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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___FUNCTIONAL_IDENTITY_H
#define _LIBCPP___FUNCTIONAL_IDENTITY_H
#include <__config>
#include <__functional/reference_wrapper.h>
#include <__type_traits/integral_constant.h>
#include <__utility/forward.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _Tp>
struct __is_identity : false_type {};
struct __identity {
template <class _Tp>
_LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Tp&& operator()(_Tp&& __t) const _NOEXCEPT {
return std::forward<_Tp>(__t);
}
using is_transparent = void;
};
template <>
struct __is_identity<__identity> : true_type {};
template <>
struct __is_identity<reference_wrapper<__identity> > : true_type {};
template <>
struct __is_identity<reference_wrapper<const __identity> > : true_type {};
#if _LIBCPP_STD_VER >= 20
struct identity {
template <class _Tp>
_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr _Tp&& operator()(_Tp&& __t) const noexcept {
return std::forward<_Tp>(__t);
}
using is_transparent = void;
};
template <>
struct __is_identity<identity> : true_type {};
template <>
struct __is_identity<reference_wrapper<identity> > : true_type {};
template <>
struct __is_identity<reference_wrapper<const identity> > : true_type {};
#endif // _LIBCPP_STD_VER >= 20
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___FUNCTIONAL_IDENTITY_H
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