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

gin/function_template.h.pump

 $$ This is a pump file for generating file templates.  Pump is a python
 $$ script that is part of the Google Test suite of utilities.  Description
 $$ can be found here:
 $$
 $$ http://code.google.com/p/googletest/wiki/PumpManual
 $$
 
 #ifndef GIN_FUNCTION_TEMPLATE_H_
 #define GIN_FUNCTION_TEMPLATE_H_
 
@@ skipping 10 matching lines @@
 #include "gin/public/gin_embedders.h"
 #include "gin/public/wrapper_info.h"
 #include "gin/wrappable.h"
 
 #include "v8/include/v8.h"
 
 namespace gin {
 
 class PerIsolateData;
 
+enum CreateFunctionTemplateFlags {
+  HolderIsFirstArgument = 1 << 0,
+};
+
 namespace internal {
 
 template<typename T>
 struct RemoveConstRef {
   typedef T Type;
 };
 template<typename T>
 struct RemoveConstRef<const T&> {
   typedef T Type;
 };
+template<typename T>
+struct RemoveConstRef<const T*> {
+  typedef T* Type;
+};
 
 
 // CallbackHolder and CallbackHolderBase are used to pass a base::Callback from
 // CreateFunctionTemplate through v8 (via v8::FunctionTemplate) to 
 // 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.
 // It inherits from Wrappable, which delete itself when both (a) the refcount
 // via base::RefCounted has dropped to zero, and (b) there are no more
 // JavaScript references in V8.
 class CallbackHolderBase : public Wrappable {
  public:
   virtual WrapperInfo* GetWrapperInfo() OVERRIDE;
   static WrapperInfo kWrapperInfo;
  protected:
   virtual ~CallbackHolderBase() {}
 };
 
 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() {}
 };
 
 
 // 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
@@ skipping 27 matching lines @@
       Arguments* args,
       const base::Callback<void($for ARG , [[P$(ARG)]])>& callback$for ARG [[,
       const P$(ARG)& a$(ARG)]]) {
     callback.Run($for ARG, [[a$(ARG)]]);
   }
 };
 
 
 ]]
 
+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 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 {
+};
+
 $range ARITY 0..MAX_ARITY
 $for ARITY [[
 $range ARG 1..ARITY
 
 template<typename R$for ARG [[, typename P$(ARG)]]>
-static void DispatchToCallback(
-    const v8::FunctionCallbackInfo<v8::Value>& info) {
-  Arguments args(info);
-  CallbackHolderBase* holder_base = NULL;
-  CHECK(args.GetData(&holder_base));
+struct Dispatcher<R($for ARG , [[P$(ARG)]])> {
+  static void DispatchToCallback(
+      const v8::FunctionCallbackInfo<v8::Value>& info) {
+    Arguments args(info);
+    CallbackHolderBase* holder_base = NULL;
+    CHECK(args.GetData(&holder_base));
 
-  typedef CallbackHolder<R($for ARG , [[P$(ARG)]])> HolderT;
-  HolderT* holder = static_cast<HolderT*>(holder_base);
+    typedef CallbackHolder<R($for ARG , [[P$(ARG)]])> HolderT;
+    HolderT* holder = static_cast<HolderT*>(holder_base);
 
 $if ARITY != 0 [[
 
 
-$for ARG [[  typename RemoveConstRef<P$(ARG)>::Type a$(ARG);
+$for ARG [[    typename RemoveConstRef<P$(ARG)>::Type a$(ARG);
 
 ]]
-  if (
-$for ARG  ||
-      [[!args.GetNext(&a$(ARG))]]) {
-    args.ThrowError();
-    return;
-  }
+    if ($for ARG  ||
+        [[!GetNextArgument(&args, holder->flags, $if ARG == 1 [[true]] $else [[false]], &a$(ARG))]]) {
+      args.ThrowError();
+      return;
+    }
 
 ]]
 
-  Invoker<R$for ARG [[, P$(ARG)]]>::Go(&args, holder->callback$for ARG [[, a$(ARG)]]);
-}
+    Invoker<R$for ARG [[, P$(ARG)]]>::Go(&args, holder->callback$for ARG [[, a$(ARG)]]);
+  }
+};
 
 ]]
 
 }  // namespace internal
 
 
 // This should be called once per-isolate to initialize the function template
 // system.
 void InitFunctionTemplates(PerIsolateData* isolate_data);
 
 
 // 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$(ARG)]]>
+// CreateFunctionTemplate creates a v8::FunctionTemplate that will create
+// JavaScript functions that execute a provided C++ function or base::Callback.
+// JavaScript arguments are automatically converted via gin::Converter, as is
+// the return value of the C++ function, if any.
+template<typename Sig>
 v8::Local<v8::FunctionTemplate> CreateFunctionTemplate(
     v8::Isolate* isolate,
-    const base::Callback<R($for ARG , [[P$(ARG)]])> callback) {
-  typedef internal::CallbackHolder<R($for ARG , [[P$(ARG)]])> HolderT;
-  scoped_refptr<HolderT> holder(new HolderT(callback));
+    const base::Callback<Sig> callback,
+    int flags = 0) {
+  typedef internal::CallbackHolder<Sig> HolderT;
+  scoped_refptr<HolderT> holder(new HolderT(callback, flags));
   return v8::FunctionTemplate::New(
-      isolate,
-      &internal::DispatchToCallback<R$for ARG [[, P$(ARG)]]>,
+      &internal::Dispatcher<Sig>::DispatchToCallback,
       ConvertToV8<internal::CallbackHolderBase*>(isolate, holder.get()));
 }
 
-]]
-
 }  // namespace gin
 
 #endif  // GIN_FUNCTION_TEMPLATE_H_