Introduces WorkflowActivityRunner.

One stop shopping to drive your activity from a workflow tree.
See the kdoc on [FragmentActivity.setContentWorkflow] in
[WorkflowActivityRunner.kt] for details.

This API is seriously locked down, suitable only for driving an entire
activity. We can open it up as other use cases emerge -- perhaps
a `WorkflowViewRunner` for embedding in legacy apps.

Closes #217

kotlin/build.gradle

@@ -17,15 +17,16 @@ buildscript {
   ext.versions = [
       'agp': '3.2.1',
       'buildTools': '28.0.3',
-      'compileSdk': '27',
+      'compileSdk': '28',
+      'lifecycle': '1.1.1',
       'minSdk': 21,
-      'targetSdk': 26,
+      'targetSdk': 28,
       'sourceCompatibility': JavaVersion.VERSION_1_8,
       'targetCompatibility': JavaVersion.VERSION_1_8,
 
       'coordinators': '0.4',
       'rxandroid2': '2.1.0',
-      'support': '26.0.2',
+      'support': '28.0.0',
       'timber': '4.7.1',
 
       'assertj': '2.6.0',
@@ -50,6 +51,7 @@ buildscript {
       'coordinators': "com.squareup.coordinators:coordinators:${versions.coordinators}",
       'constraint_layout': "com.android.support.constraint:constraint-layout:1.1.0",
       'design': "com.android.support:design:${versions.support}",
+      'lifecycle': "android.arch.lifecycle:extensions:${versions.lifecycle}",
       'rxandroid2': "io.reactivex.rxjava2:rxandroid:${versions.rxandroid2}",
       'timber': "com.jakewharton.timber:timber:${versions.timber}",
       'transition': "com.android.support:transition:${versions.support}",

kotlin/samples/tictactoe/android/build.gradle

@@ -38,6 +38,7 @@ dependencies {
   implementation deps.appcompatv7
   implementation deps.constraint_layout
   implementation deps.design
+  implementation deps.lifecycle
   implementation deps.kotlin.coroutines.rx2
   implementation deps.kotlin.reflect
   implementation deps.okio

kotlin/samples/tictactoe/android/src/main/java/com/squareup/sample/mainactivity/MainActivity.kt

@@ -17,87 +17,49 @@ package com.squareup.sample.mainactivity
 
 import android.os.Bundle
 import android.support.v7.app.AppCompatActivity
-import android.view.View
 import com.squareup.sample.authworkflow.AuthViewBindings
-import com.squareup.sample.gameworkflow.RunGameScreen
 import com.squareup.sample.gameworkflow.TicTacToeViewBindings
 import com.squareup.sample.panel.PanelContainer
-import com.squareup.workflow.ui.AlertContainerScreen
-import com.squareup.workflow.ui.HandlesBack
 import com.squareup.workflow.ui.ModalContainer
-import com.squareup.workflow.ui.ViewBinding
+import com.squareup.workflow.ui.PickledWorkflow
 import com.squareup.workflow.ui.ViewRegistry
+import com.squareup.workflow.ui.WorkflowActivityRunner
 import com.squareup.workflow.ui.backstack.BackStackContainer
 import com.squareup.workflow.ui.backstack.PushPopEffect
-import com.squareup.workflow.Snapshot
-import io.reactivex.android.schedulers.AndroidSchedulers
-import io.reactivex.disposables.CompositeDisposable
-import kotlin.reflect.jvm.jvmName
+import com.squareup.workflow.ui.setContentWorkflow
 
-/**
- * Prototype Android integration. Demonstrates:
- *
- * - preserving workflow state via the activity bundle
- * - simple two layer container, with body views and dialogs
- * - TODO: customizing stock views via wrapping (when we add a logout button to each game view)
- */
 class MainActivity : AppCompatActivity() {
   private lateinit var component: MainComponent
-
-  private lateinit var content: View
-
-  private val subs = CompositeDisposable()
-
-  private var latestSnapshot = Snapshot.EMPTY
+  private lateinit var workflowViewModel: WorkflowActivityRunner<*, *>
 
   override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
 
+    val restored = savedInstanceState?.getParcelable<PickledWorkflow>(WORKFLOW_BUNDLE_KEY)
     component = lastCustomNonConfigurationInstance as? MainComponent
         ?: MainComponent()
 
-    val snapshot = savedInstanceState?.getParcelable<ParceledSnapshot>(SNAPSHOT_NAME)
-        ?.snapshot
-    val updates = component.updates(snapshot)
-
-    val screens = updates
-        .observeOn(AndroidSchedulers.mainThread())
-        .doOnNext { latestSnapshot = it.snapshot }
-        .map { it.rendering }
-
-    val viewRegistry = buildViewRegistry()
-    val rootViewBinding: ViewBinding<RunGameScreen> =
-      viewRegistry.getBinding(AlertContainerScreen::class.jvmName)
-
-    content = rootViewBinding.buildView(screens, viewRegistry, this)
-        .apply { setContentView(this) }
+    workflowViewModel = setContentWorkflow(viewRegistry, component.mainWorkflow, restored)
   }
 
   override fun onBackPressed() {
-    if (!HandlesBack.Helper.onBackPressed(content)) super.onBackPressed()
+    if (!workflowViewModel.onBackPressed(this)) super.onBackPressed()
   }
 
   override fun onSaveInstanceState(outState: Bundle) {
     super.onSaveInstanceState(outState)
-    outState.putParcelable(SNAPSHOT_NAME, ParceledSnapshot(latestSnapshot))
-  }
-
-  override fun onDestroy() {
-    subs.clear()
-    super.onDestroy()
+    outState.putParcelable(WORKFLOW_BUNDLE_KEY, workflowViewModel.asParcelable())
   }
 
   override fun onRetainCustomNonConfigurationInstance(): Any = component
 
-  private fun buildViewRegistry(): ViewRegistry {
-    return ViewRegistry(
+  private companion object {
+    const val WORKFLOW_BUNDLE_KEY = "workflow"
+
+    val viewRegistry = ViewRegistry(
         BackStackContainer,
         ModalContainer.forAlertContainerScreen(),
         PanelContainer
     ) + AuthViewBindings + TicTacToeViewBindings + PushPopEffect
   }
-
-  private companion object {
-    val SNAPSHOT_NAME = MainActivity::class.jvmName + "-snapshot"
-  }
 }

kotlin/samples/tictactoe/android/src/main/java/com/squareup/sample/mainactivity/MainComponent.kt

@@ -21,30 +21,19 @@ import com.squareup.sample.authworkflow.RealAuthWorkflow
 import com.squareup.sample.gameworkflow.RealGameLog
 import com.squareup.sample.gameworkflow.RealRunGameWorkflow
 import com.squareup.sample.gameworkflow.RealTakeTurnsWorkflow
-import com.squareup.sample.gameworkflow.RunGameScreen
 import com.squareup.sample.gameworkflow.RunGameWorkflow
 import com.squareup.sample.gameworkflow.TakeTurnsWorkflow
 import com.squareup.sample.mainworkflow.MainWorkflow
-import com.squareup.workflow.Snapshot
-import com.squareup.workflow.WorkflowHost
-import com.squareup.workflow.WorkflowHost.Update
-import io.reactivex.Observable
 import io.reactivex.android.schedulers.AndroidSchedulers.mainThread
-import kotlinx.coroutines.experimental.Dispatchers
-import kotlinx.coroutines.experimental.rx2.asObservable
 import timber.log.Timber
 
 /**
  * Pretend generated code of a pretend DI framework.
  */
 internal class MainComponent {
 
-  private val workflowHostFactory = WorkflowHost.Factory(Dispatchers.Unconfined)
-
   private val authService = AuthService()
 
-  private fun mainWorkflow() = MainWorkflow(authWorkflow(), gameWorkflow())
-
   private fun authWorkflow(): AuthWorkflow = RealAuthWorkflow(authService)
 
   private fun gameLog() = RealGameLog(mainThread())
@@ -53,25 +42,7 @@ internal class MainComponent {
 
   private fun takeTurnsWorkflow(): TakeTurnsWorkflow = RealTakeTurnsWorkflow()
 
-  private fun workflowHost(snapshot: Snapshot?) = workflowHostFactory.run(mainWorkflow(), snapshot)
-
-  private var updates: Observable<Update<Unit, RunGameScreen>>? = null
-
-  fun updates(snapshot: Snapshot?): Observable<Update<Unit, RunGameScreen>> {
-    if (updates == null) {
-      val host = workflowHost(snapshot)
-
-      @Suppress("EXPERIMENTAL_FEATURE_WARNING")
-      updates = host.updates.asObservable(Dispatchers.Unconfined)
-          .doOnNext { Timber.d("showing: %s", it.rendering) }
-          .replay(1)
-          .autoConnect()
-
-      // autoConnect() is leaky (it's never disposed), but we want it to run
-      // forever so ¯\_(ツ)_/¯.
-    }
-    return updates!!
-  }
+  val mainWorkflow = MainWorkflow(authWorkflow(), gameWorkflow())
 
   companion object {
     init {

kotlin/workflow-ui-android/build.gradle

@@ -23,13 +23,19 @@ targetCompatibility = JavaVersion.VERSION_1_7
 android rootProject.ext.defaultAndroidConfig
 
 dependencies {
+  api project(':workflow-core')
   api project(':workflow-ui-core')
 
   api deps.coordinators
   api deps.kotlin.stdLib.jdk6
+  api deps.lifecycle
   api deps.rxjava2.rxjava2
   api deps.transition
 
+  implementation project(':workflow-runtime')
   implementation deps.appcompatv7
+  implementation deps.kotlin.coroutines.core
+  implementation deps.kotlin.coroutines.rx2
   implementation deps.kotlin.reflect
+  implementation deps.rxandroid2
 }

kotlin/workflow-ui-android/src/main/java/com/squareup/workflow/ui/HandlesBack.kt

@@ -21,14 +21,17 @@ import com.squareup.workflow.ui.HandlesBack.Helper.setConditionalBackHandler
 /**
  * Implemented by objects that want the option to intercept back button taps.
  * Can be implemented by [View] subclasses, or can be attached to a stock view via
- * [Helper].
+ * [Helper.setBackHandler].
  *
- * When implemented by a container view, the [onBackPressed] methods or tags of their
- * subviews should be invoked first.
+ * When implemented by a container view, the [onBackPressed] methods or tags of its
+ * subviews should be invoked first, via [Helper.onBackPressed]
  *
- * The typical flow of back button handling starts in the [android.app.Activity.onBackPressed]
- * calling [onBackPressed] on its content view. Each view in turn delegates to its
- * child views to give them first say.
+ * To kick things off, override [android.app.Activity.onBackPressed] to call
+ * [WorkflowActivityRunner.onBackPressed]:
+ *
+ *     override fun onBackPressed() {
+ *       if (!workflowViewModel.onBackPressed(this)) super.onBackPressed()
+ *     }
  */
 interface HandlesBack {
   /**

kotlin/workflow-ui-android/src/main/java/com/squareup/workflow/ui/ModalContainer.kt

@@ -155,7 +155,7 @@ abstract class ModalContainer<M : Any>
 
   override fun onSaveInstanceState(): Parcelable {
     return SavedState(
-        super.onSaveInstanceState(),
+        super.onSaveInstanceState()!!,
         SparseArray<Parcelable>().also { array -> base?.saveHierarchyState(array) },
         dialogs.map { it.save() }
     )
@@ -196,8 +196,8 @@ abstract class ModalContainer<M : Any>
 
     companion object CREATOR : Creator<TypeAndBundle> {
       override fun createFromParcel(parcel: Parcel): TypeAndBundle {
-        val type = parcel.readString()
-        val bundle = parcel.readBundle(TypeAndBundle::class.java.classLoader)
+        val type = parcel.readString()!!
+        val bundle = parcel.readBundle(TypeAndBundle::class.java.classLoader)!!
         return TypeAndBundle(type, bundle)
       }
 
@@ -210,13 +210,13 @@ abstract class ModalContainer<M : Any>
     val dialog: Dialog
   ) {
     fun save(): TypeAndBundle {
-      val saved = dialog.window.saveHierarchyState()
+      val saved = dialog.window!!.saveHierarchyState()
       return TypeAndBundle(screen::class.jvmName, saved)
     }
 
     fun restore(typeAndBundle: TypeAndBundle) {
       if (screen::class.jvmName == typeAndBundle.screenType) {
-        dialog.window.restoreHierarchyState(typeAndBundle.bundle)
+        dialog.window!!.restoreHierarchyState(typeAndBundle.bundle)
       }
     }
   }
@@ -244,7 +244,7 @@ abstract class ModalContainer<M : Any>
 
   private class SavedState : BaseSavedState {
     constructor(
-      superState: Parcelable,
+      superState: Parcelable?,
       bodyState: SparseArray<Parcelable>,
       dialogBundles: List<TypeAndBundle>
     ) : super(superState) {

kotlin/workflow-ui-android/src/main/java/com/squareup/workflow/ui/ModalViewContainer.kt

@@ -52,11 +52,11 @@ internal class ModalViewContainer
     return Dialog(context, dialogThemeResId).apply {
       setCancelable(false)
       setContentView(modalDecorator(view))
-      window.setLayout(WRAP_CONTENT, WRAP_CONTENT)
+      window!!.setLayout(WRAP_CONTENT, WRAP_CONTENT)
 
       if (dialogThemeResId == 0) {
         // If we don't set or clear the background drawable, the window cannot go full bleed.
-        window.setBackgroundDrawable(null)
+        window!!.setBackgroundDrawable(null)
       }
       show()
     }

kotlin/samples/tictactoe/android/src/main/java/com/squareup/sample/mainactivity/ParceledSnapshot.kt → kotlin/workflow-ui-android/src/main/java/com/squareup/workflow/ui/PickledWorkflow.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017 Square Inc.
+ * 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.
@@ -13,28 +13,32 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package com.squareup.sample.mainactivity
+package com.squareup.workflow.ui
 
 import android.os.Parcel
 import android.os.Parcelable
 import com.squareup.workflow.Snapshot
 import okio.ByteString
 
-internal class ParceledSnapshot(val snapshot: Snapshot) : Parcelable {
-
+/**
+ * A [Parcelable] snapshot of the most recent state of a [Workflow] managed by
+ * [WorkflowActivityRunner], for use in an `Activity`'s persistence `Bundle`.
+ * See [WorkflowActivityRunner.asParcelable] for details.
+ */
+class PickledWorkflow(internal val snapshot: Snapshot) : Parcelable {
   override fun describeContents(): Int = 0
 
   override fun writeToParcel(
     dest: Parcel,
     flags: Int
   ) = dest.writeByteArray(snapshot.bytes.toByteArray())
 
-  companion object CREATOR : Parcelable.Creator<ParceledSnapshot> {
-    override fun createFromParcel(parcel: Parcel): ParceledSnapshot {
-      val bytes = parcel.createByteArray()
-      return ParceledSnapshot(Snapshot.of(ByteString.of(*bytes)))
+  companion object CREATOR : Parcelable.Creator<PickledWorkflow> {
+    override fun createFromParcel(parcel: Parcel): PickledWorkflow {
+      val bytes = parcel.createByteArray()!!
+      return PickledWorkflow(Snapshot.of(ByteString.of(*bytes)))
     }
 
-    override fun newArray(size: Int): Array<ParceledSnapshot?> = arrayOfNulls(size)
+    override fun newArray(size: Int): Array<PickledWorkflow?> = arrayOfNulls(size)
   }
 }