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