Add support to save non-mutable int in StateSnapshot

redwood-lazylayout-compose/build.gradle

@@ -14,6 +14,7 @@ kotlin {
     commonMain {
       dependencies {
         api projects.redwoodLazylayoutWidget
+        implementation libs.jetbrains.compose.runtime.saveable
       }
     }
     commonTest {

redwood-lazylayout-compose/src/commonMain/kotlin/app/cash/redwood/lazylayout/compose/LazyListState.kt

@@ -15,17 +15,18 @@
  */
 package app.cash.redwood.lazylayout.compose
 
+import androidx.compose.runtime.saveable.Saver
+import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 
 @Composable
 public fun rememberLazyListState(
   initialFirstVisibleItemIndex: Int = 0,
 ): LazyListState {
-  return remember {
+  return rememberSaveable(saver = LazyListState.Saver) {
     LazyListState(
       initialFirstVisibleItemIndex,
     )
@@ -46,4 +47,17 @@ public class LazyListState(
     firstVisibleItemIndex = index
     scrollToItemTriggeredId++
   }
+  public companion object {
+    /**
+     * The default [Saver] implementation for [LazyListState].
+     */
+    public val Saver: Saver<LazyListState, *> = Saver(
+      save = { it.firstVisibleItemIndex },
+      restore = {
+        LazyListState(
+          firstVisibleItemIndex = it,
+        )
+      }
+    )
+  }
 }

redwood-treehouse-guest/src/commonMain/kotlin/app/cash/redwood/treehouse/treehouseCompose.kt

@@ -110,6 +110,7 @@ private class RedwoodZiplineTreehouseUi(
   }
 
   override fun snapshotState(): StateSnapshot? {
+    // performSave is not picking up other values, why?
     val savedState = saveableStateRegistry.performSave()
     return savedState.toStateSnapshot()
   }

redwood-treehouse/src/commonMain/kotlin/app/cash/redwood/treehouse/StateSnapshot.kt

@@ -18,20 +18,28 @@ package app.cash.redwood.treehouse
 import androidx.compose.runtime.MutableState
 import androidx.compose.runtime.mutableStateOf
 import kotlin.jvm.JvmInline
+import kotlinx.serialization.Contextual
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.JsonArray
 import kotlinx.serialization.json.JsonElement
 import kotlinx.serialization.json.JsonPrimitive
 import kotlinx.serialization.json.booleanOrNull
 import kotlinx.serialization.json.doubleOrNull
+import kotlinx.serialization.json.intOrNull
 
 @Serializable
 public class StateSnapshot(
-  public val content: Map<String, List<JsonElement?>>,
+  public val content: Map<String, List<@Contextual Saveable>>
 ) {
-  public fun toValuesMap(): Map<String, List<Any?>>? {
+  public fun toValuesMap(): Map<String, List<Any?>> {
     return content.mapValues { entry ->
-      entry.value.map { mutableStateOf(it.fromJsonElement()) }
+      entry.value.map {
+        if (it.isMutableState) {
+          mutableStateOf(it.value)
+        } else {
+          it.value.fromJsonElement()
+        }
+      }
     }
   }
 
@@ -46,10 +54,10 @@ public class StateSnapshot(
  */
 public fun Map<String, List<Any?>>.toStateSnapshot(): StateSnapshot = StateSnapshot(
   mapValues { entry ->
-    entry.value.map { element ->
-      when (element) {
-        is MutableState<*> -> element.value.toJsonElement()
-        else -> error("unexpected type: $this")
+    entry.value.map {element ->
+      when(element) {
+        is MutableState<*> -> Saveable(true, element.value.toJsonElement())
+        else -> Saveable(false, element.toJsonElement())
       }
     }
   },
@@ -58,6 +66,7 @@ public fun Map<String, List<Any?>>.toStateSnapshot(): StateSnapshot = StateSnaps
 private fun Any?.toJsonElement(): JsonElement {
   return when (this) {
     is String -> JsonPrimitive(this)
+    is Int -> JsonPrimitive(this)
     is List<*> -> JsonArray(map { it.toJsonElement() })
     is JsonElement -> this
     else -> error("unexpected type: $this")
@@ -68,11 +77,9 @@ private fun Any?.toJsonElement(): JsonElement {
 private fun JsonElement?.fromJsonElement(): Any {
   return when (this) {
     is JsonPrimitive -> {
-      if (this.isString) {
-        return content
-      }
-      return booleanOrNull ?: doubleOrNull ?: error("unexpected type: $this")
-      // TODO add other primitive types (double, float, long) when needed
+      if (this.isString) { return content }
+      return booleanOrNull ?: doubleOrNull ?: intOrNull ?: error("unexpected type: $this")
+      // TODO add other primitive types (float, long) when needed
     }
 
     is JsonArray -> listOf({ this.forEach { it.toJsonElement() } })
@@ -81,3 +88,8 @@ private fun JsonElement?.fromJsonElement(): Any {
     else -> error("unexpected type: $this")
   }
 }
+
+public data class Saveable (
+  val isMutableState: Boolean,
+  val value: JsonElement
+)

samples/emoji-search/presenter/src/commonMain/kotlin/com/example/redwood/emojisearch/presenter/EmojiSearch.kt

@@ -36,6 +36,7 @@ import app.cash.redwood.layout.compose.Column
 import app.cash.redwood.layout.compose.Row
 import app.cash.redwood.lazylayout.compose.ExperimentalRedwoodLazyLayoutApi
 import app.cash.redwood.lazylayout.compose.LazyColumn
+import app.cash.redwood.lazylayout.compose.LazyListState
 import app.cash.redwood.lazylayout.compose.items
 import app.cash.redwood.lazylayout.compose.rememberLazyListState
 import app.cash.redwood.ui.Margin
@@ -96,7 +97,9 @@ private fun LazyColumn(
     override fun SaverScope.save(value: TextFieldState) = value.text
   }
 
-  var searchTerm by rememberSaveable(stateSaver = searchTermSaver) { mutableStateOf(TextFieldState("")) }
+  var searchTerm by rememberSaveable(stateSaver = searchTermSaver) {
+    mutableStateOf(TextFieldState(""))
+  }
 
   LaunchedEffect(refreshSignal) {
     try {
@@ -173,7 +176,14 @@ private fun NestedFlexBoxContainers(httpClient: HttpClient, navigator: Navigator
     override fun SaverScope.save(value: TextFieldState) = value.text
   }
 
-  var searchTerm by rememberSaveable(stateSaver = searchTermSaver) { mutableStateOf(TextFieldState("")) }
+  var searchTerm by rememberSaveable(stateSaver = searchTermSaver) {
+    error("boom")
+    mutableStateOf(TextFieldState(""))
+  }
+  var searchTerm1 by rememberSaveable(stateSaver = searchTermSaver) {
+    error("boom")
+    mutableStateOf(TextFieldState("hhh"))
+  }
 
   LaunchedEffect(Unit) {
     try {