Added derivedValue and rememberOnViewModel

Author: wkornewald

CHANGELOG.md

@@ -5,6 +5,8 @@
 * Added reactive dependency injection solution (see `DI`) with graph tracking that can even re-create ViewModels when a DI module/node is changed at runtime.
 * Added `ContextualVal`/`ContextualValSuspend` for coroutine-local variables (like thread-locals or `CompositionLocal` for coroutines).
 * Made the experimental `ReactiveViewModel` more flexible by building it around `ContextualVal`.
+* Added Composable `rememberOnViewModel { ... }` which remembers the block's result across configuration changes.
+* Added Composable `DI.derivedState { ... }` and `DI.derivedValue { ... }` which remember the block's result until a dependency changes and re-render the UI when needed.
 * Changed `loading` and all `withLoading` parameters from `MutableValueFlow` to `MutableStateFlow`.
 * Changed `increment()`/`decrement()` and `replace` to work on `MutableStateFlow` instead of `MutableValueFlow`.
 * Added `MutableStateFlow.replaceAndGet` and `getAndReplace` which are like their similarly named `updateAndGet`/`getAndUpdate` counterparts, but with the value passed as `this`.

reactivestate-compose/src/composeMain/kotlin/com/ensody/reactivestate/compose/DIExt.kt

@@ -0,0 +1,21 @@
+package com.ensody.reactivestate.compose
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.State
+import androidx.compose.runtime.collectAsState
+import com.ensody.reactivestate.DIImpl
+import com.ensody.reactivestate.DIResolver
+import com.ensody.reactivestate.ExperimentalReactiveStateApi
+
+@ExperimentalReactiveStateApi
+@Composable
+public inline fun <reified T> DIImpl.derivedValue(key: Any? = null, crossinline block: DIResolver.() -> T): T =
+    derivedState(key = key) { block() }.value
+
+@ExperimentalReactiveStateApi
+@Composable
+public inline fun <reified T> DIImpl.derivedState(key: Any? = null, crossinline block: DIResolver.() -> T): State<T> =
+    // TODO: Use qualifiedName once JS supports it
+    rememberOnViewModel(key = "${T::class.simpleName}|$key") {
+        this@derivedState.derived { block() }
+    }.collectAsState()

reactivestate-compose/src/composeMain/kotlin/com/ensody/reactivestate/compose/RememberExt.kt

@@ -0,0 +1,21 @@
+package com.ensody.reactivestate.compose
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.currentCompositeKeyHash
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewmodel.compose.viewModel
+import com.ensody.reactivestate.ExperimentalReactiveStateApi
+import com.ensody.reactivestate.InternalReactiveStateApi
+
+@ExperimentalReactiveStateApi
+@OptIn(InternalReactiveStateApi::class)
+@Composable
+public inline fun <reified T> rememberOnViewModel(key: Any? = null, crossinline block: () -> T): T {
+    val realKey = key ?: currentCompositeKeyHash.toString()
+    // TODO: Use qualifiedName once JS supports it
+    val fullKey = "rememberOnViewModel:${T::class.simpleName}:$realKey"
+    return viewModel(key = fullKey) { RememberViewModel(block()) }.value
+}
+
+@InternalReactiveStateApi
+public class RememberViewModel<T>(public val value: T) : ViewModel()

reactivestate-compose/src/composeMain/kotlin/com/ensody/reactivestate/compose/ViewModelExt.kt

@@ -71,7 +71,7 @@ public inline fun <reified T : Any?> onViewModel(
     crossinline provider: ReactiveStateContext.() -> T,
 ): State<T> {
     // TODO: Use qualifiedName once JS supports it
-    val fullKey = (key ?: "") + ":onViewModel:${T::class.simpleName}"
+    val fullKey = "onViewModel:${T::class.simpleName}:$key"
     val storage = rememberSaveable<MutableMap<String, Any?>> { mutableMapOf() }
     return viewModel(viewModelStoreOwner = viewModelStoreOwner, key = fullKey) {
         WrapperViewModel { viewModelScope ->

reactivestate-core/src/commonMain/kotlin/com/ensody/reactivestate/DI.kt

@@ -103,7 +103,6 @@ public class DIImpl {
             get(state.factory)()
         }
         deps[klass]?.also {
-            // TODO: Can we set both in a single go?
             it.versionOfDependencies.value = 0
             it.factory.value = factory
         } ?: run { deps[klass] = State(newValue, MutableStateFlow(factory)) }