Rewrite gin/function_template.h to use C++11 variadic templates.

gin/function_template.h

-// This file was GENERATED by command:
-//     pump.py function_template.h.pump
-// DO NOT EDIT BY HAND!!!
+// Copyright 2014 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 GIN_FUNCTION_TEMPLATE_H_
 #define GIN_FUNCTION_TEMPLATE_H_
 
-// Copyright 2013 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.
-
 #include "base/callback.h"
 #include "base/logging.h"
 #include "gin/arguments.h"
 #include "gin/converter.h"
 #include "gin/gin_export.h"
 #include "v8/include/v8.h"
 
 namespace gin {
 
 class PerIsolateData;
@@ skipping 50 matching lines @@
       : CallbackHolderBase(isolate), callback(callback), flags(flags) {}
   base::Callback<Sig> callback;
   int flags;
  private:
   virtual ~CallbackHolder() {}
 
   DISALLOW_COPY_AND_ASSIGN(CallbackHolder);
 };
 
 
-// This set of templates invokes a base::Callback, converts the return type to a
+// This template struct invokes a base::Callback, converts the return type to a
 // JavaScript value, and returns that value to script via the provided
 // gin::Arguments object.
-//
+template <typename R, typename... A>
+struct Invoker {
+  inline static void Go(
+      Arguments* args,
+      const base::Callback<R(A...)>& callback,
+      const A&... a) {
+    args->Return(callback.Run(a...));
+  }
+};
+
 // In C++, you can declare the function foo(void), but you can't pass a void
 // expression to foo. As a result, we must specialize the case of Callbacks that
 // have the void return type.
-template<typename R, typename P1 = void, typename P2 = void,
-    typename P3 = void, typename P4 = void, typename P5 = void,
-    typename P6 = void>
-struct Invoker {
+template <typename... A>
+struct Invoker<void, A...> {
   inline static void Go(
       Arguments* args,
-      const base::Callback<R(P1, P2, P3, P4, P5, P6)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3,
-      const P4& a4,
-      const P5& a5,
-      const P6& a6) {
-    args->Return(callback.Run(a1, a2, a3, a4, a5, a6));
+      const base::Callback<void(A...)>& callback,
+      const A&... a) {
+    callback.Run(a...);
   }
 };
-template<typename P1, typename P2, typename P3, typename P4, typename P5,
-    typename P6>
-struct Invoker<void, P1, P2, P3, P4, P5, P6> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void(P1, P2, P3, P4, P5, P6)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3,
-      const P4& a4,
-      const P5& a5,
-      const P6& a6) {
-    callback.Run(a1, a2, a3, a4, a5, a6);
-  }
-};
-
-template<typename R, typename P1, typename P2, typename P3, typename P4,
-    typename P5>
-struct Invoker<R, P1, P2, P3, P4, P5, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R(P1, P2, P3, P4, P5)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3,
-      const P4& a4,
-      const P5& a5) {
-    args->Return(callback.Run(a1, a2, a3, a4, a5));
-  }
-};
-template<typename P1, typename P2, typename P3, typename P4, typename P5>
-struct Invoker<void, P1, P2, P3, P4, P5, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void(P1, P2, P3, P4, P5)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3,
-      const P4& a4,
-      const P5& a5) {
-    callback.Run(a1, a2, a3, a4, a5);
-  }
-};
-
-template<typename R, typename P1, typename P2, typename P3, typename P4>
-struct Invoker<R, P1, P2, P3, P4, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R(P1, P2, P3, P4)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3,
-      const P4& a4) {
-    args->Return(callback.Run(a1, a2, a3, a4));
-  }
-};
-template<typename P1, typename P2, typename P3, typename P4>
-struct Invoker<void, P1, P2, P3, P4, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void(P1, P2, P3, P4)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3,
-      const P4& a4) {
-    callback.Run(a1, a2, a3, a4);
-  }
-};
-
-template<typename R, typename P1, typename P2, typename P3>
-struct Invoker<R, P1, P2, P3, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R(P1, P2, P3)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3) {
-    args->Return(callback.Run(a1, a2, a3));
-  }
-};
-template<typename P1, typename P2, typename P3>
-struct Invoker<void, P1, P2, P3, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void(P1, P2, P3)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3) {
-    callback.Run(a1, a2, a3);
-  }
-};
-
-template<typename R, typename P1, typename P2>
-struct Invoker<R, P1, P2, void, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R(P1, P2)>& callback,
-      const P1& a1,
-      const P2& a2) {
-    args->Return(callback.Run(a1, a2));
-  }
-};
-template<typename P1, typename P2>
-struct Invoker<void, P1, P2, void, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void(P1, P2)>& callback,
-      const P1& a1,
-      const P2& a2) {
-    callback.Run(a1, a2);
-  }
-};
-
-template<typename R, typename P1>
-struct Invoker<R, P1, void, void, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R(P1)>& callback,
-      const P1& a1) {
-    args->Return(callback.Run(a1));
-  }
-};
-template<typename P1>
-struct Invoker<void, P1, void, void, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void(P1)>& callback,
-      const P1& a1) {
-    callback.Run(a1);
-  }
-};
-
-template<typename R>
-struct Invoker<R, void, void, void, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R()>& callback) {
-    args->Return(callback.Run());
-  }
-};
-template<>
-struct Invoker<void, void, void, void, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void()>& callback) {
-    callback.Run();
-  }
-};
-
 
 template<typename T>
 bool GetNextArgument(Arguments* args, int create_flags, bool is_first,
                      T* result) {
   if (is_first && (create_flags & HolderIsFirstArgument) != 0) {
     return args->GetHolder(result);
   } else {
     return args->GetNext(result);
   }
 }
@@ skipping 18 matching lines @@
   return true;
 }
 
 
 // DispatchToCallback converts all the JavaScript arguments to C++ types and
 // invokes the base::Callback.
 template<typename Sig>
 struct Dispatcher {
 };
 
-template<typename R>
-struct Dispatcher<R()> {
+template <typename R, typename... A>
+class Dispatcher<R(A...)> {
+ public:
+  template <typename T>
+  struct TypeTag {};
+
   static void DispatchToCallback(
       const v8::FunctionCallbackInfo<v8::Value>& info) {
     Arguments args(info);
-    v8::Handle<v8::External> v8_holder;
-    CHECK(args.GetData(&v8_holder));
-    CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
-        v8_holder->Value());
-
-    typedef CallbackHolder<R()> HolderT;
-    HolderT* holder = static_cast<HolderT*>(holder_base);
-
-    Invoker<R>::Go(&args, holder->callback);
-  }
-};
-
-template<typename R, typename P1>
-struct Dispatcher<R(P1)> {
-  static void DispatchToCallback(
-      const v8::FunctionCallbackInfo<v8::Value>& info) {
-    Arguments args(info);
-    v8::Handle<v8::External> v8_holder;
-    CHECK(args.GetData(&v8_holder));
-    CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
-        v8_holder->Value());
-
-    typedef CallbackHolder<R(P1)> HolderT;
-    HolderT* holder = static_cast<HolderT*>(holder_base);
-
-    typename CallbackParamTraits<P1>::LocalType a1;
-    if (!GetNextArgument(&args, holder->flags, true, &a1)) {
-      args.ThrowError();
-      return;
-    }
-
-    Invoker<R, P1>::Go(&args, holder->callback, a1);
-  }
-};
-
-template<typename R, typename P1, typename P2>
-struct Dispatcher<R(P1, P2)> {
-  static void DispatchToCallback(
-      const v8::FunctionCallbackInfo<v8::Value>& info) {
-    Arguments args(info);
-    v8::Handle<v8::External> v8_holder;
-    CHECK(args.GetData(&v8_holder));
-    CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
-        v8_holder->Value());
-
-    typedef CallbackHolder<R(P1, P2)> HolderT;
-    HolderT* holder = static_cast<HolderT*>(holder_base);
-
-    typename CallbackParamTraits<P1>::LocalType a1;
-    typename CallbackParamTraits<P2>::LocalType a2;
-    if (!GetNextArgument(&args, holder->flags, true, &a1) ||
-        !GetNextArgument(&args, holder->flags, false, &a2)) {
-      args.ThrowError();
-      return;
-    }
-
-    Invoker<R, P1, P2>::Go(&args, holder->callback, a1, a2);
-  }
-};
-
-template<typename R, typename P1, typename P2, typename P3>
-struct Dispatcher<R(P1, P2, P3)> {
-  static void DispatchToCallback(
-      const v8::FunctionCallbackInfo<v8::Value>& info) {
-    Arguments args(info);
-    v8::Handle<v8::External> v8_holder;
-    CHECK(args.GetData(&v8_holder));
-    CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
-        v8_holder->Value());
-
-    typedef CallbackHolder<R(P1, P2, P3)> HolderT;
-    HolderT* holder = static_cast<HolderT*>(holder_base);
-
-    typename CallbackParamTraits<P1>::LocalType a1;
-    typename CallbackParamTraits<P2>::LocalType a2;
-    typename CallbackParamTraits<P3>::LocalType a3;
-    if (!GetNextArgument(&args, holder->flags, true, &a1) ||
-        !GetNextArgument(&args, holder->flags, false, &a2) ||
-        !GetNextArgument(&args, holder->flags, false, &a3)) {
-      args.ThrowError();
-      return;
-    }
-
-    Invoker<R, P1, P2, P3>::Go(&args, holder->callback, a1, a2, a3);
-  }
-};
-
-template<typename R, typename P1, typename P2, typename P3, typename P4>
-struct Dispatcher<R(P1, P2, P3, P4)> {
-  static void DispatchToCallback(
-      const v8::FunctionCallbackInfo<v8::Value>& info) {
-    Arguments args(info);
-    v8::Handle<v8::External> v8_holder;
-    CHECK(args.GetData(&v8_holder));
-    CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
-        v8_holder->Value());
-
-    typedef CallbackHolder<R(P1, P2, P3, P4)> HolderT;
-    HolderT* holder = static_cast<HolderT*>(holder_base);
-
-    typename CallbackParamTraits<P1>::LocalType a1;
-    typename CallbackParamTraits<P2>::LocalType a2;
-    typename CallbackParamTraits<P3>::LocalType a3;
-    typename CallbackParamTraits<P4>::LocalType a4;
-    if (!GetNextArgument(&args, holder->flags, true, &a1) ||
-        !GetNextArgument(&args, holder->flags, false, &a2) ||
-        !GetNextArgument(&args, holder->flags, false, &a3) ||
-        !GetNextArgument(&args, holder->flags, false, &a4)) {
-      args.ThrowError();
-      return;
-    }
-
-    Invoker<R, P1, P2, P3, P4>::Go(&args, holder->callback, a1, a2, a3, a4);
-  }
-};
-
-template<typename R, typename P1, typename P2, typename P3, typename P4,
-    typename P5>
-struct Dispatcher<R(P1, P2, P3, P4, P5)> {
-  static void DispatchToCallback(
-      const v8::FunctionCallbackInfo<v8::Value>& info) {
-    Arguments args(info);
     v8::Handle<v8::External> v8_holder;
     CHECK(args.GetData(&v8_holder));
     CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
         v8_holder->Value());
 
-    typedef CallbackHolder<R(P1, P2, P3, P4, P5)> HolderT;
+    typedef CallbackHolder<R(A...)> HolderT;
     HolderT* holder = static_cast<HolderT*>(holder_base);
+    bool all_arguments_ok = true;
+    bool is_first_argument = true;
+    InvokeCallback{
+          &all_arguments_ok, &args, holder->callback,
+          PassNextArgument(
+              &all_arguments_ok, &is_first_argument,
+              &args, holder->flags,
+              TypeTag<typename CallbackParamTraits<A>::LocalType>())...};
+  }
 
-    typename CallbackParamTraits<P1>::LocalType a1;
-    typename CallbackParamTraits<P2>::LocalType a2;
-    typename CallbackParamTraits<P3>::LocalType a3;
-    typename CallbackParamTraits<P4>::LocalType a4;
-    typename CallbackParamTraits<P5>::LocalType a5;
-    if (!GetNextArgument(&args, holder->flags, true, &a1) ||
-        !GetNextArgument(&args, holder->flags, false, &a2) ||
-        !GetNextArgument(&args, holder->flags, false, &a3) ||
-        !GetNextArgument(&args, holder->flags, false, &a4) ||
-        !GetNextArgument(&args, holder->flags, false, &a5)) {
-      args.ThrowError();
-      return;
+ private:
+  template <typename T>
+  static T PassNextArgument(bool* all_arguments_ok, bool* is_first,
+                            Arguments* args, int create_flags, TypeTag<T>) {
+    // Short-circuit if getting some previous argument has already failed:
+    if (!*all_arguments_ok)
+      return T();
+
+    T value = T();
+    *all_arguments_ok = GetNextArgument(args, create_flags, *is_first, &value);
+    *is_first = false;
+    return value;
+  }
+
+  struct InvokeCallback {
+    InvokeCallback(bool* all_arguments_ok, Arguments* args,
+                   const base::Callback<R(A...)>& callback,
+                   const A&... actual_args) {
+      if (!*all_arguments_ok) {;
+        args->ThrowError();
+        return;
+      }
+
+      Invoker<R, A...>::Go(args, callback, actual_args...);
     }
-
-    Invoker<R, P1, P2, P3, P4, P5>::Go(&args, holder->callback, a1, a2, a3, a4,
-        a5);
-  }
-};
-
-template<typename R, typename P1, typename P2, typename P3, typename P4,
-    typename P5, typename P6>
-struct Dispatcher<R(P1, P2, P3, P4, P5, P6)> {
-  static void DispatchToCallback(
-      const v8::FunctionCallbackInfo<v8::Value>& info) {
-    Arguments args(info);
-    v8::Handle<v8::External> v8_holder;
-    CHECK(args.GetData(&v8_holder));
-    CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
-        v8_holder->Value());
-
-    typedef CallbackHolder<R(P1, P2, P3, P4, P5, P6)> HolderT;
-    HolderT* holder = static_cast<HolderT*>(holder_base);
-
-    typename CallbackParamTraits<P1>::LocalType a1;
-    typename CallbackParamTraits<P2>::LocalType a2;
-    typename CallbackParamTraits<P3>::LocalType a3;
-    typename CallbackParamTraits<P4>::LocalType a4;
-    typename CallbackParamTraits<P5>::LocalType a5;
-    typename CallbackParamTraits<P6>::LocalType a6;
-    if (!GetNextArgument(&args, holder->flags, true, &a1) ||
-        !GetNextArgument(&args, holder->flags, false, &a2) ||
-        !GetNextArgument(&args, holder->flags, false, &a3) ||
-        !GetNextArgument(&args, holder->flags, false, &a4) ||
-        !GetNextArgument(&args, holder->flags, false, &a5) ||
-        !GetNextArgument(&args, holder->flags, false, &a6)) {
-      args.ThrowError();
-      return;
-    }
-
-    Invoker<R, P1, P2, P3, P4, P5, P6>::Go(&args, holder->callback, a1, a2, a3,
-        a4, a5, a6);
-  }
+  };
 };
 
 }  // namespace internal
 
 
 // CreateFunctionTemplate creates a v8::FunctionTemplate that will create
 // JavaScript functions that execute a provided C++ function or base::Callback.
 // JavaScript arguments are automatically converted via gin::Converter, as is
 // the return value of the C++ function, if any.
 template<typename Sig>
@@ skipping 20 matching lines @@
   typedef internal::CallbackHolder<Sig> HolderT;
   HolderT* holder = new HolderT(isolate, callback, callback_flags);
   tmpl->SetCallAsFunctionHandler(&internal::Dispatcher<Sig>::DispatchToCallback,
                                  ConvertToV8<v8::Handle<v8::External> >(
                                      isolate, holder->GetHandle(isolate)));
 }
 
 }  // namespace gin
 
 #endif  // GIN_FUNCTION_TEMPLATE_H_