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; 160 161 162template <class _Tp> 163struct __is_std_array : false_type {}; 164 165template <class _Tp, size_t _Sz> 166struct __is_std_array<array<_Tp, _Sz>> : true_type {}; 167 168template <class _Tp> 169struct __is_std_span : false_type {}; 170 171template <class _Tp, size_t _Sz> 172struct __is_std_span<span<_Tp, _Sz>> : true_type {}; 173 174#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 175template <class _Range, class _ElementType> 176concept __span_compatible_range = 177 ranges::contiguous_range<_Range> && 178 ranges::sized_range<_Range> && 179 (ranges::borrowed_range<_Range> || is_const_v<_ElementType>) && 180 !__is_std_span<remove_cvref_t<_Range>>::value && 181 !__is_std_array<remove_cvref_t<_Range>>::value && 182 !is_array_v<remove_cvref_t<_Range>> && 183 is_convertible_v<remove_reference_t<ranges::range_reference_t<_Range>>(*)[], _ElementType(*)[]>; 184#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 185 186template <typename _Tp, size_t _Extent> 187class _LIBCPP_TEMPLATE_VIS span { 188public: 189// constants and types 190 using element_type = _Tp; 191 using value_type = remove_cv_t<_Tp>; 192 using size_type = size_t; 193 using difference_type = ptrdiff_t; 194 using pointer = _Tp *; 195 using const_pointer = const _Tp *; 196 using reference = _Tp &; 197 using const_reference = const _Tp &; 198#if (_LIBCPP_DEBUG_LEVEL == 2) || defined(_LIBCPP_ABI_SPAN_POINTER_ITERATORS) 199 using iterator = pointer; 200#else 201 using iterator = __wrap_iter<pointer>; 202#endif 203 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 204 205 static constexpr size_type extent = _Extent; 206 207// [span.cons], span constructors, copy, assignment, and destructor 208 template <size_t _Sz = _Extent, enable_if_t<_Sz == 0, nullptr_t> = nullptr> 209 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data{nullptr} {} 210 211 constexpr span (const span&) noexcept = default; 212 constexpr span& operator=(const span&) noexcept = default; 213 214#if _LIBCPP_STD_VER > 17 215 template <class _It, 216 enable_if_t<contiguous_iterator<_It> && 217 is_convertible_v<remove_reference_t<iter_reference_t<_It>>(*)[], element_type (*)[]>, 218 nullptr_t> = nullptr> 219 _LIBCPP_INLINE_VISIBILITY 220 constexpr explicit span(_It __first, size_type __count) 221 : __data{_VSTD::to_address(__first)} { 222 (void)__count; 223 _LIBCPP_ASSERT(_Extent == __count, "size mismatch in span's constructor (iterator, len)"); 224 } 225 226 template < 227 class _It, class _End, 228 enable_if_t<is_convertible_v<remove_reference_t<iter_reference_t<_It> > (*)[], element_type (*)[]> && 229 contiguous_iterator<_It> && sized_sentinel_for<_End, _It> && !is_convertible_v<_End, size_t>, 230 nullptr_t> = nullptr> 231 _LIBCPP_INLINE_VISIBILITY 232 constexpr explicit span(_It __first, _End __last) : __data{_VSTD::to_address(__first)} { 233 (void)__last; 234 _LIBCPP_ASSERT((__last - __first >= 0), "invalid range in span's constructor (iterator, sentinel)"); 235 _LIBCPP_ASSERT(__last - __first == _Extent, 236 "invalid range in span's constructor (iterator, sentinel): last - first != extent"); 237 } 238#endif // _LIBCPP_STD_VER > 17 239 240 _LIBCPP_INLINE_VISIBILITY constexpr span(type_identity_t<element_type> (&__arr)[_Extent]) noexcept : __data{__arr} {} 241 242 template <class _OtherElementType, 243 enable_if_t<is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 244 _LIBCPP_INLINE_VISIBILITY 245 constexpr span(array<_OtherElementType, _Extent>& __arr) noexcept : __data{__arr.data()} {} 246 247 template <class _OtherElementType, 248 enable_if_t<is_convertible_v<const _OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 249 _LIBCPP_INLINE_VISIBILITY 250 constexpr span(const array<_OtherElementType, _Extent>& __arr) noexcept : __data{__arr.data()} {} 251 252#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 253 template <__span_compatible_range<element_type> _Range> 254 _LIBCPP_INLINE_VISIBILITY 255 constexpr explicit span(_Range&& __r) : __data{ranges::data(__r)} { 256 _LIBCPP_ASSERT(ranges::size(__r) == _Extent, "size mismatch in span's constructor (range)"); 257 } 258#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 259 260 template <class _OtherElementType> 261 _LIBCPP_INLINE_VISIBILITY 262 constexpr span(const span<_OtherElementType, _Extent>& __other, 263 enable_if_t< 264 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 265 nullptr_t> = nullptr) 266 : __data{__other.data()} {} 267 268 template <class _OtherElementType> 269 _LIBCPP_INLINE_VISIBILITY 270 constexpr explicit span(const span<_OtherElementType, dynamic_extent>& __other, 271 enable_if_t< 272 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 273 nullptr_t> = nullptr) noexcept 274 : __data{__other.data()} { _LIBCPP_ASSERT(_Extent == __other.size(), "size mismatch in span's constructor (other span)"); } 275 276 277// ~span() noexcept = default; 278 279 template <size_t _Count> 280 _LIBCPP_INLINE_VISIBILITY 281 constexpr span<element_type, _Count> first() const noexcept 282 { 283 static_assert(_Count <= _Extent, "Count out of range in span::first()"); 284 return span<element_type, _Count>{data(), _Count}; 285 } 286 287 template <size_t _Count> 288 _LIBCPP_INLINE_VISIBILITY 289 constexpr span<element_type, _Count> last() const noexcept 290 { 291 static_assert(_Count <= _Extent, "Count out of range in span::last()"); 292 return span<element_type, _Count>{data() + size() - _Count, _Count}; 293 } 294 295 _LIBCPP_INLINE_VISIBILITY 296 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 297 { 298 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::first(count)"); 299 return {data(), __count}; 300 } 301 302 _LIBCPP_INLINE_VISIBILITY 303 constexpr span<element_type, dynamic_extent> last(size_type __count) const noexcept 304 { 305 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::last(count)"); 306 return {data() + size() - __count, __count}; 307 } 308 309 template <size_t _Offset, size_t _Count = dynamic_extent> 310 _LIBCPP_INLINE_VISIBILITY 311 constexpr auto subspan() const noexcept 312 -> span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset> 313 { 314 static_assert(_Offset <= _Extent, "Offset out of range in span::subspan()"); 315 static_assert(_Count == dynamic_extent || _Count <= _Extent - _Offset, "Offset + count out of range in span::subspan()"); 316 317 using _ReturnType = span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset>; 318 return _ReturnType{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 319 } 320 321 322 _LIBCPP_INLINE_VISIBILITY 323 constexpr span<element_type, dynamic_extent> 324 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 325 { 326 _LIBCPP_ASSERT(__offset <= size(), "Offset out of range in span::subspan(offset, count)"); 327 _LIBCPP_ASSERT(__count <= size() || __count == dynamic_extent, "Count out of range in span::subspan(offset, count)"); 328 if (__count == dynamic_extent) 329 return {data() + __offset, size() - __offset}; 330 _LIBCPP_ASSERT(__count <= size() - __offset, "Offset + count out of range in span::subspan(offset, count)"); 331 return {data() + __offset, __count}; 332 } 333 334 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return _Extent; } 335 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return _Extent * sizeof(element_type); } 336 [[nodiscard]] _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return _Extent == 0; } 337 338 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 339 { 340 _LIBCPP_ASSERT(__idx < size(), "span<T,N>[] index out of bounds"); 341 return __data[__idx]; 342 } 343 344 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 345 { 346 _LIBCPP_ASSERT(!empty(), "span<T, N>::front() on empty span"); 347 return __data[0]; 348 } 349 350 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 351 { 352 _LIBCPP_ASSERT(!empty(), "span<T, N>::back() on empty span"); 353 return __data[size()-1]; 354 } 355 356 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; } 357 358// [span.iter], span iterator support 359 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { return iterator(data()); } 360 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { return iterator(data() + size()); } 361 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 362 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 363 364 _LIBCPP_INLINE_VISIBILITY span<const byte, _Extent * sizeof(element_type)> __as_bytes() const noexcept 365 { return span<const byte, _Extent * sizeof(element_type)>{reinterpret_cast<const byte *>(data()), size_bytes()}; } 366 367 _LIBCPP_INLINE_VISIBILITY span<byte, _Extent * sizeof(element_type)> __as_writable_bytes() const noexcept 368 { return span<byte, _Extent * sizeof(element_type)>{reinterpret_cast<byte *>(data()), size_bytes()}; } 369 370private: 371 pointer __data; 372 373}; 374 375 376template <typename _Tp> 377class _LIBCPP_TEMPLATE_VIS span<_Tp, dynamic_extent> { 378private: 379 380public: 381// constants and types 382 using element_type = _Tp; 383 using value_type = remove_cv_t<_Tp>; 384 using size_type = size_t; 385 using difference_type = ptrdiff_t; 386 using pointer = _Tp *; 387 using const_pointer = const _Tp *; 388 using reference = _Tp &; 389 using const_reference = const _Tp &; 390#if (_LIBCPP_DEBUG_LEVEL == 2) || defined(_LIBCPP_ABI_SPAN_POINTER_ITERATORS) 391 using iterator = pointer; 392#else 393 using iterator = __wrap_iter<pointer>; 394#endif 395 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 396 397 static constexpr size_type extent = dynamic_extent; 398 399// [span.cons], span constructors, copy, assignment, and destructor 400 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data{nullptr}, __size{0} {} 401 402 constexpr span (const span&) noexcept = default; 403 constexpr span& operator=(const span&) noexcept = default; 404 405#if _LIBCPP_STD_VER > 17 406 template <class _It, 407 enable_if_t<contiguous_iterator<_It> && 408 is_convertible_v<remove_reference_t<iter_reference_t<_It> > (*)[], element_type (*)[]>, 409 nullptr_t> = nullptr> 410 _LIBCPP_INLINE_VISIBILITY 411 constexpr span(_It __first, size_type __count) 412 : __data{_VSTD::to_address(__first)}, __size{__count} {} 413 414 template < 415 class _It, class _End, 416 enable_if_t<is_convertible_v<remove_reference_t<iter_reference_t<_It> > (*)[], element_type (*)[]> && 417 contiguous_iterator<_It> && sized_sentinel_for<_End, _It> && !is_convertible_v<_End, size_t>, 418 nullptr_t> = nullptr> 419 _LIBCPP_INLINE_VISIBILITY 420 constexpr span(_It __first, _End __last) 421 : __data(_VSTD::to_address(__first)), __size(__last - __first) {} 422#endif // _LIBCPP_STD_VER > 17 423 424 template <size_t _Sz> 425 _LIBCPP_INLINE_VISIBILITY 426 constexpr span(type_identity_t<element_type> (&__arr)[_Sz]) noexcept : __data{__arr}, __size{_Sz} {} 427 428 template <class _OtherElementType, size_t _Sz, 429 enable_if_t<is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 430 _LIBCPP_INLINE_VISIBILITY 431 constexpr span(array<_OtherElementType, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {} 432 433 template <class _OtherElementType, size_t _Sz, 434 enable_if_t<is_convertible_v<const _OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 435 _LIBCPP_INLINE_VISIBILITY 436 constexpr span(const array<_OtherElementType, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {} 437 438#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 439 template <__span_compatible_range<element_type> _Range> 440 _LIBCPP_INLINE_VISIBILITY 441 constexpr span(_Range&& __r) : __data(ranges::data(__r)), __size{ranges::size(__r)} {} 442#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 443 444 template <class _OtherElementType, size_t _OtherExtent> 445 _LIBCPP_INLINE_VISIBILITY 446 constexpr span(const span<_OtherElementType, _OtherExtent>& __other, 447 enable_if_t< 448 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 449 nullptr_t> = nullptr) noexcept 450 : __data{__other.data()}, __size{__other.size()} {} 451 452// ~span() noexcept = default; 453 454 template <size_t _Count> 455 _LIBCPP_INLINE_VISIBILITY 456 constexpr span<element_type, _Count> first() const noexcept 457 { 458 _LIBCPP_ASSERT(_Count <= size(), "Count out of range in span::first()"); 459 return span<element_type, _Count>{data(), _Count}; 460 } 461 462 template <size_t _Count> 463 _LIBCPP_INLINE_VISIBILITY 464 constexpr span<element_type, _Count> last() const noexcept 465 { 466 _LIBCPP_ASSERT(_Count <= size(), "Count out of range in span::last()"); 467 return span<element_type, _Count>{data() + size() - _Count, _Count}; 468 } 469 470 _LIBCPP_INLINE_VISIBILITY 471 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 472 { 473 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::first(count)"); 474 return {data(), __count}; 475 } 476 477 _LIBCPP_INLINE_VISIBILITY 478 constexpr span<element_type, dynamic_extent> last (size_type __count) const noexcept 479 { 480 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::last(count)"); 481 return {data() + size() - __count, __count}; 482 } 483 484 template <size_t _Offset, size_t _Count = dynamic_extent> 485 _LIBCPP_INLINE_VISIBILITY 486 constexpr span<element_type, _Count> subspan() const noexcept 487 { 488 _LIBCPP_ASSERT(_Offset <= size(), "Offset out of range in span::subspan()"); 489 _LIBCPP_ASSERT(_Count == dynamic_extent || _Count <= size() - _Offset, "Offset + count out of range in span::subspan()"); 490 return span<element_type, _Count>{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 491 } 492 493 constexpr span<element_type, dynamic_extent> 494 _LIBCPP_INLINE_VISIBILITY 495 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 496 { 497 _LIBCPP_ASSERT(__offset <= size(), "Offset out of range in span::subspan(offset, count)"); 498 _LIBCPP_ASSERT(__count <= size() || __count == dynamic_extent, "count out of range in span::subspan(offset, count)"); 499 if (__count == dynamic_extent) 500 return {data() + __offset, size() - __offset}; 501 _LIBCPP_ASSERT(__count <= size() - __offset, "Offset + count out of range in span::subspan(offset, count)"); 502 return {data() + __offset, __count}; 503 } 504 505 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return __size; } 506 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return __size * sizeof(element_type); } 507 [[nodiscard]] _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return __size == 0; } 508 509 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 510 { 511 _LIBCPP_ASSERT(__idx < size(), "span<T>[] index out of bounds"); 512 return __data[__idx]; 513 } 514 515 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 516 { 517 _LIBCPP_ASSERT(!empty(), "span<T>[].front() on empty span"); 518 return __data[0]; 519 } 520 521 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 522 { 523 _LIBCPP_ASSERT(!empty(), "span<T>[].back() on empty span"); 524 return __data[size()-1]; 525 } 526 527 528 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; } 529 530// [span.iter], span iterator support 531 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { return iterator(data()); } 532 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { return iterator(data() + size()); } 533 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 534 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 535 536 _LIBCPP_INLINE_VISIBILITY span<const byte, dynamic_extent> __as_bytes() const noexcept 537 { return {reinterpret_cast<const byte *>(data()), size_bytes()}; } 538 539 _LIBCPP_INLINE_VISIBILITY span<byte, dynamic_extent> __as_writable_bytes() const noexcept 540 { return {reinterpret_cast<byte *>(data()), size_bytes()}; } 541 542private: 543 pointer __data; 544 size_type __size; 545}; 546 547#if _LIBCPP_STD_VER > 17 548template <class _Tp, size_t _Extent> 549inline constexpr bool ranges::enable_borrowed_range<span<_Tp, _Extent> > = true; 550 551template <class _ElementType, size_t _Extent> 552inline constexpr bool ranges::enable_view<span<_ElementType, _Extent>> = true; 553#endif // _LIBCPP_STD_VER > 17 554 555// as_bytes & as_writable_bytes 556template <class _Tp, size_t _Extent> 557_LIBCPP_INLINE_VISIBILITY 558auto as_bytes(span<_Tp, _Extent> __s) noexcept 559-> decltype(__s.__as_bytes()) 560{ return __s.__as_bytes(); } 561 562template <class _Tp, size_t _Extent> 563_LIBCPP_INLINE_VISIBILITY 564auto as_writable_bytes(span<_Tp, _Extent> __s) noexcept 565-> enable_if_t<!is_const_v<_Tp>, decltype(__s.__as_writable_bytes())> 566{ return __s.__as_writable_bytes(); } 567 568#if _LIBCPP_STD_VER > 17 569template<contiguous_iterator _It, class _EndOrSize> 570 span(_It, _EndOrSize) -> span<remove_reference_t<iter_reference_t<_It>>>; 571#endif // _LIBCPP_STD_VER > 17 572 573template<class _Tp, size_t _Sz> 574 span(_Tp (&)[_Sz]) -> span<_Tp, _Sz>; 575 576template<class _Tp, size_t _Sz> 577 span(array<_Tp, _Sz>&) -> span<_Tp, _Sz>; 578 579template<class _Tp, size_t _Sz> 580 span(const array<_Tp, _Sz>&) -> span<const _Tp, _Sz>; 581 582#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 583template<ranges::contiguous_range _Range> 584 span(_Range&&) -> span<remove_reference_t<ranges::range_reference_t<_Range>>>; 585#endif 586 587#endif // _LIBCPP_STD_VER > 17 588 589_LIBCPP_END_NAMESPACE_STD 590 591_LIBCPP_POP_MACROS 592 593#endif // _LIBCPP_SPAN 594