Introduces AndroidViewRendering, de-emphasizes ViewRegistry

rjrjr · rjrjr · commit 4e63f72e8789 · 2020-11-19T09:51:54.000-08:00
`AndroidViewRendering` is implemented by renderings that can provide their own
`ViewFactory`. `ViewRegistry.buildView` looks to see if a given rendering
implements that method if it fails to find an entry for it -- note that we
look for a registration first, so `ViewRegistry` is able override the default.

Given this, it's no longer crucial for developers to define and provide a
`ViewRegistry`, so we get rid of all the nannying that forced them to provide
one.
diff --git a/samples/hello-workflow/src/main/java/com/squareup/sample/helloworkflow/HelloView.kt b/samples/hello-workflow/src/main/java/com/squareup/sample/helloworkflow/HelloView.kt
@@ -0,0 +1,19 @@
+package com.squareup.sample.helloworkflow
+
+import com.squareup.sample.helloworkflow.databinding.HelloGoodbyeLayoutBinding
+import com.squareup.workflow1.ui.AndroidViewRendering
+import com.squareup.workflow1.ui.LayoutRunner
+import com.squareup.workflow1.ui.ViewFactory
+import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
+
+@OptIn(WorkflowUiExperimentalApi::class)
+data class HelloView(
+  val message: String,
+  val onClick: () -> Unit
+) : AndroidViewRendering<HelloView> {
+  override val viewFactory: ViewFactory<HelloView> =
+    LayoutRunner.bind(HelloGoodbyeLayoutBinding::inflate) { r, _ ->
+      helloMessage.text = r.message
+      helloMessage.setOnClickListener { r.onClick() }
+    }
+}
diff --git a/samples/hello-workflow/src/main/java/com/squareup/sample/helloworkflow/HelloViewFactory.kt b/samples/hello-workflow/src/main/java/com/squareup/sample/helloworkflow/HelloViewFactory.kt
diff --git a/samples/hello-workflow/src/main/java/com/squareup/sample/helloworkflow/HelloWorkflow.kt b/samples/hello-workflow/src/main/java/com/squareup/sample/helloworkflow/HelloWorkflow.kt
@@ -1,21 +1,5 @@
-/*
- * Copyright 2019 Square Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
 package com.squareup.sample.helloworkflow
 
-import com.squareup.sample.helloworkflow.HelloWorkflow.Rendering
 import com.squareup.sample.helloworkflow.HelloWorkflow.State
 import com.squareup.sample.helloworkflow.HelloWorkflow.State.Goodbye
 import com.squareup.sample.helloworkflow.HelloWorkflow.State.Hello
@@ -24,31 +8,26 @@ import com.squareup.workflow1.StatefulWorkflow
 import com.squareup.workflow1.action
 import com.squareup.workflow1.parse
 
-object HelloWorkflow : StatefulWorkflow<Unit, State, Nothing, Rendering>() {
+object HelloWorkflow : StatefulWorkflow<Unit, State, Nothing, HelloView>() {
   enum class State {
     Hello,
     Goodbye
   }
 
-  data class Rendering(
-    val message: String,
-    val onClick: () -> Unit
-  )
-
   override fun initialState(
     props: Unit,
     snapshot: Snapshot?
   ): State = snapshot?.bytes?.parse { source -> if (source.readInt() == 1) Hello else Goodbye }
-      ?: Hello
+    ?: Hello
 
   override fun render(
     props: Unit,
     state: State,
     context: RenderContext
-  ): Rendering {
-    return Rendering(
-        message = state.name,
-        onClick = { context.actionSink.send(helloAction) }
+  ): HelloView {
+    return HelloView(
+      message = state.name,
+      onClick = { context.actionSink.send(helloAction) }
     )
   }
 
diff --git a/samples/hello-workflow/src/main/java/com/squareup/sample/helloworkflow/HelloWorkflowActivity.kt b/samples/hello-workflow/src/main/java/com/squareup/sample/helloworkflow/HelloWorkflowActivity.kt
@@ -1,36 +1,17 @@
-/*
- * Copyright 2019 Square Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
 package com.squareup.sample.helloworkflow
 
 import android.os.Bundle
 import androidx.appcompat.app.AppCompatActivity
 import com.squareup.workflow1.SimpleLoggingWorkflowInterceptor
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
-import com.squareup.workflow1.ui.ViewRegistry
 import com.squareup.workflow1.ui.WorkflowRunner
 import com.squareup.workflow1.ui.setContentWorkflow
 
-@OptIn(WorkflowUiExperimentalApi::class)
-private val viewRegistry = ViewRegistry(HelloViewFactory)
-
 @OptIn(WorkflowUiExperimentalApi::class)
 class HelloWorkflowActivity : AppCompatActivity() {
   override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
-    setContentWorkflow(viewRegistry) {
+    setContentWorkflow {
       WorkflowRunner.Config(
           HelloWorkflow,
           interceptors = listOf(SimpleLoggingWorkflowInterceptor())
diff --git a/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/AndroidViewRendering.kt b/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/AndroidViewRendering.kt
@@ -0,0 +1,6 @@
+package com.squareup.workflow1.ui
+
+@WorkflowUiExperimentalApi
+interface AndroidViewRendering<V : AndroidViewRendering<V>> {
+  val viewFactory: ViewFactory<V>
+}
diff --git a/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/CompositeViewRegistry.kt b/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/CompositeViewRegistry.kt
@@ -42,14 +42,7 @@ internal class CompositeViewRegistry private constructor(
 
   override fun <RenderingT : Any> getFactoryFor(
     renderingType: KClass<out RenderingT>
-  ): ViewFactory<RenderingT> = getRegistryFor(renderingType).getFactoryFor(renderingType)
-
-  private fun getRegistryFor(renderingType: KClass<out Any>): ViewRegistry {
-    return requireNotNull(registriesByKey[renderingType]) {
-      "A ${ViewFactory::class.java.name} should have been registered " +
-          "to display a $renderingType."
-    }
-  }
+  ): ViewFactory<RenderingT>? = registriesByKey[renderingType]?.getFactoryFor(renderingType)
 
   companion object {
     private fun mergeRegistries(vararg registries: ViewRegistry): Map<KClass<*>, ViewRegistry> {
diff --git a/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/NamedViewFactory.kt b/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/NamedViewFactory.kt
@@ -1,18 +1,3 @@
-/*
- * Copyright 2019 Square Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
 package com.squareup.workflow1.ui
 
 /**
diff --git a/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/TypedViewRegistry.kt b/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/TypedViewRegistry.kt
@@ -40,11 +40,8 @@ internal class TypedViewRegistry private constructor(
 
   override fun <RenderingT : Any> getFactoryFor(
     renderingType: KClass<out RenderingT>
-  ): ViewFactory<RenderingT> {
+  ): ViewFactory<RenderingT>? {
     @Suppress("UNCHECKED_CAST")
-    return requireNotNull(bindings[renderingType] as? ViewFactory<RenderingT>) {
-      "A ${ViewFactory::class.java.name} should have been registered " +
-          "to display a $renderingType."
-    }
+    return bindings[renderingType] as? ViewFactory<RenderingT>
   }
 }
diff --git a/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/ViewEnvironment.kt b/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/ViewEnvironment.kt
@@ -30,17 +30,11 @@ typealias ContainerHints = ViewEnvironment
  * its children via [View.showRendering][android.view.View.showRendering] et al.
  * Allows container views to give descendants information about the context in which
  * they're drawing.
- *
- * Every [ViewEnvironment] includes a [ViewRegistry]. This allows container views to
- * make recursive [ViewRegistry.buildView] calls to build child views to show nested renderings.
  */
 @WorkflowUiExperimentalApi
-class ViewEnvironment private constructor(
-  private val map: Map<ViewEnvironmentKey<*>, Any>
+class ViewEnvironment(
+  val map: Map<ViewEnvironmentKey<*>, Any> = emptyMap()
 ) {
-  constructor(registry: ViewRegistry) :
-      this(mapOf<ViewEnvironmentKey<*>, Any>(ViewRegistry to registry))
-
   @Suppress("UNCHECKED_CAST")
   operator fun <T : Any> get(key: ViewEnvironmentKey<T>): T = map[key] as? T ?: key.default
 
diff --git a/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/ViewRegistry.kt b/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/ViewRegistry.kt
@@ -70,17 +70,15 @@ interface ViewRegistry {
   /**
    * This method is not for general use, use [WorkflowViewStub] instead.
    *
-   * Returns the [ViewFactory] that was registered for the given [renderingType].
-   *
-   * @throws IllegalArgumentException if no factory can be found for type [RenderingT]
+   * Returns the [ViewFactory] that was registered for the given [renderingType], or null
+   * if none was found.
    */
   fun <RenderingT : Any> getFactoryFor(
     renderingType: KClass<out RenderingT>
-  ): ViewFactory<RenderingT>
+  ): ViewFactory<RenderingT>?
 
   companion object : ViewEnvironmentKey<ViewRegistry>(ViewRegistry::class) {
-    override val default: ViewRegistry
-      get() = error("There should always be a ViewRegistry hint, this is bug in Workflow.")
+    override val default: ViewRegistry get() = ViewRegistry()
   }
 }
 
@@ -105,7 +103,7 @@ fun ViewRegistry(): ViewRegistry = TypedViewRegistry()
  * It is usually more convenient to use [WorkflowViewStub] than to call this method directly.
  *
  * Creates a [View] to display [initialRendering], which can be updated via calls
- * to [View.showRendering].
+ * to [View.showRendering]. Uses
  *
  * @throws IllegalArgumentException if no factory can be find for type [RenderingT]
  *
@@ -119,19 +117,27 @@ fun <RenderingT : Any> ViewRegistry.buildView(
   contextForNewView: Context,
   container: ViewGroup? = null
 ): View {
-  return getFactoryFor(initialRendering::class)
-      .buildView(
-          initialRendering,
-          initialViewEnvironment,
-          contextForNewView,
-          container
-      )
-      .apply {
-        check(this.getRendering<Any>() != null) {
-          "View.bindShowRendering should have been called for $this, typically by the " +
-              "${ViewFactory::class.java.name} that created it."
-        }
+  @Suppress("UNCHECKED_CAST")
+  val factory: ViewFactory<RenderingT> = getFactoryFor(initialRendering::class)
+    ?: (initialRendering as? AndroidViewRendering<*>)?.viewFactory as ViewFactory<RenderingT>
+    ?: throw IllegalArgumentException(
+      "A ${ViewFactory::class.qualifiedName} should have been registered " +
+        "to display ${initialRendering::class.qualifiedName} instances, or that class " +
+        "should implement ${ViewFactory::class.simpleName}<${initialRendering::class.simpleName}>."
+    )
+
+  return factory.buildView(
+    initialRendering,
+    initialViewEnvironment,
+    contextForNewView,
+    container
+  )
+    .apply {
+      check(this.getRendering<Any>() != null) {
+        "View.bindShowRendering should have been called for $this, typically by the " +
+          "${ViewFactory::class.java.name} that created it."
       }
+    }
 }
 
 /**
diff --git a/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/WorkflowLayout.kt b/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/WorkflowLayout.kt
@@ -50,26 +50,14 @@ class WorkflowLayout(
 
   private var restoredChildState: SparseArray<Parcelable>? = null
 
-  /**
-   * Subscribes to [renderings], and uses [registry] to
-   * [build a new view][ViewRegistry.buildView] each time a new type of rendering is received,
-   * making that view the only child of this one.
-   */
-  fun start(
-    renderings: Flow<Any>,
-    registry: ViewRegistry
-  ) {
-    start(renderings, ViewEnvironment(registry))
-  }
-
   /**
    * Subscribes to [renderings], and uses the [ViewRegistry] in the given [environment] to
    * [build a new view][ViewRegistry.buildView] each time a new type of rendering is received,
    * making that view the only child of this one.
    */
   fun start(
     renderings: Flow<Any>,
-    environment: ViewEnvironment
+    environment: ViewEnvironment = ViewEnvironment()
   ) {
     val envWithDefaults = environment.withDefaultViewFactories()
     takeWhileAttached(renderings) { show(it, envWithDefaults) }
@@ -89,7 +77,7 @@ class WorkflowLayout(
     }
   }
 
-  override fun onSaveInstanceState(): Parcelable? {
+  override fun onSaveInstanceState(): Parcelable {
     return SavedState(
         super.onSaveInstanceState()!!,
         SparseArray<Parcelable>().also { array -> showing.actual.saveHierarchyState(array) }
diff --git a/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/WorkflowRunner.kt b/workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/WorkflowRunner.kt
@@ -155,7 +155,7 @@ interface WorkflowRunner<out OutputT> {
  */
 @WorkflowUiExperimentalApi
 fun <PropsT, OutputT> FragmentActivity.setContentWorkflow(
-  viewEnvironment: ViewEnvironment,
+  viewEnvironment: ViewEnvironment = ViewEnvironment(),
   configure: () -> Config<PropsT, OutputT>,
   onResult: (OutputT) -> Unit
 ): WorkflowRunner<OutputT> {
@@ -176,28 +176,6 @@ fun <PropsT, OutputT> FragmentActivity.setContentWorkflow(
   return runner
 }
 
-/**
- * Call this method from [FragmentActivity.onCreate], instead of [FragmentActivity.setContentView].
- * It creates a [WorkflowRunner] for this activity, if one doesn't already exist, and
- * sets a view driven by that model as the content view.
- *
- * @param registry used to display workflow renderings.
- *
- * @param configure function defining the root workflow and its environment. Called only
- * once per [lifecycle][FragmentActivity.getLifecycle], and always called from the UI thread.
- *
- * @param onResult function called with the first (and only) output emitted by the root workflow,
- * handy for passing to [FragmentActivity.setResult]. The workflow is ended once it emits any
- * values, so this is also a good place from which to call [FragmentActivity.finish]. Called
- * only while the activity is active, and always called from the UI thread.
- */
-@WorkflowUiExperimentalApi
-fun <PropsT, OutputT> FragmentActivity.setContentWorkflow(
-  registry: ViewRegistry,
-  configure: () -> Config<PropsT, OutputT>,
-  onResult: (OutputT) -> Unit
-): WorkflowRunner<OutputT> = setContentWorkflow(ViewEnvironment(registry), configure, onResult)
-
 /**
  * For workflows that produce no output, call this method from [FragmentActivity.onCreate]
  * instead of [FragmentActivity.setContentView].
@@ -211,23 +189,6 @@ fun <PropsT, OutputT> FragmentActivity.setContentWorkflow(
  */
 @WorkflowUiExperimentalApi
 fun <PropsT> FragmentActivity.setContentWorkflow(
-  viewEnvironment: ViewEnvironment,
+  viewEnvironment: ViewEnvironment = ViewEnvironment(),
   configure: () -> Config<PropsT, Nothing>
 ): WorkflowRunner<Nothing> = setContentWorkflow(viewEnvironment, configure) {}
-
-/**
- * For workflows that produce no output, call this method from [FragmentActivity.onCreate]
- * instead of [FragmentActivity.setContentView].
- * It creates a [WorkflowRunner] for this activity, if one doesn't already exist, and
- * sets a view driven by that model as the content view.
- *
- * @param registry used to display workflow renderings.
- *
- * @param configure function defining the root workflow and its environment. Called only
- * once per [lifecycle][FragmentActivity.getLifecycle], and always called from the UI thread.
- */
-@WorkflowUiExperimentalApi
-fun <PropsT> FragmentActivity.setContentWorkflow(
-  registry: ViewRegistry,
-  configure: () -> Config<PropsT, Nothing>
-): WorkflowRunner<Nothing> = setContentWorkflow(ViewEnvironment(registry), configure) {}

Original file line number	Diff line number	Diff line change
`@@ -40,11 +40,8 @@ internal class TypedViewRegistry private constructor(`
`40`	`40`
`41`	`41`	`override fun <RenderingT : Any> getFactoryFor(`
`42`	`42`	`renderingType: KClass<out RenderingT>`
`43`		`- ): ViewFactory<RenderingT> {`
	`43`	`+ ): ViewFactory<RenderingT>? {`
`44`	`44`	`@Suppress("UNCHECKED_CAST")`
`45`		`- return requireNotNull(bindings[renderingType] as? ViewFactory<RenderingT>) {`
`46`		`- "A ${ViewFactory::class.java.name} should have been registered " +`
`47`		`- "to display a $renderingType."`
`48`		`- }`
	`45`	`+ return bindings[renderingType] as? ViewFactory<RenderingT>`
`49`	`46`	`}`
`50`	`47`	`}`