Draft: apps APIs in Pepper

ppapi/cpp/output_traits.h

Index: ppapi/cpp/output_traits.h
diff --git a/ppapi/cpp/output_traits.h b/ppapi/cpp/output_traits.h
index 31cdbbe11220eccddd739c7fac6f00d27be6409f..f0f1809e1ba4b389f96023ab4c37bef1fdd5d3b6 100644
--- a/ppapi/cpp/output_traits.h
+++ b/ppapi/cpp/output_traits.h
@@ -9,6 +9,9 @@
 
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/cpp/array_output.h"
+#include "ppapi/cpp/dev/array_dev.h"
+#include "ppapi/cpp/dev/from_c_type_converter_dev.h"
+#include "ppapi/cpp/dev/struct_wrapper_base_dev.h"
 #include "ppapi/cpp/resource.h"
 
 /// @file
@@ -123,17 +126,40 @@ struct ResourceCallbackOutputTraits {
   }
 };
 
+template<typename T>
+struct StructWrapperCallbackOutputTraits {
+  typedef typename T::COutputType APIArgType;
+  typedef FromCTypeConverter<T> StorageType;
+
+  static inline APIArgType StorageToAPIArg(StorageType& t) {
+    return t.StartRawUpdate();
+  }
+
+  static inline T& StorageToPluginArg(StorageType& t) {
+    t.EndRawUpdate();
+    return t.value();
+  }
+
+  static inline void Initialize(StorageType* /* t */) {}
+};
+
 // The general templatized base class for all CallbackOutputTraits. This class
-// covers both resources and POD (ints, structs, etc.) by inheriting from the
-// appropriate base class depending on whether the given type derives from
-// pp::Resource. This trick allows us to do this once rather than writing
-// specializations for every resource object type.
+// covers resources, struct wrapper objects and POD (ints, structs, etc.)
+// by inheriting from the appropriate base class depending on whether the given
+// type derives from pp::Resource or StructWrapperIdentifier. This trick
+// allows us to do this once rather than writing specializations for every
+// object type.
+// TODO(yzshen): I will need to add specializtion for Optional<T>. Other than
+// that I think it should be fine.
 template<typename T>
 struct CallbackOutputTraits
-    : public InheritIf<GenericCallbackOutputTraits<T>,
-                       !IsBaseOf<Resource, T>::value>,
-      public InheritIf<ResourceCallbackOutputTraits<T>,
-                       IsBaseOf<Resource, T>::value> {
+    : public InheritIf<ResourceCallbackOutputTraits<T>,
+                       IsBaseOf<Resource, T>::value>,
+      public InheritIf<StructWrapperCallbackOutputTraits<T>,
+                       IsBaseOf<StructWrapperIdentifier, T>::value>,
+      public InheritIf<GenericCallbackOutputTraits<T>,
+                       !IsBaseOf<Resource, T>::value &&
+                       !IsBaseOf<StructWrapperIdentifier, T>::value> {
 };
 
 // A specialization of CallbackOutputTraits for pp::Var output parameters.
@@ -184,6 +210,24 @@ struct CallbackOutputTraits<bool> {
   }
 };
 
+template<typename T>
+struct CallbackOutputTraits<Array<T> > {
+  typedef typename Array<T>::COutputType APIArgType;
+  typedef Array<T> StorageType;
+
+  static inline APIArgType StorageToAPIArg(StorageType& t) {
+    return t.StartRawUpdate();
+  }
+
+  static inline Array<T>& StorageToPluginArg(StorageType& t) {
+    t.EndRawUpdate();
+    return t;
+  }
+
+  static inline void Initialize(StorageType* t) {
+  }
+};
+
 // Array output parameters -----------------------------------------------------
 
 // Output traits for vectors of all "plain old data" (POD) types. It is