Gazebo Utils

API Reference

3.1.0
NeverDestroyed.hh
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1/*
2 * Copyright (C) 2021 Open Source Robotics Foundation
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 *
16 */
17
18#ifndef GZ_UTILS_NEVERDESTROYED_HH_
19#define GZ_UTILS_NEVERDESTROYED_HH_
20
21#include <new>
22#include <type_traits>
23#include <utility>
24
25namespace gz
26{
27namespace utils
28{
116//
117// The above examples are repeated in the unit test; keep them in sync.
118template <typename T>
120{
122 public: template <typename... Args>
123 explicit NeverDestroyed(Args &&... args)
124 {
125 // Uses "placement new" to construct a `T` in `storage_`.
126 new (&this->storage) T(std::forward<Args>(args)...);
127 }
128
130 public: ~NeverDestroyed() = default;
131
133 public: NeverDestroyed(const NeverDestroyed &) = delete;
134
136 public: NeverDestroyed(NeverDestroyed &&) = delete;
137
139 public: NeverDestroyed &operator=(const NeverDestroyed &) = delete;
140
142 public: NeverDestroyed &operator=(NeverDestroyed &&) noexcept = delete;
143
145 public: T &Access()
146 {
147 return *reinterpret_cast<T *>(&this->storage);
148 }
149
150 public: const T &Access() const
151 {
152 return *reinterpret_cast<const T *>(&this->storage);
153 }
154
155 private: typename std::aligned_storage<sizeof(T), alignof(T)>::type storage;
156};
157} // namespace utils
158} // namespace gz
159
160#endif // GZ_UTILS_NEVERDESTROYED_HH_