rtc_base/containers/identity.h

/*
 *  Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

// This implementation is borrowed from Chromium.

#ifndef RTC_BASE_CONTAINERS_IDENTITY_H_
#define RTC_BASE_CONTAINERS_IDENTITY_H_

#include <utility>

namespace webrtc {

// Implementation of C++20's std::identity.
//
// Reference:
// - https://en.cppreference.com/w/cpp/utility/functional/identity
// - https://wg21.link/func.identity
struct identity {
  template <typename T>
  constexpr T&& operator()(T&& t) const noexcept {
    return std::forward<T>(t);
  }

  using is_transparent = void;
};

}  // namespace webrtc

#endif  // RTC_BASE_CONTAINERS_IDENTITY_H_