Create `autoSubscribable` property delegate

1 files changed, 13 insertions, 0 deletions

diff --git a/android/src/main/kotlin/net/mullvad/talpid/util/EventNotifier.kt b/android/src/main/kotlin/net/mullvad/talpid/util/EventNotifier.kt
index 581078ab58..405722f010 100644
--- a/android/src/main/kotlin/net/mullvad/talpid/util/EventNotifier.kt
+++ b/android/src/main/kotlin/net/mullvad/talpid/util/EventNotifier.kt
@@ -55,3 +55,16 @@ class EventNotifier<T>(private val initialValue: T) {
         notify(newValue)
     }
 }
+
+fun <T> autoSubscribable(id: Any, fallback: T, listener: (T) -> Unit) =
+    observable<EventNotifier<T>?>(null) { _, old, new ->
+        if (old != new) {
+            old?.unsubscribe(id)
+
+            if (new == null) {
+                listener.invoke(fallback)
+            } else {
+                new.subscribe(id, listener)
+            }
+        }
+    }