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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _PSTL_EXECUTION_IMPL_H
#define _PSTL_EXECUTION_IMPL_H
#include <__config>
#include <__iterator/iterator_traits.h>
#include <__type_traits/conditional.h>
#include <__type_traits/conjunction.h>
#include <__type_traits/decay.h>
#include <__type_traits/integral_constant.h>
#include <__type_traits/is_base_of.h>
#include <__pstl/internal/execution_defs.h>
#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
namespace __pstl {
namespace __internal {
template <typename _IteratorTag, typename... _IteratorTypes>
using __are_iterators_of = std::conjunction<
std::is_base_of<_IteratorTag, typename std::iterator_traits<std::decay_t<_IteratorTypes>>::iterator_category>...>;
template <typename... _IteratorTypes>
using __are_random_access_iterators = __are_iterators_of<std::random_access_iterator_tag, _IteratorTypes...>;
struct __serial_backend_tag {};
struct __tbb_backend_tag {};
struct __openmp_backend_tag {};
# if defined(_PSTL_PAR_BACKEND_TBB)
using __par_backend_tag = __tbb_backend_tag;
# elif defined(_PSTL_PAR_BACKEND_OPENMP)
using __par_backend_tag = __openmp_backend_tag;
# elif defined(_PSTL_PAR_BACKEND_SERIAL)
using __par_backend_tag = __serial_backend_tag;
# else
# error "A parallel backend must be specified";
# endif
template <class _IsVector>
struct __serial_tag {
using __is_vector = _IsVector;
};
template <class _IsVector>
struct __parallel_tag {
using __is_vector = _IsVector;
// backend tag can be change depending on
// TBB availability in the environment
using __backend_tag = __par_backend_tag;
};
template <class _IsVector, class... _IteratorTypes>
using __tag_type =
typename std::conditional<__internal::__are_random_access_iterators<_IteratorTypes...>::value,
__parallel_tag<_IsVector>,
__serial_tag<_IsVector>>::type;
template <class... _IteratorTypes>
_LIBCPP_HIDE_FROM_ABI __serial_tag</*_IsVector = */ std::false_type>
__select_backend(__pstl::execution::sequenced_policy, _IteratorTypes&&...) {
return {};
}
template <class... _IteratorTypes>
_LIBCPP_HIDE_FROM_ABI __serial_tag<__internal::__are_random_access_iterators<_IteratorTypes...>>
__select_backend(__pstl::execution::unsequenced_policy, _IteratorTypes&&...) {
return {};
}
template <class... _IteratorTypes>
_LIBCPP_HIDE_FROM_ABI __tag_type</*_IsVector = */ std::false_type, _IteratorTypes...>
__select_backend(__pstl::execution::parallel_policy, _IteratorTypes&&...) {
return {};
}
template <class... _IteratorTypes>
_LIBCPP_HIDE_FROM_ABI __tag_type<__internal::__are_random_access_iterators<_IteratorTypes...>, _IteratorTypes...>
__select_backend(__pstl::execution::parallel_unsequenced_policy, _IteratorTypes&&...) {
return {};
}
} // namespace __internal
} // namespace __pstl
#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
#endif /* _PSTL_EXECUTION_IMPL_H */
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