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//===----------------------------------------------------------------------===//
//
// 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___ALGORITHM_COPY_MOVE_COMMON_H
#define _LIBCPP___ALGORITHM_COPY_MOVE_COMMON_H
#include <__algorithm/iterator_operations.h>
#include <__algorithm/unwrap_iter.h>
#include <__algorithm/unwrap_range.h>
#include <__config>
#include <__iterator/iterator_traits.h>
#include <__memory/pointer_traits.h>
#include <__type_traits/enable_if.h>
#include <__type_traits/is_always_bitcastable.h>
#include <__type_traits/is_constant_evaluated.h>
#include <__type_traits/is_copy_constructible.h>
#include <__type_traits/is_trivially_assignable.h>
#include <__type_traits/is_trivially_copyable.h>
#include <__type_traits/is_volatile.h>
#include <__utility/move.h>
#include <__utility/pair.h>
#include <cstddef>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
// Type traits.
template <class _From, class _To>
struct __can_lower_copy_assignment_to_memmove {
static const bool value =
// If the types are always bitcastable, it's valid to do a bitwise copy between them.
__is_always_bitcastable<_From, _To>::value &&
// Reject conversions that wouldn't be performed by the regular built-in assignment (e.g. between arrays).
is_trivially_assignable<_To&, const _From&>::value &&
// `memmove` doesn't accept `volatile` pointers, make sure the optimization SFINAEs away in that case.
!is_volatile<_From>::value &&
!is_volatile<_To>::value;
};
template <class _From, class _To>
struct __can_lower_move_assignment_to_memmove {
static const bool value =
__is_always_bitcastable<_From, _To>::value &&
is_trivially_assignable<_To&, _From&&>::value &&
!is_volatile<_From>::value &&
!is_volatile<_To>::value;
};
// `memmove` algorithms implementation.
template <class _In, class _Out>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_In*, _Out*>
__copy_trivial_impl(_In* __first, _In* __last, _Out* __result) {
const size_t __n = static_cast<size_t>(__last - __first);
::__builtin_memmove(__result, __first, __n * sizeof(_Out));
return std::make_pair(__last, __result + __n);
}
template <class _In, class _Out>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_In*, _Out*>
__copy_backward_trivial_impl(_In* __first, _In* __last, _Out* __result) {
const size_t __n = static_cast<size_t>(__last - __first);
__result -= __n;
::__builtin_memmove(__result, __first, __n * sizeof(_Out));
return std::make_pair(__last, __result);
}
// Iterator unwrapping and dispatching to the correct overload.
template <class _F1, class _F2>
struct __overload : _F1, _F2 {
using _F1::operator();
using _F2::operator();
};
template <class _InIter, class _Sent, class _OutIter, class = void>
struct __can_rewrap : false_type {};
template <class _InIter, class _Sent, class _OutIter>
struct __can_rewrap<_InIter,
_Sent,
_OutIter,
// Note that sentinels are always copy-constructible.
__enable_if_t< is_copy_constructible<_InIter>::value &&
is_copy_constructible<_OutIter>::value > > : true_type {};
template <class _Algorithm,
class _InIter,
class _Sent,
class _OutIter,
__enable_if_t<__can_rewrap<_InIter, _Sent, _OutIter>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 pair<_InIter, _OutIter>
__unwrap_and_dispatch(_InIter __first, _Sent __last, _OutIter __out_first) {
auto __range = std::__unwrap_range(__first, std::move(__last));
auto __result = _Algorithm()(std::move(__range.first), std::move(__range.second), std::__unwrap_iter(__out_first));
return std::make_pair(std::__rewrap_range<_Sent>(std::move(__first), std::move(__result.first)),
std::__rewrap_iter(std::move(__out_first), std::move(__result.second)));
}
template <class _Algorithm,
class _InIter,
class _Sent,
class _OutIter,
__enable_if_t<!__can_rewrap<_InIter, _Sent, _OutIter>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 pair<_InIter, _OutIter>
__unwrap_and_dispatch(_InIter __first, _Sent __last, _OutIter __out_first) {
return _Algorithm()(std::move(__first), std::move(__last), std::move(__out_first));
}
template <class _IterOps, class _InValue, class _OutIter, class = void>
struct __can_copy_without_conversion : false_type {};
template <class _IterOps, class _InValue, class _OutIter>
struct __can_copy_without_conversion<
_IterOps,
_InValue,
_OutIter,
__enable_if_t<is_same<_InValue, typename _IterOps::template __value_type<_OutIter> >::value> > : true_type {};
template <class _AlgPolicy,
class _NaiveAlgorithm,
class _OptimizedAlgorithm,
class _InIter,
class _Sent,
class _OutIter>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 pair<_InIter, _OutIter>
__dispatch_copy_or_move(_InIter __first, _Sent __last, _OutIter __out_first) {
#ifdef _LIBCPP_COMPILER_GCC
// GCC doesn't support `__builtin_memmove` during constant evaluation.
if (__libcpp_is_constant_evaluated()) {
return std::__unwrap_and_dispatch<_NaiveAlgorithm>(std::move(__first), std::move(__last), std::move(__out_first));
}
#else
// In Clang, `__builtin_memmove` only supports fully trivially copyable types (just having trivial copy assignment is
// insufficient). Also, conversions are not supported.
if (__libcpp_is_constant_evaluated()) {
using _InValue = typename _IterOps<_AlgPolicy>::template __value_type<_InIter>;
if (!is_trivially_copyable<_InValue>::value ||
!__can_copy_without_conversion<_IterOps<_AlgPolicy>, _InValue, _OutIter>::value) {
return std::__unwrap_and_dispatch<_NaiveAlgorithm>(std::move(__first), std::move(__last), std::move(__out_first));
}
}
#endif // _LIBCPP_COMPILER_GCC
using _Algorithm = __overload<_NaiveAlgorithm, _OptimizedAlgorithm>;
return std::__unwrap_and_dispatch<_Algorithm>(std::move(__first), std::move(__last), std::move(__out_first));
}
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___ALGORITHM_COPY_MOVE_COMMON_H
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