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| 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_COPY_MOVE_COMMON_H |
| 10 | #define _LIBCPP___ALGORITHM_COPY_MOVE_COMMON_H |
| 11 | |
| 12 | #include <__algorithm/unwrap_iter.h> |
| 13 | #include <__algorithm/unwrap_range.h> |
| 14 | #include <__config> |
| 15 | #include <__cstddef/size_t.h> |
| 16 | #include <__iterator/iterator_traits.h> |
| 17 | #include <__memory/pointer_traits.h> |
| 18 | #include <__string/constexpr_c_functions.h> |
| 19 | #include <__type_traits/enable_if.h> |
| 20 | #include <__type_traits/is_always_bitcastable.h> |
| 21 | #include <__type_traits/is_constant_evaluated.h> |
| 22 | #include <__type_traits/is_constructible.h> |
| 23 | #include <__type_traits/is_trivially_assignable.h> |
| 24 | #include <__type_traits/is_volatile.h> |
| 25 | #include <__utility/move.h> |
| 26 | #include <__utility/pair.h> |
| 27 | |
| 28 | #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| 29 | # pragma GCC system_header |
| 30 | #endif |
| 31 | |
| 32 | _LIBCPP_PUSH_MACROS |
| 33 | #include <__undef_macros> |
| 34 | |
| 35 | _LIBCPP_BEGIN_NAMESPACE_STD |
| 36 | |
| 37 | // Type traits. |
| 38 | |
| 39 | template <class _From, class _To> |
| 40 | struct __can_lower_copy_assignment_to_memmove { |
| 41 | static const bool value = |
| 42 | // If the types are always bitcastable, it's valid to do a bitwise copy between them. |
| 43 | __is_always_bitcastable<_From, _To>::value && |
| 44 | // Reject conversions that wouldn't be performed by the regular built-in assignment (e.g. between arrays). |
| 45 | is_trivially_assignable<_To&, const _From&>::value && |
| 46 | // `memmove` doesn't accept `volatile` pointers, make sure the optimization SFINAEs away in that case. |
| 47 | !is_volatile<_From>::value && !is_volatile<_To>::value; |
| 48 | }; |
| 49 | |
| 50 | template <class _From, class _To> |
| 51 | struct __can_lower_move_assignment_to_memmove { |
| 52 | static const bool value = |
| 53 | __is_always_bitcastable<_From, _To>::value && is_trivially_assignable<_To&, _From&&>::value && |
| 54 | !is_volatile<_From>::value && !is_volatile<_To>::value; |
| 55 | }; |
| 56 | |
| 57 | // `memmove` algorithms implementation. |
| 58 | |
| 59 | template <class _In, class _Out> |
| 60 | _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_In*, _Out*> |
| 61 | __copy_trivial_impl(_In* __first, _In* __last, _Out* __result) { |
| 62 | const size_t __n = static_cast<size_t>(__last - __first); |
| 63 | |
| 64 | std::__constexpr_memmove(__result, __first, __element_count(__n)); |
| 65 | |
| 66 | return std::make_pair(__last, __result + __n); |
| 67 | } |
| 68 | |
| 69 | template <class _In, class _Out> |
| 70 | _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_In*, _Out*> |
| 71 | __copy_backward_trivial_impl(_In* __first, _In* __last, _Out* __result) { |
| 72 | const size_t __n = static_cast<size_t>(__last - __first); |
| 73 | __result -= __n; |
| 74 | |
| 75 | std::__constexpr_memmove(__result, __first, __element_count(__n)); |
| 76 | |
| 77 | return std::make_pair(__last, __result); |
| 78 | } |
| 79 | |
| 80 | // Iterator unwrapping and dispatching to the correct overload. |
| 81 | |
| 82 | template <class _InIter, class _OutIter> |
| 83 | struct __can_rewrap |
| 84 | : integral_constant<bool, is_copy_constructible<_InIter>::value && is_copy_constructible<_OutIter>::value> {}; |
| 85 | |
| 86 | template <class _Algorithm, |
| 87 | class _InIter, |
| 88 | class _Sent, |
| 89 | class _OutIter, |
| 90 | __enable_if_t<__can_rewrap<_InIter, _OutIter>::value, int> = 0> |
| 91 | _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 pair<_InIter, _OutIter> |
| 92 | __copy_move_unwrap_iters(_InIter __first, _Sent __last, _OutIter __out_first) { |
| 93 | auto __range = std::__unwrap_range(__first, std::move(__last)); |
| 94 | auto __result = _Algorithm()(std::move(__range.first), std::move(__range.second), std::__unwrap_iter(__out_first)); |
| 95 | return std::make_pair(std::__rewrap_range<_Sent>(std::move(__first), std::move(__result.first)), |
| 96 | std::__rewrap_iter(std::move(__out_first), std::move(__result.second))); |
| 97 | } |
| 98 | |
| 99 | template <class _Algorithm, |
| 100 | class _InIter, |
| 101 | class _Sent, |
| 102 | class _OutIter, |
| 103 | __enable_if_t<!__can_rewrap<_InIter, _OutIter>::value, int> = 0> |
| 104 | _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 pair<_InIter, _OutIter> |
| 105 | __copy_move_unwrap_iters(_InIter __first, _Sent __last, _OutIter __out_first) { |
| 106 | return _Algorithm()(std::move(__first), std::move(__last), std::move(__out_first)); |
| 107 | } |
| 108 | |
| 109 | _LIBCPP_END_NAMESPACE_STD |
| 110 | |
| 111 | _LIBCPP_POP_MACROS |
| 112 | |
| 113 | #endif // _LIBCPP___ALGORITHM_COPY_MOVE_COMMON_H |
| 114 |
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