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...> 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 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