Differential D138364 Diff 476707 libcxx/include/__algorithm/copy_move_common.h

Changeset View

Standalone View

libcxx/include/__algorithm/copy_move_common.h

This file was added.

				//===----------------------------------------------------------------------===//
				//
				// 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/integral_constant.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/remove_reference.h>
				#include <__utility/move.h>
				#include <__utility/pair.h>

				#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
				# pragma GCC system_header
				#endif

				_LIBCPP_BEGIN_NAMESPACE_STD

				// Type trait.
				template <class _InRef, class _OutRef,
				class _In = __libcpp_remove_reference_t<_InRef>,
				class _Out = __libcpp_remove_reference_t<_OutRef>>
				using __enable_if_memmovable = __enable_if_t<
				sizeof(_In) == sizeof(_Out) &&
				is_trivially_assignable<_OutRef, _InRef>::value &&
				(std::is_same<_In, _Out>::value \|\| (
				std::is_integral<_In>::value &&
				std::is_integral<_Out>::value &&
				!std::is_same<_In, bool>::value &&
				!std::is_same<_Out, bool>::value))
				, int>;

				// `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