App APIs in Pepper: C++ APIs

ppapi/cpp/dev/struct_wrapper_output_traits_dev.h

+// Copyright (c) 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 PPAPI_CPP_DEV_STRUCT_WRAPPER_OUTPUT_TRAITS_DEV_
+#define PPAPI_CPP_DEV_STRUCT_WRAPPER_OUTPUT_TRAITS_DEV_
+
+namespace pp {
+namespace internal {
+
+// This class is used as the base class for CallbackOutputTraits specialized for
+// C struct wrappers.
+template <typename T>
+struct StructWrapperOutputTraits {
+  typedef typename T::CType* APIArgType;
+  typedef T StorageType;
+
+  // Returns the underlying C struct of |t|, which can be passed to the browser
+  // as an output parameter.
+  static inline APIArgType StorageToAPIArg(StorageType& t) {
+    return t.StartRawUpdate();
+  }
+
+  // For each |t| passed into StorageToAPIArg(), this method must be called
+  // exactly once in order to match StartRawUpdate() and EndRawUpdate().
+  static inline T& StorageToPluginArg(StorageType& t) {
+    t.EndRawUpdate();
+    return t;
+  }
+
+  static inline void Initialize(StorageType* /* t */) {}
+};
+
+}  // namespace internal
+}  // namespace pp
+
+#endif  // PPAPI_CPP_DEV_STRUCT_WRAPPER_OUTPUT_TRAITS_DEV_