identity.h (645B)
1 // Copyright 2020 The Chromium Authors 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_FUNCTIONAL_IDENTITY_H_ 6 #define BASE_FUNCTIONAL_IDENTITY_H_ 7 8 #include <utility> 9 10 namespace base { 11 12 // Implementation of C++20's std::identity. 13 // 14 // Reference: 15 // - https://en.cppreference.com/w/cpp/utility/functional/identity 16 // - https://wg21.link/func.identity 17 struct identity { 18 template <typename T> 19 constexpr T&& operator()(T&& t) const noexcept { 20 return std::forward<T>(t); 21 } 22 23 using is_transparent = void; 24 }; 25 26 } // namespace base 27 28 #endif // BASE_FUNCTIONAL_IDENTITY_H_