Use Cancellation in NavigationSource and Relay

decompose/api/android/decompose.api

@@ -111,8 +111,7 @@ public abstract interface class com/arkivanov/decompose/router/children/NavState
 }
 
 public abstract interface class com/arkivanov/decompose/router/children/NavigationSource {
-	public abstract fun subscribe (Lkotlin/jvm/functions/Function1;)V
-	public abstract fun unsubscribe (Lkotlin/jvm/functions/Function1;)V
+	public abstract fun subscribe (Lkotlin/jvm/functions/Function1;)Lcom/arkivanov/decompose/Cancellation;
 }
 
 public final class com/arkivanov/decompose/router/children/SimpleChildNavState : com/arkivanov/decompose/router/children/ChildNavState {
@@ -131,8 +130,7 @@ public final class com/arkivanov/decompose/router/children/SimpleChildNavState :
 public final class com/arkivanov/decompose/router/children/SimpleNavigation : com/arkivanov/decompose/router/children/NavigationSource {
 	public fun <init> ()V
 	public final fun navigate (Ljava/lang/Object;)V
-	public fun subscribe (Lkotlin/jvm/functions/Function1;)V
-	public fun unsubscribe (Lkotlin/jvm/functions/Function1;)V
+	public fun subscribe (Lkotlin/jvm/functions/Function1;)Lcom/arkivanov/decompose/Cancellation;
 }
 
 public final class com/arkivanov/decompose/router/pages/ChildPages {

decompose/api/jvm/decompose.api

@@ -95,8 +95,7 @@ public abstract interface class com/arkivanov/decompose/router/children/NavState
 }
 
 public abstract interface class com/arkivanov/decompose/router/children/NavigationSource {
-	public abstract fun subscribe (Lkotlin/jvm/functions/Function1;)V
-	public abstract fun unsubscribe (Lkotlin/jvm/functions/Function1;)V
+	public abstract fun subscribe (Lkotlin/jvm/functions/Function1;)Lcom/arkivanov/decompose/Cancellation;
 }
 
 public final class com/arkivanov/decompose/router/children/SimpleChildNavState : com/arkivanov/decompose/router/children/ChildNavState {
@@ -115,8 +114,7 @@ public final class com/arkivanov/decompose/router/children/SimpleChildNavState :
 public final class com/arkivanov/decompose/router/children/SimpleNavigation : com/arkivanov/decompose/router/children/NavigationSource {
 	public fun <init> ()V
 	public final fun navigate (Ljava/lang/Object;)V
-	public fun subscribe (Lkotlin/jvm/functions/Function1;)V
-	public fun unsubscribe (Lkotlin/jvm/functions/Function1;)V
+	public fun subscribe (Lkotlin/jvm/functions/Function1;)Lcom/arkivanov/decompose/Cancellation;
 }
 
 public final class com/arkivanov/decompose/router/pages/ChildPages {

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

@@ -50,11 +50,11 @@ internal class Relay<T>(
         }
     }
 
-    fun subscribe(observer: (T) -> Unit) {
+    fun subscribe(observer: (T) -> Unit): Cancellation {
         lock.synchronized { observers += observer }
-    }
 
-    fun unsubscribe(observer: (T) -> Unit) {
-        lock.synchronized { observers -= observer }
+        return Cancellation {
+            lock.synchronized { observers -= observer }
+        }
     }
 }

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

@@ -166,19 +166,17 @@ fun <C : Any, T : Any, E : Any, N : NavState<C>, S : Any> ComponentContext.child
 
     mainBackHandler.register(backCallback)
 
-    val eventObserver: (E) -> Unit =
-        { event ->
+    val cancellation =
+        source.subscribe { event ->
             val oldState = navigator.navState
             navigator.navigate(navState = navTransformer(navigator.navState, event))
             val newState = navigator.navState
             onAfterNavigate(newState, oldState)
             onEventComplete(event, newState, oldState)
         }
 
-    source.subscribe(eventObserver)
-
     lifecycle.doOnDestroy {
-        source.unsubscribe(eventObserver)
+        cancellation.cancel()
         stateKeeper.unregister(key = key)
         mainBackHandler.unregister(backCallback)
     }

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

@@ -1,13 +1,13 @@
 package com.arkivanov.decompose.router.children
 
+import com.arkivanov.decompose.Cancellation
+
 /**
  * Represents a generic source of navigation events.
  *
  * @see [children]
  */
 interface NavigationSource<out T : Any> {
 
-    fun subscribe(observer: (T) -> Unit)
-
-    fun unsubscribe(observer: (T) -> Unit)
+    fun subscribe(observer: (T) -> Unit): Cancellation
 }

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

@@ -1,5 +1,6 @@
 package com.arkivanov.decompose.router.children
 
+import com.arkivanov.decompose.Cancellation
 import com.arkivanov.decompose.Relay
 
 /**
@@ -10,13 +11,8 @@ class SimpleNavigation<T : Any> : NavigationSource<T> {
 
     private val relay = Relay<T>(isMainThreadCheckEnabled = true)
 
-    override fun subscribe(observer: (T) -> Unit) {
+    override fun subscribe(observer: (T) -> Unit): Cancellation =
         relay.subscribe(observer)
-    }
-
-    override fun unsubscribe(observer: (T) -> Unit) {
-        relay.unsubscribe(observer)
-    }
 
     /**
      * Broadcasts the navigation event to every subscribed observer.

decompose/src/commonMain/kotlin/com/arkivanov/decompose/router/pages/DefaultPagesNavigation.kt

@@ -1,19 +1,15 @@
 package com.arkivanov.decompose.router.pages
 
+import com.arkivanov.decompose.Cancellation
 import com.arkivanov.decompose.Relay
 import com.arkivanov.decompose.router.pages.PagesNavigationSource.Event
 
 internal class DefaultPagesNavigation<C : Any> : PagesNavigation<C> {
 
     private val relay = Relay<Event<C>>()
 
-    override fun subscribe(observer: (Event<C>) -> Unit) {
+    override fun subscribe(observer: (Event<C>) -> Unit): Cancellation =
         relay.subscribe(observer)
-    }
-
-    override fun unsubscribe(observer: (Event<C>) -> Unit) {
-        relay.unsubscribe(observer)
-    }
 
     override fun navigate(transformer: (Pages<C>) -> Pages<C>, onComplete: (newPages: Pages<C>, oldPages: Pages<C>) -> Unit) {
         relay.accept(Event(transformer, onComplete))

decompose/src/commonMain/kotlin/com/arkivanov/decompose/router/slot/DefaultSlotNavigation.kt

@@ -1,5 +1,6 @@
 package com.arkivanov.decompose.router.slot
 
+import com.arkivanov.decompose.Cancellation
 import com.arkivanov.decompose.Relay
 import com.arkivanov.decompose.router.slot.SlotNavigationSource.Event
 
@@ -14,11 +15,6 @@ internal class DefaultSlotNavigation<C : Any> : SlotNavigation<C> {
         relay.accept(Event(transformer, onComplete))
     }
 
-    override fun subscribe(observer: (Event<C>) -> Unit) {
+    override fun subscribe(observer: (Event<C>) -> Unit): Cancellation =
         relay.subscribe(observer)
-    }
-
-    override fun unsubscribe(observer: (Event<C>) -> Unit) {
-        relay.unsubscribe(observer)
-    }
 }

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

@@ -1,5 +1,6 @@
 package com.arkivanov.decompose.router.stack
 
+import com.arkivanov.decompose.Cancellation
 import com.arkivanov.decompose.Relay
 import com.arkivanov.decompose.router.stack.StackNavigationSource.Event
 
@@ -11,11 +12,6 @@ internal class DefaultStackNavigation<C : Any> : StackNavigation<C> {
         relay.accept(Event(transformer, onComplete))
     }
 
-    override fun subscribe(observer: (Event<C>) -> Unit) {
+    override fun subscribe(observer: (Event<C>) -> Unit): Cancellation =
         relay.subscribe(observer)
-    }
-
-    override fun unsubscribe(observer: (Event<C>) -> Unit) {
-        relay.unsubscribe(observer)
-    }
 }

decompose/src/commonTest/kotlin/com/arkivanov/decompose/RelayTest.kt

@@ -38,8 +38,7 @@ class RelayTest {
         val relay = Relay<Int>()
         var isEmitted = false
         val observer: (Int) -> Unit = { isEmitted = true }
-        relay.subscribe(observer)
-        relay.unsubscribe(observer)
+        relay.subscribe(observer).cancel()
 
         relay.accept(1)