Created StackNavigationHandler and Misc other updates

navigation-compose/src/androidMain/kotlin/com.chrynan.navigation.compose/AndroidNavContainer.kt

@@ -25,7 +25,7 @@ internal actual fun <Context, Key> InternalNavContainer(
  }
  }
 
- BackHandler { navigator.goBack() }
+ BackHandler(enabled = navigator.canGoBack()) { navigator.goBack() }
 }
 
 @Composable
@@ -44,5 +44,5 @@ internal actual fun <Context, Key, NavigationScope : ComposeNavigationKeyScope<K
  }
  }
 
- BackHandler { navigator.goBack() }
+ BackHandler(enabled = navigator.canGoBack()) { navigator.goBack() }
 }

navigation-core/src/androidMain/kotlin/com.chrynan.navigation/AndroidNavigationHandler.kt

@@ -3,5 +3,5 @@ package com.chrynan.navigation
 /**
  * A [NavigationHandler] used on the Android platform that uses an [AndroidNavigationScope].
  */
-fun interface AndroidNavigationHandler<I : NavigationIntent> :
- NavigationHandler<NavigationEvent<I>, AndroidNavigationScope>
+interface AndroidNavigationHandler<Intent : NavigationIntent> :
+ NavigationEventHandler<Intent, AndroidNavigationScope>

navigation-core/src/androidMain/kotlin/com.chrynan.navigation/AndroidNavigator.kt

@@ -4,12 +4,12 @@ package com.chrynan.navigation
 
 import android.app.Activity
 
-internal class AndroidNavigator<I : NavigationIntent>(
- private val handler: AndroidNavigationHandler<I>,
+internal class AndroidNavigator<Intent : NavigationIntent>(
+ private val handler: AndroidNavigationHandler<Intent>,
  private val scope: AndroidNavigationScope
-) : NavigationEventNavigator<I> {
+) : NavigationEventNavigator<Intent> {
 
- override fun navigate(event: NavigationEvent<I>) {
+ override fun navigate(event: NavigationEvent<Intent>) {
  handler.apply {
  scope.onNavigate(event = event)
  }
@@ -32,10 +32,10 @@ internal class AndroidNavigator<I : NavigationIntent>(
  * navigator.goBack()
  * ```
  */
-fun <I : NavigationIntent> navigator(
+fun <Intent : NavigationIntent> navigator(
  activity: Activity,
- handler: AndroidNavigationHandler<I>
-): NavigationEventNavigator<I> {
+ handler: AndroidNavigationHandler<Intent>
+): NavigationEventNavigator<Intent> {
  val scope = AndroidNavigationScope(activity = activity)
 
  return AndroidNavigator(handler = handler, scope = scope)
@@ -54,21 +54,25 @@ fun <I : NavigationIntent> navigator(
  * navigator.goBack()
  * ```
  */
-fun <I : NavigationIntent> navigator(
+fun <Intent : NavigationIntent> navigator(
  activity: Activity,
+ canGoBack: () -> Boolean = { false },
  onGoBack: () -> Unit = { activity.onBackPressed() },
  onGoUp: () -> Unit = { activity.onBackPressed() },
- onGoTo: (intent: I) -> Unit
-): NavigationEventNavigator<I> {
+ onGoTo: (intent: Intent) -> Unit
+): NavigationEventNavigator<Intent> {
  val scope = AndroidNavigationScope(activity = activity)
 
  return AndroidNavigator(
- handler = { event ->
- when (event) {
- is NavigationEvent.Back -> onGoBack()
- is NavigationEvent.Up -> onGoUp()
- is NavigationEvent.To -> onGoTo(event.intent)
- }
+ handler = object : AndroidNavigationHandler<Intent> {
+
+ override fun AndroidNavigationScope.onGoBack() = onGoBack()
+
+ override fun AndroidNavigationScope.onGoUp() = onGoUp()
+
+ override fun AndroidNavigationScope.onGoTo(intent: Intent) = onGoTo(intent)
+
+ override fun AndroidNavigationScope.canGoBack(): Boolean = canGoBack()
  },
  scope = scope
  )

navigation-core/src/commonMain/kotlin/com.chrynan.navigation/NavigationEvent.kt

@@ -8,13 +8,13 @@ package com.chrynan.navigation
  * @see [Navigator.navigate]
  * @see [NavigationHandler.onNavigate]
  */
-sealed class NavigationEvent<I : NavigationIntent> {
+sealed class NavigationEvent<Intent : NavigationIntent> {
 
- class Back<I : NavigationIntent> internal constructor() : NavigationEvent<I>()
+ class Back<Intent : NavigationIntent> internal constructor() : NavigationEvent<Intent>()
 
- class Up<I : NavigationIntent> internal constructor() : NavigationEvent<I>()
+ class Up<Intent : NavigationIntent> internal constructor() : NavigationEvent<Intent>()
 
- data class To<I : NavigationIntent> internal constructor(val intent: I) : NavigationEvent<I>()
+ data class To<Intent : NavigationIntent> internal constructor(val intent: Intent) : NavigationEvent<Intent>()
 
  companion object
 }

navigation-core/src/commonMain/kotlin/com.chrynan.navigation/NavigationEventHandler.kt

@@ -6,21 +6,24 @@ package com.chrynan.navigation
  * A [NavigationHandler] that provides distinct functions for each of the possible
  * [NavigationEvent]s.
  */
-interface NavigationEventHandler<I : NavigationIntent, S : NavigationScope> :
- NavigationHandler<NavigationEvent<I>, S> {
+interface NavigationEventHandler<Intent : NavigationIntent, Scope : NavigationScope> :
+ NavigationHandler<NavigationEvent<Intent>, Scope>,
+ StackNavigationHandler<NavigationEvent<Intent>, Scope> {
 
- fun S.onGoBack()
+ fun Scope.onGoBack()
 
- fun S.onGoUp()
+ fun Scope.onGoUp()
 
- fun S.onGoTo(intent: I)
+ fun Scope.onGoTo(intent: Intent)
 
- override fun S.onNavigate(event: NavigationEvent<I>) =
+ override fun Scope.onNavigate(event: NavigationEvent<Intent>) =
  when (event) {
  is NavigationEvent.Back -> onGoBack()
  is NavigationEvent.Up -> onGoUp()
  is NavigationEvent.To -> onGoTo(intent = event.intent)
  }
 
+ override fun Scope.canGoBack(): Boolean = false
+
  companion object
 }

navigation-core/src/commonMain/kotlin/com.chrynan.navigation/NavigationEventNavigator.kt

@@ -6,28 +6,28 @@ package com.chrynan.navigation
  * A [Navigator] that navigates using [NavigationEvent]s. This is typically the base [Navigator] but not every UI
  * framework can use it, such as Jetpack Compose, so it is separate from the [Navigator] interface.
  */
-interface NavigationEventNavigator<I : NavigationIntent> : Navigator {
+interface NavigationEventNavigator<Intent : NavigationIntent> : Navigator {
 
  /**
  * Navigates to the provided [event].
  */
- fun navigate(event: NavigationEvent<I>)
+ fun navigate(event: NavigationEvent<Intent>)
 }
 
 /**
  * A convenience function for calling [NavigationEventNavigator.navigate] with [NavigationEvent.Back].
  */
-fun <I : NavigationIntent> NavigationEventNavigator<I>.goBack() =
+fun <Intent : NavigationIntent> NavigationEventNavigator<Intent>.goBack() =
  navigate(event = NavigationEvent.Back())
 
 /**
  * A convenience function for calling [NavigationEventNavigator.navigate] with [NavigationEvent.Up].
  */
-fun <I : NavigationIntent> NavigationEventNavigator<I>.goUp() =
+fun <Intent : NavigationIntent> NavigationEventNavigator<Intent>.goUp() =
  navigate(event = NavigationEvent.Up())
 
 /**
  * A convenience function for calling [NavigationEventNavigator.navigate] with [NavigationEvent.To].
  */
-fun <I : NavigationIntent> NavigationEventNavigator<I>.goTo(intent: I) =
+fun <Intent : NavigationIntent> NavigationEventNavigator<Intent>.goTo(intent: Intent) =
  navigate(event = NavigationEvent.To(intent = intent))

navigation-core/src/commonMain/kotlin/com.chrynan.navigation/StackNavigationHandler.kt

@@ -0,0 +1,14 @@
+package com.chrynan.navigation
+
+/**
+ * An extension on the [NavigationHandler] that provides functions to determine back navigation capability.
+ */
+interface StackNavigationHandler<Event : Any, Scope : NavigationScope> : NavigationHandler<Event, Scope> {
+
+ /**
+ * Determines whether a back navigation can be handled.
+ */
+ fun Scope.canGoBack(): Boolean
+
+ companion object
+}