState;
+	public final fun newArray (I)[Lcom/arkivanov/decompose/router/stack/StackSavedNavState;
 	public synthetic fun newArray (I)[Ljava/lang/Object;
 }
 

decompose/api/jvm/decompose.api

@@ -111,9 +111,7 @@ public final class com/arkivanov/decompose/router/overlay/OverlayNavigationFacto
 	public static final fun OverlayNavigation ()Lcom/arkivanov/decompose/router/overlay/OverlayNavigation;
 }
 
-public abstract interface class com/arkivanov/decompose/router/overlay/OverlayNavigationSource {
-	public abstract fun subscribe (Lkotlin/jvm/functions/Function1;)V
-	public abstract fun unsubscribe (Lkotlin/jvm/functions/Function1;)V
+public abstract interface class com/arkivanov/decompose/router/overlay/OverlayNavigationSource : com/arkivanov/decompose/router/children/NavigationSource {
 }
 
 public final class com/arkivanov/decompose/router/overlay/OverlayNavigationSource$Event {
@@ -167,9 +165,7 @@ public final class com/arkivanov/decompose/router/stack/StackNavigationFactoryKt
 	public static final fun StackNavigation ()Lcom/arkivanov/decompose/router/stack/StackNavigation;
 }
 
-public abstract interface class com/arkivanov/decompose/router/stack/StackNavigationSource {
-	public abstract fun subscribe (Lkotlin/jvm/functions/Function1;)V
-	public abstract fun unsubscribe (Lkotlin/jvm/functions/Function1;)V
+public abstract interface class com/arkivanov/decompose/router/stack/StackNavigationSource : com/arkivanov/decompose/router/children/NavigationSource {
 }
 
 public final class com/arkivanov/decompose/router/stack/StackNavigationSource$Event {

decompose/src/commonMain/kotlin/com/arkivanov/decompose/GettingList.kt

@@ -0,0 +1,10 @@
+package com.arkivanov.decompose
+
+internal class GettingList<out T>(
+    override val size: Int,
+    private val get: (Int) -> T,
+) : AbstractList<T>() {
+
+    override fun get(index: Int): T =
+        get.invoke(index)
+}

decompose/src/commonMain/kotlin/com/arkivanov/decompose/router/children/ChildrenFactory.kt

@@ -2,6 +2,7 @@ package com.arkivanov.decompose.router.children
 
 import com.arkivanov.decompose.Child
 import com.arkivanov.decompose.ComponentContext
+import com.arkivanov.decompose.ExperimentalDecomposeApi
 import com.arkivanov.decompose.backhandler.child
 import com.arkivanov.decompose.value.MutableValue
 import com.arkivanov.decompose.value.Value
@@ -52,6 +53,7 @@ import com.arkivanov.essenty.statekeeper.consume
  * @param childFactory a factory function that creates new child component instances.
  * @return an observable [Value] of the resulting children state.
  */
+@ExperimentalDecomposeApi
 fun <C : Any, T : Any, E : Any, N : NavState<C>, S : Any> ComponentContext.children(
     source: NavigationSource<E>,
     key: String,

decompose/src/commonMain/kotlin/com/arkivanov/decompose/router/children/ChildrenNavigator.kt

@@ -111,9 +111,12 @@ internal class ChildrenNavigator<out C : Any, out T : Any, N : NavState<C>>(
     }
 
     private fun switch(newStates: List<ChildNavState<C>>) {
+        val newConfigurations = newStates.mapTo(HashSet(), ChildNavState<C>::configuration)
+        check(newConfigurations.size == newStates.size) { "Configurations must be unique" }
+
         val oldItems = items.associateBy(ChildItem<C, *>::configuration)
         val newItems = prepareNewItems(newStates = newStates, oldItems = oldItems)
-        destroyOldItems(newStates = newStates, oldItems = oldItems.values)
+        destroyOldItems(newConfigurations = newConfigurations, oldItems = oldItems.values)
         processNewItems(newItems = newItems)
     }
 
@@ -176,13 +179,12 @@ internal class ChildrenNavigator<out C : Any, out T : Any, N : NavState<C>>(
     }
 
     private fun destroyOldItems(
-        newStates: List<ChildNavState<C>>,
+        newConfigurations: Set<C>,
         oldItems: Collection<ChildItem<C, T>>,
     ) {
-        val newStatesSet = newStates.mapTo(HashSet(), ChildNavState<C>::configuration)
         for (item in oldItems) {
             val child = item as? Created ?: continue
-            if (item.configuration !in newStatesSet) {
+            if (item.configuration !in newConfigurations) {
                 child.backHandler.stop()
                 child.instanceKeeperDispatcher.destroy()
                 child.lifecycleRegistry.destroy()

decompose/src/commonMain/kotlin/com/arkivanov/decompose/router/overlay/ChildOverlayFactory.kt

@@ -2,17 +2,14 @@ package com.arkivanov.decompose.router.overlay
 
 import com.arkivanov.decompose.Child
 import com.arkivanov.decompose.ComponentContext
-import com.arkivanov.decompose.Optional
-import com.arkivanov.decompose.instancekeeper.attachTo
-import com.arkivanov.decompose.optionalOf
-import com.arkivanov.decompose.router.stack.StackNavigationSource
-import com.arkivanov.decompose.router.stack.childStack
+import com.arkivanov.decompose.ExperimentalDecomposeApi
+import com.arkivanov.decompose.router.children.ChildNavState.Status
+import com.arkivanov.decompose.router.children.NavState
+import com.arkivanov.decompose.router.children.SimpleChildNavState
+import com.arkivanov.decompose.router.children.children
 import com.arkivanov.decompose.value.Value
-import com.arkivanov.decompose.value.operator.map
-import com.arkivanov.essenty.instancekeeper.InstanceKeeperDispatcher
 import com.arkivanov.essenty.parcelable.Parcelable
 import com.arkivanov.essenty.parcelable.ParcelableContainer
-import com.arkivanov.essenty.statekeeper.StateKeeperDispatcher
 import kotlin.reflect.KClass
 
 /**
@@ -30,6 +27,7 @@ import kotlin.reflect.KClass
  * @param childFactory a factory function that creates new child instances.
  * @return an observable [Value] of [ChildOverlay].
  */
+@OptIn(ExperimentalDecomposeApi::class)
 fun <C : Parcelable, T : Any> ComponentContext.childOverlay(
     source: OverlayNavigationSource<C>,
     configurationClass: KClass<out C>,
@@ -39,25 +37,36 @@ fun <C : Parcelable, T : Any> ComponentContext.childOverlay(
     handleBackButton: Boolean = false,
     childFactory: (configuration: C, ComponentContext) -> T,
 ): Value<ChildOverlay<C, T>> =
-    childStack(
-        lifecycle = lifecycle,
-        stateKeeper = if (persistent) stateKeeper else StateKeeperDispatcher(),
-        instanceKeeper = if (persistent) instanceKeeper else InstanceKeeperDispatcher().attachTo(lifecycle),
-        backHandler = backHandler,
-        source = StackNavigationSourceImpl(source),
-        initialStack = { configurationStack(initialConfiguration()) },
-        saveConfiguration = { ParcelableContainer(it.value) },
-        restoreConfiguration = { optionalOf(it.consume(configurationClass)) },
+    children(
+        source = source,
         key = key,
-        handleBackButton = handleBackButton,
-        childFactory = { configuration, componentContext ->
-            if (configuration.value != null) {
-                optionalOf(childFactory(configuration.value, componentContext))
+        initialNavState = { OverlayNavState(configuration = initialConfiguration()) },
+        saveNavState = { navState -> ParcelableContainer(navState.configuration?.takeIf { persistent }) },
+        restoreNavState = { container -> OverlayNavState(container.consume(configurationClass)) },
+        navTransformer = { navState, event -> OverlayNavState(configuration = event.transformer(navState.configuration)) },
+        onEventComplete = { event, newNavState, oldNavState -> event.onComplete(newNavState.configuration, oldNavState.configuration) },
+        backTransformer = { navState ->
+            if (handleBackButton && (navState.configuration != null)) {
+                { OverlayNavState(configuration = null) }
             } else {
-                optionalOf()
+                null
             }
         },
-    ).map { it.active.toChildOverlay() }
+        stateMapper = { _, children -> ChildOverlay(overlay = children.firstOrNull() as? Child.Created?) },
+        childFactory = childFactory,
+    )
+
+private data class OverlayNavState<out C : Any>(
+    val configuration: C?,
+) : NavState<C> {
+
+    override val children: List<SimpleChildNavState<C>> =
+        if (configuration == null) {
+            emptyList()
+        } else {
+            listOf(SimpleChildNavState(configuration = configuration, status = Status.ACTIVE))
+        }
+}
 
 /**
  * A convenience extension function for [ComponentContext.childOverlay].
@@ -79,47 +88,3 @@ inline fun <reified C : Parcelable, T : Any> ComponentContext.childOverlay(
         handleBackButton = handleBackButton,
         childFactory = childFactory,
     )
-
-private fun <C : Parcelable, T : Any> Child.Created<Optional<C>, Optional<T>>.toChildOverlay(): ChildOverlay<C, T> =
-    if ((configuration.value != null) && (instance.value != null)) {
-        ChildOverlay(
-            overlay = Child.Created(
-                configuration = configuration.value,
-                instance = instance.value,
-            )
-        )
-    } else {
-        ChildOverlay()
-    }
-
-private fun <C : Any> configurationStack(configuration: C?): List<Optional<C>> =
-    listOfNotNull(optionalOf(), configuration?.let(::optionalOf))
-
-private class StackNavigationSourceImpl<C : Parcelable>(
-    private val delegate: OverlayNavigationSource<C>,
-) : StackNavigationSource<Optional<C>> {
-
-    private var map = HashMap<(StackNavigationSource.Event<Optional<C>>) -> Unit, (OverlayNavigationSource.Event<C>) -> Unit>()
-
-    override fun subscribe(observer: (StackNavigationSource.Event<Optional<C>>) -> Unit) {
-        check(observer !in map)
-
-        val sourceObserver: (OverlayNavigationSource.Event<C>) -> Unit = { observer(it.toStackEvent()) }
-        map += observer to sourceObserver
-        delegate.subscribe(sourceObserver)
-    }
-
-    private fun OverlayNavigationSource.Event<C>.toStackEvent(): StackNavigationSource.Event<Optional<C>> =
-        StackNavigationSource.Event(
-            transformer = { stack -> configurationStack(transformer(stack.last().value)) },
-            onComplete = { newStack, oldStack ->
-                onComplete(newStack.lastOrNull()?.value, oldStack.lastOrNull()?.value)
-            },
-        )
-
-    override fun unsubscribe(observer: (StackNavigationSource.Event<Optional<C>>) -> Unit) {
-        map.remove(observer)?.also {
-            delegate.unsubscribe(it)
-        }
-    }
-}

decompose/src/commonMain/kotlin/com/arkivanov/decompose/router/overlay/OverlayNavigationSource.kt

@@ -1,15 +1,13 @@
 package com.arkivanov.decompose.router.overlay
 
+import com.arkivanov.decompose.router.children.NavigationSource
+
 /**
  * Represents a source of navigation events for `Child Overlay`.
  *
  * @see OverlayNavigator
  */
-interface OverlayNavigationSource<C : Any> {
-
-    fun subscribe(observer: (Event<C>) -> Unit)
-
-    fun unsubscribe(observer: (Event<C>) -> Unit)
+interface OverlayNavigationSource<C : Any> : NavigationSource<OverlayNavigationSource.Event<C>> {
 
     class Event<C : Any>(
         val transformer: (configuration: C?) -> C?,

decompose/src/commonMain/kotlin/com/arkivanov/decompose/router/stack/ChildStack.kt

@@ -1,6 +1,7 @@
 package com.arkivanov.decompose.router.stack
 
 import com.arkivanov.decompose.Child
+import com.arkivanov.decompose.GettingList
 
 /**
  * A state holder for `Child Stack`.
@@ -20,19 +21,8 @@ data class ChildStack<out C : Any, out T : Any>(
     /**
      * Returns the full stack of component configurations, ordered from tail to head.
      */
-    val items: List<Child<C, T>> = Items(active = active, backStack = backStack)
-
-    private class Items<out C : Any, out T : Any>(
-        private val active: Child.Created<C, T>,
-        private val backStack: List<Child<C, T>> = emptyList(),
-    ) : AbstractList<Child<C, T>>() {
-        override val size: Int get() = backStack.size + 1
-
-        override fun get(index: Int): Child<C, T> =
-            when {
-                (index < 0) || (index >= size) -> throw IndexOutOfBoundsException("Index is out of bounds: index=$index, size=$size")
-                index < backStack.size -> backStack[index]
-                else -> active
-            }
-    }
+    val items: List<Child<C, T>> =
+        GettingList(size = backStack.size + 1) { index ->
+            backStack.getOrNull(index) ?: active
+        }
 }