Flatten layout during traversal

Summary: Move from a nested structure to a flatten one for data exchange, this will allow us to only send sections of the UI in the future

Reviewed By: lblasa

Differential Revision: D38982138

fbshipit-source-id: d578a07a6d2d7e117fbd741bd6e33062223ce10d

android/src/main/java/com/facebook/flipper/plugins/uidebugger/UIDebuggerFlipperPlugin.kt

@@ -8,12 +8,14 @@
 package com.facebook.flipper.plugins.uidebugger
 
 import android.app.Application
+import android.util.Log
 import com.facebook.flipper.core.FlipperConnection
 import com.facebook.flipper.core.FlipperPlugin
-import com.facebook.flipper.plugins.uidebugger.common.Node
 import com.facebook.flipper.plugins.uidebugger.core.ApplicationInspector
 import com.facebook.flipper.plugins.uidebugger.core.ApplicationRef
 import com.facebook.flipper.plugins.uidebugger.core.Context
+import com.facebook.flipper.plugins.uidebugger.model.InitEvent
+import com.facebook.flipper.plugins.uidebugger.model.NativeScanEvent
 import kotlinx.serialization.json.Json
 
 val LogTag = "FlipperUIDebugger"
@@ -32,17 +34,22 @@ class UIDebuggerFlipperPlugin(val application: Application) : FlipperPlugin {
     this.connection = connection
     // temp solution, get from descriptor
     val inspector = ApplicationInspector(context)
-    val root: Node = inspector.inspect()!!
-    val initEvent = InitEvent(System.identityHashCode(application).toString())
 
+    val rootDescriptor =
+        inspector.descriptorRegister.descriptorForClassUnsafe(context.applicationRef.javaClass)
     connection.send(
         InitEvent.name,
         Json.encodeToString(
-            InitEvent.serializer(), InitEvent(System.identityHashCode(application).toString())))
+            InitEvent.serializer(), InitEvent(rootDescriptor.getId(context.applicationRef))))
 
-    connection.send(
-        NativeScanEvent.name,
-        Json.encodeToString(NativeScanEvent.serializer(), NativeScanEvent(root)))
+    try {
+      val nodes = inspector.traversal.traverse()
+      connection.send(
+          NativeScanEvent.name,
+          Json.encodeToString(NativeScanEvent.serializer(), NativeScanEvent(nodes)))
+    } catch (e: java.lang.Exception) {
+      Log.e(LogTag, e.message.toString(), e)
+    }
   }
 
   @Throws(Exception::class)

android/src/main/java/com/facebook/flipper/plugins/uidebugger/common/Node.kt

@@ -1,16 +0,0 @@
-/*
- * Copyright (c) Meta Platforms, Inc. and affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-package com.facebook.flipper.plugins.uidebugger.common
-
-@kotlinx.serialization.Serializable
-class Node() {
-  var id: String? = null
-  var name: String? = null
-  var attributes: Map<String, InspectableObject> = mapOf()
-  var children: List<Node>? = null
-}

android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/ApplicationInspector.kt

@@ -9,16 +9,11 @@ package com.facebook.flipper.plugins.uidebugger.core
 
 import android.view.View
 import android.view.ViewTreeObserver
-import com.facebook.flipper.plugins.uidebugger.common.Node
 import com.facebook.flipper.plugins.uidebugger.descriptors.DescriptorRegister
 
 class ApplicationInspector(val context: Context) {
   val descriptorRegister = DescriptorRegister.withDefaults()
-  val traversal = LayoutTraversal(descriptorRegister)
-
-  fun inspect(): Node? {
-    return traversal.inspect(context.application)
-  }
+  val traversal = LayoutTraversal(descriptorRegister, context.applicationRef)
 
   fun attachListeners(view: View) {
     // An OnGlobalLayoutListener watches the entire hierarchy for layout changes
@@ -49,7 +44,6 @@ class ApplicationInspector(val context: Context) {
           }
 
           override fun onRootViewRemoved(view: View) {}
-
           override fun onRootViewsChanged(views: java.util.List<View>) {}
         })
 

android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/Context.kt

@@ -7,4 +7,4 @@
 
 package com.facebook.flipper.plugins.uidebugger.core
 
-class Context(val application: ApplicationRef) {}
+class Context(val applicationRef: ApplicationRef) {}

android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/LayoutTraversal.kt

@@ -7,63 +7,57 @@
 
 package com.facebook.flipper.plugins.uidebugger.core
 
+import android.util.Log
+import com.facebook.flipper.plugins.uidebugger.LogTag
 import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
-import com.facebook.flipper.plugins.uidebugger.common.Node
 import com.facebook.flipper.plugins.uidebugger.descriptors.Descriptor
 import com.facebook.flipper.plugins.uidebugger.descriptors.DescriptorRegister
+import com.facebook.flipper.plugins.uidebugger.model.Node
 
-class LayoutTraversal(private val descriptorRegister: DescriptorRegister) {
-  class IntermediateNode(val node: Node) {
-    var children: List<Any>? = null
-  }
+class LayoutTraversal(
+    private val descriptorRegister: DescriptorRegister,
+    val root: ApplicationRef
+) {
 
   internal inline fun Descriptor<*>.asAny(): Descriptor<Any> = this as Descriptor<Any>
 
-  private fun describe(obj: Any): IntermediateNode {
-    var intermediate = IntermediateNode(Node())
+  /** Traverses the native android hierarchy */
+  fun traverse(): List<Node> {
 
-    val descriptor = descriptorRegister.descriptorForClass(obj::class.java)
-    descriptor?.let { descriptor ->
-      val anyDescriptor = descriptor.asAny()
+    val result = mutableListOf<Node>()
+    val stack = mutableListOf<Any>()
+    stack.add(this.root)
 
-      intermediate.node.id = anyDescriptor.getId(obj)
-      intermediate.node.name = anyDescriptor.getName(obj)
+    while (stack.isNotEmpty()) {
 
-      val attributes = mutableMapOf<String, InspectableObject>()
-      anyDescriptor.getData(obj, attributes)
-      intermediate.node.attributes = attributes
+      val node = stack.removeLast()
 
-      val children = mutableListOf<Any>()
-      anyDescriptor.getChildren(obj, children)
-      intermediate.children = children
-    }
+      try {
 
-    return intermediate
-  }
+        val descriptor = descriptorRegister.descriptorForClassUnsafe(node::class.java).asAny()
 
-  private fun traverse(entry: Any): Node? {
-    val root = describe(entry)
-    root?.let { intermediate ->
-      val queue = mutableListOf<IntermediateNode>()
-      queue.add(intermediate)
+        val children = mutableListOf<Any>()
+        descriptor.getChildren(node, children)
 
-      while (queue.isNotEmpty()) {
-        val intermediateNode = queue.removeFirst()
-
-        val children = mutableListOf<Node>()
-        intermediateNode.children?.forEach {
-          val intermediateChild = describe(it)
-          children.add(intermediateChild.node)
-          queue.add(intermediateChild)
+        val childrenIds = mutableListOf<String>()
+        for (child in children) {
+          // it might make sense one day to remove id from the descriptor since its always the
+          // hash code
+          val childDescriptor =
+              descriptorRegister.descriptorForClassUnsafe(child::class.java).asAny()
+          childrenIds.add(childDescriptor.getId(child))
+          stack.add(child)
         }
-        intermediateNode.node.children = children
+
+        val attributes = mutableMapOf<String, InspectableObject>()
+        descriptor.getData(node, attributes)
+
+        result.add(Node(descriptor.getId(node), descriptor.getName(node), attributes, childrenIds))
+      } catch (exception: Exception) {
+        Log.e(LogTag, "Error while processing node ${node.javaClass.name} ${node} ", exception)
       }
     }
 
-    return root?.node
-  }
-
-  fun inspect(applicationRef: ApplicationRef): Node? {
-    return traverse(applicationRef)
+    return result
   }
 }

android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ApplicationRefDescriptor.kt

@@ -12,7 +12,7 @@ import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 import com.facebook.flipper.plugins.uidebugger.core.ApplicationRef
 import com.facebook.flipper.plugins.uidebugger.core.RootViewResolver
 
-class ApplicationDescriptor : AbstractChainedDescriptor<ApplicationRef>() {
+class ApplicationRefDescriptor : AbstractChainedDescriptor<ApplicationRef>() {
   val rootResolver = RootViewResolver()
 
   override fun onInit() {}

android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/DescriptorRegister.kt

@@ -13,6 +13,7 @@ import android.view.ViewGroup
 import android.view.Window
 import android.widget.Button
 import android.widget.TextView
+import com.facebook.flipper.plugins.uidebugger.common.UIDebuggerException
 import com.facebook.flipper.plugins.uidebugger.core.ApplicationRef
 
 class DescriptorRegister {
@@ -23,7 +24,7 @@ class DescriptorRegister {
     fun withDefaults(): DescriptorRegister {
       val mapping = DescriptorRegister()
       mapping.register(Any::class.java, ObjectDescriptor())
-      mapping.register(ApplicationRef::class.java, ApplicationDescriptor())
+      mapping.register(ApplicationRef::class.java, ApplicationRefDescriptor())
       mapping.register(Activity::class.java, ActivityDescriptor())
       mapping.register(Window::class.java, WindowDescriptor())
       mapping.register(ViewGroup::class.java, ViewGroupDescriptor())
@@ -57,11 +58,16 @@ class DescriptorRegister {
     register[clazz] = descriptor
   }
 
-  fun descriptorForClass(clazz: Class<*>): Descriptor<*>? {
-    var clazz = clazz
+  fun <T> descriptorForClass(clazz: Class<T>): Descriptor<T>? {
+    var clazz: Class<*> = clazz
     while (!register.containsKey(clazz)) {
       clazz = clazz.superclass
     }
-    return register[clazz]
+    return register[clazz] as Descriptor<T>
+  }
+
+  fun <T> descriptorForClassUnsafe(clazz: Class<T>): Descriptor<T> {
+    return descriptorForClass(clazz)
+        ?: throw UIDebuggerException("No descriptor found for ${clazz.name}")
   }
 }

android/src/main/java/com/facebook/flipper/plugins/uidebugger/model/Events.kt

@@ -5,21 +5,18 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-package com.facebook.flipper.plugins.uidebugger
-
-import com.facebook.flipper.plugins.uidebugger.common.Node
+package com.facebook.flipper.plugins.uidebugger.model
 
 @kotlinx.serialization.Serializable
 data class InitEvent(val rootId: String) {
   companion object {
-    val name = "init"
+    const val name = "init"
   }
 }
 
-// TODO flatten the tree into normalised list
 @kotlinx.serialization.Serializable
-data class NativeScanEvent(val root: Node) {
+data class NativeScanEvent(val nodes: List<Node>) {
   companion object {
-    val name = "nativeScan"
+    const val name = "nativeScan"
   }
 }

android/src/main/java/com/facebook/flipper/plugins/uidebugger/model/Node.kt

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.flipper.plugins.uidebugger.model
+
+import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
+
+@kotlinx.serialization.Serializable
+data class Node(
+    val id: String,
+    val name: String,
+    val attributes: Map<String, InspectableObject>,
+    val children: List<String>
+)