clang-r433403b/include/c++/v1/__functional/not_fn.h

// -*- 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_NOT_FN_H
#define _LIBCPP___FUNCTIONAL_NOT_FN_H

#include <__config>
#include <__functional/perfect_forward.h>
#include <__functional/invoke.h>
#include <utility>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

#if _LIBCPP_STD_VER > 14

struct __not_fn_op
{
    template<class... _Args>
    static _LIBCPP_CONSTEXPR_AFTER_CXX17 auto __call(_Args&&... __args)
    noexcept(noexcept(!_VSTD::invoke(_VSTD::forward<_Args>(__args)...)))
    -> decltype(      !_VSTD::invoke(_VSTD::forward<_Args>(__args)...))
    { return          !_VSTD::invoke(_VSTD::forward<_Args>(__args)...); }
};

template<class _Fn,
         class = _EnableIf<is_constructible_v<decay_t<_Fn>, _Fn> &&
                           is_move_constructible_v<_Fn>>>
_LIBCPP_CONSTEXPR_AFTER_CXX17 auto not_fn(_Fn&& __f)
{
    return __perfect_forward<__not_fn_op, _Fn>(_VSTD::forward<_Fn>(__f));
}

#endif // _LIBCPP_STD_VER > 14

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___FUNCTIONAL_NOT_FN_H