Gin: Add support for binding JS methods to C++ instance methods.

gin/function_template.h

Index: gin/function_template.h
diff --git a/gin/function_template.h b/gin/function_template.h
index 643131776b8fac78617d2d1d3d39281c9696a282..b2badfa7dfb48d58f6ab9822aacb97bfbb01488e 100644
--- a/gin/function_template.h
+++ b/gin/function_template.h
@@ -26,15 +26,23 @@ namespace gin {
 
 class PerIsolateData;
 
+enum CreateFunctionTemplateFlags {
+  HolderIsFirstArgument = 1 << 0,
+};
+
 namespace internal {
 
 template<typename T>
-struct RemoveConstRef {
-  typedef T Type;
+struct CallbackParamTraits {
+  typedef T LocalType;
+};
+template<typename T>
+struct CallbackParamTraits<const T&> {
+  typedef T LocalType;
 };
 template<typename T>
-struct RemoveConstRef<const T&> {
-  typedef T Type;
+struct CallbackParamTraits<const T*> {
+  typedef T* LocalType;
 };
 
 
@@ -58,9 +66,10 @@ class CallbackHolderBase : public Wrappable {
 template<typename Sig>
 class CallbackHolder : public CallbackHolderBase {
  public:
-  CallbackHolder(const base::Callback<Sig>& callback)
-      : callback(callback) {}
+  CallbackHolder(const base::Callback<Sig>& callback, int flags)
+      : callback(callback), flags(flags) {}
   base::Callback<Sig> callback;
+  int flags;
  private:
   virtual ~CallbackHolder() {}
 };
@@ -180,108 +189,141 @@ struct Invoker<void, void, void, void, void> {
 };
 
 
+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);
+  }
+}
+
+// For advanced use cases, we allow callers to request the unparsed Arguments
+// object and poke around in it directly.
+inline bool GetNextArgument(Arguments* args, int create_flags, bool is_first,
+                            Arguments* result) {
+  *result = *args;
+  return true;
+}
+
+
 // DispatchToCallback converts all the JavaScript arguments to C++ types and
 // invokes the base::Callback.
+template<typename Sig>
+struct Dispatcher {
+};
+
 template<typename R>
-static void DispatchToCallback(
-    const v8::FunctionCallbackInfo<v8::Value>& info) {
-  Arguments args(info);
-  CallbackHolderBase* holder_base = NULL;
-  CHECK(args.GetData(&holder_base));
+struct Dispatcher<R()> {
+  static void DispatchToCallback(
+      const v8::FunctionCallbackInfo<v8::Value>& info) {
+    Arguments args(info);
+    CallbackHolderBase* holder_base = NULL;
+    CHECK(args.GetData(&holder_base));
 
-  typedef CallbackHolder<R()> HolderT;
-  HolderT* holder = static_cast<HolderT*>(holder_base);
+    typedef CallbackHolder<R()> HolderT;
+    HolderT* holder = static_cast<HolderT*>(holder_base);
 
-  Invoker<R>::Go(&args, holder->callback);
-}
+    Invoker<R>::Go(&args, holder->callback);
+  }
+};
 
 template<typename R, typename P1>
-static void DispatchToCallback(
-    const v8::FunctionCallbackInfo<v8::Value>& info) {
-  Arguments args(info);
-  CallbackHolderBase* holder_base = NULL;
-  CHECK(args.GetData(&holder_base));
-
-  typedef CallbackHolder<R(P1)> HolderT;
-  HolderT* holder = static_cast<HolderT*>(holder_base);
-
-  typename RemoveConstRef<P1>::Type a1;
-  if (!args.GetNext(&a1)) {
-    args.ThrowError();
-    return;
+struct Dispatcher<R(P1)> {
+  static void DispatchToCallback(
+      const v8::FunctionCallbackInfo<v8::Value>& info) {
+    Arguments args(info);
+    CallbackHolderBase* holder_base = NULL;
+    CHECK(args.GetData(&holder_base));
+
+    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);
   }
-
-  Invoker<R, P1>::Go(&args, holder->callback, a1);
-}
+};
 
 template<typename R, typename P1, typename P2>
-static void DispatchToCallback(
-    const v8::FunctionCallbackInfo<v8::Value>& info) {
-  Arguments args(info);
-  CallbackHolderBase* holder_base = NULL;
-  CHECK(args.GetData(&holder_base));
-
-  typedef CallbackHolder<R(P1, P2)> HolderT;
-  HolderT* holder = static_cast<HolderT*>(holder_base);
-
-  typename RemoveConstRef<P1>::Type a1;
-  typename RemoveConstRef<P2>::Type a2;
-  if (!args.GetNext(&a1) ||
-      !args.GetNext(&a2)) {
-    args.ThrowError();
-    return;
+struct Dispatcher<R(P1, P2)> {
+  static void DispatchToCallback(
+      const v8::FunctionCallbackInfo<v8::Value>& info) {
+    Arguments args(info);
+    CallbackHolderBase* holder_base = NULL;
+    CHECK(args.GetData(&holder_base));
+
+    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);
   }
-
-  Invoker<R, P1, P2>::Go(&args, holder->callback, a1, a2);
-}
+};
 
 template<typename R, typename P1, typename P2, typename P3>
-static void DispatchToCallback(
-    const v8::FunctionCallbackInfo<v8::Value>& info) {
-  Arguments args(info);
-  CallbackHolderBase* holder_base = NULL;
-  CHECK(args.GetData(&holder_base));
-
-  typedef CallbackHolder<R(P1, P2, P3)> HolderT;
-  HolderT* holder = static_cast<HolderT*>(holder_base);
-
-  typename RemoveConstRef<P1>::Type a1;
-  typename RemoveConstRef<P2>::Type a2;
-  typename RemoveConstRef<P3>::Type a3;
-  if (!args.GetNext(&a1) ||
-      !args.GetNext(&a2) ||
-      !args.GetNext(&a3)) {
-    args.ThrowError();
-    return;
+struct Dispatcher<R(P1, P2, P3)> {
+  static void DispatchToCallback(
+      const v8::FunctionCallbackInfo<v8::Value>& info) {
+    Arguments args(info);
+    CallbackHolderBase* holder_base = NULL;
+    CHECK(args.GetData(&holder_base));
+
+    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);
   }
-
-  Invoker<R, P1, P2, P3>::Go(&args, holder->callback, a1, a2, a3);
-}
+};
 
 template<typename R, typename P1, typename P2, typename P3, typename P4>
-static void DispatchToCallback(
-    const v8::FunctionCallbackInfo<v8::Value>& info) {
-  Arguments args(info);
-  CallbackHolderBase* holder_base = NULL;
-  CHECK(args.GetData(&holder_base));
-
-  typedef CallbackHolder<R(P1, P2, P3, P4)> HolderT;
-  HolderT* holder = static_cast<HolderT*>(holder_base);
-
-  typename RemoveConstRef<P1>::Type a1;
-  typename RemoveConstRef<P2>::Type a2;
-  typename RemoveConstRef<P3>::Type a3;
-  typename RemoveConstRef<P4>::Type a4;
-  if (!args.GetNext(&a1) ||
-      !args.GetNext(&a2) ||
-      !args.GetNext(&a3) ||
-      !args.GetNext(&a4)) {
-    args.ThrowError();
-    return;
+struct Dispatcher<R(P1, P2, P3, P4)> {
+  static void DispatchToCallback(
+      const v8::FunctionCallbackInfo<v8::Value>& info) {
+    Arguments args(info);
+    CallbackHolderBase* holder_base = NULL;
+    CHECK(args.GetData(&holder_base));
+
+    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);
   }
-
-  Invoker<R, P1, P2, P3, P4>::Go(&args, holder->callback, a1, a2, a3, a4);
-}
+};
 
 }  // namespace internal
 
@@ -299,66 +341,19 @@ struct Converter<internal::CallbackHolderBase*>
     : public WrappableConverter<internal::CallbackHolderBase> {};
 
 
-// Creates a v8::FunctionTemplate that will run the provided base::Callback each
-// time it is called. JavaScript arguments and return values are converted via
-// gin::Converter.
-template<typename R>
-v8::Local<v8::FunctionTemplate> CreateFunctionTemplate(
-    v8::Isolate* isolate,
-    const base::Callback<R()> callback) {
-  typedef internal::CallbackHolder<R()> HolderT;
-  gin::Handle<HolderT> holder = CreateHandle(isolate, new HolderT(callback));
-  return v8::FunctionTemplate::New(
-      isolate,
-      &internal::DispatchToCallback<R>,
-      ConvertToV8<internal::CallbackHolderBase*>(isolate, holder.get()));
-}
-
-template<typename R, typename P1>
-v8::Local<v8::FunctionTemplate> CreateFunctionTemplate(
-    v8::Isolate* isolate,
-    const base::Callback<R(P1)> callback) {
-  typedef internal::CallbackHolder<R(P1)> HolderT;
-  gin::Handle<HolderT> holder = CreateHandle(isolate, new HolderT(callback));
-  return v8::FunctionTemplate::New(
-      isolate,
-      &internal::DispatchToCallback<R, P1>,
-      ConvertToV8<internal::CallbackHolderBase*>(isolate, holder.get()));
-}
-
-template<typename R, typename P1, typename P2>
-v8::Local<v8::FunctionTemplate> CreateFunctionTemplate(
-    v8::Isolate* isolate,
-    const base::Callback<R(P1, P2)> callback) {
-  typedef internal::CallbackHolder<R(P1, P2)> HolderT;
-  gin::Handle<HolderT> holder = CreateHandle(isolate, new HolderT(callback));
-  return v8::FunctionTemplate::New(
-      isolate,
-      &internal::DispatchToCallback<R, P1, P2>,
-      ConvertToV8<internal::CallbackHolderBase*>(isolate, holder.get()));
-}
-
-template<typename R, typename P1, typename P2, typename P3>
-v8::Local<v8::FunctionTemplate> CreateFunctionTemplate(
-    v8::Isolate* isolate,
-    const base::Callback<R(P1, P2, P3)> callback) {
-  typedef internal::CallbackHolder<R(P1, P2, P3)> HolderT;
-  gin::Handle<HolderT> holder = CreateHandle(isolate, new HolderT(callback));
-  return v8::FunctionTemplate::New(
-      isolate,
-      &internal::DispatchToCallback<R, P1, P2, P3>,
-      ConvertToV8<internal::CallbackHolderBase*>(isolate, holder.get()));
-}
-
-template<typename R, typename P1, typename P2, typename P3, typename P4>
+// 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>
 v8::Local<v8::FunctionTemplate> CreateFunctionTemplate(
-    v8::Isolate* isolate,
-    const base::Callback<R(P1, P2, P3, P4)> callback) {
-  typedef internal::CallbackHolder<R(P1, P2, P3, P4)> HolderT;
-  gin::Handle<HolderT> holder = CreateHandle(isolate, new HolderT(callback));
+    v8::Isolate* isolate, const base::Callback<Sig> callback,
+    int callback_flags = 0) {
+  typedef internal::CallbackHolder<Sig> HolderT;
+  gin::Handle<HolderT> holder = CreateHandle(
+      isolate, new HolderT(callback, callback_flags));
   return v8::FunctionTemplate::New(
-      isolate,
-      &internal::DispatchToCallback<R, P1, P2, P3, P4>,
+      &internal::Dispatcher<Sig>::DispatchToCallback,
       ConvertToV8<internal::CallbackHolderBase*>(isolate, holder.get()));
 }