Generalize non-define registration with MEDIAPIPE_STATIC_REGISTRATOR_TEMPLATE

PiperOrigin-RevId: 547929982

mediapipe/framework/api2/node.h

@@ -64,57 +64,13 @@ class CalculatorBaseFactoryFor<
 namespace api2 {
 namespace internal {
 
-// Defining a member of this type causes P to be ODR-used, which forces its
+MEDIAPIPE_STATIC_REGISTRATOR_TEMPLATE(
-// instantiation if it's a static member of a template.
+    NodeRegistrator, mediapipe::CalculatorBaseRegistry, T::kCalculatorName,
-// Previously we depended on the pointer's value to determine whether the size
+    absl::make_unique<mediapipe::internal::CalculatorBaseFactoryFor<T>>)
-// of a character array is 0 or 1, forcing it to be instantiated so the
-// compiler can determine the object's layout. But using it as a template
-// argument is more compact.
-template <auto* P>
-struct ForceStaticInstantiation {
-#ifdef _MSC_VER
-  // Just having it as the template argument does not count as a use for
-  // MSVC.
-  static constexpr bool Use() { return P != nullptr; }
-  char force_static[Use()];
-#endif  // _MSC_VER
-};
 
-// Helper template for forcing the definition of a static registration token.
+MEDIAPIPE_STATIC_REGISTRATOR_TEMPLATE(SubgraphRegistrator,
-template <typename T>
+                                      mediapipe::SubgraphRegistry,
-struct NodeRegistrationStatic {
+                                      T::kCalculatorName, absl::make_unique<T>)
-  static NoDestructor<mediapipe::RegistrationToken> registration;
-
-  static mediapipe::RegistrationToken Make() {
-    return mediapipe::CalculatorBaseRegistry::Register(
-        T::kCalculatorName,
-        absl::make_unique<mediapipe::internal::CalculatorBaseFactoryFor<T>>);
-  }
-
-  using RequireStatics = ForceStaticInstantiation<&registration>;
-};
-
-// Static members of template classes can be defined in the header.
-template <typename T>
-NoDestructor<mediapipe::RegistrationToken>
-    NodeRegistrationStatic<T>::registration(NodeRegistrationStatic<T>::Make());
-
-template <typename T>
-struct SubgraphRegistrationImpl {
-  static NoDestructor<mediapipe::RegistrationToken> registration;
-
-  static mediapipe::RegistrationToken Make() {
-    return mediapipe::SubgraphRegistry::Register(T::kCalculatorName,
-                                                 absl::make_unique<T>);
-  }
-
-  using RequireStatics = ForceStaticInstantiation<&registration>;
-};
-
-template <typename T>
-NoDestructor<mediapipe::RegistrationToken>
-    SubgraphRegistrationImpl<T>::registration(
-        SubgraphRegistrationImpl<T>::Make());
 
 }  // namespace internal
 
@@ -127,14 +83,7 @@ template <class Impl = void>
 class RegisteredNode;
 
 template <class Impl>
-class RegisteredNode : public Node {
+class RegisteredNode : public Node, private internal::NodeRegistrator<Impl> {};
- private:
-  // The member below triggers instantiation of the registration static.
-  // Note that the constructor of calculator subclasses is only invoked through
-  // the registration token, and so we cannot simply use the static in the
-  // constructor.
-  typename internal::NodeRegistrationStatic<Impl>::RequireStatics register_;
-};
 
 // No-op version for backwards compatibility.
 template <>
@@ -216,10 +165,9 @@ class NodeImpl : public RegisteredNode<Impl>, public Intf {
 // TODO: verify that the subgraph config fully implements the
 // declared interface.
 template <class Intf, class Impl>
-class SubgraphImpl : public Subgraph, public Intf {
+class SubgraphImpl : public Subgraph,
- private:
+                     public Intf,
-  typename internal::SubgraphRegistrationImpl<Impl>::RequireStatics register_;
+                     private internal::SubgraphRegistrator<Impl> {};
-};
 
 // This macro is used to register a calculator that does not use automatic
 // registration. Deprecated.

mediapipe/framework/deps/registration.h

@@ -144,6 +144,23 @@ template <typename T>
 struct WrapStatusOr<absl::StatusOr<T>> {
   using type = absl::StatusOr<T>;
 };
+
+// Defining a member of this type causes P to be ODR-used, which forces its
+// instantiation if it's a static member of a template.
+// Previously we depended on the pointer's value to determine whether the size
+// of a character array is 0 or 1, forcing it to be instantiated so the
+// compiler can determine the object's layout. But using it as a template
+// argument is more compact.
+template <auto* P>
+struct ForceStaticInstantiation {
+#ifdef _MSC_VER
+  // Just having it as the template argument does not count as a use for
+  // MSVC.
+  static constexpr bool Use() { return P != nullptr; }
+  char force_static[Use()];
+#endif  // _MSC_VER
+};
+
 }  // namespace registration_internal
 
 class NamespaceAllowlist {
@@ -408,6 +425,64 @@ class GlobalFactoryRegistry {
       new mediapipe::RegistrationToken(                                        \
           RegistryType::Register(#name, __VA_ARGS__))
 
+// Defines a utility registrator class which can be used to automatically
+// register factory functions.
+//
+// Example:
+// === Defining a registry ================================================
+//
+//  class Component {};
+//
+//  using ComponentRegistry = GlobalFactoryRegistry<std::unique_ptr<Component>>;
+//
+// === Defining a registrator =============================================
+//
+//  MEDIAPIPE_STATIC_REGISTRATOR_TEMPLATE(ComponentRegistrator,
+//                                        ComponentRegistry, T::kName,
+//                                        absl::make_unique<T>);
+//
+// === Defining and registering a new component. ==========================
+//
+//  class MyComponent : public Component,
+//                      private ComponentRegistrator<MyComponent> {
+//   public:
+//    static constexpr char kName[] = "MyComponent";
+//    ...
+//  };
+//
+// NOTE:
+// - MyComponent is automatically registered in ComponentRegistry by
+//   "MyComponent" name.
+// - Every component is require to provide its name (T::kName here.)
+#define MEDIAPIPE_STATIC_REGISTRATOR_TEMPLATE(RegistratorName, RegistryType,  \
+                                              name, ...)                      \
+  template <typename T>                                                       \
+  struct Internal##RegistratorName {                                          \
+    static NoDestructor<mediapipe::RegistrationToken> registration;           \
+                                                                              \
+    static mediapipe::RegistrationToken Make() {                              \
+      return RegistryType::Register(name, __VA_ARGS__);                       \
+    }                                                                         \
+                                                                              \
+    using RequireStatics =                                                    \
+        registration_internal::ForceStaticInstantiation<&registration>;       \
+  };                                                                          \
+  /* Static members of template classes can be defined in the header. */      \
+  template <typename T>                                                       \
+  NoDestructor<mediapipe::RegistrationToken>                                  \
+      Internal##RegistratorName<T>::registration(                             \
+          Internal##RegistratorName<T>::Make());                              \
+                                                                              \
+  template <typename T>                                                       \
+  class RegistratorName {                                                     \
+   private:                                                                   \
+    /* The member below triggers instantiation of the registration static. */ \
+    /* Note that the constructor of calculator subclasses is only invoked  */ \
+    /* through the registration token, and so we cannot simply use the     */ \
+    /* static in theconstructor.                                           */ \
+    typename Internal##RegistratorName<T>::RequireStatics register_;          \
+  };
+
 }  // namespace mediapipe
 
 #endif  // MEDIAPIPE_DEPS_REGISTRATION_H_