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The C and C++ Include Header Files

cat -n /usr/include/c++/15/pstl/execution_impl.h

     1	// -*- C++ -*-
     2	//===-- execution_impl.h --------------------------------------------------===//
     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 _PSTL_EXECUTION_IMPL_H
    11	#define _PSTL_EXECUTION_IMPL_H
    12	
    13	#include <iterator>
    14	#include <type_traits>
    15	
    16	#include "execution_defs.h"
    17	
    18	namespace __pstl
    19	{
    20	namespace __internal
    21	{
    22	#if __glibcxx_concepts
    23	template<typename _Iter>
    24	  concept __is_random_access_iter
    25	    = std::is_base_of_v<std::random_access_iterator_tag,
    26				std::__iter_category_t<_Iter>>
    27	      || std::random_access_iterator<_Iter>;
    28	
    29	template <typename... _IteratorTypes>
    30	  using __are_random_access_iterators
    31	    = std::bool_constant<(__is_random_access_iter<std::remove_cvref_t<_IteratorTypes>> && ...)>;
    32	#else
    33	template <typename... _IteratorTypes>
    34	using __are_random_access_iterators
    35	    = std::__and_<
    36		std::is_base_of<std::random_access_iterator_tag,
    37				std::__iter_category_t<std::__remove_cvref_t<_IteratorTypes>>>...
    38	      >;
    39	#endif
    40	
    41	struct __serial_backend_tag
    42	{
    43	};
    44	struct __tbb_backend_tag
    45	{
    46	};
    47	struct __openmp_backend_tag
    48	{
    49	};
    50	
    51	#if defined(_PSTL_PAR_BACKEND_TBB)
    52	using __par_backend_tag = __tbb_backend_tag;
    53	#elif defined(_PSTL_PAR_BACKEND_OPENMP)
    54	using __par_backend_tag = __openmp_backend_tag;
    55	#elif defined(_PSTL_PAR_BACKEND_SERIAL)
    56	using __par_backend_tag = __serial_backend_tag;
    57	#else
    58	#    error "A parallel backend must be specified";
    59	#endif
    60	
    61	template <class _IsVector>
    62	struct __serial_tag
    63	{
    64	    using __is_vector = _IsVector;
    65	};
    66	
    67	template <class _IsVector>
    68	struct __parallel_tag
    69	{
    70	    using __is_vector = _IsVector;
    71	    // backend tag can be change depending on
    72	    // TBB availability in the environment
    73	    using __backend_tag = __par_backend_tag;
    74	};
    75	
    76	template <class _IsVector, class... _IteratorTypes>
    77	using __tag_type = typename std::conditional<__internal::__are_random_access_iterators<_IteratorTypes...>::value,
    78	                                             __parallel_tag<_IsVector>, __serial_tag<_IsVector>>::type;
    79	
    80	template <class... _IteratorTypes>
    81	__serial_tag</*_IsVector = */ std::false_type>
    82	__select_backend(__pstl::execution::sequenced_policy, _IteratorTypes&&...)
    83	{
    84	    return {};
    85	}
    86	
    87	template <class... _IteratorTypes>
    88	__serial_tag<__internal::__are_random_access_iterators<_IteratorTypes...>>
    89	__select_backend(__pstl::execution::unsequenced_policy, _IteratorTypes&&...)
    90	{
    91	    return {};
    92	}
    93	
    94	template <class... _IteratorTypes>
    95	__tag_type</*_IsVector = */ std::false_type, _IteratorTypes...>
    96	__select_backend(__pstl::execution::parallel_policy, _IteratorTypes&&...)
    97	{
    98	    return {};
    99	}
   100	
   101	template <class... _IteratorTypes>
   102	__tag_type<__internal::__are_random_access_iterators<_IteratorTypes...>, _IteratorTypes...>
   103	__select_backend(__pstl::execution::parallel_unsequenced_policy, _IteratorTypes&&...)
   104	{
   105	    return {};
   106	}
   107	
   108	} // namespace __internal
   109	} // namespace __pstl
   110	
   111	#endif /* _PSTL_EXECUTION_IMPL_H */