From 4436128d075ee05521c4dd43956522437b8b2dfa Mon Sep 17 00:00:00 2001
From: Luke De Feo <lukedefeo@fb.com>
Date: Mon, 12 Sep 2022 03:48:43 -0700
Subject: [PATCH] Descriptor clean up

Summary:
Now that we have the tree observer we can make descriptors completely about describing an object. To that end we have removed init method and made them all object to indicate to future readers their singleton nature.

onGetActive child was made open instead of abstract to avoid needed to override in all subclasses

Reviewed By: lblasa

Differential Revision: D39387935

fbshipit-source-id: 802b8afdd9aa639daecf10d774ca5b960ee48003
---
 .../descriptors/AbstractChainedDescriptor.kt  | 10 +-----
 .../descriptors/ActivityDescriptor.kt         |  6 +---
 .../descriptors/ApplicationRefDescriptor.kt   |  9 +----
 .../descriptors/ButtonDescriptor.kt           |  7 +---
 .../descriptors/DescriptorRegister.kt         | 18 +++++-----
 .../uidebugger/descriptors/NodeDescriptor.kt  | 10 ++++--
 .../descriptors/ObjectDescriptor.kt           |  8 ++---
 .../descriptors/TextViewDescriptor.kt         |  8 +----
 .../uidebugger/descriptors/ViewDescriptor.kt  | 36 ++++++++-----------
 .../descriptors/ViewGroupDescriptor.kt        | 30 +++++++---------
 .../descriptors/ViewPagerDescriptor.kt        |  2 +-
 .../descriptors/WindowDescriptor.kt           | 12 +------
 12 files changed, 52 insertions(+), 104 deletions(-)

diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/AbstractChainedDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/AbstractChainedDescriptor.kt
index 51896a363..cd3eccf8c 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/AbstractChainedDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/AbstractChainedDescriptor.kt
@@ -26,14 +26,6 @@ abstract class AbstractChainedDescriptor<T> : Descriptor<T>(), ChainedDescriptor
     return mSuper
   }
 
-  /** Initialize a descriptor. */
-  final override fun init() {
-    mSuper?.init()
-    onInit()
-  }
-
-  open fun onInit() {}
-
   final override fun getActiveChild(node: T): Any? {
     // ask each descriptor in the chain for an active child, if none available look up the chain
     // until no more super descriptors
@@ -58,7 +50,7 @@ abstract class AbstractChainedDescriptor<T> : Descriptor<T>(), ChainedDescriptor
     return onGetName(node)
   }
 
-  abstract fun onGetActiveChild(node: T): Any?
+  open fun onGetActiveChild(node: T): Any? = null
 
   abstract fun onGetName(node: T): String
 
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ActivityDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ActivityDescriptor.kt
index 69d958979..e18dc9fca 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ActivityDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ActivityDescriptor.kt
@@ -11,11 +11,7 @@ import android.app.Activity
 import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 import com.facebook.flipper.plugins.uidebugger.stetho.FragmentCompat
 
-class ActivityDescriptor : AbstractChainedDescriptor<Activity>() {
-  override fun onInit() {}
-  override fun onGetActiveChild(node: Activity): Any? {
-    return null
-  }
+object ActivityDescriptor : AbstractChainedDescriptor<Activity>() {
 
   override fun onGetId(activity: Activity): String {
     return Integer.toString(System.identityHashCode(activity))
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ApplicationRefDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ApplicationRefDescriptor.kt
index d76b8fbf7..534038b48 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ApplicationRefDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ApplicationRefDescriptor.kt
@@ -8,12 +8,10 @@
 package com.facebook.flipper.plugins.uidebugger.descriptors
 
 import android.app.Activity
-import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 import com.facebook.flipper.plugins.uidebugger.core.ApplicationRef
 
-class ApplicationRefDescriptor : AbstractChainedDescriptor<ApplicationRef>() {
+object ApplicationRefDescriptor : AbstractChainedDescriptor<ApplicationRef>() {
 
-  override fun onInit() {}
   override fun onGetActiveChild(node: ApplicationRef): Any? {
     return if (node.activitiesStack.size > 0) node.activitiesStack.last() else null
   }
@@ -34,9 +32,4 @@ class ApplicationRefDescriptor : AbstractChainedDescriptor<ApplicationRef>() {
       children.add(activity)
     }
   }
-
-  override fun onGetData(
-      applicationRef: ApplicationRef,
-      attributeSections: MutableMap<String, InspectableObject>
-  ) {}
 }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ButtonDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ButtonDescriptor.kt
index 740e4a548..ff040474e 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ButtonDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ButtonDescriptor.kt
@@ -10,7 +10,7 @@ package com.facebook.flipper.plugins.uidebugger.descriptors
 import android.widget.Button
 import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 
-class ButtonDescriptor : AbstractChainedDescriptor<Button>() {
+object ButtonDescriptor : AbstractChainedDescriptor<Button>() {
 
   override fun onGetId(button: Button): String {
     return Integer.toString(System.identityHashCode(button))
@@ -24,9 +24,4 @@ class ButtonDescriptor : AbstractChainedDescriptor<Button>() {
       button: Button,
       attributeSections: MutableMap<String, InspectableObject>
   ) {}
-
-  override fun onGetChildren(button: Button, children: MutableList<Any>) {}
-  override fun onGetActiveChild(node: Button): Any? {
-    return null
-  }
 }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/DescriptorRegister.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/DescriptorRegister.kt
index 7dc90dc04..0824741c4 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/DescriptorRegister.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/DescriptorRegister.kt
@@ -24,15 +24,15 @@ class DescriptorRegister {
 
     fun withDefaults(): DescriptorRegister {
       val mapping = DescriptorRegister()
-      mapping.register(Any::class.java, ObjectDescriptor())
-      mapping.register(ApplicationRef::class.java, ApplicationRefDescriptor())
-      mapping.register(Activity::class.java, ActivityDescriptor())
-      mapping.register(Window::class.java, WindowDescriptor())
-      mapping.register(ViewGroup::class.java, ViewGroupDescriptor())
-      mapping.register(View::class.java, ViewDescriptor())
-      mapping.register(TextView::class.java, TextViewDescriptor())
-      mapping.register(Button::class.java, ButtonDescriptor())
-      mapping.register(ViewPager::class.java, ViewPagerDescriptor())
+      mapping.register(Any::class.java, ObjectDescriptor)
+      mapping.register(ApplicationRef::class.java, ApplicationRefDescriptor)
+      mapping.register(Activity::class.java, ActivityDescriptor)
+      mapping.register(Window::class.java, WindowDescriptor)
+      mapping.register(ViewGroup::class.java, ViewGroupDescriptor)
+      mapping.register(View::class.java, ViewDescriptor)
+      mapping.register(TextView::class.java, TextViewDescriptor)
+      mapping.register(Button::class.java, ButtonDescriptor)
+      mapping.register(ViewPager::class.java, ViewPagerDescriptor)
 
       for (clazz in mapping.register.keys) {
         val descriptor: Descriptor<*>? = mapping.register[clazz]
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/NodeDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/NodeDescriptor.kt
index c6f196f31..af41f2b6c 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/NodeDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/NodeDescriptor.kt
@@ -9,10 +9,14 @@ package com.facebook.flipper.plugins.uidebugger.descriptors
 
 import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 
-interface NodeDescriptor<T> {
-  /** Initialize a descriptor. */
-  fun init()
+/*
+ Descriptors are an extension point used during traversal to extract data out of arbitary
+ objects in the hierachy. Descriptors can represent native view or declarative components or
+ any type of object such as an activity
 
+ Descriptors should be stateless and each descriptor should be a singleton
+*/
+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].
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ObjectDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ObjectDescriptor.kt
index 95eeeebca..54e06adce 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ObjectDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ObjectDescriptor.kt
@@ -9,11 +9,9 @@ package com.facebook.flipper.plugins.uidebugger.descriptors
 
 import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 
-class ObjectDescriptor : Descriptor<Any>() {
-  override fun init() {}
-  override fun getActiveChild(node: Any): Any? {
-    return null
-  }
+object ObjectDescriptor : Descriptor<Any>() {
+
+  override fun getActiveChild(node: Any): Any? = null
 
   override fun getId(obj: Any): String {
     return Integer.toString(System.identityHashCode(obj))
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/TextViewDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/TextViewDescriptor.kt
index 0dcfd9e2d..ee8ed8d48 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/TextViewDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/TextViewDescriptor.kt
@@ -10,7 +10,7 @@ package com.facebook.flipper.plugins.uidebugger.descriptors
 import android.widget.TextView
 import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 
-class TextViewDescriptor : AbstractChainedDescriptor<TextView>() {
+object TextViewDescriptor : AbstractChainedDescriptor<TextView>() {
 
   override fun onGetId(textView: TextView): String {
     return Integer.toString(System.identityHashCode(textView))
@@ -20,14 +20,8 @@ class TextViewDescriptor : AbstractChainedDescriptor<TextView>() {
     return textView.javaClass.simpleName
   }
 
-  override fun onGetChildren(textView: TextView, children: MutableList<Any>) {}
-
   override fun onGetData(
       textView: TextView,
       attributeSections: MutableMap<String, InspectableObject>
   ) {}
-
-  override fun onGetActiveChild(node: TextView): Any? {
-    return null
-  }
 }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewDescriptor.kt
index 8953e3b4a..aa337238a 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewDescriptor.kt
@@ -22,7 +22,7 @@ import com.facebook.flipper.plugins.uidebugger.common.InspectableValue
 import com.facebook.flipper.plugins.uidebugger.stetho.ResourcesUtil
 import java.lang.reflect.Field
 
-class ViewDescriptor : AbstractChainedDescriptor<View>() {
+object ViewDescriptor : AbstractChainedDescriptor<View>() {
 
   override fun onGetId(view: View): String {
     return Integer.toBinaryString(System.identityHashCode(view))
@@ -32,8 +32,6 @@ class ViewDescriptor : AbstractChainedDescriptor<View>() {
     return view.javaClass.simpleName
   }
 
-  override fun onGetChildren(view: View, children: MutableList<Any>) {}
-
   override fun onGetData(view: View, attributeSections: MutableMap<String, InspectableObject>) {
     val positionOnScreen = IntArray(2)
     view.getLocationOnScreen(positionOnScreen)
@@ -239,25 +237,19 @@ class ViewDescriptor : AbstractChainedDescriptor<View>() {
                   "FILL_HORIZONTAL" to Gravity.FILL_HORIZONTAL,
               )) {}
 
-  companion object {
-    private var KeyedTagsField: Field? = null
-    private var ListenerInfoField: Field? = null
-    private var OnClickListenerField: Field? = null
+  private var KeyedTagsField: Field? = null
+  private var ListenerInfoField: Field? = null
+  private var OnClickListenerField: Field? = null
 
-    init {
-      try {
-        KeyedTagsField = View::class.java.getDeclaredField("mKeyedTags")
-        KeyedTagsField?.let { field -> field.isAccessible = true }
-        ListenerInfoField = View::class.java.getDeclaredField("mListenerInfo")
-        ListenerInfoField?.let { field -> field.isAccessible = true }
-        val viewInfoClassName = View::class.java.name + "\$ListenerInfo"
-        OnClickListenerField = Class.forName(viewInfoClassName).getDeclaredField("mOnClickListener")
-        OnClickListenerField?.let { field -> field.isAccessible = true }
-      } catch (ignored: Exception) {}
-    }
-  }
-
-  override fun onGetActiveChild(node: View): Any? {
-    return null
+  init {
+    try {
+      KeyedTagsField = View::class.java.getDeclaredField("mKeyedTags")
+      KeyedTagsField?.let { field -> field.isAccessible = true }
+      ListenerInfoField = View::class.java.getDeclaredField("mListenerInfo")
+      ListenerInfoField?.let { field -> field.isAccessible = true }
+      val viewInfoClassName = View::class.java.name + "\$ListenerInfo"
+      OnClickListenerField = Class.forName(viewInfoClassName).getDeclaredField("mOnClickListener")
+      OnClickListenerField?.let { field -> field.isAccessible = true }
+    } catch (ignored: Exception) {}
   }
 }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewGroupDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewGroupDescriptor.kt
index 9184efb6b..24b7c5a8c 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewGroupDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewGroupDescriptor.kt
@@ -18,7 +18,7 @@ import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 import com.facebook.flipper.plugins.uidebugger.common.InspectableValue
 import com.facebook.flipper.plugins.uidebugger.stetho.FragmentCompat
 
-class ViewGroupDescriptor : AbstractChainedDescriptor<ViewGroup>() {
+object ViewGroupDescriptor : AbstractChainedDescriptor<ViewGroup>() {
 
   override fun onGetId(viewGroup: ViewGroup): String {
     return Integer.toString(System.identityHashCode(viewGroup))
@@ -69,24 +69,18 @@ class ViewGroupDescriptor : AbstractChainedDescriptor<ViewGroup>() {
                   "LAYOUT_MODE_OPTICAL_BOUNDS" to ViewGroupCompat.LAYOUT_MODE_OPTICAL_BOUNDS,
               )) {}
 
-  companion object {
-    private fun getAttachedFragmentForView(v: View): Any? {
-      return try {
-        val fragment = FragmentCompat.findFragmentForView(v)
-        var added = false
-        if (fragment is Fragment) {
-          added = fragment.isAdded
-        } else if (fragment is androidx.fragment.app.Fragment) {
-          added = fragment.isAdded
-        }
-        if (added) fragment else null
-      } catch (e: RuntimeException) {
-        null
+  private fun getAttachedFragmentForView(v: View): Any? {
+    return try {
+      val fragment = FragmentCompat.findFragmentForView(v)
+      var added = false
+      if (fragment is Fragment) {
+        added = fragment.isAdded
+      } else if (fragment is androidx.fragment.app.Fragment) {
+        added = fragment.isAdded
       }
+      if (added) fragment else null
+    } catch (e: RuntimeException) {
+      null
     }
   }
-
-  override fun onGetActiveChild(node: ViewGroup): Any? {
-    return null
-  }
 }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewPagerDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewPagerDescriptor.kt
index 09d08d1da..f9ec967d7 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewPagerDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewPagerDescriptor.kt
@@ -9,7 +9,7 @@ package com.facebook.flipper.plugins.uidebugger.descriptors
 
 import androidx.viewpager.widget.ViewPager
 
-class ViewPagerDescriptor : AbstractChainedDescriptor<ViewPager>() {
+object ViewPagerDescriptor : AbstractChainedDescriptor<ViewPager>() {
 
   override fun onGetId(node: ViewPager): String = System.identityHashCode(node).toString()
 
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/WindowDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/WindowDescriptor.kt
index 8e74a57ae..61250cec5 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/WindowDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/WindowDescriptor.kt
@@ -8,9 +8,8 @@
 package com.facebook.flipper.plugins.uidebugger.descriptors
 
 import android.view.Window
-import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 
-class WindowDescriptor : AbstractChainedDescriptor<Window>() {
+object WindowDescriptor : AbstractChainedDescriptor<Window>() {
 
   override fun onGetId(window: Window): String {
     return Integer.toString(System.identityHashCode(window))
@@ -23,13 +22,4 @@ class WindowDescriptor : AbstractChainedDescriptor<Window>() {
   override fun onGetChildren(window: Window, children: MutableList<Any>) {
     children.add(window.decorView)
   }
-
-  override fun onGetData(
-      window: Window,
-      attributeSections: MutableMap<String, InspectableObject>
-  ) {}
-
-  override fun onGetActiveChild(node: Window): Any? {
-    return null
-  }
 }