import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

mfbt/UniquePtrExtensions.h

@@ -0,0 +1,57 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Useful extensions to UniquePtr. */
+
+#ifndef mozilla_UniquePtrExtensions_h
+#define mozilla_UniquePtrExtensions_h
+
+#include "mozilla/fallible.h"
+#include "mozilla/UniquePtr.h"
+
+namespace mozilla {
+
+/**
+ * MakeUniqueFallible works exactly like MakeUnique, except that the memory
+ * allocation performed is done fallibly, i.e. it can return nullptr.
+ */
+template<typename T, typename... Args>
+typename detail::UniqueSelector<T>::SingleObject
+MakeUniqueFallible(Args&&... aArgs)
+{
+  return UniquePtr<T>(new (fallible) T(Forward<Args>(aArgs)...));
+}
+
+template<typename T>
+typename detail::UniqueSelector<T>::UnknownBound
+MakeUniqueFallible(decltype(sizeof(int)) aN)
+{
+  typedef typename RemoveExtent<T>::Type ArrayType;
+  return UniquePtr<T>(new (fallible) ArrayType[aN]());
+}
+
+template<typename T, typename... Args>
+typename detail::UniqueSelector<T>::KnownBound
+MakeUniqueFallible(Args&&... aArgs) = delete;
+
+namespace detail {
+
+template<typename T>
+struct FreePolicy
+{
+  void operator()(const void* ptr) {
+    free(const_cast<void*>(ptr));
+  }
+};
+
+} // namespace detail
+
+template<typename T>
+using UniqueFreePtr = UniquePtr<T, detail::FreePolicy<T>>;
+
+} // namespace mozilla
+
+#endif // mozilla_UniquePtrExtensions_h