Rework CallApi*Stubs.

src/interface-descriptors.h

Index: src/interface-descriptors.h
diff --git a/src/interface-descriptors.h b/src/interface-descriptors.h
index d62bee52039fd406d23df241a977f1b42f1190cf..8f9f5384ad833e9d7eb66c5ddd1fb82ed96f40f8 100644
--- a/src/interface-descriptors.h
+++ b/src/interface-descriptors.h
@@ -67,8 +67,14 @@ class PlatformInterfaceDescriptor;
   V(Named)                                    \
   V(CallHandler)                              \
   V(ArgumentAdaptor)                          \
-  V(ApiFunction)                              \
-  V(ApiAccessor)                              \
+  V(ApiCallbackWith0Args)                     \
+  V(ApiCallbackWith1Args)                     \
+  V(ApiCallbackWith2Args)                     \
+  V(ApiCallbackWith3Args)                     \
+  V(ApiCallbackWith4Args)                     \
+  V(ApiCallbackWith5Args)                     \
+  V(ApiCallbackWith6Args)                     \
+  V(ApiCallbackWith7Args)                     \
   V(ApiGetter)                                \
   V(LoadGlobalViaContext)                     \
   V(StoreGlobalViaContext)                    \
@@ -199,6 +205,7 @@ class CallInterfaceDescriptor {
   void Initialize(Isolate* isolate, CallDescriptors::Key key) {
     if (!data()->IsInitialized()) {
       CallInterfaceDescriptorData* d = isolate->call_descriptor_data(key);
+      DCHECK(d == data());  // d should be a modifiable pointer to data().
       InitializePlatformSpecific(d);
       FunctionType* function_type = BuildCallInterfaceDescriptorFunctionType(
           isolate, d->register_param_count());
@@ -210,18 +217,20 @@ class CallInterfaceDescriptor {
   const CallInterfaceDescriptorData* data_;
 };
 
+#define DECLARE_DESCRIPTOR_WITH_BASE(name, base)           \
+ public:                                                   \
+  explicit name(Isolate* isolate) : base(isolate, key()) { \
+    Initialize(isolate, key());                            \
+  }                                                        \
+  static inline CallDescriptors::Key key();
 
 #define DECLARE_DESCRIPTOR(name, base)                                         \
-  explicit name(Isolate* isolate) : base(isolate, key()) {                     \
-    Initialize(isolate, key());                                                \
-  }                                                                            \
-                                                                               \
+  DECLARE_DESCRIPTOR_WITH_BASE(name, base)                                     \
  protected:                                                                    \
   void InitializePlatformSpecific(CallInterfaceDescriptorData* data) override; \
   name(Isolate* isolate, CallDescriptors::Key key) : base(isolate, key) {}     \
                                                                                \
- public:                                                                       \
-  static inline CallDescriptors::Key key();
+ public:
 
 #define DECLARE_DESCRIPTOR_WITH_CUSTOM_FUNCTION_TYPE(name, base) \
   DECLARE_DESCRIPTOR(name, base)                                 \
@@ -689,18 +698,83 @@ class ArgumentAdaptorDescriptor : public CallInterfaceDescriptor {
                                                CallInterfaceDescriptor)
 };
 
+// The ApiCallback*Descriptors have a lot of boilerplate. Because
+// - the macros in this file assumes a class name ends in "Descriptor",
+// - the platform-specific part is independent of the number of arguments,
+// - several macros assume static dispatch,
+// we have a regular 'base' class, plus a templated base class for a given
+// number of arguments.
+//
+// Neither 'base' class is meant to be instantiated directly, and neither
+// has public constructors to ensure this is so.
+//
+// The simplest usage for all the ApiCallback*Descriptors is probably
+//   ApiCallbackDescriptorBase::ForArgs(isolate, argc)
+class ApiCallbackDescriptorBase : public CallInterfaceDescriptor {
+ public:
+  static CallInterfaceDescriptor ForArgs(Isolate* isolate, int argc);
+
+ protected:
+  void InitializePlatformSpecific(CallInterfaceDescriptorData* data) override;
+  ApiCallbackDescriptorBase(Isolate* isolate, CallDescriptors::Key key)
+      : CallInterfaceDescriptor(isolate, key) {}
+};
+
+template <int argc>

[danno, 2016/03/04 18:07:43]

Is this template magic really necessary? Can you not just create a new macro
DECLARE_API_CALLBACK_WITH_ARGS_DESCRIPTOR with a integer argument that does that
same? It seems a little less magic.

[vogelheim, 2016/03/08 12:59:27]

Removed, and replaced with DECLARE_DESCRIPTOR_WITH_BASE_AND_FUNCTION_TYPE_ARG.

This does look nicer.

+class ApiCallbackWithArgsBase : public ApiCallbackDescriptorBase {
+ protected:
+  ApiCallbackWithArgsBase(Isolate* isolate, CallDescriptors::Key key)
+      : ApiCallbackDescriptorBase(isolate, key) {}
+  FunctionType* BuildCallInterfaceDescriptorFunctionType(
+      Isolate* isolate, int register_param_count) override;
+};
 
-class ApiFunctionDescriptor : public CallInterfaceDescriptor {
+class ApiCallbackWith0ArgsDescriptor : public ApiCallbackWithArgsBase<0> {
  public:
-  DECLARE_DESCRIPTOR_WITH_CUSTOM_FUNCTION_TYPE(ApiFunctionDescriptor,
-                                               CallInterfaceDescriptor)
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith0ArgsDescriptor,
+                               ApiCallbackWithArgsBase<0>)
 };
 
+class ApiCallbackWith1ArgsDescriptor : public ApiCallbackWithArgsBase<1> {
+ public:
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith1ArgsDescriptor,
+                               ApiCallbackWithArgsBase<1>)
+};
 
-class ApiAccessorDescriptor : public CallInterfaceDescriptor {
+class ApiCallbackWith2ArgsDescriptor : public ApiCallbackWithArgsBase<2> {
  public:
-  DECLARE_DESCRIPTOR_WITH_CUSTOM_FUNCTION_TYPE(ApiAccessorDescriptor,
-                                               CallInterfaceDescriptor)
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith2ArgsDescriptor,
+                               ApiCallbackWithArgsBase<2>)
+};
+
+class ApiCallbackWith3ArgsDescriptor : public ApiCallbackWithArgsBase<3> {
+ public:
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith3ArgsDescriptor,
+                               ApiCallbackWithArgsBase<3>)
+};
+
+class ApiCallbackWith4ArgsDescriptor : public ApiCallbackWithArgsBase<4> {
+ public:
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith4ArgsDescriptor,
+                               ApiCallbackWithArgsBase<4>)
+};
+
+class ApiCallbackWith5ArgsDescriptor : public ApiCallbackWithArgsBase<5> {
+ public:
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith5ArgsDescriptor,
+                               ApiCallbackWithArgsBase<5>)
+};
+
+class ApiCallbackWith6ArgsDescriptor : public ApiCallbackWithArgsBase<6> {
+ public:
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith6ArgsDescriptor,
+                               ApiCallbackWithArgsBase<6>)
+};
+
+class ApiCallbackWith7ArgsDescriptor : public ApiCallbackWithArgsBase<7> {
+ public:
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith7ArgsDescriptor,
+                               ApiCallbackWithArgsBase<7>)
 };
 
 
@@ -744,7 +818,7 @@ class GrowArrayElementsDescriptor : public CallInterfaceDescriptor {
   static const Register KeyRegister();
 };
 
-class InterpreterDispatchDescriptor  : public CallInterfaceDescriptor {
+class InterpreterDispatchDescriptor : public CallInterfaceDescriptor {
  public:
   DECLARE_DESCRIPTOR_WITH_CUSTOM_FUNCTION_TYPE(InterpreterDispatchDescriptor,
                                                CallInterfaceDescriptor)
@@ -777,8 +851,9 @@ class InterpreterCEntryDescriptor : public CallInterfaceDescriptor {
   DECLARE_DESCRIPTOR(InterpreterCEntryDescriptor, CallInterfaceDescriptor)
 };
 
+#undef DECLARE_DESCRIPTOR_WITH_BASE
 #undef DECLARE_DESCRIPTOR
-
+#undef DECLARE_DESCRIPTOR_WITH_CUSTOM_FUNCTION_TYPE
 
 // We define the association between CallDescriptors::Key and the specialized
 // descriptor here to reduce boilerplate and mistakes.