Adam Lesinski | 7ff3ee1 | 2015-12-14 16:08:50 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2015 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #ifndef AAPT_UTIL_TYPETRAITS_H |
| 18 | #define AAPT_UTIL_TYPETRAITS_H |
| 19 | |
| 20 | #include <type_traits> |
| 21 | |
| 22 | namespace aapt { |
| 23 | |
Adam Lesinski | cacb28f | 2016-10-19 12:18:14 -0700 | [diff] [blame^] | 24 | #define DEFINE_HAS_BINARY_OP_TRAIT(name, op) \ |
| 25 | template <typename T, typename U> \ |
| 26 | struct name { \ |
| 27 | template <typename V, typename W> \ |
| 28 | static constexpr decltype(std::declval<V>() op std::declval<W>(), bool()) \ |
| 29 | test(int) { \ |
| 30 | return true; \ |
| 31 | } \ |
| 32 | template <typename V, typename W> \ |
| 33 | static constexpr bool test(...) { \ |
| 34 | return false; \ |
| 35 | } \ |
| 36 | static constexpr bool value = test<T, U>(int()); \ |
| 37 | } |
Adam Lesinski | 7ff3ee1 | 2015-12-14 16:08:50 -0800 | [diff] [blame] | 38 | |
| 39 | DEFINE_HAS_BINARY_OP_TRAIT(has_eq_op, ==); |
| 40 | DEFINE_HAS_BINARY_OP_TRAIT(has_lt_op, <); |
| 41 | |
| 42 | /** |
| 43 | * Type trait that checks if two types can be equated (==) and compared (<). |
| 44 | */ |
| 45 | template <typename T, typename U> |
| 46 | struct is_comparable { |
Adam Lesinski | cacb28f | 2016-10-19 12:18:14 -0700 | [diff] [blame^] | 47 | static constexpr bool value = |
| 48 | has_eq_op<T, U>::value && has_lt_op<T, U>::value; |
Adam Lesinski | 7ff3ee1 | 2015-12-14 16:08:50 -0800 | [diff] [blame] | 49 | }; |
| 50 | |
Adam Lesinski | cacb28f | 2016-10-19 12:18:14 -0700 | [diff] [blame^] | 51 | } // namespace aapt |
Adam Lesinski | 7ff3ee1 | 2015-12-14 16:08:50 -0800 | [diff] [blame] | 52 | |
| 53 | #endif /* AAPT_UTIL_TYPETRAITS_H */ |