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