1 // -*- C++ -*-
2 //===----------------------------------------------------------------------===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #ifndef _LIBCPP___FUNCTIONAL_NOT_FN_H
11 #define _LIBCPP___FUNCTIONAL_NOT_FN_H
12 
13 #include <__config>
14 #include <__functional/invoke.h>
15 #include <__functional/perfect_forward.h>
16 #include <__type_traits/decay.h>
17 #include <__type_traits/enable_if.h>
18 #include <__type_traits/is_constructible.h>
19 #include <__type_traits/is_move_constructible.h>
20 #include <__utility/forward.h>
21 
22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
23 #  pragma GCC system_header
24 #endif
25 
26 _LIBCPP_BEGIN_NAMESPACE_STD
27 
28 #if _LIBCPP_STD_VER >= 17
29 
30 struct __not_fn_op {
31     template <class... _Args>
32     _LIBCPP_HIDE_FROM_ABI
33     _LIBCPP_CONSTEXPR_SINCE_CXX20 auto operator()(_Args&&... __args) const
34         noexcept(noexcept(!_VSTD::invoke(_VSTD::forward<_Args>(__args)...)))
35         -> decltype(      !_VSTD::invoke(_VSTD::forward<_Args>(__args)...))
36         { return          !_VSTD::invoke(_VSTD::forward<_Args>(__args)...); }
37 };
38 
39 template <class _Fn>
40 struct __not_fn_t : __perfect_forward<__not_fn_op, _Fn> {
41     using __perfect_forward<__not_fn_op, _Fn>::__perfect_forward;
42 };
43 
44 template <class _Fn, class = enable_if_t<
45     is_constructible_v<decay_t<_Fn>, _Fn> &&
46     is_move_constructible_v<decay_t<_Fn>>
47 >>
48 _LIBCPP_HIDE_FROM_ABI
49 _LIBCPP_CONSTEXPR_SINCE_CXX20 auto not_fn(_Fn&& __f) {
50     return __not_fn_t<decay_t<_Fn>>(_VSTD::forward<_Fn>(__f));
51 }
52 
53 #endif // _LIBCPP_STD_VER >= 17
54 
55 _LIBCPP_END_NAMESPACE_STD
56 
57 #endif // _LIBCPP___FUNCTIONAL_NOT_FN_H
58