traversal

Summary: This adds a simple traversal to the UI. As it stands, it will most likely be updated in future iterations.

Reviewed By: LukeDefeo

Differential Revision: D38907292

fbshipit-source-id: 98cea1f971a4ef37ba2d1c75b882dd44df29bb3a

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

@@ -11,6 +11,7 @@ import android.app.Application
 import com.facebook.flipper.core.FlipperConnection
 import com.facebook.flipper.core.FlipperObject
 import com.facebook.flipper.core.FlipperPlugin
+import com.facebook.flipper.plugins.uidebugger.core.ApplicationInspector
 import com.facebook.flipper.plugins.uidebugger.core.ApplicationRef
 import com.facebook.flipper.plugins.uidebugger.core.Context
 
@@ -32,6 +33,9 @@ class UIDebuggerFlipperPlugin(val application: Application) : FlipperPlugin {
         FlipperObject.Builder()
             .put("rootId", System.identityHashCode(application).toString())
             .build())
+
+    val inspector = ApplicationInspector(context)
+    val root = inspector.inspect()
   }
 
   @Throws(Exception::class)

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

@@ -0,0 +1,17 @@
+/*
+ * 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
+
+import java.lang.ref.WeakReference
+
+class Node(val ref: WeakReference<Any>) {
+  var id: String? = null
+  var name: String? = null
+  var attributes: Map<String, Any?>? = null
+  var children: List<Node>? = null
+}

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

@@ -9,17 +9,15 @@ package com.facebook.flipper.plugins.uidebugger.core
 
 import android.view.View
 import android.view.ViewTreeObserver
-import java.util.List
+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 traverse(view: View) {
-    val inspector =
-        LayoutVisitor.create(
-            object : LayoutVisitor.Visitor {
-              override fun visit(view: View) {}
-            })
-    inspector.traverse(view)
+  fun inspect(): Node? {
+    return traversal.inspect(context.application)
   }
 
   fun attachListeners(view: View) {
@@ -52,14 +50,10 @@ class ApplicationInspector(val context: Context) {
 
           override fun onRootViewRemoved(view: View) {}
 
-          override fun onRootViewsChanged(views: List<View>) {}
+          override fun onRootViewsChanged(views: java.util.List<View>) {}
         })
 
     val activeRoots = rootResolver.listActiveRootViews()
-    activeRoots?.let { roots ->
-      for (root: RootViewResolver.RootView in roots) {
-        traverse(root.view)
-      }
-    }
+    activeRoots?.let { roots -> for (root: RootViewResolver.RootView in roots) {} }
   }
 }

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

@@ -0,0 +1,69 @@
+/*
+ * 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.core
+
+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 java.lang.ref.WeakReference
+
+class LayoutTraversal(private val descriptorRegister: DescriptorRegister) {
+  class IntermediateNode(val node: Node) {
+    var children: List<Any>? = null
+  }
+
+  internal inline fun Descriptor<*>.asAny(): Descriptor<Any> = this as Descriptor<Any>
+
+  private fun describe(obj: Any): IntermediateNode {
+    var intermediate = IntermediateNode(Node(WeakReference(obj)))
+
+    val descriptor = descriptorRegister.descriptorForClass(obj::class.java)
+    descriptor?.let { descriptor ->
+      val anyDescriptor = descriptor.asAny()
+
+      intermediate.node.id = anyDescriptor.getId(obj)
+      intermediate.node.name = anyDescriptor.getName(obj)
+
+      val attributes = mutableMapOf<String, Any?>()
+      anyDescriptor.getData(obj, attributes)
+      intermediate.node.attributes = attributes
+
+      val children = mutableListOf<Any>()
+      anyDescriptor.getChildren(obj, children)
+      intermediate.children = children
+    }
+
+    return intermediate
+  }
+
+  private fun traverse(entry: Any): Node? {
+    val root = describe(entry)
+    root?.let { intermediate ->
+      val queue = mutableListOf<IntermediateNode>()
+      queue.add(intermediate)
+
+      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)
+        }
+        intermediateNode.node.children = children
+      }
+    }
+
+    return root?.node
+  }
+
+  fun inspect(applicationRef: ApplicationRef): Node? {
+    return traverse(applicationRef)
+  }
+}

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

@@ -36,7 +36,7 @@ abstract class AbstractChainedDescriptor<T> : Descriptor<T>(), ChainedDescriptor
    * A globally unique ID used to identify a node in a hierarchy. If your node does not have a
    * globally unique ID it is fine to rely on [System.identityHashCode].
    */
-  override fun getId(node: T): String? {
+  override fun getId(node: T): String {
     return onGetId(node)
   }
 
@@ -46,7 +46,7 @@ abstract class AbstractChainedDescriptor<T> : Descriptor<T>(), ChainedDescriptor
    * The name used to identify this node in the inspector. Does not need to be unique. A good
    * default is to use the class name of the node.
    */
-  override fun getName(node: T): String? {
+  override fun getName(node: T): String {
     return onGetName(node)
   }
 

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

@@ -15,13 +15,13 @@ interface NodeDescriptor<T> {
    * A globally unique ID used to identify a node in a hierarchy. If your node does not have a
    * globally unique ID it is fine to rely on [System.identityHashCode].
    */
-  fun getId(node: T): String?
+  fun getId(node: T): String
 
   /**
    * The name used to identify this node in the inspector. Does not need to be unique. A good
    * default is to use the class name of the node.
    */
-  fun getName(node: T): String?
+  fun getName(node: T): String
 
   /** The children this node exposes in the inspector. */
   fun getChildren(node: T, children: MutableList<Any>)