Mojo: more idiomatic C++ bindings

mojo/public/cpp/bindings/lib/bindings_internal.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_BINDINGS_INTERNAL_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_BINDINGS_INTERNAL_H_
 
+#include "mojo/public/cpp/bindings/lib/template_util.h"
 #include "mojo/public/cpp/system/core.h"
 
 namespace mojo {
-template <typename S> class InterfaceHandle;
+class String;
 
 namespace internal {
 template <typename T> class Array_Data;
 
 #pragma pack(push, 1)
 
 struct StructHeader {
   uint32_t num_bytes;
   uint32_t num_fields;
 };
@@ skipping 33 matching lines @@
     *ptr = T();
 }
 
 template <typename T>
 T FetchAndReset(T* ptr) {
   T temp = *ptr;
   *ptr = T();
   return temp;
 }
 
-template <typename T>
-class WrapperHelper {
- public:
-  static const T Wrap(const typename T::Data* data) {
-    return T(typename T::Wrap(), const_cast<typename T::Data*>(data));
-  }
-  static typename T::Data* Unwrap(const T& object) {
-    return const_cast<typename T::Data*>(object.data_);
-  }
+template <typename T> struct IsHandle {
+  static const bool value = false;
+};
+template <> struct IsHandle<Handle> {
+  static const bool value = true;
+};
+template <> struct IsHandle<DataPipeConsumerHandle> {

[yzshen1, 2014/05/27 22:16:59]

It might make sense to define IsHandle<> with the help of something like
IsBaseOf<>:
https://code.google.com/p/chromium/codesearch#chromium/src/ppapi/cpp/output_t...

That way we don't have to worry about updating this list when new subclasses of
Handle are added.

+  static const bool value = true;
+};
+template <> struct IsHandle<DataPipeProducerHandle> {
+  static const bool value = true;
+};
+template <> struct IsHandle<MessagePipeHandle> {
+  static const bool value = true;
+};
+template <> struct IsHandle<SharedBufferHandle> {
+  static const bool value = true;
 };
 
-template <typename Data>
-inline const typename Data::Wrapper Wrap(const Data* data) {
-  return WrapperHelper<typename Data::Wrapper>::Wrap(data);
-}
+template <typename T, bool kMoveOnly = IsMoveOnlyType<T>::value>
+struct WrapperTraits;
 
-template <typename T>
-inline typename T::Data* Unwrap(const T& object) {
-  return WrapperHelper<T>::Unwrap(object);
-}
-
-template <typename T> struct TypeTraits {
-  static const bool kIsHandle = false;
-  static const bool kIsObject = true;
+template <typename T> struct WrapperTraits<T, false> {
+  typedef T DataType;
 };
-template <> struct TypeTraits<bool> {
-  static const bool kIsHandle = false;
-  static const bool kIsObject = false;
+template <typename H> struct WrapperTraits<ScopedHandleBase<H>, true> {
+  typedef H DataType;
 };
-template <> struct TypeTraits<char> {
-  static const bool kIsHandle = false;
-  static const bool kIsObject = false;
+template <typename S> struct WrapperTraits<S, true> {
+  typedef typename S::Data_* DataType;
 };
-template <> struct TypeTraits<int8_t> {
-  static const bool kIsHandle = false;
-  static const bool kIsObject = false;
-};
-template <> struct TypeTraits<int16_t> {
-  static const bool kIsHandle = false;
-  static const bool kIsObject = false;
-};
-template <> struct TypeTraits<int32_t> {
-  static const bool kIsHandle = false;
-  static const bool kIsObject = false;
-};
-template <> struct TypeTraits<int64_t> {
-  static const bool kIsHandle = false;
-  static const bool kIsObject = false;
-};
-template <> struct TypeTraits<uint8_t> {
-  static const bool kIsHandle = false;
-  static const bool kIsObject = false;
-};
-template <> struct TypeTraits<uint16_t> {
-  static const bool kIsHandle = false;
-  static const bool kIsObject = false;
-};
-template <> struct TypeTraits<uint32_t> {
-  static const bool kIsHandle = false;
-  static const bool kIsObject = false;
-};
-template <> struct TypeTraits<uint64_t> {
-  static const bool kIsHandle = false;
-  static const bool kIsObject = false;
-};
-template <> struct TypeTraits<float> {
-  static const bool kIsHandle = false;
-  static const bool kIsObject = false;
-};
-template <> struct TypeTraits<double> {
-  static const bool kIsHandle = false;
-  static const bool kIsObject = false;
-};
-template <> struct TypeTraits<Handle> {
-  static const bool kIsHandle = true;
-  static const bool kIsObject = false;
-};
-template <> struct TypeTraits<DataPipeConsumerHandle> {
-  static const bool kIsHandle = true;
-  static const bool kIsObject = false;
-};
-template <> struct TypeTraits<DataPipeProducerHandle> {
-  static const bool kIsHandle = true;
-  static const bool kIsObject = false;
-};
-template <> struct TypeTraits<MessagePipeHandle> {
-  static const bool kIsHandle = true;
-  static const bool kIsObject = false;
-};
-template <typename S> struct TypeTraits<InterfaceHandle<S> > {
-  static const bool kIsHandle = true;
-  static const bool kIsObject = false;
-};
-
-template <typename T> class ObjectTraits {};
 
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_BINDINGS_INTERNAL_H_