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
23namespace arrow {
24namespace internal {
25
26/// \brief Metafunction to allow checking if a type matches any of another set of types
27template <typename...>
28struct IsOneOf : std::false_type {}; /// Base case: nothing has matched
29
30template <typename T, typename U, typename... Args>
31struct 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
37template <typename T, typename... Args>
38using EnableIfIsOneOf = typename std::enable_if<IsOneOf<T, Args...>::value, T>::type;
39
40/// \brief is_null_pointer from C++17
41template <typename T>
42struct 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