xref: /freebsd-src/contrib/llvm-project/libcxx/include/__functional/identity.h (revision fe6060f10f634930ff71b7c50291ddc610da2475)
1*fe6060f1SDimitry Andric // -*- C++ -*-
2*fe6060f1SDimitry Andric //===----------------------------------------------------------------------===//
3*fe6060f1SDimitry Andric //
4*fe6060f1SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5*fe6060f1SDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
6*fe6060f1SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7*fe6060f1SDimitry Andric //
8*fe6060f1SDimitry Andric //===----------------------------------------------------------------------===//
9*fe6060f1SDimitry Andric 
10*fe6060f1SDimitry Andric #ifndef _LIBCPP___FUNCTIONAL_IDENTITY_H
11*fe6060f1SDimitry Andric #define _LIBCPP___FUNCTIONAL_IDENTITY_H
12*fe6060f1SDimitry Andric 
13*fe6060f1SDimitry Andric #include <__config>
14*fe6060f1SDimitry Andric #include <utility>
15*fe6060f1SDimitry Andric 
16*fe6060f1SDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
17*fe6060f1SDimitry Andric #pragma GCC system_header
18*fe6060f1SDimitry Andric #endif
19*fe6060f1SDimitry Andric 
20*fe6060f1SDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD
21*fe6060f1SDimitry Andric 
22*fe6060f1SDimitry Andric #if _LIBCPP_STD_VER > 17
23*fe6060f1SDimitry Andric 
24*fe6060f1SDimitry Andric struct identity {
25*fe6060f1SDimitry Andric     template<class _Tp>
26*fe6060f1SDimitry Andric     _LIBCPP_NODISCARD_EXT constexpr _Tp&& operator()(_Tp&& __t) const noexcept
27*fe6060f1SDimitry Andric     {
28*fe6060f1SDimitry Andric         return _VSTD::forward<_Tp>(__t);
29*fe6060f1SDimitry Andric     }
30*fe6060f1SDimitry Andric 
31*fe6060f1SDimitry Andric     using is_transparent = void;
32*fe6060f1SDimitry Andric };
33*fe6060f1SDimitry Andric #endif // _LIBCPP_STD_VER > 17
34*fe6060f1SDimitry Andric 
35*fe6060f1SDimitry Andric _LIBCPP_END_NAMESPACE_STD
36*fe6060f1SDimitry Andric 
37*fe6060f1SDimitry Andric #endif // _LIBCPP___FUNCTIONAL_IDENTITY_H
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