Rendering Workflows from ComposeWorkflow.

Author: zach-klippenstein

samples/compose-samples/src/main/java/com/squareup/sample/compose/nestedrenderings/NestedRenderingsActivity.kt

@@ -10,6 +10,7 @@ import androidx.compose.ui.graphics.Color
 import androidx.lifecycle.SavedStateHandle
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import com.squareup.workflow1.SimpleLoggingWorkflowInterceptor
 import com.squareup.workflow1.WorkflowExperimentalRuntime
 import com.squareup.workflow1.config.AndroidRuntimeConfigTools
 import com.squareup.workflow1.mapRendering
@@ -47,7 +48,8 @@ class NestedRenderingsActivity : AppCompatActivity() {
         workflow = RecursiveWorkflow.mapRendering { it.withEnvironment(viewEnvironment) },
         scope = viewModelScope,
         savedStateHandle = savedState,
-        runtimeConfig = AndroidRuntimeConfigTools.getAppWorkflowRuntimeConfig()
+        runtimeConfig = AndroidRuntimeConfigTools.getAppWorkflowRuntimeConfig(),
+        interceptors = listOf(SimpleLoggingWorkflowInterceptor())
       )
     }
   }

samples/compose-samples/src/main/java/com/squareup/sample/compose/nestedrenderings/RecursiveWorkflow.kt

@@ -1,13 +1,16 @@
 package com.squareup.sample.compose.nestedrenderings
 
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.saveable.rememberSaveable
+import androidx.compose.runtime.setValue
 import com.squareup.sample.compose.databinding.LegacyViewBinding
 import com.squareup.sample.compose.nestedrenderings.RecursiveWorkflow.LegacyRendering
 import com.squareup.sample.compose.nestedrenderings.RecursiveWorkflow.Rendering
-import com.squareup.sample.compose.nestedrenderings.RecursiveWorkflow.State
-import com.squareup.workflow1.Snapshot
-import com.squareup.workflow1.StatefulWorkflow
-import com.squareup.workflow1.action
-import com.squareup.workflow1.renderChild
+import com.squareup.workflow1.WorkflowExperimentalApi
+import com.squareup.workflow1.compose.ComposeWorkflow
+import com.squareup.workflow1.compose.renderChild
 import com.squareup.workflow1.ui.AndroidScreen
 import com.squareup.workflow1.ui.Screen
 import com.squareup.workflow1.ui.ScreenViewFactory
@@ -20,9 +23,8 @@ import com.squareup.workflow1.ui.ScreenViewFactory
  * to force it to go through the legacy view layer. This way this sample both demonstrates pass-
  * through Composable renderings as well as adapting in both directions.
  */
-object RecursiveWorkflow : StatefulWorkflow<Unit, State, Nothing, Screen>() {
-
-  data class State(val children: Int = 0)
+@OptIn(WorkflowExperimentalApi::class)
+object RecursiveWorkflow : ComposeWorkflow<Unit, Nothing, Screen>() {
 
   /**
    * A rendering from a [RecursiveWorkflow].
@@ -49,33 +51,18 @@ object RecursiveWorkflow : StatefulWorkflow<Unit, State, Nothing, Screen>() {
     )
   }
 
-  override fun initialState(
+  @Composable override fun produceRendering(
     props: Unit,
-    snapshot: Snapshot?
-  ): State = State()
-
-  override fun render(
-    renderProps: Unit,
-    renderState: State,
-    context: RenderContext<Unit, State, Nothing>
-  ): Rendering {
+    emitOutput: (Nothing) -> Unit
+  ): Screen {
+    var children by rememberSaveable { mutableStateOf(0) }
     return Rendering(
-      children = List(renderState.children) { i ->
-        val child = context.renderChild(RecursiveWorkflow, key = i.toString())
+      children = List(children) { i ->
+        val child = renderChild(RecursiveWorkflow)
         if (i % 2 == 0) child else LegacyRendering(child)
       },
-      onAddChildClicked = { context.actionSink.send(addChild()) },
-      onResetClicked = { context.actionSink.send(reset()) }
+      onAddChildClicked = { children++ },
+      onResetClicked = { children = 0 }
     )
   }
-
-  override fun snapshotState(state: State): Snapshot? = null
-
-  private fun addChild() = action("addChild") {
-    state = state.copy(children = state.children + 1)
-  }
-
-  private fun reset() = action("reset") {
-    state = State()
-  }
 }

workflow-core/src/commonMain/kotlin/com/squareup/workflow1/compose/ComposeWorkflow.kt

@@ -38,3 +38,38 @@ public abstract class ComposeWorkflow<PropsT, OutputT, out RenderingT> :
     )
   }
 }
+
+@WorkflowExperimentalApi
+@WorkflowComposable
+@Composable
+public fun <PropsT, OutputT, RenderingT> renderChild(
+  workflow: Workflow<PropsT, OutputT, RenderingT>,
+  props: PropsT,
+  onOutput: ((OutputT) -> Unit)?
+): RenderingT {
+  val renderer = LocalWorkflowComposableRenderer.current
+  return renderer.renderChild(workflow, props, onOutput)
+}
+
+@WorkflowExperimentalApi
+@WorkflowComposable
+@Composable
+inline fun <OutputT, RenderingT> renderChild(
+  workflow: Workflow<Unit, OutputT, RenderingT>,
+  noinline onOutput: ((OutputT) -> Unit)?
+): RenderingT = renderChild(workflow, props = Unit, onOutput)
+
+@WorkflowExperimentalApi
+@WorkflowComposable
+@Composable
+inline fun <PropsT, RenderingT> renderChild(
+  workflow: Workflow<PropsT, Nothing, RenderingT>,
+  props: PropsT,
+): RenderingT = renderChild(workflow, props, onOutput = null)
+
+@WorkflowExperimentalApi
+@WorkflowComposable
+@Composable
+inline fun <RenderingT> renderChild(
+  workflow: Workflow<Unit, Nothing, RenderingT>,
+): RenderingT = renderChild(workflow, props = Unit, onOutput = null)

workflow-core/src/commonMain/kotlin/com/squareup/workflow1/compose/WorkflowComposableRenderer.kt

@@ -0,0 +1,23 @@
+package com.squareup.workflow1.compose
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.staticCompositionLocalOf
+import com.squareup.workflow1.Workflow
+import com.squareup.workflow1.WorkflowExperimentalApi
+
+// TODO mark these with a separate InternalWorkflow annotation
+
+@WorkflowExperimentalApi
+public val LocalWorkflowComposableRenderer =
+  staticCompositionLocalOf<WorkflowComposableRenderer> { error("No renderer") }
+
+@WorkflowExperimentalApi
+public interface WorkflowComposableRenderer {
+
+  @Composable
+  fun <PropsT, OutputT, RenderingT> renderChild(
+    childWorkflow: Workflow<PropsT, OutputT, RenderingT>,
+    props: PropsT,
+    onOutput: ((OutputT) -> Unit)?
+  ): RenderingT
+}

workflow-runtime/src/commonMain/kotlin/com/squareup/workflow1/SimpleLoggingWorkflowInterceptor.kt

@@ -3,6 +3,9 @@ package com.squareup.workflow1
 import androidx.compose.runtime.Composable
 import com.squareup.workflow1.WorkflowInterceptor.RenderContextInterceptor
 import com.squareup.workflow1.WorkflowInterceptor.WorkflowSession
+import com.squareup.workflow1.compose.LocalWorkflowComposableRenderer
+import com.squareup.workflow1.compose.WorkflowComposableRenderer
+import com.squareup.workflow1.internal.compose.withCompositionLocals
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Job
 
@@ -57,8 +60,39 @@ public open class SimpleLoggingWorkflowInterceptor : WorkflowInterceptor {
     emitOutput: (O) -> Unit,
     proceed: @Composable (P, (O) -> Unit) -> R,
     session: WorkflowSession
-  ): R = logMethod("onRenderComposeWorkflow", session) {
-    proceed(renderProps, emitOutput)
+  ): R = logMethod("onRenderComposeWorkflow", session, "renderProps" to renderProps) {
+    val childRenderer = LocalWorkflowComposableRenderer.current
+    val loggingRenderer = androidx.compose.runtime.remember(childRenderer) {
+      SimpleLoggingWorkflowComposableRenderer(session, childRenderer)
+    }
+    withCompositionLocals(LocalWorkflowComposableRenderer provides loggingRenderer) {
+      proceed(renderProps, /* emitOutput= */{ output ->
+        logMethod("onEmitOutput", session, "output" to output) {
+          emitOutput(output)
+        }
+      })
+    }
+  }
+
+  @OptIn(WorkflowExperimentalApi::class)
+  private inner class SimpleLoggingWorkflowComposableRenderer(
+    val session: WorkflowSession,
+    val childRenderer: WorkflowComposableRenderer
+  ) : WorkflowComposableRenderer {
+    @Composable
+    override fun <PropsT, OutputT, RenderingT> renderChild(
+      childWorkflow: Workflow<PropsT, OutputT, RenderingT>,
+      props: PropsT,
+      onOutput: ((OutputT) -> Unit)?
+    ): RenderingT {
+      logMethod("onRenderChild", session, "workflow" to childWorkflow, "props" to props) {
+        return childRenderer.renderChild(childWorkflow, props, onOutput = { output ->
+          logMethod("onOutput", session, "output" to output) {
+            onOutput?.invoke(output)
+          }
+        })
+      }
+    }
   }
 
   override fun <S> onSnapshotState(

workflow-runtime/src/commonMain/kotlin/com/squareup/workflow1/WorkflowInterceptor.kt

@@ -482,3 +482,14 @@ private class InterceptedRenderContext<P, S, O>(
     return coroutineContext
   }
 }
+
+internal fun WorkflowSession.workflowSessionToString(): String {
+  val parentDescription = parent?.let { "WorkflowInstance(…)" }
+  return "WorkflowInstance(" +
+    "identifier=$identifier, " +
+    "renderKey=$renderKey, " +
+    "instanceId=$sessionId, " +
+    "parent=$parentDescription" +
+    ")"
+}
+

workflow-runtime/src/commonMain/kotlin/com/squareup/workflow1/internal/AbstractWorkflowNode.kt

@@ -13,7 +13,8 @@ import com.squareup.workflow1.WorkflowInterceptor
 import com.squareup.workflow1.WorkflowInterceptor.WorkflowSession
 import com.squareup.workflow1.WorkflowTracer
 import com.squareup.workflow1.compose.ComposeWorkflow
-import com.squareup.workflow1.internal.compose.ComposeWorkflowNode
+import com.squareup.workflow1.internal.compose.ComposeWorkflowNodeAdapter
+import com.squareup.workflow1.workflowSessionToString
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CoroutineName
 import kotlinx.coroutines.CoroutineScope
@@ -37,7 +38,7 @@ internal fun <PropsT, OutputT, RenderingT> createWorkflowNode(
   interceptor: WorkflowInterceptor = NoopWorkflowInterceptor,
   idCounter: IdCounter? = null
 ): AbstractWorkflowNode<PropsT, OutputT, RenderingT> = when (workflow) {
-  is ComposeWorkflow<*, *, *> -> ComposeWorkflowNode(
+  is ComposeWorkflow<*, *, *> -> ComposeWorkflowNodeAdapter(
     id = id,
     workflow = workflow as ComposeWorkflow,
     initialProps = initialProps,
@@ -91,15 +92,7 @@ internal abstract class AbstractWorkflowNode<PropsT, OutputT, RenderingT>(
   final override val renderKey: String get() = id.name
   final override val sessionId: Long = idCounter.createId()
 
-  final override fun toString(): String {
-    val parentDescription = parent?.let { "WorkflowInstance(…)" }
-    return "WorkflowInstance(" +
-      "identifier=$identifier, " +
-      "renderKey=$renderKey, " +
-      "instanceId=$sessionId, " +
-      "parent=$parentDescription" +
-      ")"
-  }
+  final override fun toString(): String = workflowSessionToString()
 
   /**
    * Walk the tree of workflows, rendering each one and using

workflow-runtime/src/commonMain/kotlin/com/squareup/workflow1/internal/compose/ComposeChildNode.kt

@@ -0,0 +1,29 @@
+package com.squareup.workflow1.internal.compose
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.currentCompositeKeyHash
+import com.squareup.workflow1.ActionProcessingResult
+import com.squareup.workflow1.TreeSnapshot
+import com.squareup.workflow1.Workflow
+import com.squareup.workflow1.internal.WorkflowNodeId
+import kotlinx.coroutines.selects.SelectBuilder
+
+internal interface ComposeChildNode<PropsT, OutputT, RenderingT> {
+
+  val id: WorkflowNodeId
+
+  @Composable fun produceRendering(
+    workflow: Workflow<PropsT, OutputT, RenderingT>,
+    props: PropsT
+  ): RenderingT
+
+  fun snapshot(): TreeSnapshot
+
+  fun onNextAction(selector: SelectBuilder<ActionProcessingResult>): Boolean
+}
+
+@OptIn(ExperimentalStdlibApi::class)
+@Composable
+internal fun rememberChildRenderKey(): String {
+  return currentCompositeKeyHash.toHexString(HexFormat.Default)
+}