libcxx/include/__algorithm/pstl_frontend_dispatch.h

   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