| // Copyright 2020 The Pigweed Authors |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); you may not |
| // use this file except in compliance with the License. You may obtain a copy of |
| // the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| // License for the specific language governing permissions and limitations under |
| // the License. |
| #pragma once |
| |
| #include <type_traits> |
| |
| namespace pw::kvs { |
| |
| namespace internal { |
| template <typename T, typename = decltype(std::span(std::declval<T>()))> |
| constexpr bool ConvertsToSpan(int) { |
| return true; |
| } |
| |
| // If the expression std::span(T) fails, then the type can't be converted to a |
| // std::span. |
| template <typename T> |
| constexpr bool ConvertsToSpan(...) { |
| return false; |
| } |
| |
| } // namespace internal |
| |
| // Traits class to detect if the type converts to a std::span. |
| template <typename T> |
| struct ConvertsToSpan |
| : public std::bool_constant< |
| internal::ConvertsToSpan<std::remove_reference_t<T>>(0)> {}; |
| |
| } // namespace pw::kvs |
