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[libc++] Merge the implementations of ranges::copy_n and std::copy_n and fix vector::insert to assign #157444

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[libc++] Merge the implementations of ranges::copy_n and std::copy_n and fix vector::insert to assign #157444

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65 changes: 49 additions & 16 deletions libcxx/include/__algorithm/copy_n.h
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Original file line number Diff line number Diff line change
Expand Up @@ -10,31 +10,63 @@
#define _LIBCPP___ALGORITHM_COPY_N_H

#include <__algorithm/copy.h>
#include <__algorithm/iterator_operations.h>
#include <__config>
#include <__iterator/iterator_traits.h>
#include <__type_traits/enable_if.h>
#include <__utility/convert_to_integral.h>
#include <__utility/move.h>
#include <__utility/pair.h>

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

_LIBCPP_PUSH_MACROS
#include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD

template <class _AlgPolicy,
class _InIter,
class _OutIter,
__enable_if_t<__has_random_access_iterator_category<_InIter>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InIter, _OutIter>
__copy_n(_InIter __first, typename _IterOps<_AlgPolicy>::template __difference_type<_InIter> __n, _OutIter __result) {
return std::__copy(__first, __first + __n, std::move(__result));
}

template <class _AlgPolicy,
class _InIter,
class _OutIter,
__enable_if_t<!__has_random_access_iterator_category<_InIter>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InIter, _OutIter>
__copy_n(_InIter __first, typename _IterOps<_AlgPolicy>::template __difference_type<_InIter> __n, _OutIter __result) {
while (__n != 0) {
*__result = *__first;
++__first;
++__result;
--__n;
}
return std::make_pair(std::move(__first), std::move(__result));
}

// The InputIterator case is handled specially here because it's been written in a way to avoid incrementing __first
// if not absolutely required. This was done to allow its use with istream_iterator and we want to avoid breaking
// people, at least currently.
// See https://github.com/llvm/llvm-project/commit/99847d2bf132854fffa019bab19818768102ccad
template <class _InputIterator,
class _Size,
class _OutputIterator,
__enable_if_t<__has_input_iterator_category<_InputIterator>::value &&
!__has_random_access_iterator_category<_InputIterator>::value,
int> = 0>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result) {
typedef decltype(std::__convert_to_integral(__orig_n)) _IntegralSize;
_IntegralSize __n = __orig_n;
if (__n > 0) {
__enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
copy_n(_InputIterator __first, _Size __n, _OutputIterator __result) {
using _IntegralSize = decltype(std::__convert_to_integral(__n));
_IntegralSize __converted = __n;
if (__converted > 0) {
*__result = *__first;
++__result;
for (--__n; __n > 0; --__n) {
for (--__converted; __converted > 0; --__converted) {
++__first;
*__result = *__first;
++__result;
Expand All @@ -46,15 +78,16 @@ copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result) {
template <class _InputIterator,
class _Size,
class _OutputIterator,
__enable_if_t<__has_random_access_iterator_category<_InputIterator>::value, int> = 0>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result) {
typedef typename iterator_traits<_InputIterator>::difference_type difference_type;
typedef decltype(std::__convert_to_integral(__orig_n)) _IntegralSize;
_IntegralSize __n = __orig_n;
return std::copy(__first, __first + difference_type(__n), __result);
__enable_if_t<!__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
copy_n(_InputIterator __first, _Size __n, _OutputIterator __result) {
using _IntegralSize = decltype(std::__convert_to_integral(__n));
_IntegralSize __converted = __n;
return std::__copy_n<_ClassicAlgPolicy>(__first, __iter_difference_t<_InputIterator>(__converted), __result).second;
}

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#endif // _LIBCPP___ALGORITHM_COPY_N_H
29 changes: 3 additions & 26 deletions libcxx/include/__algorithm/ranges_copy_n.h
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Original file line number Diff line number Diff line change
Expand Up @@ -9,16 +9,12 @@
#ifndef _LIBCPP___ALGORITHM_RANGES_COPY_N_H
#define _LIBCPP___ALGORITHM_RANGES_COPY_N_H

#include <__algorithm/copy.h>
#include <__algorithm/copy_n.h>
#include <__algorithm/in_out_result.h>
#include <__algorithm/iterator_operations.h>
#include <__algorithm/ranges_copy.h>
#include <__config>
#include <__functional/identity.h>
#include <__iterator/concepts.h>
#include <__iterator/incrementable_traits.h>
#include <__iterator/unreachable_sentinel.h>
#include <__iterator/wrap_iter.h>
#include <__utility/move.h>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
Expand All @@ -37,32 +33,13 @@ namespace ranges {
template <class _Ip, class _Op>
using copy_n_result = in_out_result<_Ip, _Op>;

// TODO: Merge this with copy_n
struct __copy_n {
template <class _InIter, class _DiffType, class _OutIter>
_LIBCPP_HIDE_FROM_ABI constexpr static copy_n_result<_InIter, _OutIter>
__go(_InIter __first, _DiffType __n, _OutIter __result) {
while (__n != 0) {
*__result = *__first;
++__first;
++__result;
--__n;
}
return {std::move(__first), std::move(__result)};
}

template <random_access_iterator _InIter, class _DiffType, random_access_iterator _OutIter>
_LIBCPP_HIDE_FROM_ABI constexpr static copy_n_result<_InIter, _OutIter>
__go(_InIter __first, _DiffType __n, _OutIter __result) {
auto __ret = std::__copy(__first, __first + __n, __result);
return {__ret.first, __ret.second};
}

template <input_iterator _Ip, weakly_incrementable _Op>
requires indirectly_copyable<_Ip, _Op>
_LIBCPP_HIDE_FROM_ABI constexpr copy_n_result<_Ip, _Op>
operator()(_Ip __first, iter_difference_t<_Ip> __n, _Op __result) const {
return __go(std::move(__first), __n, std::move(__result));
auto __res = std::__copy_n<_RangeAlgPolicy>(std::move(__first), __n, std::move(__result));
return {std::move(__res.first), std::move(__res.second)};
}
};

Expand Down
24 changes: 4 additions & 20 deletions libcxx/include/__vector/vector.h
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,6 @@
#include <__algorithm/min.h>
#include <__algorithm/move.h>
#include <__algorithm/move_backward.h>
#include <__algorithm/ranges_copy_n.h>
#include <__algorithm/rotate.h>
#include <__assert>
#include <__config>
Expand Down Expand Up @@ -628,8 +627,7 @@ class vector {
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
__assign_with_size(_Iterator __first, _Sentinel __last, difference_type __n);

template <class _Iterator,
__enable_if_t<!is_same<decltype(*std::declval<_Iterator&>())&&, value_type&&>::value, int> = 0>
template <class _Iterator, __enable_if_t<!is_same<__iter_value_t<_Iterator>, value_type>::value, int> = 0>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
__insert_assign_n_unchecked(_Iterator __first, difference_type __n, pointer __position) {
for (pointer __end_position = __position + __n; __position != __end_position; ++__position, (void)++__first) {
Expand All @@ -638,18 +636,10 @@ class vector {
}
}

template <class _Iterator,
__enable_if_t<is_same<decltype(*std::declval<_Iterator&>())&&, value_type&&>::value, int> = 0>
template <class _Iterator, __enable_if_t<is_same<__iter_value_t<_Iterator>, value_type>::value, int> = 0>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
__insert_assign_n_unchecked(_Iterator __first, difference_type __n, pointer __position) {
#if _LIBCPP_STD_VER >= 23
if constexpr (!forward_iterator<_Iterator>) { // Handles input-only sized ranges for insert_range
ranges::copy_n(std::move(__first), __n, __position);
} else
#endif
{
std::copy_n(__first, __n, __position);
}
std::__copy_n(std::move(__first), __n, __position);
}

template <class _InputIterator, class _Sentinel>
Expand Down Expand Up @@ -1083,14 +1073,8 @@ vector<_Tp, _Allocator>::__assign_with_size(_Iterator __first, _Sentinel __last,
size_type __new_size = static_cast<size_type>(__n);
if (__new_size <= capacity()) {
if (__new_size > size()) {
#if _LIBCPP_STD_VER >= 23
auto __mid = ranges::copy_n(std::move(__first), size(), this->__begin_).in;
auto __mid = std::__copy_n(std::move(__first), size(), this->__begin_).first;
__construct_at_end(std::move(__mid), std::move(__last), __new_size - size());
#else
_Iterator __mid = std::next(__first, size());
std::copy(__first, __mid, this->__begin_);
__construct_at_end(__mid, __last, __new_size - size());
#endif
} else {
pointer __m = std::__copy(std::move(__first), __last, this->__begin_).second;
this->__destruct_at_end(__m);
Expand Down
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