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
25 template <class _Fn, class ..._Args>
26 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 invoke_result_t<_Fn, _Args...>
invoke(_Fn && __f,_Args &&...__args)27 invoke(_Fn&& __f, _Args&&... __args)
28 noexcept(is_nothrow_invocable_v<_Fn, _Args...>)
29 {
30 return _VSTD::__invoke(_VSTD::forward<_Fn>(__f), _VSTD::forward<_Args>(__args)...);
31 }
32
33 #endif // _LIBCPP_STD_VER >= 17
34
35 #if _LIBCPP_STD_VER >= 23
36 template <class _Result, class _Fn, class... _Args>
37 requires is_invocable_r_v<_Result, _Fn, _Args...>
38 _LIBCPP_HIDE_FROM_ABI constexpr _Result
invoke_r(_Fn && __f,_Args &&...__args)39 invoke_r(_Fn&& __f, _Args&&... __args) noexcept(is_nothrow_invocable_r_v<_Result, _Fn, _Args...>) {
40 if constexpr (is_void_v<_Result>) {
41 static_cast<void>(std::invoke(std::forward<_Fn>(__f), std::forward<_Args>(__args)...));
42 } else {
43 // TODO: Use reference_converts_from_temporary_v once implemented
44 // using _ImplicitInvokeResult = invoke_result_t<_Fn, _Args...>;
45 // static_assert(!reference_converts_from_temporary_v<_Result, _ImplicitInvokeResult>,
46 static_assert(true,
47 "Returning from invoke_r would bind a temporary object to the reference return type, "
48 "which would result in a dangling reference.");
49 return std::invoke(std::forward<_Fn>(__f), std::forward<_Args>(__args)...);
50 }
51 }
52 #endif
53
54 _LIBCPP_END_NAMESPACE_STD
55
56 #endif // _LIBCPP___FUNCTIONAL_INVOKE_H
57