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___VECTOR_LAYOUT_H
10#define _LIBCPP___VECTOR_LAYOUT_H
11
12#include <__assert>
13#include <__config>
14#include <__debug_utils/sanitizers.h>
15#include <__memory/allocator_traits.h>
16#include <__memory/compressed_pair.h>
17#include <__memory/pointer_traits.h>
18#include <__memory/swap_allocator.h>
19#include <__memory/uninitialized_algorithms.h>
20#include <__split_buffer>
21#include <__type_traits/is_nothrow_constructible.h>
22#include <__utility/exchange.h>
23#include <__utility/move.h>
24#include <__utility/swap.h>
25
26#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
27# pragma GCC system_header
28#endif
29
30_LIBCPP_PUSH_MACROS
31#include <__undef_macros>
32
33_LIBCPP_BEGIN_NAMESPACE_STD
34
35/// Defines `std::vector`'s storage layout and any operations that are affected by a change in the
36/// layout.
37///
38/// `std::vector` can be represented in a variety of ways. Each representation strongly influences
39/// the codegen when calling vector operations, which can significantly impact runtime performance
40/// and memory utilisation. libc++ provides two alternative layouts for `std::vector`, although only
41/// one can be active for an entire binary:
42///
43/// * pointer-based layout (stable ABI default)
44/// * size-based layout (unstable ABI alternative)
45//
46/// We describe these layouts below. All vector representations have a pointer that points to where
47/// the memory is allocated (called `__begin_`).
48///
49/// **Pointer-based layout**
50///
51/// The pointer-based layout uses two more pointers in addition to `__begin_`. The second pointer
52/// (called `__end_`) points past the end of the part of the buffer that holds valid elements.
53/// Another pointer (called `__capacity_`) points past the end of the allocated buffer. The original
54/// libc++ `std::vector` implementation only provided the pointer-based layout. libc++ continues to
55/// use the pointer-based layout, by default, in order to maintain binary compatibility with
56/// existing software.
57///
58/// The `__end_` pointer has three primary use-cases:
59/// * to compute the size of the vector; and
60/// * to construct the past-the-end iterator; and
61/// * to indicate where the next element should be appended.
62///
63/// The `__capacity_` is used to compute the capacity of the vector, which lets the vector know how
64/// many elements can be added to the vector before a reallocation is necessary.
65///
66/// __begin_ = 0xE4FD0, __end_ = 0xE4FF0, __capacity_ = 0xE5000
67/// 0xE4FD0 0xE4FF0 0xE5000
68/// v v v
69/// +---------------+--------+--------+--------+--------+--------+--------+---------------------+
70/// | ????????????? | 3174 | 5656 | 648 | 489 | ------ | ------ | ??????????????????? |
71/// +---------------+--------+--------+--------+--------+--------+--------+---------------------+
72/// ^ ^ ^
73/// __begin_ __end_ __capacity_
74///
75/// Figure 1: A visual representation of a pointer-based `std::vector<short>`. This vector has
76/// four elements, with the capacity to store six. Boxes with numbers are valid elements within
77/// the vector, and boxes with `xx` have been allocated, but aren't being used as elements right
78/// now.
79///
80/// This is the default layout for libc++.
81///
82/// **Size-based layout**
83///
84/// The size-based layout uses integers to track its size and capacity, and computes pointers to
85/// past-the-end of the valid range and the whole buffer only when it's necessary. Programs using
86/// the size-based layout have been measured to yield improved compute and memory performance over
87/// the pointer-based layout. Despite these promising measurements, the size-based layout is opt-in,
88/// to preserve ABI compatibility with prebuilt binaries. Given the improved performance, we
89/// recommend preferring the size-based layout in the absence of such ABI constraints.
90///
91/// __begin_ = 0xE4FD0, __size_ = 4, __capacity_ = 6
92/// 0xE4FD0
93/// v
94/// +---------------+--------+--------+--------+--------+--------+--------+---------------------+
95/// | ????????????? | 3174 | 5656 | 648 | 489 | ------ | ------ | ??????????????????? |
96/// +---------------+--------+--------+--------+--------+--------+--------+---------------------+
97/// ^
98/// __begin_
99///
100/// Figure 2: A visual representation of this a size-based layout. Blank boxes are not a part
101/// of the vector's allocated buffer.
102///
103/// **Class design**
104///
105/// __vector_layout was designed with the following goals:
106/// 1. to abstractly represent the buffer's boundaries; and
107/// 2. to limit the number of `#ifdef` blocks that a reader needs to pass through; and
108/// 3. given (1) and (2), to have no logically identical components in multiple `#ifdef` clauses.
109///
110/// To facilitate these goals, there is a single `__vector_layout` definition. Users must choose
111/// their vector's layout when libc++ is being configured, so there is no need to manage multiple
112/// vector layout types (e.g. `__vector_size_layout`, `__vector_pointer_layout`, etc.). In doing so,
113/// we reduce a significant portion of duplicate code.
114template <class _Tp, class _Allocator>
115class __vector_layout {
116public:
117 using value_type _LIBCPP_NODEBUG = _Tp;
118 using allocator_type _LIBCPP_NODEBUG = _Allocator;
119 using __alloc_traits _LIBCPP_NODEBUG = allocator_traits<allocator_type>;
120 using size_type _LIBCPP_NODEBUG = typename __alloc_traits::size_type;
121 using pointer _LIBCPP_NODEBUG = typename __alloc_traits::pointer;
122 using const_pointer _LIBCPP_NODEBUG = typename __alloc_traits::const_pointer;
123#ifdef _LIBCPP_ABI_VECTOR_LAYOUT_SIZE_BASED
124 using _SplitBuffer _LIBCPP_NODEBUG = __split_buffer<_Tp, _Allocator, __split_buffer_size_layout>;
125 using __bound_type _LIBCPP_NODEBUG = size_type;
126#else
127 using _SplitBuffer _LIBCPP_NODEBUG = __split_buffer<_Tp, _Allocator, __split_buffer_pointer_layout>;
128 using __bound_type _LIBCPP_NODEBUG = pointer;
129#endif
130
131 // Cannot be defaulted, since `_LIBCPP_COMPRESSED_PAIR` isn't an aggregate before C++14.
132 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __vector_layout()
133 _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
134 : __capacity_() {}
135
136 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI explicit __vector_layout(allocator_type const& __a)
137 _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value)
138 : __capacity_(), __alloc_(__a) {}
139
140 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI explicit __vector_layout(allocator_type&& __a)
141 _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
142 : __capacity_(), __alloc_(std::move(__a)) {}
143
144 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __vector_layout(__vector_layout&& __other)
145 _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value);
146
147 /// Returns a reference to the stored allocator.
148 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI allocator_type& __alloc() _NOEXCEPT {
149 return __alloc_;
150 }
151
152 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI allocator_type const&
153 __alloc() const _NOEXCEPT {
154 return __alloc_;
155 }
156
157 /// Returns a pointer to the beginning of the buffer.
158 ///
159 /// `__begin_ptr()` is not called `data()` because `vector::data()` returns `T*`, but `__begin_`
160 /// is allowed to be a fancy pointer.
161 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI pointer __begin_ptr() _NOEXCEPT {
162 return __begin_;
163 }
164
165 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI const_pointer __begin_ptr() const _NOEXCEPT {
166 return __begin_;
167 }
168
169 /// Returns a built-in pointer to the beginning of the buffer.
170 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI _Tp* __data() _NOEXCEPT {
171 return std::__to_address(__begin_);
172 }
173
174 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI _Tp const* __data() const _NOEXCEPT {
175 return std::__to_address(__begin_);
176 }
177
178 /// Returns how many elements can be added before a reallocation occurs.
179 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI size_type
180 __remaining_capacity() const _NOEXCEPT;
181
182 /// Sets the member pointing to the first element in the vector to `__new_begin`, the member used
183 /// to obtain the vector's bound to the equivalent of `__new_size`, and the member that represents
184 /// the vector's capacity to the equivalent to `__new_capacity`.
185 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
186 __set_layout(pointer __new_begin, size_type __new_size, size_type __new_capacity) _NOEXCEPT;
187
188 /// Sets the member used to obtain the vector's bound to the equivalent of `__ptr`.
189 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __set_bound_using_pointer(pointer __ptr) _NOEXCEPT;
190
191 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __reset_without_allocator() _NOEXCEPT;
192 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __swap(__vector_layout& __other) _NOEXCEPT;
193 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
194 __move_assign_without_allocator(__vector_layout& __other) _NOEXCEPT;
195
196 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __relocate(_SplitBuffer& __buffer);
197 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI pointer
198 __relocate_with_pivot(_SplitBuffer& __buffer, pointer __pivot);
199
200 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI size_type __size() const _NOEXCEPT;
201 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI size_type __capacity() const _NOEXCEPT;
202 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI bool __empty() const _NOEXCEPT;
203 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI pointer __end_ptr() _NOEXCEPT;
204 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI const_pointer __end_ptr() const _NOEXCEPT;
205 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI pointer __capacity_ptr() _NOEXCEPT;
206 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI const_pointer __capacity_ptr() const _NOEXCEPT;
207 [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI bool __invariants() const _NOEXCEPT;
208
209private:
210 pointer __begin_ = nullptr;
211
212#ifdef _LIBCPP_ABI_VECTOR_LAYOUT_SIZE_BASED
213 size_type __size_ = 0;
214 size_type __capacity_ = 0;
215 _LIBCPP_NO_UNIQUE_ADDRESS allocator_type __alloc_;
216#else
217 pointer __end_ = nullptr;
218 _LIBCPP_COMPRESSED_PAIR(pointer, __capacity_ = nullptr, allocator_type, __alloc_);
219#endif
220
221 _LIBCPP_CONSTEXPR_SINCE_CXX20
222 _LIBCPP_HIDE_FROM_ABI void __annotate_contiguous_container(const void* __old_mid, const void* __new_mid) const {
223 std::__annotate_contiguous_container<_Allocator>(__data(), __data() + __capacity(), __old_mid, __new_mid);
224 }
225
226 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __annotate_new(size_type __current_size) const _NOEXCEPT {
227 __annotate_contiguous_container(old_mid: __data() + __capacity(), new_mid: __data() + __current_size);
228 }
229
230 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __annotate_delete() const _NOEXCEPT {
231 __annotate_contiguous_container(old_mid: __data() + __size(), new_mid: __data() + __capacity());
232 }
233};
234
235#ifdef _LIBCPP_ABI_VECTOR_LAYOUT_SIZE_BASED
236template <class _Tp, class _Alloc>
237_LIBCPP_CONSTEXPR_SINCE_CXX20 __vector_layout<_Tp, _Alloc>::__vector_layout(__vector_layout&& __other)
238 _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
239 : __begin_(std::__exchange(__other.__begin_, nullptr)),
240 __size_(std::__exchange(__other.__size_, 0)),
241 __capacity_(std::__exchange(__other.__capacity_, 0)),
242 __alloc_(std::move(__other.__alloc_)) {}
243
244template <class _Tp, class _Alloc>
245_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::size_type
246__vector_layout<_Tp, _Alloc>::__remaining_capacity() const _NOEXCEPT {
247 return __capacity_ - __size_;
248}
249
250template <class _Tp, class _Alloc>
251_LIBCPP_CONSTEXPR_SINCE_CXX20 void __vector_layout<_Tp, _Alloc>::__set_layout(
252 pointer __new_begin, size_type __new_size, size_type __new_capacity) _NOEXCEPT {
253 __begin_ = __new_begin;
254 __size_ = __new_size;
255 __capacity_ = __new_capacity;
256}
257
258template <class _Tp, class _Alloc>
259_LIBCPP_CONSTEXPR_SINCE_CXX20 void __vector_layout<_Tp, _Alloc>::__set_bound_using_pointer(pointer __ptr) _NOEXCEPT {
260 __size_ = static_cast<size_type>(__ptr - __begin_);
261}
262
263template <class _Tp, class _Alloc>
264_LIBCPP_CONSTEXPR_SINCE_CXX20 void __vector_layout<_Tp, _Alloc>::__reset_without_allocator() _NOEXCEPT {
265 __begin_ = nullptr;
266 __size_ = 0;
267 __capacity_ = 0;
268}
269
270template <class _Tp, class _Alloc>
271_LIBCPP_CONSTEXPR_SINCE_CXX20 void __vector_layout<_Tp, _Alloc>::__swap(__vector_layout& __other) _NOEXCEPT {
272 using std::swap;
273 swap(__begin_, __other.__begin_);
274 swap(__size_, __other.__size_);
275 swap(__capacity_, __other.__capacity_);
276 std::__swap_allocator(__alloc_, __other.__alloc_);
277}
278
279template <class _Tp, class _Alloc>
280_LIBCPP_CONSTEXPR_SINCE_CXX20 void
281__vector_layout<_Tp, _Alloc>::__move_assign_without_allocator(__vector_layout& __other) _NOEXCEPT {
282 __begin_ = __other.__begin_;
283 __size_ = __other.__size_;
284 __capacity_ = __other.__capacity_;
285
286 __other.__reset_without_allocator();
287}
288
289template <class _Tp, class _Alloc>
290_LIBCPP_CONSTEXPR_SINCE_CXX20 void __vector_layout<_Tp, _Alloc>::__relocate(_SplitBuffer& __buffer) {
291 __annotate_delete();
292 __buffer.__relocate(__begin_, __size_, __capacity_);
293 __annotate_new(__size_);
294}
295
296template <class _Tp, class _Alloc>
297_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::pointer
298__vector_layout<_Tp, _Alloc>::__relocate_with_pivot(_SplitBuffer& __buffer, pointer __pivot) {
299 __annotate_delete();
300 auto __result = __buffer.__relocate_with_pivot(__pivot, __begin_, __size_, __capacity_);
301 __annotate_new(__size_);
302 return __result;
303}
304
305template <class _Tp, class _Alloc>
306_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::size_type
307__vector_layout<_Tp, _Alloc>::__size() const _NOEXCEPT {
308 return __size_;
309}
310
311template <class _Tp, class _Alloc>
312_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::size_type
313__vector_layout<_Tp, _Alloc>::__capacity() const _NOEXCEPT {
314 return __capacity_;
315}
316
317template <class _Tp, class _Alloc>
318_LIBCPP_CONSTEXPR_SINCE_CXX20 bool __vector_layout<_Tp, _Alloc>::__empty() const _NOEXCEPT {
319 return __size_ == 0;
320}
321
322template <class _Tp, class _Alloc>
323_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::pointer
324__vector_layout<_Tp, _Alloc>::__end_ptr() _NOEXCEPT {
325 return __begin_ + __size_;
326}
327
328template <class _Tp, class _Alloc>
329_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::const_pointer
330__vector_layout<_Tp, _Alloc>::__end_ptr() const _NOEXCEPT {
331 return __begin_ + __size_;
332}
333
334template <class _Tp, class _Alloc>
335_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::pointer
336__vector_layout<_Tp, _Alloc>::__capacity_ptr() _NOEXCEPT {
337 return __begin_ + __capacity_;
338}
339
340template <class _Tp, class _Alloc>
341_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::const_pointer
342__vector_layout<_Tp, _Alloc>::__capacity_ptr() const _NOEXCEPT {
343 return __begin_ + __capacity_;
344}
345
346template <class _Tp, class _Alloc>
347_LIBCPP_CONSTEXPR_SINCE_CXX20 bool __vector_layout<_Tp, _Alloc>::__invariants() const _NOEXCEPT {
348 if (__begin_ == nullptr)
349 return __size_ == 0 && __capacity_ == 0;
350 return __size_ <= __capacity_;
351}
352#else // !defined(_LIBCPP_ABI_VECTOR_LAYOUT_SIZE_BASED)
353template <class _Tp, class _Alloc>
354_LIBCPP_CONSTEXPR_SINCE_CXX20 __vector_layout<_Tp, _Alloc>::__vector_layout(__vector_layout&& __other)
355 _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
356 : __begin_(std::__exchange(__other.__begin_, nullptr)),
357 __end_(std::__exchange(__other.__end_, nullptr)),
358 __capacity_(std::__exchange(__other.__capacity_, nullptr)),
359 __alloc_(std::move(__other.__alloc_)) {}
360
361template <class _Tp, class _Alloc>
362_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::size_type
363__vector_layout<_Tp, _Alloc>::__remaining_capacity() const _NOEXCEPT {
364 return __capacity_ - __end_;
365}
366
367template <class _Tp, class _Alloc>
368_LIBCPP_CONSTEXPR_SINCE_CXX20 void __vector_layout<_Tp, _Alloc>::__set_layout(
369 pointer __new_begin, size_type __new_size, size_type __new_capacity) _NOEXCEPT {
370 __begin_ = __new_begin;
371 __end_ = __new_begin + __new_size;
372 __capacity_ = __new_begin + __new_capacity;
373}
374
375template <class _Tp, class _Alloc>
376_LIBCPP_CONSTEXPR_SINCE_CXX20 void __vector_layout<_Tp, _Alloc>::__set_bound_using_pointer(pointer __ptr) _NOEXCEPT {
377 __end_ = __ptr;
378}
379
380template <class _Tp, class _Alloc>
381_LIBCPP_CONSTEXPR_SINCE_CXX20 void __vector_layout<_Tp, _Alloc>::__reset_without_allocator() _NOEXCEPT {
382 __begin_ = nullptr;
383 __end_ = nullptr;
384 __capacity_ = nullptr;
385}
386
387template <class _Tp, class _Alloc>
388_LIBCPP_CONSTEXPR_SINCE_CXX20 void __vector_layout<_Tp, _Alloc>::__swap(__vector_layout& __other) _NOEXCEPT {
389 using std::swap;
390 swap(__begin_, __other.__begin_);
391 swap(__end_, __other.__end_);
392 swap(__capacity_, __other.__capacity_);
393 std::__swap_allocator(__alloc_, __other.__alloc_);
394}
395
396template <class _Tp, class _Alloc>
397_LIBCPP_CONSTEXPR_SINCE_CXX20 void
398__vector_layout<_Tp, _Alloc>::__move_assign_without_allocator(__vector_layout& __other) _NOEXCEPT {
399 __begin_ = __other.__begin_;
400 __end_ = __other.__end_;
401 __capacity_ = __other.__capacity_;
402
403 __other.__reset_without_allocator();
404}
405
406template <class _Tp, class _Alloc>
407_LIBCPP_CONSTEXPR_SINCE_CXX20 void __vector_layout<_Tp, _Alloc>::__relocate(_SplitBuffer& __buffer) {
408 __annotate_delete();
409 __buffer.__relocate(__begin_, __end_, __capacity_);
410 __annotate_new(current_size: __size());
411}
412
413template <class _Tp, class _Alloc>
414_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::pointer
415__vector_layout<_Tp, _Alloc>::__relocate_with_pivot(_SplitBuffer& __buffer, pointer __pivot) {
416 __annotate_delete();
417 auto __result = __buffer.__relocate_with_pivot(__pivot, __begin_, __end_, __capacity_);
418 __annotate_new(current_size: __size());
419 return __result;
420}
421
422template <class _Tp, class _Alloc>
423_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::size_type
424__vector_layout<_Tp, _Alloc>::__size() const _NOEXCEPT {
425 return static_cast<size_type>(__end_ - __begin_);
426}
427
428template <class _Tp, class _Alloc>
429_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::size_type
430__vector_layout<_Tp, _Alloc>::__capacity() const _NOEXCEPT {
431 return static_cast<size_type>(__capacity_ - __begin_);
432}
433
434template <class _Tp, class _Alloc>
435_LIBCPP_CONSTEXPR_SINCE_CXX20 bool __vector_layout<_Tp, _Alloc>::__empty() const _NOEXCEPT {
436 return __begin_ == __end_;
437}
438
439template <class _Tp, class _Alloc>
440_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::pointer
441__vector_layout<_Tp, _Alloc>::__end_ptr() _NOEXCEPT {
442 return __end_;
443}
444
445template <class _Tp, class _Alloc>
446_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::const_pointer
447__vector_layout<_Tp, _Alloc>::__end_ptr() const _NOEXCEPT {
448 return __end_;
449}
450
451template <class _Tp, class _Alloc>
452_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::pointer
453__vector_layout<_Tp, _Alloc>::__capacity_ptr() _NOEXCEPT {
454 return __capacity_;
455}
456
457template <class _Tp, class _Alloc>
458_LIBCPP_CONSTEXPR_SINCE_CXX20 typename __vector_layout<_Tp, _Alloc>::const_pointer
459__vector_layout<_Tp, _Alloc>::__capacity_ptr() const _NOEXCEPT {
460 return __capacity_;
461}
462
463template <class _Tp, class _Alloc>
464_LIBCPP_CONSTEXPR_SINCE_CXX20 bool __vector_layout<_Tp, _Alloc>::__invariants() const _NOEXCEPT {
465 if (__begin_ == nullptr)
466 return __end_ == nullptr && __capacity_ == nullptr;
467 if (__begin_ > __end_)
468 return false;
469 if (__begin_ == __capacity_)
470 return false;
471 return __end_ <= __capacity_;
472}
473#endif // _LIBCPP_ABI_VECTOR_LAYOUT_SIZE_BASED
474
475_LIBCPP_END_NAMESPACE_STD
476
477_LIBCPP_POP_MACROS
478
479#endif // _LIBCPP___VECTOR_LAYOUT_H
480