Merge pull request #1267 from square/ray/remember-event-handler

*BREAKING* Introduces `BaseRenderContext.remember` and stable `eventHandlers`.

Author: rjrjr

benchmarks/performance-poetry/complex-poetry/src/main/java/com/squareup/benchmarks/performance/complex/poetry/instrumentation/ActionHandlingTracingInterceptor.kt

@@ -12,12 +12,12 @@ import com.squareup.workflow1.WorkflowInterceptor.WorkflowSession
  * particular events.
  *
  * If you want to trace how long Workflow takes to process a UI event, then
- * annotate the [RenderContext.eventHandler] name argument with [keyForTrace]. That will cause
+ * annotate the `RenderContext.eventHandler` name argument with [keyForTrace]. That will cause
  * this interceptor to pick it up when the action is sent into the sink and trace that main thread
  * message.
  *
- * If you want to trace how long Workflow takes to process the result of a [Worker], then
- * annotate the [Worker] using [TraceableWorker] which will set it up with a key such that when
+ * If you want to trace how long Workflow takes to process the result of a `Worker`, then
+ * annotate the `Worker` using [TraceableWorker] which will set it up with a key such that when
  * the action for the result is sent to the sink the main thread message will be traced.
  */
 class ActionHandlingTracingInterceptor : WorkflowInterceptor, Resettable {

samples/compose-samples/src/main/java/com/squareup/sample/compose/inlinerendering/InlineRenderingWorkflow.kt

@@ -3,7 +3,6 @@
 package com.squareup.sample.compose.inlinerendering
 
 import androidx.compose.animation.AnimatedContent
-import androidx.compose.animation.ExperimentalAnimationApi
 import androidx.compose.animation.SizeTransform
 import androidx.compose.animation.fadeIn
 import androidx.compose.animation.fadeOut
@@ -38,12 +37,15 @@ object InlineRenderingWorkflow : StatefulWorkflow<Unit, Int, Nothing, Screen>()
     renderProps: Unit,
     renderState: Int,
     context: RenderContext
-  ) = ComposeScreen {
-    Box {
-      Button(onClick = context.eventHandler("increment") { state += 1 }) {
-        Text("Counter: ")
-        AnimatedCounter(renderState) { counterValue ->
-          Text(counterValue.toString())
+  ): ComposeScreen {
+    val onClick = context.eventHandler("increment") { state += 1 }
+    return ComposeScreen {
+      Box {
+        Button(onClick = onClick) {
+          Text("Counter: ")
+          AnimatedCounter(renderState) { counterValue ->
+            Text(counterValue.toString())
+          }
         }
       }
     }
@@ -68,7 +70,6 @@ internal fun InlineRenderingWorkflowPreview() {
   InlineRenderingWorkflowRendering()
 }
 
-@OptIn(ExperimentalAnimationApi::class)
 @Composable
 private fun AnimatedCounter(
   counterValue: Int,
@@ -79,6 +80,7 @@ private fun AnimatedCounter(
     transitionSpec = {
       ((slideInVertically() + fadeIn()).togetherWith(slideOutVertically() + fadeOut()))
         .using(SizeTransform(clip = false))
-    }
+    },
+    label = ""
   ) { content(it) }
 }

samples/containers/poetry/src/main/java/com/squareup/sample/poetry/StanzaListWorkflow.kt

@@ -15,7 +15,7 @@ object StanzaListWorkflow : StatelessWorkflow<Props, SelectedStanza, StanzaListS
 
   data class Props(
     val poem: Poem,
-    val eventHandlerTag: (String) -> String = { "" }
+    val eventHandlerTag: (String) -> String = { it }
   )
 
   const val NO_SELECTED_STANZA = -1

samples/containers/poetry/src/main/java/com/squareup/sample/poetry/StanzaWorkflow.kt

@@ -12,7 +12,7 @@ object StanzaWorkflow : StatelessWorkflow<Props, Output, StanzaScreen>() {
   data class Props(
     val poem: Poem,
     val index: Int,
-    val eventHandlerTag: (String) -> String = { "" }
+    val eventHandlerTag: (String) -> String = { it }
   )
 
   enum class Output {

samples/dungeon/timemachine/src/test/java/com/squareup/sample/timemachine/TimeMachineWorkflowTest.kt

@@ -25,7 +25,10 @@ class TimeMachineWorkflowTest {
     val delegateWorkflow = Workflow.stateful<String, Nothing, DelegateRendering>(
       initialState = "initial",
       render = { renderState ->
-        DelegateRendering(renderState, setState = eventHandler("") { s -> state = s })
+        DelegateRendering(
+          renderState,
+          setState = eventHandler("setState") { s -> state = s }
+        )
       }
     )
     val clock = TestTimeSource()

samples/nested-overlays/src/main/java/com/squareup/sample/nestedoverlays/NestedOverlaysWorkflow.kt

@@ -62,7 +62,7 @@ object NestedOverlaysWorkflow : StatefulWorkflow<Unit, State, Nothing, Screen>()
               name = R.string.close,
               onClick = closeOuter
             ),
-            context.toggleInnerSheetButton(renderState),
+            context.toggleInnerSheetButton(name = "inner", renderState),
             color = android.R.color.holo_green_light,
             showEditText = true,
           ),
@@ -103,33 +103,59 @@ object NestedOverlaysWorkflow : StatefulWorkflow<Unit, State, Nothing, Screen>()
       name = "outer",
       overlays = listOfNotNull(outerSheet),
       body = TopAndBottomBarsScreen(
-        topBar = if (!renderState.showTopBar) null else context.topBottomBar(renderState),
+        topBar = if (!renderState.showTopBar) {
+          null
+        } else {
+          context.topBottomBar(
+            top = true,
+            renderState
+          )
+        },
         content = BodyAndOverlaysScreen(
           name = "inner",
           body = bodyBarButtons,
           overlays = listOfNotNull(innerSheet)
         ),
-        bottomBar = if (!renderState.showBottomBar) null else context.topBottomBar(renderState)
+        bottomBar = if (!renderState.showBottomBar) {
+          null
+        } else {
+          context.topBottomBar(
+            top = false,
+            renderState
+          )
+        }
       )
     )
   }
 
   override fun snapshotState(state: State) = null
 
   private fun RenderContext.topBottomBar(
+    top: Boolean,
     renderState: State
-  ) = ButtonBar(
-    toggleInnerSheetButton(renderState),
-    Button(
-      name = R.string.cover_all,
-      onClick = eventHandler("cover everything") { state = state.copy(showOuterSheet = true) }
+  ): ButtonBar {
+    val name = if (top) "top" else "bottom"
+    return ButtonBar(
+      toggleInnerSheetButton(
+        name = name,
+        renderState = renderState,
+      ),
+      Button(
+        name = R.string.cover_all,
+        onClick = eventHandler("$name cover everything") {
+          state = state.copy(showOuterSheet = true)
+        }
+      )
     )
-  )
+  }
 
-  private fun RenderContext.toggleInnerSheetButton(renderState: State) =
+  private fun RenderContext.toggleInnerSheetButton(
+    name: String,
+    renderState: State
+  ) =
     Button(
       name = if (renderState.showInnerSheet) R.string.reveal_body else R.string.cover_body,
-      onClick = eventHandler("reveal / cover body") {
+      onClick = eventHandler("$name: reveal / cover body") {
         state = state.copy(showInnerSheet = !state.showInnerSheet)
       }
     )