b4ecfd3c46
Reviewed By: #libc, ldionne Spies: ldionne, Mordante, libcxx-commits Differential Revision: https://reviews.llvm.org/D139554
58 lines
1.4 KiB
C++
58 lines
1.4 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___FUNCTIONAL_IDENTITY_H
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#define _LIBCPP___FUNCTIONAL_IDENTITY_H
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#include <__config>
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#include <__type_traits/integral_constant.h>
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#include <__utility/forward.h>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_STD
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template <class _Tp>
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struct __is_identity : false_type {};
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struct __identity {
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template <class _Tp>
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_LIBCPP_NODISCARD _LIBCPP_CONSTEXPR _Tp&& operator()(_Tp&& __t) const _NOEXCEPT {
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return std::forward<_Tp>(__t);
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}
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using is_transparent = void;
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};
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template <>
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struct __is_identity<__identity> : true_type {};
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#if _LIBCPP_STD_VER >= 20
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struct identity {
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template<class _Tp>
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_LIBCPP_NODISCARD_EXT constexpr _Tp&& operator()(_Tp&& __t) const noexcept
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{
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return _VSTD::forward<_Tp>(__t);
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}
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using is_transparent = void;
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};
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template <>
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struct __is_identity<identity> : true_type {};
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#endif // _LIBCPP_STD_VER >= 20
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___FUNCTIONAL_IDENTITY_H
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