1 files changed, 73 insertions, 14 deletions

diff --git a/gin/function_template.h.pump b/gin/function_template.h.pump
index 802e048b..7e90324 100644
--- a/gin/function_template.h.pump
+++ b/gin/function_template.h.pump
@@ -36,12 +36,10 @@ struct RemoveConstRef<const T&> {
   typedef T Type;
 };
 
-}  // namespace internal
-
 
 // CallbackHolder and CallbackHolderBase are used to pass a base::Callback from
 // CreateFunctionTemplate through v8 (via v8::FunctionTemplate) to 
-// DispatchCallback, where it is invoked.
+// DispatchToCallback, where it is invoked.
 //
 // v8::FunctionTemplate only supports passing void* as data so how do we know
 // when to delete the base::Callback? That's where CallbackHolderBase comes in.
@@ -57,10 +55,6 @@ class CallbackHolderBase : public Wrappable {
   virtual ~CallbackHolderBase() {}
 };
 
-template<>
-struct Converter<CallbackHolderBase*>
-    : public WrappableConverter<CallbackHolderBase> {};
-
 template<typename Sig>
 class CallbackHolder : public CallbackHolderBase {
  public:
@@ -71,6 +65,51 @@ class CallbackHolder : public CallbackHolderBase {
   virtual ~CallbackHolder() {}
 };
 
+
+// This set of templates invokes a base::Callback, converts the return type to a
+// JavaScript value, and returns that value to script via the provided
+// gin::Arguments object.
+//
+// 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.
+
+$range ARITY 0..MAX_ARITY
+$for ARITY [[
+$var INV_ARITY = MAX_ARITY - ARITY
+$range ARG 1..INV_ARITY
+$range VOID INV_ARITY+1..MAX_ARITY
+
+$if ARITY == 0 [[
+template<typename R$for ARG [[, typename P$(ARG) = void]]>
+struct Invoker {
+]] $else [[
+template<typename R$for ARG [[, typename P$(ARG)]]>
+struct Invoker<R$for ARG [[, P$(ARG)]]$for VOID [[, void]]> {
+]]
+
+  inline static void Go(
+      Arguments* args,
+      const base::Callback<R($for ARG , [[P$(ARG)]])>& callback$for ARG [[, 
+      const P$(ARG)& a$(ARG)]]) {
+    args->Return(callback.Run($for ARG, [[a$(ARG)]]));
+  }
+};
+template<$for ARG , [[typename P$(ARG)]]>
+struct Invoker<void$for ARG [[, P$(ARG)]]$for VOID [[, void]]> {
+  inline static void Go(
+      Arguments* args,
+      const base::Callback<void($for ARG , [[P$(ARG)]])>& callback$for ARG [[,
+      const P$(ARG)& a$(ARG)]]) {
+    callback.Run($for ARG, [[a$(ARG)]]);
+  }
+};
+
+
+]]
+
+// DispatchToCallback converts all the JavaScript arguments to C++ types and
+// invokes the base::Callback.
 $range ARITY 0..MAX_ARITY
 $for ARITY [[
 $range ARG 1..ARITY
@@ -82,13 +121,13 @@ static void DispatchToCallback(
   CallbackHolderBase* holder_base = NULL;
   CHECK(args.GetData(&holder_base));
 
-  typedef CallbackHolder<void($for ARG , [[P$(ARG)]])> HolderT;
+  typedef CallbackHolder<R($for ARG , [[P$(ARG)]])> HolderT;
   HolderT* holder = static_cast<HolderT*>(holder_base);
 
 $if ARITY != 0 [[
 
 
-$for ARG [[  typename internal::RemoveConstRef<P$(ARG)>::Type a$(ARG);
+$for ARG [[  typename RemoveConstRef<P$(ARG)>::Type a$(ARG);
 
 ]]
   if (
@@ -100,18 +139,38 @@ $for ARG  ||
 
 ]]
 
-  holder->callback.Run($for ARG , [[a$(ARG)]]);
+  Invoker<R$for ARG [[, P$(ARG)]]>::Go(&args, holder->callback$for ARG [[, a$(ARG)]]);
 }
 
+]]
+
+}  // namespace internal
+
+
+// This has to be outside the internal namespace because template
+// specializations must be declared in the same namespace as the original
+// template.
+template<>
+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.
+$range ARITY 0..MAX_ARITY
+$for ARITY [[
+$range ARG 1..ARITY
+
 template<typename R$for ARG [[, typename P$(ARG)]]>
-v8::Local<v8::FunctionTemplate> CreateFunctionTempate(
+v8::Local<v8::FunctionTemplate> CreateFunctionTemplate(
     v8::Isolate* isolate,
     const base::Callback<R($for ARG , [[P$(ARG)]])> callback) {
-  typedef CallbackHolder<void($for ARG , [[P$(ARG)]])> HolderT;
+  typedef internal::CallbackHolder<R($for ARG , [[P$(ARG)]])> HolderT;
   scoped_refptr<HolderT> holder(new HolderT(callback));
   return v8::FunctionTemplate::New(
-      &DispatchToCallback<R$for ARG [[, P$(ARG)]]>,
-      ConvertToV8<CallbackHolderBase*>(isolate, holder.get()));
+      &internal::DispatchToCallback<R$for ARG [[, P$(ARG)]]>,
+      ConvertToV8<internal::CallbackHolderBase*>(isolate, holder.get()));
 }
 
 ]]