Jim Flynn | 6217c3d | 2022-06-14 10:58:23 +0100 | [diff] [blame] | 1 | // |
| 2 | // Copyright (c) MapBox All rights reserved. |
| 3 | // SPDX-License-Identifier: BSD-3-Clause |
| 4 | // |
| 5 | |
James Ward | 22a4e15 | 2020-09-25 11:43:21 +0100 | [diff] [blame] | 6 | #ifndef MAPBOX_UTIL_VARIANT_VISITOR_HPP |
| 7 | #define MAPBOX_UTIL_VARIANT_VISITOR_HPP |
| 8 | |
| 9 | #include <utility> |
| 10 | |
| 11 | namespace mapbox { |
| 12 | namespace util { |
| 13 | |
| 14 | template <typename... Fns> |
| 15 | struct visitor; |
| 16 | |
| 17 | template <typename Fn> |
| 18 | struct visitor<Fn> : Fn |
| 19 | { |
| 20 | using Fn::operator(); |
| 21 | |
| 22 | template<typename T> |
Jim Flynn | 6217c3d | 2022-06-14 10:58:23 +0100 | [diff] [blame] | 23 | visitor(T&& fn) : Fn(std::forward<T>(fn)) {} |
James Ward | 22a4e15 | 2020-09-25 11:43:21 +0100 | [diff] [blame] | 24 | }; |
| 25 | |
| 26 | template <typename Fn, typename... Fns> |
| 27 | struct visitor<Fn, Fns...> : Fn, visitor<Fns...> |
| 28 | { |
| 29 | using Fn::operator(); |
| 30 | using visitor<Fns...>::operator(); |
| 31 | |
| 32 | template<typename T, typename... Ts> |
| 33 | visitor(T&& fn, Ts&&... fns) |
| 34 | : Fn(std::forward<T>(fn)) |
| 35 | , visitor<Fns...>(std::forward<Ts>(fns)...) {} |
| 36 | }; |
| 37 | |
| 38 | template <typename... Fns> |
| 39 | visitor<typename std::decay<Fns>::type...> make_visitor(Fns&&... fns) |
| 40 | { |
| 41 | return visitor<typename std::decay<Fns>::type...> |
| 42 | (std::forward<Fns>(fns)...); |
| 43 | } |
Jim Flynn | 6217c3d | 2022-06-14 10:58:23 +0100 | [diff] [blame] | 44 | |
James Ward | 22a4e15 | 2020-09-25 11:43:21 +0100 | [diff] [blame] | 45 | } // namespace util |
| 46 | } // namespace mapbox |
| 47 | |
| 48 | #endif // MAPBOX_UTIL_VARIANT_VISITOR_HPP |