LIBINT  2.6.0
singleton.h
1 /*
2  * Copyright (C) 2004-2019 Edward F. Valeev
3  *
4  * This file is part of Libint.
5  *
6  * Libint is free software: you can redistribute it and/or modify
7  * it under the terms of the GNU Lesser General Public License as published by
8  * the Free Software Foundation, either version 3 of the License, or
9  * (at your option) any later version.
10  *
11  * Libint is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public License
17  * along with Libint. If not, see <http://www.gnu.org/licenses/>.
18  *
19  */
20 
21 #ifndef _libint2_include_libint2_util_singleton_h_
22 #define _libint2_include_libint2_util_singleton_h_
23 
24 #include <memory>
25 
26 namespace libint2 {
27  namespace detail {
28 
29  template <typename T> class managed_singleton {
30  public:
31  static T* instance() {
32  if (not instance_)
33  instance_ = std::unique_ptr<T>(new T);
34  return instance_.get();
35  }
36  static bool instance_exists() {
37  return instance_.get() != nullptr;
38  }
39  static void delete_instance() {
40  instance_.reset();
41  }
42  private:
43  managed_singleton() = delete;
44  static std::unique_ptr<T> instance_;
45  };
46  template <typename T> std::unique_ptr<T> managed_singleton<T>::instance_;
47 
48  } // namespace libint2::detail
49 } // namespace libint2
50 
51 #endif /* header guard */
Defaults definitions for various parameters assumed by Libint.
Definition: algebra.cc:24
Definition: singleton.h:29