[#310] Ensure NavTarget and State are parcelable

Author: LachlanMcKee

libraries/core/src/main/kotlin/com/bumble/appyx/core/children/ChildEntry.kt

@@ -1,11 +1,12 @@
 package com.bumble.appyx.core.children
 
+import android.os.Parcelable
 import com.bumble.appyx.core.navigation.NavKey
 import com.bumble.appyx.core.node.Node
 import com.bumble.appyx.core.state.SavedStateMap
 
 // custom equals/hashCode for MutableStateFlow and equality checks
-sealed class ChildEntry<T> {
+sealed class ChildEntry<T : Parcelable> {
     abstract val key: NavKey<T>
 
     override fun equals(other: Any?): Boolean =
@@ -18,12 +19,12 @@ sealed class ChildEntry<T> {
         "$key@${javaClass.simpleName}"
 
     /** All public APIs should return this type of child which is ready to work with. */
-    class Initialized<T>(
+    class Initialized<T : Parcelable>(
         override val key: NavKey<T>,
         val node: Node,
     ) : ChildEntry<T>()
 
-    class Suspended<T>(
+    class Suspended<T : Parcelable>(
         override val key: NavKey<T>,
         val savedState: SavedStateMap?,
     ) : ChildEntry<T>()

libraries/core/src/main/kotlin/com/bumble/appyx/core/children/ChildEntryExt.kt

@@ -1,8 +1,9 @@
 package com.bumble.appyx.core.children
 
+import android.os.Parcelable
 import com.bumble.appyx.core.node.Node
 
-val <T> ChildEntry<T>.nodeOrNull: Node?
+val <T : Parcelable> ChildEntry<T>.nodeOrNull: Node?
     get() =
         when (this) {
             is ChildEntry.Initialized -> node

libraries/core/src/main/kotlin/com/bumble/appyx/core/children/ChildNodeCreationManager.kt

@@ -1,5 +1,6 @@
 package com.bumble.appyx.core.children
 
+import android.os.Parcelable
 import androidx.lifecycle.coroutineScope
 import com.bumble.appyx.core.modality.AncestryInfo
 import com.bumble.appyx.core.modality.BuildContext
@@ -21,7 +22,7 @@ import kotlinx.coroutines.launch
  *
  * Lifecycle of these nodes is managed in [com.bumble.appyx.core.lifecycle.ChildNodeLifecycleManager].
  */
-internal class ChildNodeCreationManager<NavTarget : Any>(
+internal class ChildNodeCreationManager<NavTarget : Parcelable>(
     private var savedStateMap: SavedStateMap?,
     private val customisations: NodeCustomisationDirectory,
     private val keepMode: ChildEntry.KeepMode,

libraries/core/src/main/kotlin/com/bumble/appyx/core/composable/Child.kt

@@ -1,5 +1,6 @@
 package com.bumble.appyx.core.composable
 
+import android.os.Parcelable
 import androidx.compose.animation.core.Transition
 import androidx.compose.foundation.layout.Box
 import androidx.compose.runtime.Composable
@@ -32,7 +33,7 @@ import com.bumble.appyx.core.navigation.transition.TransitionParams
 import kotlinx.coroutines.flow.map
 
 @Composable
-fun <NavTarget : Any, State> ParentNode<NavTarget>.Child(
+fun <NavTarget : Parcelable, State : Parcelable> ParentNode<NavTarget>.Child(
     navElement: NavElement<NavTarget, out State>,
     saveableStateHolder: SaveableStateHolder,
     transitionParams: TransitionParams,
@@ -87,7 +88,7 @@ private class ChildRendererImpl(
 }
 
 @Composable
-fun <NavTarget : Any, State> ParentNode<NavTarget>.Child(
+fun <NavTarget : Parcelable, State : Parcelable> ParentNode<NavTarget>.Child(
     navElement: NavElement<NavTarget, out State>,
     modifier: Modifier = Modifier,
     transitionHandler: TransitionHandler<NavTarget, State> = JumpToEndTransitionHandler(),
@@ -125,7 +126,7 @@ fun <NavTarget : Any, State> ParentNode<NavTarget>.Child(
     }
 }
 
-private fun <NavTarget : Any, State> NavElement<NavTarget, State>.createDescriptor(
+private fun <NavTarget : Parcelable, State : Parcelable> NavElement<NavTarget, State>.createDescriptor(
     transitionParams: TransitionParams
 ) =
     TransitionDescriptor(
@@ -137,15 +138,15 @@ private fun <NavTarget : Any, State> NavElement<NavTarget, State>.createDescript
     )
 
 @Composable
-fun <R, S> NavModel<R, S>?.childrenAsState(): State<NavElements<R, out S>> =
+fun <R : Parcelable, S : Parcelable> NavModel<R, S>?.childrenAsState(): State<NavElements<R, out S>> =
     if (this != null) {
         elements.collectAsState()
     } else {
         remember { mutableStateOf(emptyList()) }
     }
 
 @Composable
-fun <R, S> NavModel<R, S>?.visibleChildrenAsState(): State<NavElements<R, out S>> =
+fun <R : Parcelable, S : Parcelable> NavModel<R, S>?.visibleChildrenAsState(): State<NavElements<R, out S>> =
     if (this != null) {
         val visibleElementsFlow = remember { screenState.map { it.onScreen } }
         visibleElementsFlow.collectAsState(emptyList())

libraries/core/src/main/kotlin/com/bumble/appyx/core/composable/Children.kt

@@ -1,5 +1,6 @@
 package com.bumble.appyx.core.composable
 
+import android.os.Parcelable
 import androidx.compose.foundation.layout.Box
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.collectAsState
@@ -26,7 +27,7 @@ import kotlinx.coroutines.flow.map
 import kotlin.reflect.KClass
 
 @Composable
-inline fun <reified NavTarget : Any, State> ParentNode<NavTarget>.Children(
+inline fun <reified NavTarget : Parcelable, State : Parcelable> ParentNode<NavTarget>.Children(
     navModel: NavModel<NavTarget, State>,
     modifier: Modifier = Modifier,
     transitionHandler: TransitionHandler<NavTarget, State> = JumpToEndTransitionHandler(),
@@ -63,7 +64,7 @@ inline fun <reified NavTarget : Any, State> ParentNode<NavTarget>.Children(
     }
 }
 
-class ChildrenTransitionScope<T : Any, S>(
+class ChildrenTransitionScope<T : Parcelable, S : Parcelable>(
     private val transitionHandler: TransitionHandler<T, S>,
     private val transitionParams: TransitionParams,
     private val navModel: NavModel<T, S>

libraries/core/src/main/kotlin/com/bumble/appyx/core/lifecycle/ChildNodeLifecycleManager.kt

@@ -1,5 +1,6 @@
 package com.bumble.appyx.core.lifecycle
 
+import android.os.Parcelable
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.LifecycleRegistry
 import com.bumble.appyx.core.children.ChildEntry
@@ -23,7 +24,7 @@ import kotlinx.coroutines.launch
  * Hosts [LifecycleRegistry] to manage the current node lifecycle
  * and updates lifecycle of children nodes when updated.
  */
-internal class ChildNodeLifecycleManager<NavTarget>(
+internal class ChildNodeLifecycleManager<NavTarget : Parcelable>(
     private val navModel: NavModel<NavTarget, *>,
     private val children: StateFlow<ChildEntryMap<NavTarget>>,
     private val coroutineScope: CoroutineScope,
@@ -86,7 +87,7 @@ internal class ChildNodeLifecycleManager<NavTarget>(
         }
     }
 
-    private fun <NavTarget> Flow<NavModelAdapter.ScreenState<NavTarget, *>>.keys() =
+    private fun <NavTarget : Parcelable> Flow<NavModelAdapter.ScreenState<NavTarget, *>>.keys() =
         this
             .map { screenState ->
                 ScreenState(
@@ -100,7 +101,7 @@ internal class ChildNodeLifecycleManager<NavTarget>(
         nodeOrNull?.updateLifecycleState(state)
     }
 
-    private data class ScreenState<NavTarget>(
+    private data class ScreenState<NavTarget : Parcelable>(
         val onScreen: List<NavKey<NavTarget>> = emptyList(),
         val offScreen: List<NavKey<NavTarget>> = emptyList(),
     )

libraries/core/src/main/kotlin/com/bumble/appyx/core/navigation/BaseNavModel.kt

@@ -1,5 +1,6 @@
 package com.bumble.appyx.core.navigation
 
+import android.os.Parcelable
 import androidx.activity.OnBackPressedCallback
 import com.bumble.appyx.core.mapState
 import com.bumble.appyx.core.navigation.backpresshandlerstrategies.BackPressHandlerStrategy
@@ -28,7 +29,7 @@ import kotlin.coroutines.EmptyCoroutineContext
  *
  * If more granular configuration is required, you should inherit NavModel interface instead.
  */
-abstract class BaseNavModel<NavTarget, State>(
+abstract class BaseNavModel<NavTarget : Parcelable, State : Parcelable>(
     private val backPressHandler: BackPressHandlerStrategy<NavTarget, State> = DontHandleBackPress(),
     private val operationStrategy: OperationStrategy<NavTarget, State> = ExecuteImmediately(),
     private val screenResolver: OnScreenStateResolver<State>,

libraries/core/src/main/kotlin/com/bumble/appyx/core/navigation/EmptyNavModel.kt

@@ -1,17 +1,18 @@
 package com.bumble.appyx.core.navigation
 
+import android.os.Parcelable
 import com.bumble.appyx.core.navigation.onscreen.OnScreenStateResolver
 
 /**
  * An implementation of a NavModel that won't add any children.
  * This is potentially useful if your ParentNode only uses
  * [com.bumble.appyx.core.navigation.model.permanent.PermanentNavModel]
  */
-class EmptyNavModel<NavTarget, State> : BaseNavModel<NavTarget, State>(
+class EmptyNavModel<NavTarget : Parcelable> : BaseNavModel<NavTarget, EmptyState>(
     savedStateMap = null,
     finalState = null,
     screenResolver = OnScreenStateResolver { true }
 ) {
-    override val initialElements: NavElements<NavTarget, State>
+    override val initialElements: NavElements<NavTarget, EmptyState>
         get() = emptyList()
 }

libraries/core/src/main/kotlin/com/bumble/appyx/core/navigation/EmptyState.kt

@@ -0,0 +1,12 @@
+package com.bumble.appyx.core.navigation
+
+import android.os.Parcelable
+import kotlinx.parcelize.Parcelize
+
+@Suppress("PARCELABLE_PRIMARY_CONSTRUCTOR_IS_EMPTY")
+@Parcelize
+class EmptyState internal constructor() : Parcelable {
+    companion object {
+        val INSTANCE = EmptyState()
+    }
+}

libraries/core/src/main/kotlin/com/bumble/appyx/core/navigation/NavElement.kt

@@ -7,18 +7,18 @@ import kotlinx.parcelize.RawValue
 
 @Parcelize
 @Immutable
-class NavElement<NavTarget, State> private constructor(
-    val key: @RawValue NavKey<NavTarget>,
-    val fromState: @RawValue State,
-    val targetState: @RawValue State,
-    val operation: @RawValue Operation<NavTarget, State>,
+class NavElement<NavTarget : Parcelable, State : Parcelable> private constructor(
+    val key: NavKey<NavTarget>,
+    val fromState: State,
+    val targetState: State,
+    val operation: Operation<NavTarget, State>,
     val transitionHistory: List<Pair<State, State>>
 ) : Parcelable {
     constructor(
-        key: @RawValue NavKey<NavTarget>,
-        fromState: @RawValue State,
-        targetState: @RawValue State,
-        operation: @RawValue Operation<NavTarget, State>,
+        key: NavKey<NavTarget>,
+        fromState: State,
+        targetState: State,
+        operation: Operation<NavTarget, State>,
     ) : this(
         key,
         fromState,