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 MakeUniqueFallible(
  23     Args&&... aArgs) {
  24   return UniquePtr<T>(new (fallible) T(std::forward<Args>(aArgs)...));
  25 }
  26
  27 template <typename T>
  28 typename detail::UniqueSelector<T>::UnknownBound MakeUniqueFallible(
  29     decltype(sizeof(int)) aN) {
  30   typedef typename RemoveExtent<T>::Type ArrayType;
  31   return UniquePtr<T>(new (fallible) ArrayType[aN]());
  32 }
  33
  34 template <typename T, typename... Args>
  35 typename detail::UniqueSelector<T>::KnownBound MakeUniqueFallible(
  36     Args&&... aArgs) = delete;
  37
  38 namespace detail {
  39
  40 template <typename T>
  41 struct FreePolicy {
  42   void operator()(const void* ptr) { free(const_cast<void*>(ptr)); }
  43 };
  44
  45 }  // namespace detail
  46
  47 template <typename T>
  48 using UniqueFreePtr = UniquePtr<T, detail::FreePolicy<T>>;
  49
  50 }  // namespace mozilla
  51
  52 #endif  // mozilla_UniquePtrExtensions_h