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_INVOKE_H
11#define _LIBCPP___FUNCTIONAL_INVOKE_H
12
13#include <__config>
14#include <__type_traits/invoke.h>
15#include <__type_traits/is_void.h>
16#include <__utility/forward.h>
17
18#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
19# pragma GCC system_header
20#endif
21
22_LIBCPP_BEGIN_NAMESPACE_STD
23
24#if _LIBCPP_STD_VER >= 17
25
26template <class _Fn, class... _Args>
27_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 invoke_result_t<_Fn, _Args...>
28invoke(_Fn&& __f, _Args&&... __args) noexcept(is_nothrow_invocable_v<_Fn, _Args...>) {
29 return std::__invoke(std::forward<_Fn>(__f), std::forward<_Args>(__args)...);
30}
31
32#endif // _LIBCPP_STD_VER >= 17
33
34#if _LIBCPP_STD_VER >= 23
35template <class _Result, class _Fn, class... _Args>
36 requires is_invocable_r_v<_Result, _Fn, _Args...>
37_LIBCPP_HIDE_FROM_ABI constexpr _Result
38invoke_r(_Fn&& __f, _Args&&... __args) noexcept(is_nothrow_invocable_r_v<_Result, _Fn, _Args...>) {
39 if constexpr (is_void_v<_Result>) {
40 static_cast<void>(std::invoke(std::forward<_Fn>(__f), std::forward<_Args>(__args)...));
41 } else {
42 // TODO: Use reference_converts_from_temporary_v once implemented
43 // using _ImplicitInvokeResult = invoke_result_t<_Fn, _Args...>;
44 // static_assert(!reference_converts_from_temporary_v<_Result, _ImplicitInvokeResult>,
45 static_assert(true,
46 "Returning from invoke_r would bind a temporary object to the reference return type, "
47 "which would result in a dangling reference.");
48 return std::invoke(std::forward<_Fn>(__f), std::forward<_Args>(__args)...);
49 }
50}
51#endif
52
53_LIBCPP_END_NAMESPACE_STD
54
55#endif // _LIBCPP___FUNCTIONAL_INVOKE_H
56