Refactor SKSubDescriptor

Reviewed By: d16r

Differential Revision: D20458337

fbshipit-source-id: e8ea848c6e2f7521c5a6c6eb4110bba0bfe25593

docs/extending/layout-inspector.md

@@ -115,50 +115,17 @@ Sometimes all you need is to extend the functionality of an existing descriptor.
 
 ### Subdescriptors
 
-If you want to extend the `SKComponentKitLayoutDescriptor` and add an additional section based on the nodes of the `SKComponentLayoutDescriptor`, you will have to subclass `SKSubDescriptor`.
+If you want to extend the `SKComponentKitLayoutDescriptor` and add an additional section based on the nodes of the `SKComponentLayoutDescriptor`, you can use `SKSubDescriptor`.
 
 ```objc
-#import <FlipperKitLayoutComponentKitSupport/SKSubDescriptor.h>
+#import <FlipperKitLayoutComponentKitSupport/SKComponentLayoutWrapper.h>
 
-@interface YourSubDescriptor: SKSubDescriptor
+NSString *YourSubDescriptor(SKComponentLayoutWrapper *)node {
-
+	return @"Meta data";
-@end
-
-
-@implementation YourSubDescriptor
-
-- (NSString *) getName {
-  return @"Section Name";
 }
 
-- (NSString *)getDataForNode:(SKComponentLayoutWrapper *)node {
+// At setup time, you must register it:
-	return @"Meta data"
+[SKComponentLayoutDescriptor registerSubDescriptor:&YourSubDescriptor forName:@"Section Name"];
-}
-
-@end
-
-#endif
 ```
 
-Once you have implemented the descriptor, you will have to setup the Layout plugin as follows.
+Swift support is not yet available because you must access `SKComponentLayoutWrapper` to implement a subdescriptor.
-
-<!--DOCUSAURUS_CODE_TABS-->
-<!--Objective-C-->
-```objc
-NSArray<SKSubDescriptor *> *registeredSubDescriptors = @[ yourSubDescriptors ];
-SKDescriptorMapper *layoutDescriptorMapper = [[SKDescriptorMapper alloc] initWithDefaults];
-[FlipperKitLayoutComponentKitSupport setUpWithDescriptorMapper: layoutDescriptorMapper subDescriptors: registeredSubDescriptors];
-[client addPlugin: [[FlipperKitLayoutPlugin alloc] initWithRootNode: application
-                                           withDescriptorMapper: layoutDescriptorMapper]];
-```
-<!--Swift-->
-```swift
-let subDescriptors = [ yourSubDescriptors ]
-let layoutDescriptorMapper = SKDescriptorMapper(defaults: ())
-FlipperKitLayoutComponentKitSupport.setUpWith(layoutDescriptorMapper, subDescriptors: subDescriptors)
-client?.add(FlipperKitLayoutPlugin(rootNode: application, with: layoutDescriptorMapper!))
-
-```
-<!--END_DOCUSAURUS_CODE_TABS-->
-
-

iOS/Plugins/FlipperKitLayoutPlugin/FlipperKitLayoutComponentKitSupport/FlipperKitLayoutComponentKitSupport.h

@@ -8,13 +8,9 @@
 #import <Foundation/Foundation.h>
 
 #import <FlipperKitLayoutPlugin/SKDescriptorMapper.h>
-#import "SKSubDescriptor.h"
 
 @interface FlipperKitLayoutComponentKitSupport : NSObject
 
 + (void)setUpWithDescriptorMapper:(SKDescriptorMapper*)mapper;
 
-+ (void)setUpWithDescriptorMapper:(SKDescriptorMapper*)mapper
-                   subDescriptors:(NSArray<SKSubDescriptor*>*)subDescriptors;
-
 @end

iOS/Plugins/FlipperKitLayoutPlugin/FlipperKitLayoutComponentKitSupport/FlipperKitLayoutComponentKitSupport.mm

@@ -17,22 +17,9 @@
 #import "SKComponentLayoutDescriptor.h"
 #import "SKComponentLayoutWrapper.h"
 #import "SKComponentRootViewDescriptor.h"
-#import "SKSubDescriptor.h"
 
 @implementation FlipperKitLayoutComponentKitSupport
 
-+ (void)setUpWithDescriptorMapper:(SKDescriptorMapper*)mapper
-                   subDescriptors:(NSArray<SKSubDescriptor*>*)subDescriptors {
-  [mapper registerDescriptor:[[SKComponentRootViewDescriptor alloc]
-                                 initWithDescriptorMapper:mapper]
-                    forClass:[CKComponentRootView class]];
-  SKComponentLayoutDescriptor* layoutDescriptor =
-      [[SKComponentLayoutDescriptor alloc] initWithDescriptorMapper:mapper];
-  [layoutDescriptor addSubDescriptors:subDescriptors];
-  [mapper registerDescriptor:layoutDescriptor
-                    forClass:[SKComponentLayoutWrapper class]];
-}
-
 + (void)setUpWithDescriptorMapper:(SKDescriptorMapper*)mapper {
   // What we really want here is "forProtocol:@protocol(CKInspectableView)" but
   // no such luck.

iOS/Plugins/FlipperKitLayoutPlugin/FlipperKitLayoutComponentKitSupport/SKComponentLayoutDescriptor.h

@@ -14,6 +14,7 @@
 @interface SKComponentLayoutDescriptor
     : SKNodeDescriptor<SKComponentLayoutWrapper*>
 
-- (void)addSubDescriptors:(NSArray<SKSubDescriptor*>*)subDescriptors;
++ (void)registerSubDescriptor:(SKSubDescriptor)descriptor
+                      forName:(NSString*)name;
 
 @end

iOS/Plugins/FlipperKitLayoutPlugin/FlipperKitLayoutComponentKitSupport/SKComponentLayoutDescriptor.mm

@@ -9,6 +9,9 @@
 
 #import "SKComponentLayoutDescriptor.h"
 
+#import <utility>
+#import <vector>
+
 #import <ComponentKit/CKComponent.h>
 #import <ComponentKit/CKComponentAccessibility.h>
 #import <ComponentKit/CKComponentActionInternal.h>
@@ -29,15 +32,18 @@
 #import "SKSubDescriptor.h"
 #import "Utils.h"
 
-@implementation SKComponentLayoutDescriptor {
+@implementation SKComponentLayoutDescriptor
-  NSArray<SKSubDescriptor*>* _registeredSubdescriptors;
+
+static std::vector<std::pair<NSString*, SKSubDescriptor>>& subDescriptors() {
+  // Avoid a global constructor; we want to lazily initialize this when needed.
+  static std::vector<std::pair<NSString*, SKSubDescriptor>> d;
+  return d;
 }
 
-- (void)setUp {
++ (void)registerSubDescriptor:(SKSubDescriptor)descriptor
-  [super setUp];
+                      forName:(NSString*)name {
-
+  if (name && descriptor) {
-  if (!_registeredSubdescriptors) {
+    subDescriptors().push_back({name, descriptor});
-    _registeredSubdescriptors = [NSArray new];
   }
 }
 
@@ -90,8 +96,8 @@
   NSMutableDictionary<NSString*, NSObject*>* extraData =
       [[NSMutableDictionary alloc] init];
 
-  for (SKSubDescriptor* s in _registeredSubdescriptors) {
+  for (const auto& pair : subDescriptors()) {
-    [extraData setObject:[s getDataForNode:node] forKey:[s getName]];
+    [extraData setObject:pair.second(node) forKey:pair.first];
   }
   if (extraData.count > 0) {
     [data addObject:[SKNamed newWithName:@"Extra Sections"
@@ -102,10 +108,6 @@
   return data;
 }
 
-- (void)addSubDescriptors:(nonnull NSArray<SKSubDescriptor*>*)subDescriptors {
-  _registeredSubdescriptors = subDescriptors;
-}
-
 - (NSDictionary<NSString*, NSObject*>*)propsForFlexboxChild:
     (CKFlexboxComponentChild)child {
   return @{

iOS/Plugins/FlipperKitLayoutPlugin/FlipperKitLayoutComponentKitSupport/SKSubDescriptor.h

@@ -10,20 +10,8 @@
 @class SKComponentLayoutWrapper;
 
 /**
- A SKSubDescriptor is an object which knows how to expose an Object of type T
+ A SKSubDescriptor is a function which knows how to expose additional data
- to the SKLayoutDescriptor. This class is for frameworks wanting to pass data
+ to SKLayoutDescriptor. This class is for frameworks wanting to pass data
  along through the Layout Descriptor.
  */
-@interface SKSubDescriptor : NSObject
+typedef NSString* (*SKSubDescriptor)(SKComponentLayoutWrapper* node);
-
-/**
- This is the SubDescriptor name.
- */
-- (NSString*)getName;
-
-/**
- This is the data the SubDescriptor wants to pass up to the SKLayoutDescriptor.
- */
-- (NSString*)getDataForNode:(SKComponentLayoutWrapper*)node;
-
-@end

iOS/Plugins/FlipperKitLayoutPlugin/FlipperKitLayoutComponentKitSupport/SKSubDescriptor.mm

@@ -4,24 +4,3 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  */
-
-#if FB_SONARKIT_ENABLED
-
-#import "SKSubDescriptor.h"
-#import "SKComponentLayoutWrapper.h"
-
-@implementation SKSubDescriptor {
-}
-
-- (NSDictionary<NSString*, NSObject*>*)getDataForNode:
-    (SKComponentLayoutWrapper*)node {
-  return @{};
-}
-
-- (NSString*)getName {
-  return @"";
-}
-
-@end
-
-#endif