App APIs in Pepper: C++ APIs

ppapi/cpp/dev/may_own_ptr_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_MAY_OWN_PTR_DEV_H_
+#define PPAPI_CPP_DEV_MAY_OWN_PTR_DEV_H_
+
+#include "ppapi/cpp/logging.h"
+
+namespace pp {
+
+// An annotation used along with a pointer parameter of a function to indicate
+// that the function doesn't take ownership of the pointer.
+enum NotOwned {
+  NOT_OWNED
+};
+
+namespace internal {
+
+// MayOwnPtr keeps track of whether it has ownership of the pointer it holds,
+// and deletes the pointer on destruction if it does.
+template <typename T>
+class MayOwnPtr {
+ public:
+  MayOwnPtr() : value_(new T()), owned_(true) {}

[dmichael (off chromium), 2013/12/20 18:38:00]

(requires that T have a default constructor... probably fine, just something
this design forces)

[yzshen1, 2013/12/20 19:50:43]

Right, all things that we will used with MayOwnPtr<> are C types. So when we do
T(), it will do zero initialization.

I added a comment.

+
+  // It doesn't take ownership of |value|, therefore |value| must live longer
+  // than this object.
+  MayOwnPtr(T* value, NotOwned) : value_(value), owned_(false) {
+    PP_DCHECK(value);
+  }
+
+  ~MayOwnPtr() {
+    if (owned_)
+      delete value_;
+  }
+
+  const T* get() const { return value_; }
+  T* get() { return value_; }
+
+  const T& operator*() const { return *value_; }
+  T& operator*() { return *value_; }
+
+  const T* operator->() const { return value_; }
+  T* operator->() { return value_; }
+
+  bool owned() const { return owned_; }
+
+ private:
+  // Disallow copying and assignment.
+  MayOwnPtr(const MayOwnPtr<T>&);
+  MayOwnPtr<T>& operator=(const MayOwnPtr<T>&);
+
+  T* value_;
+  bool owned_;
+};
+
+}  // namespace internal
+}  // namespace pp
+
+#endif  // PPAPI_CPP_DEV_MAY_OWN_PTR_DEV_H_