Serialize MutableState as a normal JsonObject

cashapp · Oct 6, 2023 · 3d913f2 · 3d913f2
1 parent 79eb92e
commit 3d913f2
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Showing 2 changed files with 24 additions and 30 deletions.
diff --git a/redwood-treehouse/src/commonMain/kotlin/app/cash/redwood/treehouse/StateSnapshot.kt b/redwood-treehouse/src/commonMain/kotlin/app/cash/redwood/treehouse/StateSnapshot.kt
@@ -21,23 +21,23 @@ import kotlin.jvm.JvmInline
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.JsonArray
 import kotlinx.serialization.json.JsonElement
+import kotlinx.serialization.json.JsonObject
 import kotlinx.serialization.json.JsonPrimitive
 import kotlinx.serialization.json.booleanOrNull
+import kotlinx.serialization.json.buildJsonObject
 import kotlinx.serialization.json.doubleOrNull
 import kotlinx.serialization.json.intOrNull
 
+private const val MutableStateKey = "androidx.compose.runtime.MutableState"
+
 @Serializable
 public class StateSnapshot(
-  public val content: Map<String, List<Saveable>>,
+  public val content: Map<String, List<JsonElement>>,
 ) {
   public fun toValuesMap(): Map<String, List<Any?>> {
     return content.mapValues { entry ->
       entry.value.map {
-        if (it.isMutableState) {
-          mutableStateOf(it.value.fromJsonElement())
-        } else {
-          it.value.fromJsonElement()
-        }
+        it.fromJsonElement()
       }
     }
   }
@@ -52,18 +52,12 @@ public class StateSnapshot(
  * String, Boolean, Int, List (of supported primitive types), Map (of supported primitive types)
  */
 public fun Map<String, List<Any?>>.toStateSnapshot(): StateSnapshot = StateSnapshot(
-  mapValues { entry ->
-    entry.value.map { element ->
-      when (element) {
-        is MutableState<*> -> Saveable(true, element.value.toJsonElement())
-        else -> Saveable(false, element.toJsonElement())
-      }
-    }
-  },
+  mapValues { entry -> entry.value.map { element -> element.toJsonElement() } },
 )
 
 private fun Any?.toJsonElement(): JsonElement {
   return when (this) {
+    is MutableState<*> -> JsonMutableState(value.toJsonElement())
     is String -> JsonPrimitive(this)
     is Int -> JsonPrimitive(this)
     is List<*> -> JsonArray(map { it.toJsonElement() })
@@ -74,22 +68,22 @@ private fun Any?.toJsonElement(): JsonElement {
 }
 
 private fun JsonElement?.fromJsonElement(): Any {
-  return when (this) {
-    is JsonPrimitive -> {
+  return when {
+    this is JsonPrimitive -> {
       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() } })
+    this is JsonArray -> listOf({ this.forEach { it.toJsonElement() } })
+    this is JsonObject && containsKey(MutableStateKey) ->
+      mutableStateOf(getValue(MutableStateKey).fromJsonElement())
     // TODO: map, numbers
     // is Map<*, *> -> JsonElement
     else -> error("unexpected type: $this")
   }
 }
 
-@Serializable
-public data class Saveable(
-  val isMutableState: Boolean,
-  val value: JsonElement,
-)
+internal fun JsonMutableState(element: JsonElement): JsonObject = buildJsonObject {
+  put(MutableStateKey, element)
+}
diff --git a/redwood-treehouse/src/commonTest/kotlin/app/cash/redwood/treehouse/StateSnapshotTest.kt b/redwood-treehouse/src/commonTest/kotlin/app/cash/redwood/treehouse/StateSnapshotTest.kt
@@ -47,19 +47,19 @@ class StateSnapshotTest {
     val storedStateSnapshot = storedStateSnapshot()
     val stateSnapshot = storedStateSnapshot.toStateSnapshot()
     assertThat(stateSnapshot.content).containsOnly(
-      "key1" to listOf(Saveable(true, JsonPrimitive(1))),
-      "key2" to listOf(Saveable(false, JsonPrimitive(1))),
-      "key3" to listOf(Saveable(true, JsonPrimitive("str"))),
-      "key4" to listOf(Saveable(false, JsonPrimitive("str"))),
+      "key1" to listOf(JsonMutableState(JsonPrimitive(1))),
+      "key2" to listOf(JsonPrimitive(1)),
+      "key3" to listOf(JsonMutableState(JsonPrimitive("str"))),
+      "key4" to listOf(JsonPrimitive("str")),
     )
   }
 
   private fun stateSnapshot() = StateSnapshot(
     mapOf(
-      "key1" to listOf(Saveable(true, JsonPrimitive(1))),
-      "key2" to listOf(Saveable(false, JsonPrimitive(1))),
-      "key3" to listOf(Saveable(true, JsonPrimitive("str"))),
-      "key4" to listOf(Saveable(false, JsonPrimitive("str"))),
+      "key1" to listOf(JsonMutableState(JsonPrimitive(1))),
+      "key2" to listOf(JsonPrimitive(1)),
+      "key3" to listOf(JsonMutableState(JsonPrimitive("str"))),
+      "key4" to listOf(JsonPrimitive("str")),
     ),
   )