mfbt/UniquePtrExtensions.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* Useful extensions to UniquePtr. */
   8
   9 #ifndef mozilla_UniquePtrExtensions_h
  10 #define mozilla_UniquePtrExtensions_h
  11
  12 #include "mozilla/fallible.h"
  13 #include "mozilla/UniquePtr.h"
  14
  15 namespace mozilla {
  16
  17 /**
  18  * MakeUniqueFallible works exactly like MakeUnique, except that the memory
  19  * allocation performed is done fallibly, i.e. it can return nullptr.
  20  */
  21 template<typename T, typename... Args>
  22 typename detail::UniqueSelector<T>::SingleObject
  23 MakeUniqueFallible(Args&&... aArgs)
  24 {
  25   return UniquePtr<T>(new (fallible) T(std::forward<Args>(aArgs)...));
  26 }
  27
  28 template<typename T>
  29 typename detail::UniqueSelector<T>::UnknownBound
  30 MakeUniqueFallible(decltype(sizeof(int)) aN)
  31 {
  32   typedef typename RemoveExtent<T>::Type ArrayType;
  33   return UniquePtr<T>(new (fallible) ArrayType[aN]());
  34 }
  35
  36 template<typename T, typename... Args>
  37 typename detail::UniqueSelector<T>::KnownBound
  38 MakeUniqueFallible(Args&&... aArgs) = delete;
  39
  40 namespace detail {
  41
  42 template<typename T>
  43 struct FreePolicy
  44 {
  45   void operator()(const void* ptr) {
  46     free(const_cast<void*>(ptr));
  47   }
  48 };
  49
  50 } // namespace detail
  51
  52 template<typename T>
  53 using UniqueFreePtr = UniquePtr<T, detail::FreePolicy<T>>;
  54
  55 } // namespace mozilla
  56
  57 #endif // mozilla_UniquePtrExtensions_h