1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef _LIBCPP___ALGORITHM_PSTL_FRONTEND_DISPATCH
10 #define _LIBCPP___ALGORITHM_PSTL_FRONTEND_DISPATCH
11 
12 #include <__config>
13 #include <__type_traits/is_callable.h>
14 #include <__utility/forward.h>
15 
16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
17 #  pragma GCC system_header
18 #endif
19 
20 #if _LIBCPP_STD_VER >= 17
21 
22 _LIBCPP_BEGIN_NAMESPACE_STD
23 
24 #  define _LIBCPP_PSTL_CUSTOMIZATION_POINT(name, policy)                                                               \
25     [](auto&&... __args) -> decltype(std::name<policy>(                                                                \
26                              typename __select_backend<policy>::type{}, std::forward<decltype(__args)>(__args)...)) {  \
27       return std::name<policy>(typename __select_backend<policy>::type{}, std::forward<decltype(__args)>(__args)...);  \
28     }
29 
30 template <class _SpecializedImpl, class _GenericImpl, class... _Args>
31 _LIBCPP_HIDE_FROM_ABI decltype(auto)
32 __pstl_frontend_dispatch(_SpecializedImpl __specialized_impl, _GenericImpl __generic_impl, _Args&&... __args) {
33   if constexpr (__is_callable<_SpecializedImpl, _Args...>::value) {
34     return __specialized_impl(std::forward<_Args>(__args)...);
35   } else {
36     return __generic_impl(std::forward<_Args>(__args)...);
37   }
38 }
39 
40 _LIBCPP_END_NAMESPACE_STD
41 
42 #endif // _LIBCPP_STD_VER >= 17
43 
44 #endif // _LIBCPP___ALGORITHM_PSTL_FRONTEND_DISPATCH
45