master
1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP___SPLIT_BUFFER
11#define _LIBCPP___SPLIT_BUFFER
12
13#include <__algorithm/max.h>
14#include <__algorithm/move.h>
15#include <__algorithm/move_backward.h>
16#include <__config>
17#include <__iterator/distance.h>
18#include <__iterator/iterator_traits.h>
19#include <__iterator/move_iterator.h>
20#include <__memory/allocate_at_least.h>
21#include <__memory/allocator.h>
22#include <__memory/allocator_traits.h>
23#include <__memory/compressed_pair.h>
24#include <__memory/pointer_traits.h>
25#include <__memory/swap_allocator.h>
26#include <__type_traits/conditional.h>
27#include <__type_traits/enable_if.h>
28#include <__type_traits/integral_constant.h>
29#include <__type_traits/is_nothrow_assignable.h>
30#include <__type_traits/is_nothrow_constructible.h>
31#include <__type_traits/is_replaceable.h>
32#include <__type_traits/is_swappable.h>
33#include <__type_traits/is_trivially_destructible.h>
34#include <__type_traits/is_trivially_relocatable.h>
35#include <__type_traits/remove_reference.h>
36#include <__utility/forward.h>
37#include <__utility/move.h>
38
39#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
40# pragma GCC system_header
41#endif
42
43_LIBCPP_PUSH_MACROS
44#include <__undef_macros>
45
46_LIBCPP_BEGIN_NAMESPACE_STD
47
48// __split_buffer allocates a contiguous chunk of memory and stores objects in the range [__begin_, __end_).
49// It has uninitialized memory in the ranges [__first_, __begin_) and [__end_, __cap_). That allows
50// it to grow both in the front and back without having to move the data.
51
52template <class _Tp, class _Allocator = allocator<_Tp> >
53struct __split_buffer {
54public:
55 using value_type = _Tp;
56 using allocator_type = _Allocator;
57 using __alloc_rr _LIBCPP_NODEBUG = __libcpp_remove_reference_t<allocator_type>;
58 using __alloc_traits _LIBCPP_NODEBUG = allocator_traits<__alloc_rr>;
59 using reference = value_type&;
60 using const_reference = const value_type&;
61 using size_type = typename __alloc_traits::size_type;
62 using difference_type = typename __alloc_traits::difference_type;
63 using pointer = typename __alloc_traits::pointer;
64 using const_pointer = typename __alloc_traits::const_pointer;
65 using iterator = pointer;
66 using const_iterator = const_pointer;
67
68 // A __split_buffer contains the following members which may be trivially relocatable:
69 // - pointer: may be trivially relocatable, so it's checked
70 // - allocator_type: may be trivially relocatable, so it's checked
71 // __split_buffer doesn't have any self-references, so it's trivially relocatable if its members are.
72 using __trivially_relocatable _LIBCPP_NODEBUG = __conditional_t<
73 __libcpp_is_trivially_relocatable<pointer>::value && __libcpp_is_trivially_relocatable<allocator_type>::value,
74 __split_buffer,
75 void>;
76 using __replaceable _LIBCPP_NODEBUG =
77 __conditional_t<__is_replaceable_v<pointer> && __container_allocator_is_replaceable<__alloc_traits>::value,
78 __split_buffer,
79 void>;
80
81 pointer __first_;
82 pointer __begin_;
83 pointer __end_;
84 _LIBCPP_COMPRESSED_PAIR(pointer, __cap_, allocator_type, __alloc_);
85
86 __split_buffer(const __split_buffer&) = delete;
87 __split_buffer& operator=(const __split_buffer&) = delete;
88
89 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __split_buffer()
90 _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
91 : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __cap_(nullptr) {}
92
93 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI explicit __split_buffer(__alloc_rr& __a)
94 : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __cap_(nullptr), __alloc_(__a) {}
95
96 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI explicit __split_buffer(const __alloc_rr& __a)
97 : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __cap_(nullptr), __alloc_(__a) {}
98
99 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI
100 __split_buffer(size_type __cap, size_type __start, __alloc_rr& __a);
101
102 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __split_buffer(__split_buffer&& __c)
103 _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value);
104
105 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __split_buffer(__split_buffer&& __c, const __alloc_rr& __a);
106
107 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __split_buffer& operator=(__split_buffer&& __c)
108 _NOEXCEPT_((__alloc_traits::propagate_on_container_move_assignment::value &&
109 is_nothrow_move_assignable<allocator_type>::value) ||
110 !__alloc_traits::propagate_on_container_move_assignment::value);
111
112 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI ~__split_buffer();
113
114 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return __begin_; }
115 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return __begin_; }
116
117 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT { return __end_; }
118 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return __end_; }
119
120 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void clear() _NOEXCEPT { __destruct_at_end(__begin_); }
121
122 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI size_type size() const {
123 return static_cast<size_type>(__end_ - __begin_);
124 }
125
126 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI bool empty() const { return __end_ == __begin_; }
127
128 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI size_type capacity() const {
129 return static_cast<size_type>(__cap_ - __first_);
130 }
131
132 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI size_type __front_spare() const {
133 return static_cast<size_type>(__begin_ - __first_);
134 }
135
136 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI size_type __back_spare() const {
137 return static_cast<size_type>(__cap_ - __end_);
138 }
139
140 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI reference front() { return *__begin_; }
141 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI const_reference front() const { return *__begin_; }
142 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI reference back() { return *(__end_ - 1); }
143 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI const_reference back() const { return *(__end_ - 1); }
144
145 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void shrink_to_fit() _NOEXCEPT;
146
147 template <class... _Args>
148 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void emplace_front(_Args&&... __args);
149 template <class... _Args>
150 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void emplace_back(_Args&&... __args);
151
152 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void pop_front() { __destruct_at_begin(__begin_ + 1); }
153 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void pop_back() { __destruct_at_end(__end_ - 1); }
154
155 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __construct_at_end(size_type __n);
156 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __construct_at_end(size_type __n, const_reference __x);
157
158 template <class _ForwardIterator, __enable_if_t<__has_forward_iterator_category<_ForwardIterator>::value, int> = 0>
159 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
160 __construct_at_end(_ForwardIterator __first, _ForwardIterator __last);
161
162 template <class _Iterator, class _Sentinel>
163 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
164 __construct_at_end_with_sentinel(_Iterator __first, _Sentinel __last);
165
166 template <class _Iterator>
167 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
168 __construct_at_end_with_size(_Iterator __first, size_type __n);
169
170 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __destruct_at_begin(pointer __new_begin) {
171 __destruct_at_begin(__new_begin, is_trivially_destructible<value_type>());
172 }
173
174 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __destruct_at_begin(pointer __new_begin, false_type);
175 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __destruct_at_begin(pointer __new_begin, true_type);
176
177 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __destruct_at_end(pointer __new_last) _NOEXCEPT {
178 __destruct_at_end(__new_last, false_type());
179 }
180
181 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __destruct_at_end(pointer __new_last, false_type) _NOEXCEPT;
182 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __destruct_at_end(pointer __new_last, true_type) _NOEXCEPT;
183
184 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void swap(__split_buffer& __x)
185 _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value || __is_nothrow_swappable_v<__alloc_rr>);
186
187 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI bool __invariants() const;
188
189private:
190 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(__split_buffer& __c, true_type)
191 _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value) {
192 __alloc_ = std::move(__c.__alloc_);
193 }
194
195 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(__split_buffer&, false_type) _NOEXCEPT {}
196
197 struct _ConstructTransaction {
198 _LIBCPP_CONSTEXPR_SINCE_CXX20
199 _LIBCPP_HIDE_FROM_ABI explicit _ConstructTransaction(pointer* __p, size_type __n) _NOEXCEPT
200 : __pos_(*__p),
201 __end_(*__p + __n),
202 __dest_(__p) {}
203
204 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI ~_ConstructTransaction() { *__dest_ = __pos_; }
205
206 pointer __pos_;
207 const pointer __end_;
208
209 private:
210 pointer* __dest_;
211 };
212};
213
214template <class _Tp, class _Allocator>
215_LIBCPP_CONSTEXPR_SINCE_CXX20 bool __split_buffer<_Tp, _Allocator>::__invariants() const {
216 if (__first_ == nullptr) {
217 if (__begin_ != nullptr)
218 return false;
219 if (__end_ != nullptr)
220 return false;
221 if (__cap_ != nullptr)
222 return false;
223 } else {
224 if (__begin_ < __first_)
225 return false;
226 if (__end_ < __begin_)
227 return false;
228 if (__cap_ < __end_)
229 return false;
230 }
231 return true;
232}
233
234// Default constructs __n objects starting at __end_
235// throws if construction throws
236// Precondition: __n > 0
237// Precondition: size() + __n <= capacity()
238// Postcondition: size() == size() + __n
239template <class _Tp, class _Allocator>
240_LIBCPP_CONSTEXPR_SINCE_CXX20 void __split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n) {
241 _ConstructTransaction __tx(std::addressof(this->__end_), __n);
242 for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
243 __alloc_traits::construct(__alloc_, std::__to_address(__tx.__pos_));
244 }
245}
246
247// Copy constructs __n objects starting at __end_ from __x
248// throws if construction throws
249// Precondition: __n > 0
250// Precondition: size() + __n <= capacity()
251// Postcondition: size() == old size() + __n
252// Postcondition: [i] == __x for all i in [size() - __n, __n)
253template <class _Tp, class _Allocator>
254_LIBCPP_CONSTEXPR_SINCE_CXX20 void
255__split_buffer<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x) {
256 _ConstructTransaction __tx(std::addressof(this->__end_), __n);
257 for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
258 __alloc_traits::construct(__alloc_, std::__to_address(__tx.__pos_), __x);
259 }
260}
261
262template <class _Tp, class _Allocator>
263template <class _Iterator, class _Sentinel>
264_LIBCPP_CONSTEXPR_SINCE_CXX20 void
265__split_buffer<_Tp, _Allocator>::__construct_at_end_with_sentinel(_Iterator __first, _Sentinel __last) {
266 __alloc_rr& __a = __alloc_;
267 for (; __first != __last; ++__first) {
268 if (__end_ == __cap_) {
269 size_type __old_cap = __cap_ - __first_;
270 size_type __new_cap = std::max<size_type>(2 * __old_cap, 8);
271 __split_buffer __buf(__new_cap, 0, __a);
272 for (pointer __p = __begin_; __p != __end_; ++__p, (void)++__buf.__end_)
273 __alloc_traits::construct(__buf.__alloc_, std::__to_address(__buf.__end_), std::move(*__p));
274 swap(__buf);
275 }
276 __alloc_traits::construct(__a, std::__to_address(this->__end_), *__first);
277 ++this->__end_;
278 }
279}
280template <class _Tp, class _Allocator>
281template <class _ForwardIterator, __enable_if_t<__has_forward_iterator_category<_ForwardIterator>::value, int> >
282_LIBCPP_CONSTEXPR_SINCE_CXX20 void
283__split_buffer<_Tp, _Allocator>::__construct_at_end(_ForwardIterator __first, _ForwardIterator __last) {
284 __construct_at_end_with_size(__first, std::distance(__first, __last));
285}
286
287template <class _Tp, class _Allocator>
288template <class _ForwardIterator>
289_LIBCPP_CONSTEXPR_SINCE_CXX20 void
290__split_buffer<_Tp, _Allocator>::__construct_at_end_with_size(_ForwardIterator __first, size_type __n) {
291 _ConstructTransaction __tx(std::addressof(this->__end_), __n);
292 for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_, (void)++__first) {
293 __alloc_traits::construct(__alloc_, std::__to_address(__tx.__pos_), *__first);
294 }
295}
296
297template <class _Tp, class _Allocator>
298_LIBCPP_CONSTEXPR_SINCE_CXX20 inline void
299__split_buffer<_Tp, _Allocator>::__destruct_at_begin(pointer __new_begin, false_type) {
300 while (__begin_ != __new_begin)
301 __alloc_traits::destroy(__alloc_, std::__to_address(__begin_++));
302}
303
304template <class _Tp, class _Allocator>
305_LIBCPP_CONSTEXPR_SINCE_CXX20 inline void
306__split_buffer<_Tp, _Allocator>::__destruct_at_begin(pointer __new_begin, true_type) {
307 __begin_ = __new_begin;
308}
309
310template <class _Tp, class _Allocator>
311_LIBCPP_CONSTEXPR_SINCE_CXX20 inline _LIBCPP_HIDE_FROM_ABI void
312__split_buffer<_Tp, _Allocator>::__destruct_at_end(pointer __new_last, false_type) _NOEXCEPT {
313 while (__new_last != __end_)
314 __alloc_traits::destroy(__alloc_, std::__to_address(--__end_));
315}
316
317template <class _Tp, class _Allocator>
318_LIBCPP_CONSTEXPR_SINCE_CXX20 inline _LIBCPP_HIDE_FROM_ABI void
319__split_buffer<_Tp, _Allocator>::__destruct_at_end(pointer __new_last, true_type) _NOEXCEPT {
320 __end_ = __new_last;
321}
322
323template <class _Tp, class _Allocator>
324_LIBCPP_CONSTEXPR_SINCE_CXX20
325__split_buffer<_Tp, _Allocator>::__split_buffer(size_type __cap, size_type __start, __alloc_rr& __a)
326 : __cap_(nullptr), __alloc_(__a) {
327 if (__cap == 0) {
328 __first_ = nullptr;
329 } else {
330 auto __allocation = std::__allocate_at_least(__alloc_, __cap);
331 __first_ = __allocation.ptr;
332 __cap = __allocation.count;
333 }
334 __begin_ = __end_ = __first_ + __start;
335 __cap_ = __first_ + __cap;
336}
337
338template <class _Tp, class _Allocator>
339_LIBCPP_CONSTEXPR_SINCE_CXX20 __split_buffer<_Tp, _Allocator>::~__split_buffer() {
340 clear();
341 if (__first_)
342 __alloc_traits::deallocate(__alloc_, __first_, capacity());
343}
344
345template <class _Tp, class _Allocator>
346_LIBCPP_CONSTEXPR_SINCE_CXX20 __split_buffer<_Tp, _Allocator>::__split_buffer(__split_buffer&& __c)
347 _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
348 : __first_(std::move(__c.__first_)),
349 __begin_(std::move(__c.__begin_)),
350 __end_(std::move(__c.__end_)),
351 __cap_(std::move(__c.__cap_)),
352 __alloc_(std::move(__c.__alloc_)) {
353 __c.__first_ = nullptr;
354 __c.__begin_ = nullptr;
355 __c.__end_ = nullptr;
356 __c.__cap_ = nullptr;
357}
358
359template <class _Tp, class _Allocator>
360_LIBCPP_CONSTEXPR_SINCE_CXX20
361__split_buffer<_Tp, _Allocator>::__split_buffer(__split_buffer&& __c, const __alloc_rr& __a)
362 : __cap_(nullptr), __alloc_(__a) {
363 if (__a == __c.__alloc_) {
364 __first_ = __c.__first_;
365 __begin_ = __c.__begin_;
366 __end_ = __c.__end_;
367 __cap_ = __c.__cap_;
368 __c.__first_ = nullptr;
369 __c.__begin_ = nullptr;
370 __c.__end_ = nullptr;
371 __c.__cap_ = nullptr;
372 } else {
373 auto __allocation = std::__allocate_at_least(__alloc_, __c.size());
374 __first_ = __allocation.ptr;
375 __begin_ = __end_ = __first_;
376 __cap_ = __first_ + __allocation.count;
377 typedef move_iterator<iterator> _Ip;
378 __construct_at_end(_Ip(__c.begin()), _Ip(__c.end()));
379 }
380}
381
382template <class _Tp, class _Allocator>
383_LIBCPP_CONSTEXPR_SINCE_CXX20 __split_buffer<_Tp, _Allocator>&
384__split_buffer<_Tp, _Allocator>::operator=(__split_buffer&& __c)
385 _NOEXCEPT_((__alloc_traits::propagate_on_container_move_assignment::value &&
386 is_nothrow_move_assignable<allocator_type>::value) ||
387 !__alloc_traits::propagate_on_container_move_assignment::value) {
388 clear();
389 shrink_to_fit();
390 __first_ = __c.__first_;
391 __begin_ = __c.__begin_;
392 __end_ = __c.__end_;
393 __cap_ = __c.__cap_;
394 __move_assign_alloc(__c, integral_constant<bool, __alloc_traits::propagate_on_container_move_assignment::value>());
395 __c.__first_ = __c.__begin_ = __c.__end_ = __c.__cap_ = nullptr;
396 return *this;
397}
398
399template <class _Tp, class _Allocator>
400_LIBCPP_CONSTEXPR_SINCE_CXX20 void __split_buffer<_Tp, _Allocator>::swap(__split_buffer& __x)
401 _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value || __is_nothrow_swappable_v<__alloc_rr>) {
402 std::swap(__first_, __x.__first_);
403 std::swap(__begin_, __x.__begin_);
404 std::swap(__end_, __x.__end_);
405 std::swap(__cap_, __x.__cap_);
406 std::__swap_allocator(__alloc_, __x.__alloc_);
407}
408
409template <class _Tp, class _Allocator>
410_LIBCPP_CONSTEXPR_SINCE_CXX20 void __split_buffer<_Tp, _Allocator>::shrink_to_fit() _NOEXCEPT {
411 if (capacity() > size()) {
412#if _LIBCPP_HAS_EXCEPTIONS
413 try {
414#endif // _LIBCPP_HAS_EXCEPTIONS
415 __split_buffer<value_type, __alloc_rr&> __t(size(), 0, __alloc_);
416 if (__t.capacity() < capacity()) {
417 __t.__construct_at_end(move_iterator<pointer>(__begin_), move_iterator<pointer>(__end_));
418 __t.__end_ = __t.__begin_ + (__end_ - __begin_);
419 std::swap(__first_, __t.__first_);
420 std::swap(__begin_, __t.__begin_);
421 std::swap(__end_, __t.__end_);
422 std::swap(__cap_, __t.__cap_);
423 }
424#if _LIBCPP_HAS_EXCEPTIONS
425 } catch (...) {
426 }
427#endif // _LIBCPP_HAS_EXCEPTIONS
428 }
429}
430
431template <class _Tp, class _Allocator>
432template <class... _Args>
433_LIBCPP_CONSTEXPR_SINCE_CXX20 void __split_buffer<_Tp, _Allocator>::emplace_front(_Args&&... __args) {
434 if (__begin_ == __first_) {
435 if (__end_ < __cap_) {
436 difference_type __d = __cap_ - __end_;
437 __d = (__d + 1) / 2;
438 __begin_ = std::move_backward(__begin_, __end_, __end_ + __d);
439 __end_ += __d;
440 } else {
441 size_type __c = std::max<size_type>(2 * static_cast<size_type>(__cap_ - __first_), 1);
442 __split_buffer<value_type, __alloc_rr&> __t(__c, (__c + 3) / 4, __alloc_);
443 __t.__construct_at_end(move_iterator<pointer>(__begin_), move_iterator<pointer>(__end_));
444 std::swap(__first_, __t.__first_);
445 std::swap(__begin_, __t.__begin_);
446 std::swap(__end_, __t.__end_);
447 std::swap(__cap_, __t.__cap_);
448 }
449 }
450 __alloc_traits::construct(__alloc_, std::__to_address(__begin_ - 1), std::forward<_Args>(__args)...);
451 --__begin_;
452}
453
454template <class _Tp, class _Allocator>
455template <class... _Args>
456_LIBCPP_CONSTEXPR_SINCE_CXX20 void __split_buffer<_Tp, _Allocator>::emplace_back(_Args&&... __args) {
457 if (__end_ == __cap_) {
458 if (__begin_ > __first_) {
459 difference_type __d = __begin_ - __first_;
460 __d = (__d + 1) / 2;
461 __end_ = std::move(__begin_, __end_, __begin_ - __d);
462 __begin_ -= __d;
463 } else {
464 size_type __c = std::max<size_type>(2 * static_cast<size_type>(__cap_ - __first_), 1);
465 __split_buffer<value_type, __alloc_rr&> __t(__c, __c / 4, __alloc_);
466 __t.__construct_at_end(move_iterator<pointer>(__begin_), move_iterator<pointer>(__end_));
467 std::swap(__first_, __t.__first_);
468 std::swap(__begin_, __t.__begin_);
469 std::swap(__end_, __t.__end_);
470 std::swap(__cap_, __t.__cap_);
471 }
472 }
473 __alloc_traits::construct(__alloc_, std::__to_address(__end_), std::forward<_Args>(__args)...);
474 ++__end_;
475}
476
477template <class _Tp, class _Allocator>
478_LIBCPP_CONSTEXPR_SINCE_CXX20 inline _LIBCPP_HIDE_FROM_ABI void
479swap(__split_buffer<_Tp, _Allocator>& __x, __split_buffer<_Tp, _Allocator>& __y) _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y))) {
480 __x.swap(__y);
481}
482
483_LIBCPP_END_NAMESPACE_STD
484
485_LIBCPP_POP_MACROS
486
487#endif // _LIBCPP___SPLIT_BUFFER