//===----------------------------------------------------------------------===//
//
// 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 _LIBCPP___PSTL_BACKENDS_DEFAULT_H
#define _LIBCPP___PSTL_BACKENDS_DEFAULT_H
#include <__algorithm/copy_n.h>
#include <__algorithm/equal.h>
#include <__algorithm/fill_n.h>
#include <__algorithm/for_each_n.h>
#include <__config>
#include <__functional/identity.h>
#include <__functional/not_fn.h>
#include <__functional/operations.h>
#include <__iterator/concepts.h>
#include <__iterator/iterator_traits.h>
#include <__pstl/backend_fwd.h>
#include <__pstl/dispatch.h>
#include <__utility/empty.h>
#include <__utility/forward.h>
#include <__utility/move.h>
#include <optional>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
#if _LIBCPP_STD_VER >= 17
_LIBCPP_BEGIN_NAMESPACE_STD
namespace __pstl {
//
// This file provides an incomplete PSTL backend that implements all of the PSTL algorithms
// based on a smaller set of basis operations.
//
// It is intended as a building block for other PSTL backends that implement some operations more
// efficiently but may not want to define the full set of PSTL algorithms.
//
// This backend implements all the PSTL algorithms based on the following basis operations:
//
// find_if family
// --------------
// - find
// - find_if_not
// - any_of
// - all_of
// - none_of
// - is_partitioned
//
// for_each family
// ---------------
// - for_each_n
// - fill
// - fill_n
// - replace
// - replace_if
// - generate
// - generate_n
//
// merge family
// ------------
// No other algorithms based on merge
//
// stable_sort family
// ------------------
// - sort
//
// transform_reduce and transform_reduce_binary family
// ---------------------------------------------------
// - count_if
// - count
// - equal(3 legs)
// - equal
// - reduce
//
// transform and transform_binary family
// -------------------------------------
// - replace_copy_if
// - replace_copy
// - move
// - copy
// - copy_n
// - rotate_copy
//
//////////////////////////////////////////////////////////////
// find_if family
//////////////////////////////////////////////////////////////
template <class _ExecutionPolicy>
struct __find<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<_ForwardIterator>
operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value) const noexcept {
using _FindIf = __dispatch<__find_if, __current_configuration, _ExecutionPolicy>;
return _FindIf()(
__policy, std::move(__first), std::move(__last), [&](__iter_reference<_ForwardIterator> __element) {
return __element == __value;
});
}
};
template <class _ExecutionPolicy>
struct __find_if_not<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Pred>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<_ForwardIterator>
operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Pred&& __pred) const noexcept {
using _FindIf = __dispatch<__find_if, __current_configuration, _ExecutionPolicy>;
return _FindIf()(__policy, __first, __last, std::not_fn(std::forward<_Pred>(__pred)));
}
};
template <class _ExecutionPolicy>
struct __any_of<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Pred>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<bool>
operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Pred&& __pred) const noexcept {
using _FindIf = __dispatch<__find_if, __current_configuration, _ExecutionPolicy>;
auto __res = _FindIf()(__policy, __first, __last, std::forward<_Pred>(__pred));
if (!__res)
return nullopt;
return *__res != __last;
}
};
template <class _ExecutionPolicy>
struct __all_of<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Pred>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<bool>
operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Pred&& __pred) const noexcept {
using _AnyOf = __dispatch<__any_of, __current_configuration, _ExecutionPolicy>;
auto __res = _AnyOf()(__policy, __first, __last, [&](__iter_reference<_ForwardIterator> __value) {
return !__pred(__value);
});
if (!__res)
return nullopt;
return !*__res;
}
};
template <class _ExecutionPolicy>
struct __none_of<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Pred>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<bool>
operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Pred&& __pred) const noexcept {
using _AnyOf = __dispatch<__any_of, __current_configuration, _ExecutionPolicy>;
auto __res = _AnyOf()(__policy, __first, __last, std::forward<_Pred>(__pred));
if (!__res)
return nullopt;
return !*__res;
}
};
template <class _ExecutionPolicy>
struct __is_partitioned<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Pred>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<bool>
operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Pred&& __pred) const noexcept {
using _FindIfNot = __dispatch<__find_if_not, __current_configuration, _ExecutionPolicy>;
auto __maybe_first = _FindIfNot()(__policy, std::move(__first), __last, __pred);
if (__maybe_first == nullopt)
return nullopt;
__first = *__maybe_first;
if (__first == __last)
return true;
++__first;
using _NoneOf = __dispatch<__none_of, __current_configuration, _ExecutionPolicy>;
return _NoneOf()(__policy, std::move(__first), std::move(__last), __pred);
}
};
//////////////////////////////////////////////////////////////
// for_each family
//////////////////////////////////////////////////////////////
template <class _ExecutionPolicy>
struct __for_each_n<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Size, class _Function>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__empty>
operator()(_Policy&& __policy, _ForwardIterator __first, _Size __size, _Function __func) const noexcept {
if constexpr (__has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
using _ForEach = __dispatch<__for_each, __current_configuration, _ExecutionPolicy>;
_ForwardIterator __last = __first + __size;
return _ForEach()(__policy, std::move(__first), std::move(__last), std::move(__func));
} else {
// Otherwise, use the serial algorithm to avoid doing two passes over the input
std::for_each_n(std::move(__first), __size, std::move(__func));
return __empty{};
}
}
};
template <class _ExecutionPolicy>
struct __fill<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__empty>
operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Tp const& __value) const noexcept {
using _ForEach = __dispatch<__for_each, __current_configuration, _ExecutionPolicy>;
using _Ref = __iter_reference<_ForwardIterator>;
return _ForEach()(__policy, std::move(__first), std::move(__last), [&](_Ref __element) { __element = __value; });
}
};
template <class _ExecutionPolicy>
struct __fill_n<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Size, class _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__empty>
operator()(_Policy&& __policy, _ForwardIterator __first, _Size __n, _Tp const& __value) const noexcept {
if constexpr (__has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
using _Fill = __dispatch<__fill, __current_configuration, _ExecutionPolicy>;
_ForwardIterator __last = __first + __n;
return _Fill()(__policy, std::move(__first), std::move(__last), __value);
} else {
// Otherwise, use the serial algorithm to avoid doing two passes over the input
std::fill_n(std::move(__first), __n, __value);
return optional<__empty>{__empty{}};
}
}
};
template <class _ExecutionPolicy>
struct __replace<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__empty>
operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Tp const& __old, _Tp const& __new)
const noexcept {
using _ReplaceIf = __dispatch<__replace_if, __current_configuration, _ExecutionPolicy>;
using _Ref = __iter_reference<_ForwardIterator>;
return _ReplaceIf()(
__policy, std::move(__first), std::move(__last), [&](_Ref __element) { return __element == __old; }, __new);
}
};
template <class _ExecutionPolicy>
struct __replace_if<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Pred, class _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__empty> operator()(
_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Pred&& __pred, _Tp const& __new_value)
const noexcept {
using _ForEach = __dispatch<__for_each, __current_configuration, _ExecutionPolicy>;
using _Ref = __iter_reference<_ForwardIterator>;
return _ForEach()(__policy, std::move(__first), std::move(__last), [&](_Ref __element) {
if (__pred(__element))
__element = __new_value;
});
}
};
template <class _ExecutionPolicy>
struct __generate<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Generator>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__empty>
operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Generator&& __gen) const noexcept {
using _ForEach = __dispatch<__for_each, __current_configuration, _ExecutionPolicy>;
using _Ref = __iter_reference<_ForwardIterator>;
return _ForEach()(__policy, std::move(__first), std::move(__last), [&](_Ref __element) { __element = __gen(); });
}
};
template <class _ExecutionPolicy>
struct __generate_n<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Size, class _Generator>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__empty>
operator()(_Policy&& __policy, _ForwardIterator __first, _Size __n, _Generator&& __gen) const noexcept {
using _ForEachN = __dispatch<__for_each_n, __current_configuration, _ExecutionPolicy>;
using _Ref = __iter_reference<_ForwardIterator>;
return _ForEachN()(__policy, std::move(__first), __n, [&](_Ref __element) { __element = __gen(); });
}
};
//////////////////////////////////////////////////////////////
// stable_sort family
//////////////////////////////////////////////////////////////
template <class _ExecutionPolicy>
struct __sort<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _RandomAccessIterator, class _Comp>
_LIBCPP_HIDE_FROM_ABI optional<__empty> operator()(
_Policy&& __policy, _RandomAccessIterator __first, _RandomAccessIterator __last, _Comp&& __comp) const noexcept {
using _StableSort = __dispatch<__stable_sort, __current_configuration, _ExecutionPolicy>;
return _StableSort()(__policy, std::move(__first), std::move(__last), std::forward<_Comp>(__comp));
}
};
//////////////////////////////////////////////////////////////
// transform_reduce family
//////////////////////////////////////////////////////////////
template <class _ExecutionPolicy>
struct __count_if<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Predicate>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__iter_diff_t<_ForwardIterator>> operator()(
_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Predicate&& __pred) const noexcept {
using _TransformReduce = __dispatch<__transform_reduce, __current_configuration, _ExecutionPolicy>;
using _DiffT = __iter_diff_t<_ForwardIterator>;
using _Ref = __iter_reference<_ForwardIterator>;
return _TransformReduce()(
__policy, std::move(__first), std::move(__last), _DiffT{}, std::plus{}, [&](_Ref __element) -> _DiffT {
return __pred(__element) ? _DiffT(1) : _DiffT(0);
});
}
};
template <class _ExecutionPolicy>
struct __count<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__iter_diff_t<_ForwardIterator>>
operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Tp const& __value) const noexcept {
using _CountIf = __dispatch<__count_if, __current_configuration, _ExecutionPolicy>;
using _Ref = __iter_reference<_ForwardIterator>;
return _CountIf()(__policy, std::move(__first), std::move(__last), [&](_Ref __element) -> bool {
return __element == __value;
});
}
};
template <class _ExecutionPolicy>
struct __equal_3leg<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<bool>
operator()(_Policy&& __policy,
_ForwardIterator1 __first1,
_ForwardIterator1 __last1,
_ForwardIterator2 __first2,
_Predicate&& __pred) const noexcept {
using _TransformReduce = __dispatch<__transform_reduce_binary, __current_configuration, _ExecutionPolicy>;
return _TransformReduce()(
__policy,
std::move(__first1),
std::move(__last1),
std::move(__first2),
true,
std::logical_and{},
std::forward<_Predicate>(__pred));
}
};
template <class _ExecutionPolicy>
struct __equal<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<bool>
operator()(_Policy&& __policy,
_ForwardIterator1 __first1,
_ForwardIterator1 __last1,
_ForwardIterator2 __first2,
_ForwardIterator2 __last2,
_Predicate&& __pred) const noexcept {
if constexpr (__has_random_access_iterator_category<_ForwardIterator1>::value &&
__has_random_access_iterator_category<_ForwardIterator2>::value) {
if (__last1 - __first1 != __last2 - __first2)
return false;
// Fall back to the 3 legged algorithm
using _Equal3Leg = __dispatch<__equal_3leg, __current_configuration, _ExecutionPolicy>;
return _Equal3Leg()(
__policy, std::move(__first1), std::move(__last1), std::move(__first2), std::forward<_Predicate>(__pred));
} else {
// If we don't have random access, fall back to the serial algorithm cause we can't do much
return std::equal(
std::move(__first1),
std::move(__last1),
std::move(__first2),
std::move(__last2),
std::forward<_Predicate>(__pred));
}
}
};
template <class _ExecutionPolicy>
struct __reduce<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Tp, class _BinaryOperation>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<_Tp>
operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Tp __init, _BinaryOperation&& __op)
const noexcept {
using _TransformReduce = __dispatch<__transform_reduce, __current_configuration, _ExecutionPolicy>;
return _TransformReduce()(
__policy,
std::move(__first),
std::move(__last),
std::move(__init),
std::forward<_BinaryOperation>(__op),
__identity{});
}
};
//////////////////////////////////////////////////////////////
// transform family
//////////////////////////////////////////////////////////////
template <class _ExecutionPolicy>
struct __replace_copy_if<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _ForwardOutIterator, class _Pred, class _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__empty>
operator()(_Policy&& __policy,
_ForwardIterator __first,
_ForwardIterator __last,
_ForwardOutIterator __out_it,
_Pred&& __pred,
_Tp const& __new_value) const noexcept {
using _Transform = __dispatch<__transform, __current_configuration, _ExecutionPolicy>;
using _Ref = __iter_reference<_ForwardIterator>;
auto __res =
_Transform()(__policy, std::move(__first), std::move(__last), std::move(__out_it), [&](_Ref __element) {
return __pred(__element) ? __new_value : __element;
});
if (__res == nullopt)
return nullopt;
return __empty{};
}
};
template <class _ExecutionPolicy>
struct __replace_copy<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _ForwardOutIterator, class _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__empty>
operator()(_Policy&& __policy,
_ForwardIterator __first,
_ForwardIterator __last,
_ForwardOutIterator __out_it,
_Tp const& __old_value,
_Tp const& __new_value) const noexcept {
using _ReplaceCopyIf = __dispatch<__replace_copy_if, __current_configuration, _ExecutionPolicy>;
using _Ref = __iter_reference<_ForwardIterator>;
return _ReplaceCopyIf()(
__policy,
std::move(__first),
std::move(__last),
std::move(__out_it),
[&](_Ref __element) { return __element == __old_value; },
__new_value);
}
};
// TODO: Use the std::copy/move shenanigans to forward to std::memmove
// Investigate whether we want to still forward to std::transform(policy)
// in that case for the execution::par part, or whether we actually want
// to run everything serially in that case.
template <class _ExecutionPolicy>
struct __move<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _ForwardOutIterator>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<_ForwardOutIterator>
operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _ForwardOutIterator __out_it)
const noexcept {
using _Transform = __dispatch<__transform, __current_configuration, _ExecutionPolicy>;
return _Transform()(__policy, std::move(__first), std::move(__last), std::move(__out_it), [&](auto&& __element) {
return std::move(__element);
});
}
};
// TODO: Use the std::copy/move shenanigans to forward to std::memmove
template <class _ExecutionPolicy>
struct __copy<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _ForwardOutIterator>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<_ForwardOutIterator>
operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _ForwardOutIterator __out_it)
const noexcept {
using _Transform = __dispatch<__transform, __current_configuration, _ExecutionPolicy>;
return _Transform()(__policy, std::move(__first), std::move(__last), std::move(__out_it), __identity());
}
};
template <class _ExecutionPolicy>
struct __copy_n<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _Size, class _ForwardOutIterator>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<_ForwardOutIterator>
operator()(_Policy&& __policy, _ForwardIterator __first, _Size __n, _ForwardOutIterator __out_it) const noexcept {
if constexpr (__has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
using _Copy = __dispatch<__copy, __current_configuration, _ExecutionPolicy>;
_ForwardIterator __last = __first + __n;
return _Copy()(__policy, std::move(__first), std::move(__last), std::move(__out_it));
} else {
// Otherwise, use the serial algorithm to avoid doing two passes over the input
return std::copy_n(std::move(__first), __n, std::move(__out_it));
}
}
};
template <class _ExecutionPolicy>
struct __rotate_copy<__default_backend_tag, _ExecutionPolicy> {
template <class _Policy, class _ForwardIterator, class _ForwardOutIterator>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<_ForwardOutIterator>
operator()(_Policy&& __policy,
_ForwardIterator __first,
_ForwardIterator __middle,
_ForwardIterator __last,
_ForwardOutIterator __out_it) const noexcept {
using _Copy = __dispatch<__copy, __current_configuration, _ExecutionPolicy>;
auto __result_mid = _Copy()(__policy, __middle, std::move(__last), std::move(__out_it));
if (__result_mid == nullopt)
return nullopt;
return _Copy()(__policy, std::move(__first), std::move(__middle), *std::move(__result_mid));
}
};
} // namespace __pstl
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_STD_VER >= 17
_LIBCPP_POP_MACROS
#endif // _LIBCPP___PSTL_BACKENDS_DEFAULT_H
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