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_SPAN 11#define _LIBCPP_SPAN 12 13/* 14 span synopsis 15 16namespace std { 17 18// constants 19inline constexpr size_t dynamic_extent = numeric_limits<size_t>::max(); 20 21// [views.span], class template span 22template <class ElementType, size_t Extent = dynamic_extent> 23 class span; 24 25template<class ElementType, size_t Extent> 26 inline constexpr bool ranges::enable_view<span<ElementType, Extent>> = true; 27 28template<class ElementType, size_t Extent> 29 inline constexpr bool ranges::enable_borrowed_range<span<ElementType, Extent>> = true; 30 31// [span.objectrep], views of object representation 32template <class ElementType, size_t Extent> 33 span<const byte, ((Extent == dynamic_extent) ? dynamic_extent : 34 (sizeof(ElementType) * Extent))> as_bytes(span<ElementType, Extent> s) noexcept; 35 36template <class ElementType, size_t Extent> 37 span< byte, ((Extent == dynamic_extent) ? dynamic_extent : 38 (sizeof(ElementType) * Extent))> as_writable_bytes(span<ElementType, Extent> s) noexcept; 39 40 41template <class ElementType, size_t Extent = dynamic_extent> 42class span { 43public: 44 // constants and types 45 using element_type = ElementType; 46 using value_type = remove_cv_t<ElementType>; 47 using size_type = size_t; 48 using difference_type = ptrdiff_t; 49 using pointer = element_type*; 50 using const_pointer = const element_type*; 51 using reference = element_type&; 52 using const_reference = const element_type&; 53 using iterator = implementation-defined; 54 using reverse_iterator = std::reverse_iterator<iterator>; 55 static constexpr size_type extent = Extent; 56 57 // [span.cons], span constructors, copy, assignment, and destructor 58 constexpr span() noexcept; 59 template <class It> 60 constexpr explicit(Extent != dynamic_extent) span(It first, size_type count); 61 template <class It, class End> 62 constexpr explicit(Extent != dynamic_extent) span(It first, End last); 63 template <size_t N> 64 constexpr span(type_identity_t<element_type> (&arr)[N]) noexcept; 65 template <size_t N> 66 constexpr span(array<value_type, N>& arr) noexcept; 67 template <size_t N> 68 constexpr span(const array<value_type, N>& arr) noexcept; 69 template<class R> 70 constexpr explicit(Extent != dynamic_extent) span(R&& r); 71 constexpr span(const span& other) noexcept = default; 72 template <class OtherElementType, size_t OtherExtent> 73 constexpr explicit(Extent != dynamic_extent) span(const span<OtherElementType, OtherExtent>& s) noexcept; 74 ~span() noexcept = default; 75 constexpr span& operator=(const span& other) noexcept = default; 76 77 // [span.sub], span subviews 78 template <size_t Count> 79 constexpr span<element_type, Count> first() const; 80 template <size_t Count> 81 constexpr span<element_type, Count> last() const; 82 template <size_t Offset, size_t Count = dynamic_extent> 83 constexpr span<element_type, see below> subspan() const; 84 85 constexpr span<element_type, dynamic_extent> first(size_type count) const; 86 constexpr span<element_type, dynamic_extent> last(size_type count) const; 87 constexpr span<element_type, dynamic_extent> subspan(size_type offset, size_type count = dynamic_extent) const; 88 89 // [span.obs], span observers 90 constexpr size_type size() const noexcept; 91 constexpr size_type size_bytes() const noexcept; 92 [[nodiscard]] constexpr bool empty() const noexcept; 93 94 // [span.elem], span element access 95 constexpr reference operator[](size_type idx) const; 96 constexpr reference front() const; 97 constexpr reference back() const; 98 constexpr pointer data() const noexcept; 99 100 // [span.iterators], span iterator support 101 constexpr iterator begin() const noexcept; 102 constexpr iterator end() const noexcept; 103 constexpr reverse_iterator rbegin() const noexcept; 104 constexpr reverse_iterator rend() const noexcept; 105 106private: 107 pointer data_; // exposition only 108 size_type size_; // exposition only 109}; 110 111template<class It, class EndOrSize> 112 span(It, EndOrSize) -> span<remove_reference_t<iter_reference_t<_It>>>; 113 114template<class T, size_t N> 115 span(T (&)[N]) -> span<T, N>; 116 117template<class T, size_t N> 118 span(array<T, N>&) -> span<T, N>; 119 120template<class T, size_t N> 121 span(const array<T, N>&) -> span<const T, N>; 122 123template<class R> 124 span(R&&) -> span<remove_reference_t<ranges::range_reference_t<R>>>; 125 126} // namespace std 127 128*/ 129 130#include <__assert> // all public C++ headers provide the assertion handler 131#include <__config> 132#include <__debug> 133#include <__fwd/span.h> 134#include <__iterator/bounded_iter.h> 135#include <__iterator/concepts.h> 136#include <__iterator/iterator_traits.h> 137#include <__iterator/wrap_iter.h> 138#include <__memory/pointer_traits.h> 139#include <__ranges/concepts.h> 140#include <__ranges/data.h> 141#include <__ranges/enable_borrowed_range.h> 142#include <__ranges/enable_view.h> 143#include <__ranges/size.h> 144#include <__type_traits/is_convertible.h> 145#include <__type_traits/remove_cvref.h> 146#include <__type_traits/remove_reference.h> 147#include <__type_traits/type_identity.h> 148#include <__utility/forward.h> 149#include <array> // for array 150#include <cstddef> // for byte 151#include <limits> 152#include <version> 153 154// standard-mandated includes 155 156// [iterator.range] 157#include <__iterator/access.h> 158#include <__iterator/data.h> 159#include <__iterator/empty.h> 160#include <__iterator/reverse_access.h> 161#include <__iterator/size.h> 162 163#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 164# pragma GCC system_header 165#endif 166 167_LIBCPP_PUSH_MACROS 168#include <__undef_macros> 169 170_LIBCPP_BEGIN_NAMESPACE_STD 171 172#if _LIBCPP_STD_VER >= 20 173 174template <class _Tp> 175struct __is_std_array : false_type {}; 176 177template <class _Tp, size_t _Sz> 178struct __is_std_array<array<_Tp, _Sz>> : true_type {}; 179 180template <class _Tp> 181struct __is_std_span : false_type {}; 182 183template <class _Tp, size_t _Sz> 184struct __is_std_span<span<_Tp, _Sz>> : true_type {}; 185 186template <class _Range, class _ElementType> 187concept __span_compatible_range = 188 ranges::contiguous_range<_Range> && 189 ranges::sized_range<_Range> && 190 (ranges::borrowed_range<_Range> || is_const_v<_ElementType>) && 191 !__is_std_span<remove_cvref_t<_Range>>::value && 192 !__is_std_array<remove_cvref_t<_Range>>::value && 193 !is_array_v<remove_cvref_t<_Range>> && 194 is_convertible_v<remove_reference_t<ranges::range_reference_t<_Range>>(*)[], _ElementType(*)[]>; 195 196template <class _From, class _To> 197concept __span_array_convertible = is_convertible_v<_From(*)[], _To(*)[]>; 198 199template <class _It, class _Tp> 200concept __span_compatible_iterator = contiguous_iterator<_It> && __span_array_convertible<remove_reference_t<iter_reference_t<_It>>, _Tp>; 201 202template <class _Sentinel, class _It> 203concept __span_compatible_sentinel_for = sized_sentinel_for<_Sentinel, _It> && !is_convertible_v<_Sentinel, size_t>; 204 205template <typename _Tp, size_t _Extent> 206class _LIBCPP_TEMPLATE_VIS span { 207public: 208// constants and types 209 using element_type = _Tp; 210 using value_type = remove_cv_t<_Tp>; 211 using size_type = size_t; 212 using difference_type = ptrdiff_t; 213 using pointer = _Tp *; 214 using const_pointer = const _Tp *; 215 using reference = _Tp &; 216 using const_reference = const _Tp &; 217#ifdef _LIBCPP_DEBUG_ITERATOR_BOUNDS_CHECKING 218 using iterator = __bounded_iter<pointer>; 219#else 220 using iterator = __wrap_iter<pointer>; 221#endif 222 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 223 224 static constexpr size_type extent = _Extent; 225 226// [span.cons], span constructors, copy, assignment, and destructor 227 template <size_t _Sz = _Extent> requires(_Sz == 0) 228 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data_{nullptr} {} 229 230 constexpr span (const span&) noexcept = default; 231 constexpr span& operator=(const span&) noexcept = default; 232 233 template <__span_compatible_iterator<element_type> _It> 234 _LIBCPP_INLINE_VISIBILITY 235 constexpr explicit span(_It __first, size_type __count) 236 : __data_{_VSTD::to_address(__first)} { 237 (void)__count; 238 _LIBCPP_ASSERT(_Extent == __count, "size mismatch in span's constructor (iterator, len)"); 239 } 240 241 template <__span_compatible_iterator<element_type> _It, __span_compatible_sentinel_for<_It> _End> 242 _LIBCPP_INLINE_VISIBILITY 243 constexpr explicit span(_It __first, _End __last) : __data_{_VSTD::to_address(__first)} { 244 // [span.cons]/10 245 // Throws: When and what last - first throws. 246 [[maybe_unused]] auto __dist = __last - __first; 247 _LIBCPP_ASSERT(__dist >= 0, "invalid range in span's constructor (iterator, sentinel)"); 248 _LIBCPP_ASSERT( 249 __dist == _Extent, "invalid range in span's constructor (iterator, sentinel): last - first != extent"); 250 } 251 252 _LIBCPP_INLINE_VISIBILITY constexpr span(type_identity_t<element_type> (&__arr)[_Extent]) noexcept : __data_{__arr} {} 253 254 template <__span_array_convertible<element_type> _OtherElementType> 255 _LIBCPP_INLINE_VISIBILITY 256 constexpr span(array<_OtherElementType, _Extent>& __arr) noexcept : __data_{__arr.data()} {} 257 258 template <class _OtherElementType> 259 requires __span_array_convertible<const _OtherElementType, element_type> 260 _LIBCPP_INLINE_VISIBILITY 261 constexpr span(const array<_OtherElementType, _Extent>& __arr) noexcept : __data_{__arr.data()} {} 262 263 template <__span_compatible_range<element_type> _Range> 264 _LIBCPP_INLINE_VISIBILITY 265 constexpr explicit span(_Range&& __r) : __data_{ranges::data(__r)} { 266 _LIBCPP_ASSERT(ranges::size(__r) == _Extent, "size mismatch in span's constructor (range)"); 267 } 268 269 template <__span_array_convertible<element_type> _OtherElementType> 270 _LIBCPP_INLINE_VISIBILITY 271 constexpr span(const span<_OtherElementType, _Extent>& __other) 272 : __data_{__other.data()} {} 273 274 template <__span_array_convertible<element_type> _OtherElementType> 275 _LIBCPP_INLINE_VISIBILITY 276 constexpr explicit span(const span<_OtherElementType, dynamic_extent>& __other) noexcept 277 : __data_{__other.data()} { _LIBCPP_ASSERT(_Extent == __other.size(), "size mismatch in span's constructor (other span)"); } 278 279 280// ~span() noexcept = default; 281 282 template <size_t _Count> 283 _LIBCPP_INLINE_VISIBILITY 284 constexpr span<element_type, _Count> first() const noexcept 285 { 286 static_assert(_Count <= _Extent, "span<T, N>::first<Count>(): Count out of range"); 287 return span<element_type, _Count>{data(), _Count}; 288 } 289 290 template <size_t _Count> 291 _LIBCPP_INLINE_VISIBILITY 292 constexpr span<element_type, _Count> last() const noexcept 293 { 294 static_assert(_Count <= _Extent, "span<T, N>::last<Count>(): Count out of range"); 295 return span<element_type, _Count>{data() + size() - _Count, _Count}; 296 } 297 298 _LIBCPP_INLINE_VISIBILITY 299 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 300 { 301 _LIBCPP_ASSERT(__count <= size(), "span<T, N>::first(count): count out of range"); 302 return {data(), __count}; 303 } 304 305 _LIBCPP_INLINE_VISIBILITY 306 constexpr span<element_type, dynamic_extent> last(size_type __count) const noexcept 307 { 308 _LIBCPP_ASSERT(__count <= size(), "span<T, N>::last(count): count out of range"); 309 return {data() + size() - __count, __count}; 310 } 311 312 template <size_t _Offset, size_t _Count = dynamic_extent> 313 _LIBCPP_INLINE_VISIBILITY 314 constexpr auto subspan() const noexcept 315 -> span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset> 316 { 317 static_assert(_Offset <= _Extent, "span<T, N>::subspan<Offset, Count>(): Offset out of range"); 318 static_assert(_Count == dynamic_extent || _Count <= _Extent - _Offset, "span<T, N>::subspan<Offset, Count>(): Offset + Count out of range"); 319 320 using _ReturnType = span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset>; 321 return _ReturnType{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 322 } 323 324 325 _LIBCPP_INLINE_VISIBILITY 326 constexpr span<element_type, dynamic_extent> 327 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 328 { 329 _LIBCPP_ASSERT(__offset <= size(), "span<T, N>::subspan(offset, count): offset out of range"); 330 if (__count == dynamic_extent) 331 return {data() + __offset, size() - __offset}; 332 _LIBCPP_ASSERT(__count <= size() - __offset, "span<T, N>::subspan(offset, count): offset + count out of range"); 333 return {data() + __offset, __count}; 334 } 335 336 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return _Extent; } 337 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return _Extent * sizeof(element_type); } 338 [[nodiscard]] _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return _Extent == 0; } 339 340 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 341 { 342 _LIBCPP_ASSERT(__idx < size(), "span<T, N>::operator[](index): index out of range"); 343 return __data_[__idx]; 344 } 345 346 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 347 { 348 _LIBCPP_ASSERT(!empty(), "span<T, N>::front() on empty span"); 349 return __data_[0]; 350 } 351 352 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 353 { 354 _LIBCPP_ASSERT(!empty(), "span<T, N>::back() on empty span"); 355 return __data_[size()-1]; 356 } 357 358 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data_; } 359 360// [span.iter], span iterator support 361 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { 362#ifdef _LIBCPP_DEBUG_ITERATOR_BOUNDS_CHECKING 363 return std::__make_bounded_iter(data(), data(), data() + size()); 364#else 365 return iterator(this, data()); 366#endif 367 } 368 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { 369#ifdef _LIBCPP_DEBUG_ITERATOR_BOUNDS_CHECKING 370 return std::__make_bounded_iter(data() + size(), data(), data() + size()); 371#else 372 return iterator(this, data() + size()); 373#endif 374 } 375 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 376 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 377 378 _LIBCPP_INLINE_VISIBILITY span<const byte, _Extent * sizeof(element_type)> __as_bytes() const noexcept 379 { return span<const byte, _Extent * sizeof(element_type)>{reinterpret_cast<const byte *>(data()), size_bytes()}; } 380 381 _LIBCPP_INLINE_VISIBILITY span<byte, _Extent * sizeof(element_type)> __as_writable_bytes() const noexcept 382 { return span<byte, _Extent * sizeof(element_type)>{reinterpret_cast<byte *>(data()), size_bytes()}; } 383 384private: 385 pointer __data_; 386}; 387 388 389template <typename _Tp> 390class _LIBCPP_TEMPLATE_VIS span<_Tp, dynamic_extent> { 391public: 392// constants and types 393 using element_type = _Tp; 394 using value_type = remove_cv_t<_Tp>; 395 using size_type = size_t; 396 using difference_type = ptrdiff_t; 397 using pointer = _Tp *; 398 using const_pointer = const _Tp *; 399 using reference = _Tp &; 400 using const_reference = const _Tp &; 401#ifdef _LIBCPP_DEBUG_ITERATOR_BOUNDS_CHECKING 402 using iterator = __bounded_iter<pointer>; 403#else 404 using iterator = __wrap_iter<pointer>; 405#endif 406 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 407 408 static constexpr size_type extent = dynamic_extent; 409 410// [span.cons], span constructors, copy, assignment, and destructor 411 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data_{nullptr}, __size_{0} {} 412 413 constexpr span (const span&) noexcept = default; 414 constexpr span& operator=(const span&) noexcept = default; 415 416 template <__span_compatible_iterator<element_type> _It> 417 _LIBCPP_INLINE_VISIBILITY 418 constexpr span(_It __first, size_type __count) 419 : __data_{_VSTD::to_address(__first)}, __size_{__count} {} 420 421 template <__span_compatible_iterator<element_type> _It, __span_compatible_sentinel_for<_It> _End> 422 _LIBCPP_INLINE_VISIBILITY constexpr span(_It __first, _End __last) 423 : __data_(_VSTD::to_address(__first)), __size_(__last - __first) { 424 _LIBCPP_ASSERT(__last - __first >= 0, "invalid range in span's constructor (iterator, sentinel)"); 425 } 426 427 template <size_t _Sz> 428 _LIBCPP_INLINE_VISIBILITY 429 constexpr span(type_identity_t<element_type> (&__arr)[_Sz]) noexcept : __data_{__arr}, __size_{_Sz} {} 430 431 template <__span_array_convertible<element_type> _OtherElementType, size_t _Sz> 432 _LIBCPP_INLINE_VISIBILITY 433 constexpr span(array<_OtherElementType, _Sz>& __arr) noexcept : __data_{__arr.data()}, __size_{_Sz} {} 434 435 template <class _OtherElementType, size_t _Sz> 436 requires __span_array_convertible<const _OtherElementType, element_type> 437 _LIBCPP_INLINE_VISIBILITY 438 constexpr span(const array<_OtherElementType, _Sz>& __arr) noexcept : __data_{__arr.data()}, __size_{_Sz} {} 439 440 template <__span_compatible_range<element_type> _Range> 441 _LIBCPP_INLINE_VISIBILITY 442 constexpr span(_Range&& __r) : __data_(ranges::data(__r)), __size_{ranges::size(__r)} {} 443 444 template <__span_array_convertible<element_type> _OtherElementType, size_t _OtherExtent> 445 _LIBCPP_INLINE_VISIBILITY 446 constexpr span(const span<_OtherElementType, _OtherExtent>& __other) noexcept 447 : __data_{__other.data()}, __size_{__other.size()} {} 448 449// ~span() noexcept = default; 450 451 template <size_t _Count> 452 _LIBCPP_INLINE_VISIBILITY 453 constexpr span<element_type, _Count> first() const noexcept 454 { 455 _LIBCPP_ASSERT(_Count <= size(), "span<T>::first<Count>(): Count out of range"); 456 return span<element_type, _Count>{data(), _Count}; 457 } 458 459 template <size_t _Count> 460 _LIBCPP_INLINE_VISIBILITY 461 constexpr span<element_type, _Count> last() const noexcept 462 { 463 _LIBCPP_ASSERT(_Count <= size(), "span<T>::last<Count>(): Count out of range"); 464 return span<element_type, _Count>{data() + size() - _Count, _Count}; 465 } 466 467 _LIBCPP_INLINE_VISIBILITY 468 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 469 { 470 _LIBCPP_ASSERT(__count <= size(), "span<T>::first(count): count out of range"); 471 return {data(), __count}; 472 } 473 474 _LIBCPP_INLINE_VISIBILITY 475 constexpr span<element_type, dynamic_extent> last (size_type __count) const noexcept 476 { 477 _LIBCPP_ASSERT(__count <= size(), "span<T>::last(count): count out of range"); 478 return {data() + size() - __count, __count}; 479 } 480 481 template <size_t _Offset, size_t _Count = dynamic_extent> 482 _LIBCPP_INLINE_VISIBILITY 483 constexpr span<element_type, _Count> subspan() const noexcept 484 { 485 _LIBCPP_ASSERT(_Offset <= size(), "span<T>::subspan<Offset, Count>(): Offset out of range"); 486 _LIBCPP_ASSERT(_Count == dynamic_extent || _Count <= size() - _Offset, "span<T>::subspan<Offset, Count>(): Offset + Count out of range"); 487 return span<element_type, _Count>{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 488 } 489 490 constexpr span<element_type, dynamic_extent> 491 _LIBCPP_INLINE_VISIBILITY 492 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 493 { 494 _LIBCPP_ASSERT(__offset <= size(), "span<T>::subspan(offset, count): offset out of range"); 495 if (__count == dynamic_extent) 496 return {data() + __offset, size() - __offset}; 497 _LIBCPP_ASSERT(__count <= size() - __offset, "span<T>::subspan(offset, count): offset + count out of range"); 498 return {data() + __offset, __count}; 499 } 500 501 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return __size_; } 502 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return __size_ * sizeof(element_type); } 503 [[nodiscard]] _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return __size_ == 0; } 504 505 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 506 { 507 _LIBCPP_ASSERT(__idx < size(), "span<T>::operator[](index): index out of range"); 508 return __data_[__idx]; 509 } 510 511 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 512 { 513 _LIBCPP_ASSERT(!empty(), "span<T>::front() on empty span"); 514 return __data_[0]; 515 } 516 517 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 518 { 519 _LIBCPP_ASSERT(!empty(), "span<T>::back() on empty span"); 520 return __data_[size()-1]; 521 } 522 523 524 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data_; } 525 526// [span.iter], span iterator support 527 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { 528#ifdef _LIBCPP_DEBUG_ITERATOR_BOUNDS_CHECKING 529 return std::__make_bounded_iter(data(), data(), data() + size()); 530#else 531 return iterator(this, data()); 532#endif 533 } 534 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { 535#ifdef _LIBCPP_DEBUG_ITERATOR_BOUNDS_CHECKING 536 return std::__make_bounded_iter(data() + size(), data(), data() + size()); 537#else 538 return iterator(this, data() + size()); 539#endif 540 } 541 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 542 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 543 544 _LIBCPP_INLINE_VISIBILITY span<const byte, dynamic_extent> __as_bytes() const noexcept 545 { return {reinterpret_cast<const byte *>(data()), size_bytes()}; } 546 547 _LIBCPP_INLINE_VISIBILITY span<byte, dynamic_extent> __as_writable_bytes() const noexcept 548 { return {reinterpret_cast<byte *>(data()), size_bytes()}; } 549 550private: 551 pointer __data_; 552 size_type __size_; 553}; 554 555template <class _Tp, size_t _Extent> 556inline constexpr bool ranges::enable_borrowed_range<span<_Tp, _Extent> > = true; 557 558template <class _ElementType, size_t _Extent> 559inline constexpr bool ranges::enable_view<span<_ElementType, _Extent>> = true; 560 561// as_bytes & as_writable_bytes 562template <class _Tp, size_t _Extent> 563_LIBCPP_INLINE_VISIBILITY 564auto as_bytes(span<_Tp, _Extent> __s) noexcept 565{ return __s.__as_bytes(); } 566 567template <class _Tp, size_t _Extent> requires(!is_const_v<_Tp>) 568_LIBCPP_INLINE_VISIBILITY 569auto as_writable_bytes(span<_Tp, _Extent> __s) noexcept 570{ return __s.__as_writable_bytes(); } 571 572#if _LIBCPP_STD_VER >= 20 573template<contiguous_iterator _It, class _EndOrSize> 574 span(_It, _EndOrSize) -> span<remove_reference_t<iter_reference_t<_It>>>; 575#endif // _LIBCPP_STD_VER >= 20 576 577template<class _Tp, size_t _Sz> 578 span(_Tp (&)[_Sz]) -> span<_Tp, _Sz>; 579 580template<class _Tp, size_t _Sz> 581 span(array<_Tp, _Sz>&) -> span<_Tp, _Sz>; 582 583template<class _Tp, size_t _Sz> 584 span(const array<_Tp, _Sz>&) -> span<const _Tp, _Sz>; 585 586template<ranges::contiguous_range _Range> 587 span(_Range&&) -> span<remove_reference_t<ranges::range_reference_t<_Range>>>; 588 589#endif // _LIBCPP_STD_VER >= 20 590 591_LIBCPP_END_NAMESPACE_STD 592 593_LIBCPP_POP_MACROS 594 595#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20 596# include <concepts> 597# include <functional> 598# include <iterator> 599# include <type_traits> 600#endif 601 602#endif // _LIBCPP_SPAN 603