openPMD-api
Variant.hpp
1 /* Copyright 2017-2021 Fabian Koller, Axel Huebl
2  *
3  * This file is part of openPMD-api.
4  *
5  * openPMD-api is free software: you can redistribute it and/or modify
6  * it under the terms of of either the GNU General Public License or
7  * 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  * openPMD-api 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 General Public License and the GNU Lesser General Public License
15  * for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * and the GNU Lesser General Public License along with openPMD-api.
19  * If not, see <http://www.gnu.org/licenses/>.
20  */
21 #pragma once
22 
23 #include "VariantSrc.hpp"
24 
25 #include <cstddef>
26 #include <type_traits>
27 
28 namespace openPMD
29 {
30 namespace auxiliary
31 {
39  template <class T_DTYPES, typename... T>
40  class Variant
41  {
42  static_assert(
43  std::is_enum<T_DTYPES>::value,
44  "Datatypes to Variant must be supplied as enum.");
45 
46  public:
47  using resource = variantSrc::variant<T...>;
55  Variant(resource r) : dtype{static_cast<T_DTYPES>(r.index())}, m_data{r}
56  {}
57 
65  template <typename U>
66  U get() const
67  {
68  return variantSrc::get<U>(m_data);
69  }
70 
75  resource getResource() const
76  {
77  return m_data;
78  }
79 
84  constexpr size_t index() const noexcept
85  {
86  return m_data.index();
87  }
88 
89  T_DTYPES dtype;
90 
91  private:
92  resource m_data;
93  };
94 } // namespace auxiliary
95 } // namespace openPMD
Variant(resource r)
Construct a lightweight wrapper around a generic object that indicates the concrete datatype of the s...
Definition: Variant.hpp:55
Generic object to store a set of datatypes in without losing type safety.
Definition: Variant.hpp:40
constexpr size_t index() const noexcept
Retrieve the index of the alternative that is currently been held.
Definition: Variant.hpp:84
Public definitions of openPMD-api.
Definition: Date.cpp:28
resource getResource() const
Retrieve the stored generic object.
Definition: Variant.hpp:75