Reference documentation for deal.II version 9.5.0
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variant.h
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1// ---------------------------------------------------------------------
2//
3// Copyright (C) 2022 - 2023 by the deal.II authors
4//
5// This file is part of the deal.II library.
6//
7// The deal.II library is free software; you can use it, redistribute
8// it, and/or modify it under the terms of the GNU Lesser General
9// Public License as published by the Free Software Foundation; either
10// version 2.1 of the License, or (at your option) any later version.
11// The full text of the license can be found in the file LICENSE.md at
12// the top level directory of deal.II.
13//
14// ---------------------------------------------------------------------
15#ifndef dealii_cxx17_variant_h
16#define dealii_cxx17_variant_h
17
18#include <deal.II/base/config.h>
19
20#ifdef DEAL_II_HAVE_CXX17
21# include <variant>
22#else
23# include <boost/variant.hpp>
24#endif
25
27namespace std_cxx17
28{
29#ifndef DEAL_II_HAVE_CXX17
30 using boost::get;
31 using boost::variant;
32
33 template <typename T, typename... Ts>
34 bool
35 holds_alternative(const boost::variant<Ts...> &v) noexcept
36 {
37 return boost::get<T>(&v) != nullptr;
38 }
39#else
40 using std::get;
41 using std::holds_alternative;
42 using std::variant;
43#endif
44} // namespace std_cxx17
46
47#endif // dealii_cxx17_variant_h
#define DEAL_II_NAMESPACE_OPEN
Definition config.h:472
#define DEAL_II_NAMESPACE_CLOSE
Definition config.h:473