1 | /** |
2 | * Copyright 2021 Alibaba, Inc. and its affiliates. All Rights Reserved. |
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 | * \author Hechong.xyf |
17 | * \date Aug 2019 |
18 | * \brief Interface of AiLego Utility Singleton |
19 | */ |
20 | |
21 | #ifndef __AILEGO_PATTERN_SINGLETON_H__ |
22 | #define __AILEGO_PATTERN_SINGLETON_H__ |
23 | |
24 | #include <type_traits> |
25 | |
26 | namespace ailego { |
27 | |
28 | /*! Singleton (C++11) |
29 | */ |
30 | template <typename T> |
31 | class Singleton { |
32 | public: |
33 | using ObjectType = typename std::remove_reference<T>::type; |
34 | |
35 | //! Retrieve instance of object |
36 | static ObjectType &Instance(void) noexcept( |
37 | std::is_nothrow_constructible<ObjectType>::value) { |
38 | // Since it's a static variable, if the class has already been created, |
39 | // it won't be created again. And it is thread-safe in C++11. |
40 | static ObjectType obj; |
41 | return obj; |
42 | } |
43 | |
44 | protected: |
45 | //! Constructor (Allow inheritance) |
46 | Singleton(void) {} |
47 | |
48 | private: |
49 | //! Disable them |
50 | Singleton(Singleton const &) = delete; |
51 | Singleton(Singleton &&) = delete; |
52 | Singleton &operator=(Singleton const &) = delete; |
53 | Singleton &operator=(Singleton &&) = delete; |
54 | }; |
55 | |
56 | } // namespace ailego |
57 | |
58 | #endif // __AILEGO_PATTERN_SINGLETON_H__ |
59 | |