xref: /freebsd/contrib/llvm-project/libcxx/include/__functional/not_fn.h (revision 9f44a47fd07924afc035991af15d84e6585dea4f)
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 <__utility/forward.h>
17 #include <type_traits>
18 
19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
20 #  pragma GCC system_header
21 #endif
22 
23 _LIBCPP_BEGIN_NAMESPACE_STD
24 
25 #if _LIBCPP_STD_VER > 14
26 
27 struct __not_fn_op {
28     template <class... _Args>
29     _LIBCPP_HIDE_FROM_ABI
30     _LIBCPP_CONSTEXPR_AFTER_CXX17 auto operator()(_Args&&... __args) const
31         noexcept(noexcept(!_VSTD::invoke(_VSTD::forward<_Args>(__args)...)))
32         -> decltype(      !_VSTD::invoke(_VSTD::forward<_Args>(__args)...))
33         { return          !_VSTD::invoke(_VSTD::forward<_Args>(__args)...); }
34 };
35 
36 template <class _Fn>
37 struct __not_fn_t : __perfect_forward<__not_fn_op, _Fn> {
38     using __perfect_forward<__not_fn_op, _Fn>::__perfect_forward;
39 };
40 
41 template <class _Fn, class = enable_if_t<
42     is_constructible_v<decay_t<_Fn>, _Fn> &&
43     is_move_constructible_v<decay_t<_Fn>>
44 >>
45 _LIBCPP_HIDE_FROM_ABI
46 _LIBCPP_CONSTEXPR_AFTER_CXX17 auto not_fn(_Fn&& __f) {
47     return __not_fn_t<decay_t<_Fn>>(_VSTD::forward<_Fn>(__f));
48 }
49 
50 #endif // _LIBCPP_STD_VER > 14
51 
52 _LIBCPP_END_NAMESPACE_STD
53 
54 #endif // _LIBCPP___FUNCTIONAL_NOT_FN_H
55