diff options
-rw-r--r-- | src/google/protobuf/arena.h | 84 |
1 files changed, 37 insertions, 47 deletions
diff --git a/src/google/protobuf/arena.h b/src/google/protobuf/arena.h index 16e0d50e..ac3d675b 100644 --- a/src/google/protobuf/arena.h +++ b/src/google/protobuf/arena.h @@ -490,27 +490,29 @@ class LIBPROTOBUF_EXPORT Arena { return GetArenaInternal(value, static_cast<T*>(0)); } - // Helper typetrait that indicates support for arenas in a type T at compile - // time. This is public only to allow construction of higher-level templated - // utilities. is_arena_constructable<T>::value is an instance of - // google::protobuf::internal::true_type if the message type T has arena support enabled, and - // google::protobuf::internal::false_type otherwise. - // - // This is inside Arena because only Arena has the friend relationships - // necessary to see the underlying generated code traits. - template<typename T> - struct is_arena_constructable { + private: + struct InternalIsArenaConstructableHelper { template<typename U> static char ArenaConstructable( const typename U::InternalArenaConstructable_*); template<typename U> static double ArenaConstructable(...); + }; - // This will resolve to either google::protobuf::internal::true_type or google::protobuf::internal::false_type. - typedef google::protobuf::internal::integral_constant<bool, - sizeof(ArenaConstructable<const T>(static_cast<const T*>(0))) == - sizeof(char)> type; - static const type value; + public: + // Helper typetrait that indicates support for arenas in a type T at compile + // time. This is public only to allow construction of higher-level templated + // utilities. is_arena_constructable<T>::value is true if the message type T + // has arena support enabled, and false otherwise. + // + // This is inside Arena because only Arena has the friend relationships + // necessary to see the underlying generated code traits. + template<typename T> + struct is_arena_constructable : + public google::protobuf::internal::integral_constant<bool, + sizeof(InternalIsArenaConstructableHelper::ArenaConstructable< + const T>(static_cast<const T*>(0))) == + sizeof(char)> { }; private: @@ -572,32 +574,28 @@ class LIBPROTOBUF_EXPORT Arena { return google::protobuf::internal::has_trivial_destructor<T>::value; } - // Helper typetrait that indicates whether the desctructor of type T should be - // called when arena is destroyed at compile time. This is only to allow - // construction of higher-level templated utilities. - // is_destructor_skippable<T>::value is an instance of google::protobuf::internal::true_type if the - // destructor of the message type T should not be called when arena is - // destroyed or google::protobuf::internal::has_trivial_destructor<T>::value == true, and - // google::protobuf::internal::false_type otherwise. - // - // This is inside Arena because only Arena has the friend relationships - // necessary to see the underlying generated code traits. - template<typename T> - struct is_destructor_skippable { + struct InternalIsDestructorSkippableHelper { template<typename U> static char DestructorSkippable( const typename U::DestructorSkippable_*); template<typename U> static double DestructorSkippable(...); + }; - // The raw_skippable_value const bool variable is separated from the typedef - // line below as a work-around of an NVCC 7.0 (and earlier) compiler bug. - static const bool raw_skippable_value = - sizeof(DestructorSkippable<const T>(static_cast<const T*>(0))) == - sizeof(char) || google::protobuf::internal::has_trivial_destructor<T>::value == true; - // This will resolve to either google::protobuf::internal::true_type or google::protobuf::internal::false_type. - typedef google::protobuf::internal::integral_constant<bool, raw_skippable_value> type; - static const type value; + // Helper typetrait that indicates whether the desctructor of type T should be + // called when arena is destroyed at compile time. This is only to allow + // construction of higher-level templated utilities. + // is_destructor_skippable<T>::value is true if the destructor of the message + // type T should not be called when arena is destroyed or false otherwise. + // This is inside Arena because only Arena has the friend relationships + // necessary to see the underlying generated code traits. + template<typename T> + struct is_destructor_skippable : + public google::protobuf::internal::integral_constant<bool, + sizeof(InternalIsDestructorSkippableHelper::DestructorSkippable< + const T>(static_cast<const T*>(0))) == + sizeof(char) || + google::protobuf::internal::has_trivial_destructor<T>::value> { }; @@ -780,8 +778,10 @@ class LIBPROTOBUF_EXPORT Arena { // which needs to declare google::protobuf::Map as friend of generated message. template <typename T> static void CreateInArenaStorage(T* ptr, Arena* arena) { - CreateInArenaStorageInternal(ptr, arena, is_arena_constructable<T>::value); - RegisterDestructorInternal(ptr, arena, is_destructor_skippable<T>::value); + CreateInArenaStorageInternal( + ptr, arena, typename is_arena_constructable<T>::type()); + RegisterDestructorInternal( + ptr, arena, typename is_destructor_skippable<T>::type()); } template <typename T> @@ -910,16 +910,6 @@ class LIBPROTOBUF_EXPORT Arena { // Defined above for supporting environments without RTTI. #undef RTTI_TYPE_ID -template<typename T> -const typename Arena::is_arena_constructable<T>::type - Arena::is_arena_constructable<T>::value = - typename Arena::is_arena_constructable<T>::type(); - -template<typename T> -const typename Arena::is_destructor_skippable<T>::type - Arena::is_destructor_skippable<T>::value = - typename Arena::is_destructor_skippable<T>::type(); - } // namespace protobuf } // namespace google |