Reduce the boilerplate when creating bindings

Instead, use C++ template to generate the callback trampolines and the
registration block.

sky/engine/core/compositing/Scene.cpp

@@ -7,25 +7,18 @@
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkPictureRecorder.h"
 #include "sky/engine/tonic/dart_args.h"
+#include "sky/engine/tonic/dart_binding_macros.h"
 #include "sky/engine/tonic/dart_converter.h"
 #include "sky/engine/tonic/dart_library_natives.h"
 
 namespace blink {
-namespace {
-
-void DisposeCallback(Dart_NativeArguments args) {
-  DartCall(&Scene::dispose, args);
-}
-
-}  // namespace
 
 IMPLEMENT_WRAPPERTYPEINFO(Scene);
 
-void Scene::RegisterNatives(DartLibraryNatives* natives) {
-  natives->Register({
-    { "Scene_dispose", DisposeCallback, 1, true },
-  });
-}
+#define FOR_EACH_BINDING(V) \
+  V(Scene, dispose)
+
+DART_BIND_ALL(Scene, FOR_EACH_BINDING)
 
 PassRefPtr<Scene> Scene::create(
     std::unique_ptr<sky::compositor::Layer> rootLayer,

sky/engine/core/compositing/SceneBuilder.cpp

@@ -16,17 +16,17 @@
 #include "sky/compositor/statistics_layer.h"
 #include "sky/compositor/transform_layer.h"
 #include "sky/engine/tonic/dart_args.h"
+#include "sky/engine/tonic/dart_binding_macros.h"
 #include "sky/engine/tonic/dart_converter.h"
 #include "sky/engine/tonic/dart_library_natives.h"
 
 namespace blink {
-namespace {
 
-void ConstructorCallback(Dart_NativeArguments args) {
+static void SceneBuilder_constructor(Dart_NativeArguments args) {
   DartCallConstructor(&SceneBuilder::create, args);
 }
 
-void PushTransformCallback(Dart_NativeArguments args) {
+static void SceneBuilder_pushTransform(Dart_NativeArguments args) {
   DartArgIterator it(args);
   Float64List matrix4 = it.GetNext<Float64List>();
   if (it.had_exception())
@@ -37,64 +37,27 @@ void PushTransformCallback(Dart_NativeArguments args) {
     Dart_ThrowException(es.GetDartException(args, true));
 }
 
-void PushClipRectCallback(Dart_NativeArguments args) {
-  DartCall(&SceneBuilder::pushClipRect, args);
-}
-
-void PushClipRRectCallback(Dart_NativeArguments args) {
-  DartCall(&SceneBuilder::pushClipRRect, args);
-}
-
-void PushClipPathCallback(Dart_NativeArguments args) {
-  DartCall(&SceneBuilder::pushClipPath, args);
-}
-
-void PushOpacityCallback(Dart_NativeArguments args) {
-  DartCall(&SceneBuilder::pushOpacity, args);
-}
-
-void PushColorFilterCallback(Dart_NativeArguments args) {
-  DartCall(&SceneBuilder::pushColorFilter, args);
-}
-
-void PopCallback(Dart_NativeArguments args) {
-  DartCall(&SceneBuilder::pop, args);
-}
-
-void AddPictureCallback(Dart_NativeArguments args) {
-  DartCall(&SceneBuilder::addPicture, args);
-}
-
-void AddStatisticsCallback(Dart_NativeArguments args) {
-  DartCall(&SceneBuilder::addStatistics, args);
-}
-
-void SetRasterizerTracingThresholdCallback(Dart_NativeArguments args) {
-  DartCall(&SceneBuilder::setRasterizerTracingThreshold, args);
-}
-
-void BuildCallback(Dart_NativeArguments args) {
-  DartCallAndReturn(&SceneBuilder::build, args);
-}
+IMPLEMENT_WRAPPERTYPEINFO(SceneBuilder);
 
-}  // namespace
+#define FOR_EACH_BINDING(V) \
+  V(SceneBuilder, pushClipRect) \
+  V(SceneBuilder, pushClipRRect) \
+  V(SceneBuilder, pushClipPath) \
+  V(SceneBuilder, pushOpacity) \
+  V(SceneBuilder, pushColorFilter) \
+  V(SceneBuilder, pop) \
+  V(SceneBuilder, addPicture) \
+  V(SceneBuilder, addStatistics) \
+  V(SceneBuilder, setRasterizerTracingThreshold) \
+  V(SceneBuilder, build)
 
-IMPLEMENT_WRAPPERTYPEINFO(SceneBuilder);
+FOR_EACH_BINDING(DART_NATIVE_CALLBACK)
 
 void SceneBuilder::RegisterNatives(DartLibraryNatives* natives) {
   natives->Register({
-    { "SceneBuilder_constructor", ConstructorCallback, 2, true },
-    { "SceneBuilder_pushTransform", PushTransformCallback, 2, true },
-    { "SceneBuilder_pushClipRect", PushClipRectCallback, 2, true },
-    { "SceneBuilder_pushClipRRect", PushClipRRectCallback, 3, true },
-    { "SceneBuilder_pushClipPath", PushClipPathCallback, 3, true },
-    { "SceneBuilder_pushOpacity", PushOpacityCallback, 3, true },
-    { "SceneBuilder_pushColorFilter", PushColorFilterCallback, 4, true },
-    { "SceneBuilder_pop", PopCallback, 1, true },
-    { "SceneBuilder_addPicture", AddPictureCallback, 4, true },
-    { "SceneBuilder_addStatistics", AddStatisticsCallback, 3, true },
-    { "SceneBuilder_setRasterizerTracingThreshold", SetRasterizerTracingThresholdCallback, 2, true },
-    { "SceneBuilder_build", BuildCallback, 1, true },
+    { "SceneBuilder_constructor", SceneBuilder_constructor, 2, true },
+    { "SceneBuilder_pushTransform", SceneBuilder_pushTransform, 2, true },
+FOR_EACH_BINDING(DART_REGISTER_NATIVE)
   });
 }
 

sky/engine/tonic/BUILD.gn

@@ -5,6 +5,8 @@
 source_set("tonic") {
   sources = [
     "dart_api_scope.h",
+    "dart_args.h",
+    "dart_binding_macros.h",
     "dart_class_library.cc",
     "dart_class_library.h",
     "dart_class_provider.cc",

sky/engine/tonic/dart_args.h

@@ -66,14 +66,16 @@ class IndicesForSignature {};
 template <typename ResultType,
           typename... ArgTypes>
 struct IndicesForSignature<ResultType (*)(ArgTypes...)> {
-  using type = typename IndicesGenerator<sizeof...(ArgTypes)>::type;
+  static const size_t count = sizeof...(ArgTypes);
+  using type = typename IndicesGenerator<count>::type;
 };
 
 template <typename C,
           typename ResultType,
           typename... ArgTypes>
 struct IndicesForSignature<ResultType (C::*)(ArgTypes...)> {
-  using type = typename IndicesGenerator<sizeof...(ArgTypes)>::type;
+  static const size_t count = sizeof...(ArgTypes);
+  using type = typename IndicesGenerator<count>::type;
 };
 
 template<size_t index, typename ArgType>
@@ -89,19 +91,19 @@ struct DartArgHolder {
 };
 
 template <typename IndicesType, typename T>
-class DartDecoder {
+class DartDispatcher {
 };
 
 template <size_t... indices,
           typename ResultType,
           typename... ArgTypes>
-struct DartDecoder<IndicesHolder<indices...>, ResultType (*)(ArgTypes...)>
+struct DartDispatcher<IndicesHolder<indices...>, ResultType (*)(ArgTypes...)>
     : public DartArgHolder<indices, ArgTypes>... {
   using FunctionPtr = ResultType (*)(ArgTypes...);
 
   DartArgIterator* it_;
 
-  explicit DartDecoder(DartArgIterator* it)
+  explicit DartDispatcher(DartArgIterator* it)
       : DartArgHolder<indices, ArgTypes>(it)..., it_(it) { }
 
   ResultType Dispatch(FunctionPtr func) {
@@ -109,22 +111,41 @@ struct DartDecoder<IndicesHolder<indices...>, ResultType (*)(ArgTypes...)>
   }
 };
 
+template <size_t... indices,
+          typename C,
+          typename... ArgTypes>
+struct DartDispatcher<IndicesHolder<indices...>, void (C::*)(ArgTypes...)>
+    : public DartArgHolder<indices, ArgTypes>... {
+  using FunctionPtr = void (C::*)(ArgTypes...);
+
+  DartArgIterator* it_;
+
+  explicit DartDispatcher(DartArgIterator* it)
+      : DartArgHolder<indices, ArgTypes>(it)..., it_(it) { }
+
+  void Dispatch(FunctionPtr func) {
+    (GetReceiver<C>(it_->args())->*func)(
+        DartArgHolder<indices, ArgTypes>::value...);
+  }
+};
+
 template <size_t... indices,
           typename C,
           typename ResultType,
           typename... ArgTypes>
-struct DartDecoder<IndicesHolder<indices...>, ResultType (C::*)(ArgTypes...)>
+struct DartDispatcher<IndicesHolder<indices...>, ResultType (C::*)(ArgTypes...)>
     : public DartArgHolder<indices, ArgTypes>... {
   using FunctionPtr = ResultType (C::*)(ArgTypes...);
 
   DartArgIterator* it_;
 
-  explicit DartDecoder(DartArgIterator* it)
+  explicit DartDispatcher(DartArgIterator* it)
       : DartArgHolder<indices, ArgTypes>(it)..., it_(it) { }
 
-  ResultType Dispatch(FunctionPtr func) {
-    return (GetReceiver<C>(it_->args())->*func)(
-        DartArgHolder<indices, ArgTypes>::value...);
+  void Dispatch(FunctionPtr func) {
+    DartReturn((GetReceiver<C>(it_->args())->*func)(
+                   DartArgHolder<indices, ArgTypes>::value...),
+               it_->args());
   }
 };
 
@@ -137,27 +158,17 @@ template<typename Sig>
 void DartCall(Sig func, Dart_NativeArguments args) {
   DartArgIterator it(args);
   using Indices = typename IndicesForSignature<Sig>::type;
-  DartDecoder<Indices, Sig> decoder(&it);
+  DartDispatcher<Indices, Sig> decoder(&it);
   if (it.had_exception())
     return;
   decoder.Dispatch(func);
 }
 
-template<typename Sig>
-void DartCallAndReturn(Sig func, Dart_NativeArguments args) {
-  DartArgIterator it(args);
-  using Indices = typename IndicesForSignature<Sig>::type;
-  DartDecoder<Indices, Sig> decoder(&it);
-  if (it.had_exception())
-    return;
-  DartReturn(decoder.Dispatch(func), args);
-}
-
 template<typename Sig>
 void DartCallConstructor(Sig func, Dart_NativeArguments args) {
   DartArgIterator it(args);
   using Indices = typename IndicesForSignature<Sig>::type;
-  DartDecoder<Indices, Sig> decoder(&it);
+  DartDispatcher<Indices, Sig> decoder(&it);
   if (it.had_exception())
     return;
   decoder.Dispatch(func)->AssociateWithDartWrapper(args);

sky/engine/tonic/dart_binding_macros.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SKY_ENGINE_TONIC_DART_BINDING_MACROS_H_
+#define SKY_ENGINE_TONIC_DART_BINDING_MACROS_H_
+
+#include "sky/engine/tonic/dart_args.h"
+
+#define DART_NATIVE_CALLBACK(CLASS, METHOD) \
+  static void CLASS_##METHOD(Dart_NativeArguments args) { \
+    DartCall(&CLASS::METHOD, args); \
+  }
+
+#define DART_REGISTER_NATIVE(CLASS, METHOD) \
+  { #CLASS "_" #METHOD, CLASS_##METHOD, \
+    IndicesForSignature<decltype(&CLASS::METHOD)>::count + 1, true },
+
+#define DART_BIND_ALL(CLASS, FOR_EACH) \
+FOR_EACH(DART_NATIVE_CALLBACK) \
+void CLASS::RegisterNatives(DartLibraryNatives* natives) { \
+  natives->Register({ \
+    FOR_EACH(DART_REGISTER_NATIVE) \
+  }); \
+}
+
+#endif  // SKY_ENGINE_TONIC_DART_BINDING_MACROS_H_