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> 131#include <__config> 132#include <__debug> 133#include <__iterator/concepts.h> 134#include <__iterator/wrap_iter.h> 135#include <__ranges/concepts.h> 136#include <__ranges/data.h> 137#include <__ranges/enable_borrowed_range.h> 138#include <__ranges/enable_view.h> 139#include <__ranges/size.h> 140#include <array> // for array 141#include <cstddef> // for byte 142#include <iterator> // for iterators 143#include <limits> 144#include <type_traits> // for remove_cv, etc 145#include <version> 146 147#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 148# pragma GCC system_header 149#endif 150 151_LIBCPP_PUSH_MACROS 152#include <__undef_macros> 153 154_LIBCPP_BEGIN_NAMESPACE_STD 155 156#if _LIBCPP_STD_VER > 17 157 158inline constexpr size_t dynamic_extent = numeric_limits<size_t>::max(); 159template <typename _Tp, size_t _Extent = dynamic_extent> class span; 160 161template <class _Tp> 162struct __is_std_array : false_type {}; 163 164template <class _Tp, size_t _Sz> 165struct __is_std_array<array<_Tp, _Sz>> : true_type {}; 166 167template <class _Tp> 168struct __is_std_span : false_type {}; 169 170template <class _Tp, size_t _Sz> 171struct __is_std_span<span<_Tp, _Sz>> : true_type {}; 172 173#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 174template <class _Range, class _ElementType> 175concept __span_compatible_range = 176 ranges::contiguous_range<_Range> && 177 ranges::sized_range<_Range> && 178 (ranges::borrowed_range<_Range> || is_const_v<_ElementType>) && 179 !__is_std_span<remove_cvref_t<_Range>>::value && 180 !__is_std_array<remove_cvref_t<_Range>>::value && 181 !is_array_v<remove_cvref_t<_Range>> && 182 is_convertible_v<remove_reference_t<ranges::range_reference_t<_Range>>(*)[], _ElementType(*)[]>; 183#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 184 185template <typename _Tp, size_t _Extent> 186class _LIBCPP_TEMPLATE_VIS span { 187public: 188// constants and types 189 using element_type = _Tp; 190 using value_type = remove_cv_t<_Tp>; 191 using size_type = size_t; 192 using difference_type = ptrdiff_t; 193 using pointer = _Tp *; 194 using const_pointer = const _Tp *; 195 using reference = _Tp &; 196 using const_reference = const _Tp &; 197#if (_LIBCPP_DEBUG_LEVEL == 2) || defined(_LIBCPP_ABI_SPAN_POINTER_ITERATORS) 198 using iterator = pointer; 199#else 200 using iterator = __wrap_iter<pointer>; 201#endif 202 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 203 204 static constexpr size_type extent = _Extent; 205 206// [span.cons], span constructors, copy, assignment, and destructor 207 template <size_t _Sz = _Extent, enable_if_t<_Sz == 0, nullptr_t> = nullptr> 208 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data{nullptr} {} 209 210 constexpr span (const span&) noexcept = default; 211 constexpr span& operator=(const span&) noexcept = default; 212 213 template <class _It, 214 enable_if_t<contiguous_iterator<_It> && 215 is_convertible_v<remove_reference_t<iter_reference_t<_It>>(*)[], element_type (*)[]>, 216 nullptr_t> = nullptr> 217 _LIBCPP_INLINE_VISIBILITY 218 constexpr explicit span(_It __first, size_type __count) 219 : __data{_VSTD::to_address(__first)} { 220 (void)__count; 221 _LIBCPP_ASSERT(_Extent == __count, "size mismatch in span's constructor (iterator, len)"); 222 } 223 224 template < 225 class _It, class _End, 226 enable_if_t<is_convertible_v<remove_reference_t<iter_reference_t<_It> > (*)[], element_type (*)[]> && 227 contiguous_iterator<_It> && sized_sentinel_for<_End, _It> && !is_convertible_v<_End, size_t>, 228 nullptr_t> = nullptr> 229 _LIBCPP_INLINE_VISIBILITY 230 constexpr explicit span(_It __first, _End __last) : __data{_VSTD::to_address(__first)} { 231 (void)__last; 232 _LIBCPP_ASSERT((__last - __first >= 0), "invalid range in span's constructor (iterator, sentinel)"); 233 _LIBCPP_ASSERT(__last - __first == _Extent, 234 "invalid range in span's constructor (iterator, sentinel): last - first != extent"); 235 } 236 237 _LIBCPP_INLINE_VISIBILITY constexpr span(type_identity_t<element_type> (&__arr)[_Extent]) noexcept : __data{__arr} {} 238 239 template <class _OtherElementType, 240 enable_if_t<is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 241 _LIBCPP_INLINE_VISIBILITY 242 constexpr span(array<_OtherElementType, _Extent>& __arr) noexcept : __data{__arr.data()} {} 243 244 template <class _OtherElementType, 245 enable_if_t<is_convertible_v<const _OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 246 _LIBCPP_INLINE_VISIBILITY 247 constexpr span(const array<_OtherElementType, _Extent>& __arr) noexcept : __data{__arr.data()} {} 248 249#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 250 template <__span_compatible_range<element_type> _Range> 251 _LIBCPP_INLINE_VISIBILITY 252 constexpr explicit span(_Range&& __r) : __data{ranges::data(__r)} { 253 _LIBCPP_ASSERT(ranges::size(__r) == _Extent, "size mismatch in span's constructor (range)"); 254 } 255#endif 256 257 template <class _OtherElementType> 258 _LIBCPP_INLINE_VISIBILITY 259 constexpr span(const span<_OtherElementType, _Extent>& __other, 260 enable_if_t< 261 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 262 nullptr_t> = nullptr) 263 : __data{__other.data()} {} 264 265 template <class _OtherElementType> 266 _LIBCPP_INLINE_VISIBILITY 267 constexpr explicit span(const span<_OtherElementType, dynamic_extent>& __other, 268 enable_if_t< 269 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 270 nullptr_t> = nullptr) noexcept 271 : __data{__other.data()} { _LIBCPP_ASSERT(_Extent == __other.size(), "size mismatch in span's constructor (other span)"); } 272 273 274// ~span() noexcept = default; 275 276 template <size_t _Count> 277 _LIBCPP_INLINE_VISIBILITY 278 constexpr span<element_type, _Count> first() const noexcept 279 { 280 static_assert(_Count <= _Extent, "Count out of range in span::first()"); 281 return span<element_type, _Count>{data(), _Count}; 282 } 283 284 template <size_t _Count> 285 _LIBCPP_INLINE_VISIBILITY 286 constexpr span<element_type, _Count> last() const noexcept 287 { 288 static_assert(_Count <= _Extent, "Count out of range in span::last()"); 289 return span<element_type, _Count>{data() + size() - _Count, _Count}; 290 } 291 292 _LIBCPP_INLINE_VISIBILITY 293 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 294 { 295 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::first(count)"); 296 return {data(), __count}; 297 } 298 299 _LIBCPP_INLINE_VISIBILITY 300 constexpr span<element_type, dynamic_extent> last(size_type __count) const noexcept 301 { 302 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::last(count)"); 303 return {data() + size() - __count, __count}; 304 } 305 306 template <size_t _Offset, size_t _Count = dynamic_extent> 307 _LIBCPP_INLINE_VISIBILITY 308 constexpr auto subspan() const noexcept 309 -> span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset> 310 { 311 static_assert(_Offset <= _Extent, "Offset out of range in span::subspan()"); 312 static_assert(_Count == dynamic_extent || _Count <= _Extent - _Offset, "Offset + count out of range in span::subspan()"); 313 314 using _ReturnType = span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset>; 315 return _ReturnType{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 316 } 317 318 319 _LIBCPP_INLINE_VISIBILITY 320 constexpr span<element_type, dynamic_extent> 321 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 322 { 323 _LIBCPP_ASSERT(__offset <= size(), "Offset out of range in span::subspan(offset, count)"); 324 _LIBCPP_ASSERT(__count <= size() || __count == dynamic_extent, "Count out of range in span::subspan(offset, count)"); 325 if (__count == dynamic_extent) 326 return {data() + __offset, size() - __offset}; 327 _LIBCPP_ASSERT(__count <= size() - __offset, "Offset + count out of range in span::subspan(offset, count)"); 328 return {data() + __offset, __count}; 329 } 330 331 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return _Extent; } 332 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return _Extent * sizeof(element_type); } 333 [[nodiscard]] _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return _Extent == 0; } 334 335 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 336 { 337 _LIBCPP_ASSERT(__idx < size(), "span<T,N>[] index out of bounds"); 338 return __data[__idx]; 339 } 340 341 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 342 { 343 _LIBCPP_ASSERT(!empty(), "span<T, N>::front() on empty span"); 344 return __data[0]; 345 } 346 347 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 348 { 349 _LIBCPP_ASSERT(!empty(), "span<T, N>::back() on empty span"); 350 return __data[size()-1]; 351 } 352 353 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; } 354 355// [span.iter], span iterator support 356 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { return iterator(data()); } 357 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { return iterator(data() + size()); } 358 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 359 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 360 361 _LIBCPP_INLINE_VISIBILITY span<const byte, _Extent * sizeof(element_type)> __as_bytes() const noexcept 362 { return span<const byte, _Extent * sizeof(element_type)>{reinterpret_cast<const byte *>(data()), size_bytes()}; } 363 364 _LIBCPP_INLINE_VISIBILITY span<byte, _Extent * sizeof(element_type)> __as_writable_bytes() const noexcept 365 { return span<byte, _Extent * sizeof(element_type)>{reinterpret_cast<byte *>(data()), size_bytes()}; } 366 367private: 368 pointer __data; 369 370}; 371 372 373template <typename _Tp> 374class _LIBCPP_TEMPLATE_VIS span<_Tp, dynamic_extent> { 375private: 376 377public: 378// constants and types 379 using element_type = _Tp; 380 using value_type = remove_cv_t<_Tp>; 381 using size_type = size_t; 382 using difference_type = ptrdiff_t; 383 using pointer = _Tp *; 384 using const_pointer = const _Tp *; 385 using reference = _Tp &; 386 using const_reference = const _Tp &; 387#if (_LIBCPP_DEBUG_LEVEL == 2) || defined(_LIBCPP_ABI_SPAN_POINTER_ITERATORS) 388 using iterator = pointer; 389#else 390 using iterator = __wrap_iter<pointer>; 391#endif 392 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 393 394 static constexpr size_type extent = dynamic_extent; 395 396// [span.cons], span constructors, copy, assignment, and destructor 397 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data{nullptr}, __size{0} {} 398 399 constexpr span (const span&) noexcept = default; 400 constexpr span& operator=(const span&) noexcept = default; 401 402 template <class _It, 403 enable_if_t<contiguous_iterator<_It> && 404 is_convertible_v<remove_reference_t<iter_reference_t<_It> > (*)[], element_type (*)[]>, 405 nullptr_t> = nullptr> 406 _LIBCPP_INLINE_VISIBILITY 407 constexpr span(_It __first, size_type __count) 408 : __data{_VSTD::to_address(__first)}, __size{__count} {} 409 410 template < 411 class _It, class _End, 412 enable_if_t<is_convertible_v<remove_reference_t<iter_reference_t<_It> > (*)[], element_type (*)[]> && 413 contiguous_iterator<_It> && sized_sentinel_for<_End, _It> && !is_convertible_v<_End, size_t>, 414 nullptr_t> = nullptr> 415 _LIBCPP_INLINE_VISIBILITY 416 constexpr span(_It __first, _End __last) 417 : __data(_VSTD::to_address(__first)), __size(__last - __first) {} 418 419 template <size_t _Sz> 420 _LIBCPP_INLINE_VISIBILITY 421 constexpr span(type_identity_t<element_type> (&__arr)[_Sz]) noexcept : __data{__arr}, __size{_Sz} {} 422 423 template <class _OtherElementType, size_t _Sz, 424 enable_if_t<is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 425 _LIBCPP_INLINE_VISIBILITY 426 constexpr span(array<_OtherElementType, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {} 427 428 template <class _OtherElementType, size_t _Sz, 429 enable_if_t<is_convertible_v<const _OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 430 _LIBCPP_INLINE_VISIBILITY 431 constexpr span(const array<_OtherElementType, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {} 432 433#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 434 template <__span_compatible_range<element_type> _Range> 435 _LIBCPP_INLINE_VISIBILITY 436 constexpr span(_Range&& __r) : __data(ranges::data(__r)), __size{ranges::size(__r)} {} 437#endif 438 439 template <class _OtherElementType, size_t _OtherExtent> 440 _LIBCPP_INLINE_VISIBILITY 441 constexpr span(const span<_OtherElementType, _OtherExtent>& __other, 442 enable_if_t< 443 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 444 nullptr_t> = nullptr) noexcept 445 : __data{__other.data()}, __size{__other.size()} {} 446 447// ~span() noexcept = default; 448 449 template <size_t _Count> 450 _LIBCPP_INLINE_VISIBILITY 451 constexpr span<element_type, _Count> first() const noexcept 452 { 453 _LIBCPP_ASSERT(_Count <= size(), "Count out of range in span::first()"); 454 return span<element_type, _Count>{data(), _Count}; 455 } 456 457 template <size_t _Count> 458 _LIBCPP_INLINE_VISIBILITY 459 constexpr span<element_type, _Count> last() const noexcept 460 { 461 _LIBCPP_ASSERT(_Count <= size(), "Count out of range in span::last()"); 462 return span<element_type, _Count>{data() + size() - _Count, _Count}; 463 } 464 465 _LIBCPP_INLINE_VISIBILITY 466 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 467 { 468 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::first(count)"); 469 return {data(), __count}; 470 } 471 472 _LIBCPP_INLINE_VISIBILITY 473 constexpr span<element_type, dynamic_extent> last (size_type __count) const noexcept 474 { 475 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::last(count)"); 476 return {data() + size() - __count, __count}; 477 } 478 479 template <size_t _Offset, size_t _Count = dynamic_extent> 480 _LIBCPP_INLINE_VISIBILITY 481 constexpr span<element_type, _Count> subspan() const noexcept 482 { 483 _LIBCPP_ASSERT(_Offset <= size(), "Offset out of range in span::subspan()"); 484 _LIBCPP_ASSERT(_Count == dynamic_extent || _Count <= size() - _Offset, "Offset + count out of range in span::subspan()"); 485 return span<element_type, _Count>{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 486 } 487 488 constexpr span<element_type, dynamic_extent> 489 _LIBCPP_INLINE_VISIBILITY 490 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 491 { 492 _LIBCPP_ASSERT(__offset <= size(), "Offset out of range in span::subspan(offset, count)"); 493 _LIBCPP_ASSERT(__count <= size() || __count == dynamic_extent, "count out of range in span::subspan(offset, count)"); 494 if (__count == dynamic_extent) 495 return {data() + __offset, size() - __offset}; 496 _LIBCPP_ASSERT(__count <= size() - __offset, "Offset + count out of range in span::subspan(offset, count)"); 497 return {data() + __offset, __count}; 498 } 499 500 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return __size; } 501 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return __size * sizeof(element_type); } 502 [[nodiscard]] _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return __size == 0; } 503 504 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 505 { 506 _LIBCPP_ASSERT(__idx < size(), "span<T>[] index out of bounds"); 507 return __data[__idx]; 508 } 509 510 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 511 { 512 _LIBCPP_ASSERT(!empty(), "span<T>[].front() on empty span"); 513 return __data[0]; 514 } 515 516 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 517 { 518 _LIBCPP_ASSERT(!empty(), "span<T>[].back() on empty span"); 519 return __data[size()-1]; 520 } 521 522 523 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; } 524 525// [span.iter], span iterator support 526 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { return iterator(data()); } 527 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { return iterator(data() + size()); } 528 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 529 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 530 531 _LIBCPP_INLINE_VISIBILITY span<const byte, dynamic_extent> __as_bytes() const noexcept 532 { return {reinterpret_cast<const byte *>(data()), size_bytes()}; } 533 534 _LIBCPP_INLINE_VISIBILITY span<byte, dynamic_extent> __as_writable_bytes() const noexcept 535 { return {reinterpret_cast<byte *>(data()), size_bytes()}; } 536 537private: 538 pointer __data; 539 size_type __size; 540}; 541 542template <class _Tp, size_t _Extent> 543inline constexpr bool ranges::enable_borrowed_range<span<_Tp, _Extent> > = true; 544 545template <class _ElementType, size_t _Extent> 546inline constexpr bool ranges::enable_view<span<_ElementType, _Extent>> = true; 547 548// as_bytes & as_writable_bytes 549template <class _Tp, size_t _Extent> 550_LIBCPP_INLINE_VISIBILITY 551auto as_bytes(span<_Tp, _Extent> __s) noexcept 552-> decltype(__s.__as_bytes()) 553{ return __s.__as_bytes(); } 554 555template <class _Tp, size_t _Extent> 556_LIBCPP_INLINE_VISIBILITY 557auto as_writable_bytes(span<_Tp, _Extent> __s) noexcept 558-> enable_if_t<!is_const_v<_Tp>, decltype(__s.__as_writable_bytes())> 559{ return __s.__as_writable_bytes(); } 560 561#if _LIBCPP_STD_VER > 17 562template<contiguous_iterator _It, class _EndOrSize> 563 span(_It, _EndOrSize) -> span<remove_reference_t<iter_reference_t<_It>>>; 564#endif // _LIBCPP_STD_VER > 17 565 566template<class _Tp, size_t _Sz> 567 span(_Tp (&)[_Sz]) -> span<_Tp, _Sz>; 568 569template<class _Tp, size_t _Sz> 570 span(array<_Tp, _Sz>&) -> span<_Tp, _Sz>; 571 572template<class _Tp, size_t _Sz> 573 span(const array<_Tp, _Sz>&) -> span<const _Tp, _Sz>; 574 575#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 576template<ranges::contiguous_range _Range> 577 span(_Range&&) -> span<remove_reference_t<ranges::range_reference_t<_Range>>>; 578#endif 579 580#endif // _LIBCPP_STD_VER > 17 581 582_LIBCPP_END_NAMESPACE_STD 583 584_LIBCPP_POP_MACROS 585 586#endif // _LIBCPP_SPAN 587