Jakub Mazurkiewicz c91d805e66
[libc++] Implement std::not_fn<NTTP> (#86133)
Implement `std::not_fn<NTTP>` from "P2714R1 Bind front and back to NTTP callables".
2025-01-10 14:14:14 -05:00

77 lines
2.5 KiB
C++

// -*- 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/invoke.h>
#include <__functional/perfect_forward.h>
#include <__type_traits/decay.h>
#include <__type_traits/enable_if.h>
#include <__type_traits/is_constructible.h>
#include <__type_traits/is_member_pointer.h>
#include <__type_traits/is_pointer.h>
#include <__utility/forward.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 17
struct __not_fn_op {
template <class... _Args>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 auto operator()(_Args&&... __args) const
noexcept(noexcept(!std::invoke(std::forward<_Args>(__args)...)))
-> decltype(!std::invoke(std::forward<_Args>(__args)...)) {
return !std::invoke(std::forward<_Args>(__args)...);
}
};
template <class _Fn>
struct __not_fn_t : __perfect_forward<__not_fn_op, _Fn> {
using __perfect_forward<__not_fn_op, _Fn>::__perfect_forward;
};
template <class _Fn,
class = enable_if_t< is_constructible_v<decay_t<_Fn>, _Fn> && is_move_constructible_v<decay_t<_Fn>> >>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 auto not_fn(_Fn&& __f) {
return __not_fn_t<decay_t<_Fn>>(std::forward<_Fn>(__f));
}
#endif // _LIBCPP_STD_VER >= 17
#if _LIBCPP_STD_VER >= 26
template <auto _Fn>
struct __nttp_not_fn_t {
template <class... _Args>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) const
noexcept(noexcept(!std::invoke(_Fn, std::forward<_Args>(__args)...)))
-> decltype(!std::invoke(_Fn, std::forward<_Args>(__args)...)) {
return !std::invoke(_Fn, std::forward<_Args>(__args)...);
}
};
template <auto _Fn>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI constexpr auto not_fn() noexcept {
if constexpr (using _Ty = decltype(_Fn); is_pointer_v<_Ty> || is_member_pointer_v<_Ty>)
static_assert(_Fn != nullptr, "f cannot be equal to nullptr");
return __nttp_not_fn_t<_Fn>();
}
#endif // _LIBCPP_STD_VER >= 26
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___FUNCTIONAL_NOT_FN_H