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 constexpr span& operator=(const span& other) noexcept = default; 75 76 // [span.sub], span subviews 77 template <size_t Count> 78 constexpr span<element_type, Count> first() const; 79 template <size_t Count> 80 constexpr span<element_type, Count> last() const; 81 template <size_t Offset, size_t Count = dynamic_extent> 82 constexpr span<element_type, see below> subspan() const; 83 84 constexpr span<element_type, dynamic_extent> first(size_type count) const; 85 constexpr span<element_type, dynamic_extent> last(size_type count) const; 86 constexpr span<element_type, dynamic_extent> subspan(size_type offset, size_type count = dynamic_extent) const; 87 88 // [span.obs], span observers 89 constexpr size_type size() const noexcept; 90 constexpr size_type size_bytes() const noexcept; 91 [[nodiscard]] constexpr bool empty() const noexcept; 92 93 // [span.elem], span element access 94 constexpr reference operator[](size_type idx) const; 95 constexpr reference front() const; 96 constexpr reference back() const; 97 constexpr pointer data() const noexcept; 98 99 // [span.iterators], span iterator support 100 constexpr iterator begin() const noexcept; 101 constexpr iterator end() const noexcept; 102 constexpr reverse_iterator rbegin() const noexcept; 103 constexpr reverse_iterator rend() const noexcept; 104 105private: 106 pointer data_; // exposition only 107 size_type size_; // exposition only 108}; 109 110template<class It, class EndOrSize> 111 span(It, EndOrSize) -> span<remove_reference_t<iter_reference_t<_It>>>; 112 113template<class T, size_t N> 114 span(T (&)[N]) -> span<T, N>; 115 116template<class T, size_t N> 117 span(array<T, N>&) -> span<T, N>; 118 119template<class T, size_t N> 120 span(const array<T, N>&) -> span<const T, N>; 121 122template<class R> 123 span(R&&) -> span<remove_reference_t<ranges::range_reference_t<R>>>; 124 125} // namespace std 126 127*/ 128 129#include <__assert> // all public C++ headers provide the assertion handler 130#include <__config> 131#include <__fwd/span.h> 132#include <__iterator/bounded_iter.h> 133#include <__iterator/concepts.h> 134#include <__iterator/iterator_traits.h> 135#include <__iterator/wrap_iter.h> 136#include <__memory/pointer_traits.h> 137#include <__ranges/concepts.h> 138#include <__ranges/data.h> 139#include <__ranges/enable_borrowed_range.h> 140#include <__ranges/enable_view.h> 141#include <__ranges/size.h> 142#include <__type_traits/is_convertible.h> 143#include <__type_traits/remove_cvref.h> 144#include <__type_traits/remove_reference.h> 145#include <__type_traits/type_identity.h> 146#include <__utility/forward.h> 147#include <array> // for array 148#include <cstddef> // for byte 149#include <version> 150 151// standard-mandated includes 152 153// [iterator.range] 154#include <__iterator/access.h> 155#include <__iterator/data.h> 156#include <__iterator/empty.h> 157#include <__iterator/reverse_access.h> 158#include <__iterator/size.h> 159 160#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 161# pragma GCC system_header 162#endif 163 164_LIBCPP_PUSH_MACROS 165#include <__undef_macros> 166 167_LIBCPP_BEGIN_NAMESPACE_STD 168 169#if _LIBCPP_STD_VER >= 20 170 171template <class _Tp> 172struct __is_std_array : false_type {}; 173 174template <class _Tp, size_t _Sz> 175struct __is_std_array<array<_Tp, _Sz>> : true_type {}; 176 177template <class _Tp> 178struct __is_std_span : false_type {}; 179 180template <class _Tp, size_t _Sz> 181struct __is_std_span<span<_Tp, _Sz>> : true_type {}; 182 183template <class _Range, class _ElementType> 184concept __span_compatible_range = 185 ranges::contiguous_range<_Range> && // 186 ranges::sized_range<_Range> && // 187 (ranges::borrowed_range<_Range> || is_const_v<_ElementType>) && // 188 !__is_std_span<remove_cvref_t<_Range>>::value && // 189 !__is_std_array<remove_cvref_t<_Range>>::value && // 190 !is_array_v<remove_cvref_t<_Range>> && // 191 is_convertible_v<remove_reference_t<ranges::range_reference_t<_Range>>(*)[], _ElementType(*)[]>; 192 193template <class _From, class _To> 194concept __span_array_convertible = is_convertible_v<_From(*)[], _To(*)[]>; 195 196template <class _It, class _Tp> 197concept __span_compatible_iterator = contiguous_iterator<_It> && __span_array_convertible<remove_reference_t<iter_reference_t<_It>>, _Tp>; 198 199template <class _Sentinel, class _It> 200concept __span_compatible_sentinel_for = sized_sentinel_for<_Sentinel, _It> && !is_convertible_v<_Sentinel, size_t>; 201 202template <typename _Tp, size_t _Extent> 203class _LIBCPP_TEMPLATE_VIS span { 204public: 205// constants and types 206 using element_type = _Tp; 207 using value_type = remove_cv_t<_Tp>; 208 using size_type = size_t; 209 using difference_type = ptrdiff_t; 210 using pointer = _Tp *; 211 using const_pointer = const _Tp *; 212 using reference = _Tp &; 213 using const_reference = const _Tp &; 214#ifdef _LIBCPP_ABI_BOUNDED_ITERATORS 215 using iterator = __bounded_iter<pointer>; 216#else 217 using iterator = __wrap_iter<pointer>; 218#endif 219 using reverse_iterator = std::reverse_iterator<iterator>; 220 221 static constexpr size_type extent = _Extent; 222 223// [span.cons], span constructors, copy, assignment, and destructor 224 template <size_t _Sz = _Extent> requires(_Sz == 0) 225 _LIBCPP_HIDE_FROM_ABI constexpr span() noexcept : __data_{nullptr} {} 226 227 constexpr span (const span&) noexcept = default; 228 constexpr span& operator=(const span&) noexcept = default; 229 230 template <__span_compatible_iterator<element_type> _It> 231 _LIBCPP_HIDE_FROM_ABI 232 constexpr explicit span(_It __first, size_type __count) 233 : __data_{std::to_address(__first)} { 234 (void)__count; 235 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(_Extent == __count, "size mismatch in span's constructor (iterator, len)"); 236 } 237 238 template <__span_compatible_iterator<element_type> _It, __span_compatible_sentinel_for<_It> _End> 239 _LIBCPP_HIDE_FROM_ABI 240 constexpr explicit span(_It __first, _End __last) : __data_{std::to_address(__first)} { 241 // [span.cons]/10 242 // Throws: When and what last - first throws. 243 [[maybe_unused]] auto __dist = __last - __first; 244 _LIBCPP_ASSERT_VALID_INPUT_RANGE(__dist >= 0, "invalid range in span's constructor (iterator, sentinel)"); 245 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 246 __dist == _Extent, "invalid range in span's constructor (iterator, sentinel): last - first != extent"); 247 } 248 249 _LIBCPP_HIDE_FROM_ABI constexpr span(type_identity_t<element_type> (&__arr)[_Extent]) noexcept : __data_{__arr} {} 250 251 template <__span_array_convertible<element_type> _OtherElementType> 252 _LIBCPP_HIDE_FROM_ABI 253 constexpr span(array<_OtherElementType, _Extent>& __arr) noexcept : __data_{__arr.data()} {} 254 255 template <class _OtherElementType> 256 requires __span_array_convertible<const _OtherElementType, element_type> 257 _LIBCPP_HIDE_FROM_ABI 258 constexpr span(const array<_OtherElementType, _Extent>& __arr) noexcept : __data_{__arr.data()} {} 259 260 template <__span_compatible_range<element_type> _Range> 261 _LIBCPP_HIDE_FROM_ABI 262 constexpr explicit span(_Range&& __r) : __data_{ranges::data(__r)} { 263 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 264 ranges::size(__r) == _Extent, "size mismatch in span's constructor (range)"); 265 } 266 267 template <__span_array_convertible<element_type> _OtherElementType> 268 _LIBCPP_HIDE_FROM_ABI 269 constexpr span(const span<_OtherElementType, _Extent>& __other) 270 : __data_{__other.data()} {} 271 272 template <__span_array_convertible<element_type> _OtherElementType> 273 _LIBCPP_HIDE_FROM_ABI 274 constexpr explicit span(const span<_OtherElementType, dynamic_extent>& __other) noexcept 275 : __data_{__other.data()} { 276 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 277 _Extent == __other.size(), "size mismatch in span's constructor (other span)"); 278 } 279 280 template <size_t _Count> 281 _LIBCPP_HIDE_FROM_ABI 282 constexpr span<element_type, _Count> first() const noexcept 283 { 284 static_assert(_Count <= _Extent, "span<T, N>::first<Count>(): Count out of range"); 285 return span<element_type, _Count>{data(), _Count}; 286 } 287 288 template <size_t _Count> 289 _LIBCPP_HIDE_FROM_ABI 290 constexpr span<element_type, _Count> last() const noexcept 291 { 292 static_assert(_Count <= _Extent, "span<T, N>::last<Count>(): Count out of range"); 293 return span<element_type, _Count>{data() + size() - _Count, _Count}; 294 } 295 296 _LIBCPP_HIDE_FROM_ABI 297 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 298 { 299 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__count <= size(), "span<T, N>::first(count): count out of range"); 300 return {data(), __count}; 301 } 302 303 _LIBCPP_HIDE_FROM_ABI 304 constexpr span<element_type, dynamic_extent> last(size_type __count) const noexcept 305 { 306 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__count <= size(), "span<T, N>::last(count): count out of range"); 307 return {data() + size() - __count, __count}; 308 } 309 310 template <size_t _Offset, size_t _Count = dynamic_extent> 311 _LIBCPP_HIDE_FROM_ABI 312 constexpr auto subspan() const noexcept 313 -> span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset> 314 { 315 static_assert(_Offset <= _Extent, "span<T, N>::subspan<Offset, Count>(): Offset out of range"); 316 static_assert(_Count == dynamic_extent || _Count <= _Extent - _Offset, "span<T, N>::subspan<Offset, Count>(): Offset + Count out of range"); 317 318 using _ReturnType = span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset>; 319 return _ReturnType{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 320 } 321 322 323 _LIBCPP_HIDE_FROM_ABI 324 constexpr span<element_type, dynamic_extent> 325 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 326 { 327 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 328 __offset <= size(), "span<T, N>::subspan(offset, count): offset out of range"); 329 if (__count == dynamic_extent) 330 return {data() + __offset, size() - __offset}; 331 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 332 __count <= size() - __offset, "span<T, N>::subspan(offset, count): offset + count out of range"); 333 return {data() + __offset, __count}; 334 } 335 336 _LIBCPP_HIDE_FROM_ABI constexpr size_type size() const noexcept { return _Extent; } 337 _LIBCPP_HIDE_FROM_ABI constexpr size_type size_bytes() const noexcept { return _Extent * sizeof(element_type); } 338 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool empty() const noexcept { return _Extent == 0; } 339 340 _LIBCPP_HIDE_FROM_ABI constexpr reference operator[](size_type __idx) const noexcept 341 { 342 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__idx < size(), "span<T, N>::operator[](index): index out of range"); 343 return __data_[__idx]; 344 } 345 346 _LIBCPP_HIDE_FROM_ABI constexpr reference front() const noexcept 347 { 348 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "span<T, N>::front() on empty span"); 349 return __data_[0]; 350 } 351 352 _LIBCPP_HIDE_FROM_ABI constexpr reference back() const noexcept 353 { 354 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "span<T, N>::back() on empty span"); 355 return __data_[size()-1]; 356 } 357 358 _LIBCPP_HIDE_FROM_ABI constexpr pointer data() const noexcept { return __data_; } 359 360// [span.iter], span iterator support 361 _LIBCPP_HIDE_FROM_ABI constexpr iterator begin() const noexcept { 362#ifdef _LIBCPP_ABI_BOUNDED_ITERATORS 363 return std::__make_bounded_iter(data(), data(), data() + size()); 364#else 365 return iterator(data()); 366#endif 367 } 368 _LIBCPP_HIDE_FROM_ABI constexpr iterator end() const noexcept { 369#ifdef _LIBCPP_ABI_BOUNDED_ITERATORS 370 return std::__make_bounded_iter(data() + size(), data(), data() + size()); 371#else 372 return iterator(data() + size()); 373#endif 374 } 375 _LIBCPP_HIDE_FROM_ABI constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 376 _LIBCPP_HIDE_FROM_ABI constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 377 378 _LIBCPP_HIDE_FROM_ABI 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_HIDE_FROM_ABI 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_ABI_BOUNDED_ITERATORS 402 using iterator = __bounded_iter<pointer>; 403#else 404 using iterator = __wrap_iter<pointer>; 405#endif 406 using reverse_iterator = std::reverse_iterator<iterator>; 407 408 static constexpr size_type extent = dynamic_extent; 409 410// [span.cons], span constructors, copy, assignment, and destructor 411 _LIBCPP_HIDE_FROM_ABI 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_HIDE_FROM_ABI 418 constexpr span(_It __first, size_type __count) 419 : __data_{std::to_address(__first)}, __size_{__count} {} 420 421 template <__span_compatible_iterator<element_type> _It, __span_compatible_sentinel_for<_It> _End> 422 _LIBCPP_HIDE_FROM_ABI constexpr span(_It __first, _End __last) 423 : __data_(std::to_address(__first)), __size_(__last - __first) { 424 _LIBCPP_ASSERT_VALID_INPUT_RANGE( 425 __last - __first >= 0, "invalid range in span's constructor (iterator, sentinel)"); 426 } 427 428 template <size_t _Sz> 429 _LIBCPP_HIDE_FROM_ABI 430 constexpr span(type_identity_t<element_type> (&__arr)[_Sz]) noexcept : __data_{__arr}, __size_{_Sz} {} 431 432 template <__span_array_convertible<element_type> _OtherElementType, size_t _Sz> 433 _LIBCPP_HIDE_FROM_ABI 434 constexpr span(array<_OtherElementType, _Sz>& __arr) noexcept : __data_{__arr.data()}, __size_{_Sz} {} 435 436 template <class _OtherElementType, size_t _Sz> 437 requires __span_array_convertible<const _OtherElementType, element_type> 438 _LIBCPP_HIDE_FROM_ABI 439 constexpr span(const array<_OtherElementType, _Sz>& __arr) noexcept : __data_{__arr.data()}, __size_{_Sz} {} 440 441 template <__span_compatible_range<element_type> _Range> 442 _LIBCPP_HIDE_FROM_ABI 443 constexpr span(_Range&& __r) : __data_(ranges::data(__r)), __size_{ranges::size(__r)} {} 444 445 template <__span_array_convertible<element_type> _OtherElementType, size_t _OtherExtent> 446 _LIBCPP_HIDE_FROM_ABI 447 constexpr span(const span<_OtherElementType, _OtherExtent>& __other) noexcept 448 : __data_{__other.data()}, __size_{__other.size()} {} 449 450 template <size_t _Count> 451 _LIBCPP_HIDE_FROM_ABI 452 constexpr span<element_type, _Count> first() const noexcept 453 { 454 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(_Count <= size(), "span<T>::first<Count>(): Count out of range"); 455 return span<element_type, _Count>{data(), _Count}; 456 } 457 458 template <size_t _Count> 459 _LIBCPP_HIDE_FROM_ABI 460 constexpr span<element_type, _Count> last() const noexcept 461 { 462 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(_Count <= size(), "span<T>::last<Count>(): Count out of range"); 463 return span<element_type, _Count>{data() + size() - _Count, _Count}; 464 } 465 466 _LIBCPP_HIDE_FROM_ABI 467 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 468 { 469 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__count <= size(), "span<T>::first(count): count out of range"); 470 return {data(), __count}; 471 } 472 473 _LIBCPP_HIDE_FROM_ABI 474 constexpr span<element_type, dynamic_extent> last (size_type __count) const noexcept 475 { 476 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__count <= size(), "span<T>::last(count): count out of range"); 477 return {data() + size() - __count, __count}; 478 } 479 480 template <size_t _Offset, size_t _Count = dynamic_extent> 481 _LIBCPP_HIDE_FROM_ABI 482 constexpr span<element_type, _Count> subspan() const noexcept 483 { 484 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 485 _Offset <= size(), "span<T>::subspan<Offset, Count>(): Offset out of range"); 486 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(_Count == dynamic_extent || _Count <= size() - _Offset, 487 "span<T>::subspan<Offset, Count>(): Offset + Count out of range"); 488 return span<element_type, _Count>{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 489 } 490 491 constexpr span<element_type, dynamic_extent> 492 _LIBCPP_HIDE_FROM_ABI 493 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 494 { 495 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__offset <= size(), "span<T>::subspan(offset, count): offset out of range"); 496 if (__count == dynamic_extent) 497 return {data() + __offset, size() - __offset}; 498 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 499 __count <= size() - __offset, "span<T>::subspan(offset, count): offset + count out of range"); 500 return {data() + __offset, __count}; 501 } 502 503 _LIBCPP_HIDE_FROM_ABI constexpr size_type size() const noexcept { return __size_; } 504 _LIBCPP_HIDE_FROM_ABI constexpr size_type size_bytes() const noexcept { return __size_ * sizeof(element_type); } 505 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool empty() const noexcept { return __size_ == 0; } 506 507 _LIBCPP_HIDE_FROM_ABI constexpr reference operator[](size_type __idx) const noexcept 508 { 509 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__idx < size(), "span<T>::operator[](index): index out of range"); 510 return __data_[__idx]; 511 } 512 513 _LIBCPP_HIDE_FROM_ABI constexpr reference front() const noexcept 514 { 515 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "span<T>::front() on empty span"); 516 return __data_[0]; 517 } 518 519 _LIBCPP_HIDE_FROM_ABI constexpr reference back() const noexcept 520 { 521 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "span<T>::back() on empty span"); 522 return __data_[size()-1]; 523 } 524 525 526 _LIBCPP_HIDE_FROM_ABI constexpr pointer data() const noexcept { return __data_; } 527 528// [span.iter], span iterator support 529 _LIBCPP_HIDE_FROM_ABI constexpr iterator begin() const noexcept { 530#ifdef _LIBCPP_ABI_BOUNDED_ITERATORS 531 return std::__make_bounded_iter(data(), data(), data() + size()); 532#else 533 return iterator(data()); 534#endif 535 } 536 _LIBCPP_HIDE_FROM_ABI constexpr iterator end() const noexcept { 537#ifdef _LIBCPP_ABI_BOUNDED_ITERATORS 538 return std::__make_bounded_iter(data() + size(), data(), data() + size()); 539#else 540 return iterator(data() + size()); 541#endif 542 } 543 _LIBCPP_HIDE_FROM_ABI constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 544 _LIBCPP_HIDE_FROM_ABI constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 545 546 _LIBCPP_HIDE_FROM_ABI span<const byte, dynamic_extent> __as_bytes() const noexcept 547 { return {reinterpret_cast<const byte *>(data()), size_bytes()}; } 548 549 _LIBCPP_HIDE_FROM_ABI span<byte, dynamic_extent> __as_writable_bytes() const noexcept 550 { return {reinterpret_cast<byte *>(data()), size_bytes()}; } 551 552private: 553 pointer __data_; 554 size_type __size_; 555}; 556 557template <class _Tp, size_t _Extent> 558inline constexpr bool ranges::enable_borrowed_range<span<_Tp, _Extent> > = true; 559 560template <class _ElementType, size_t _Extent> 561inline constexpr bool ranges::enable_view<span<_ElementType, _Extent>> = true; 562 563// as_bytes & as_writable_bytes 564template <class _Tp, size_t _Extent> 565_LIBCPP_HIDE_FROM_ABI 566auto as_bytes(span<_Tp, _Extent> __s) noexcept 567{ return __s.__as_bytes(); } 568 569template <class _Tp, size_t _Extent> requires(!is_const_v<_Tp>) 570_LIBCPP_HIDE_FROM_ABI 571auto as_writable_bytes(span<_Tp, _Extent> __s) noexcept 572{ return __s.__as_writable_bytes(); } 573 574#if _LIBCPP_STD_VER >= 20 575template<contiguous_iterator _It, class _EndOrSize> 576 span(_It, _EndOrSize) -> span<remove_reference_t<iter_reference_t<_It>>>; 577#endif // _LIBCPP_STD_VER >= 20 578 579template<class _Tp, size_t _Sz> 580 span(_Tp (&)[_Sz]) -> span<_Tp, _Sz>; 581 582template<class _Tp, size_t _Sz> 583 span(array<_Tp, _Sz>&) -> span<_Tp, _Sz>; 584 585template<class _Tp, size_t _Sz> 586 span(const array<_Tp, _Sz>&) -> span<const _Tp, _Sz>; 587 588template<ranges::contiguous_range _Range> 589 span(_Range&&) -> span<remove_reference_t<ranges::range_reference_t<_Range>>>; 590 591#endif // _LIBCPP_STD_VER >= 20 592 593_LIBCPP_END_NAMESPACE_STD 594 595_LIBCPP_POP_MACROS 596 597#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20 598# include <concepts> 599# include <functional> 600# include <iterator> 601# include <type_traits> 602#endif 603 604#endif // _LIBCPP_SPAN 605