1 | // Licensed to the Apache Software Foundation (ASF) under one |
2 | // or more contributor license agreements. See the NOTICE file |
3 | // distributed with this work for additional information |
4 | // regarding copyright ownership. The ASF licenses this file |
5 | // to you under the Apache License, Version 2.0 (the |
6 | // "License"); you may not use this file except in compliance |
7 | // with the License. You may obtain a copy of the License at |
8 | // |
9 | // http://www.apache.org/licenses/LICENSE-2.0 |
10 | // |
11 | // Unless required by applicable law or agreed to in writing, |
12 | // software distributed under the License is distributed on an |
13 | // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
14 | // KIND, either express or implied. See the License for the |
15 | // specific language governing permissions and limitations |
16 | // under the License. |
17 | |
18 | #ifndef ARROW_UTIL_TYPE_TRAITS_H |
19 | #define ARROW_UTIL_TYPE_TRAITS_H |
20 | |
21 | #include <type_traits> |
22 | |
23 | namespace arrow { |
24 | namespace internal { |
25 | |
26 | /// \brief Metafunction to allow checking if a type matches any of another set of types |
27 | template <typename...> |
28 | struct IsOneOf : std::false_type {}; /// Base case: nothing has matched |
29 | |
30 | template <typename T, typename U, typename... Args> |
31 | struct IsOneOf<T, U, Args...> { |
32 | /// Recursive case: T == U or T matches any other types provided (not including U). |
33 | static constexpr bool value = std::is_same<T, U>::value || IsOneOf<T, Args...>::value; |
34 | }; |
35 | |
36 | /// \brief Shorthand for using IsOneOf + std::enable_if |
37 | template <typename T, typename... Args> |
38 | using EnableIfIsOneOf = typename std::enable_if<IsOneOf<T, Args...>::value, T>::type; |
39 | |
40 | /// \brief is_null_pointer from C++17 |
41 | template <typename T> |
42 | struct is_null_pointer : std::is_same<std::nullptr_t, typename std::remove_cv<T>::type> { |
43 | }; |
44 | |
45 | } // namespace internal |
46 | } // namespace arrow |
47 | |
48 | #endif // ARROW_UTIL_TYPE_TRAITS_H |
49 | |