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 <limits> 150#include <version> 151 152// standard-mandated includes 153 154// [iterator.range] 155#include <__iterator/access.h> 156#include <__iterator/data.h> 157#include <__iterator/empty.h> 158#include <__iterator/reverse_access.h> 159#include <__iterator/size.h> 160 161#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 162# pragma GCC system_header 163#endif 164 165_LIBCPP_PUSH_MACROS 166#include <__undef_macros> 167 168_LIBCPP_BEGIN_NAMESPACE_STD 169 170#if _LIBCPP_STD_VER >= 20 171 172template <class _Tp> 173struct __is_std_array : false_type {}; 174 175template <class _Tp, size_t _Sz> 176struct __is_std_array<array<_Tp, _Sz>> : true_type {}; 177 178template <class _Tp> 179struct __is_std_span : false_type {}; 180 181template <class _Tp, size_t _Sz> 182struct __is_std_span<span<_Tp, _Sz>> : true_type {}; 183 184template <class _Range, class _ElementType> 185concept __span_compatible_range = 186 ranges::contiguous_range<_Range> && 187 ranges::sized_range<_Range> && 188 (ranges::borrowed_range<_Range> || is_const_v<_ElementType>) && 189 !__is_std_span<remove_cvref_t<_Range>>::value && 190 !__is_std_array<remove_cvref_t<_Range>>::value && 191 !is_array_v<remove_cvref_t<_Range>> && 192 is_convertible_v<remove_reference_t<ranges::range_reference_t<_Range>>(*)[], _ElementType(*)[]>; 193 194template <class _From, class _To> 195concept __span_array_convertible = is_convertible_v<_From(*)[], _To(*)[]>; 196 197template <class _It, class _Tp> 198concept __span_compatible_iterator = contiguous_iterator<_It> && __span_array_convertible<remove_reference_t<iter_reference_t<_It>>, _Tp>; 199 200template <class _Sentinel, class _It> 201concept __span_compatible_sentinel_for = sized_sentinel_for<_Sentinel, _It> && !is_convertible_v<_Sentinel, size_t>; 202 203template <typename _Tp, size_t _Extent> 204class _LIBCPP_TEMPLATE_VIS span { 205public: 206// constants and types 207 using element_type = _Tp; 208 using value_type = remove_cv_t<_Tp>; 209 using size_type = size_t; 210 using difference_type = ptrdiff_t; 211 using pointer = _Tp *; 212 using const_pointer = const _Tp *; 213 using reference = _Tp &; 214 using const_reference = const _Tp &; 215#ifdef _LIBCPP_ABI_BOUNDED_ITERATORS 216 using iterator = __bounded_iter<pointer>; 217#else 218 using iterator = __wrap_iter<pointer>; 219#endif 220 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 221 222 static constexpr size_type extent = _Extent; 223 224// [span.cons], span constructors, copy, assignment, and destructor 225 template <size_t _Sz = _Extent> requires(_Sz == 0) 226 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data_{nullptr} {} 227 228 constexpr span (const span&) noexcept = default; 229 constexpr span& operator=(const span&) noexcept = default; 230 231 template <__span_compatible_iterator<element_type> _It> 232 _LIBCPP_INLINE_VISIBILITY 233 constexpr explicit span(_It __first, size_type __count) 234 : __data_{_VSTD::to_address(__first)} { 235 (void)__count; 236 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(_Extent == __count, "size mismatch in span's constructor (iterator, len)"); 237 } 238 239 template <__span_compatible_iterator<element_type> _It, __span_compatible_sentinel_for<_It> _End> 240 _LIBCPP_INLINE_VISIBILITY 241 constexpr explicit span(_It __first, _End __last) : __data_{_VSTD::to_address(__first)} { 242 // [span.cons]/10 243 // Throws: When and what last - first throws. 244 [[maybe_unused]] auto __dist = __last - __first; 245 _LIBCPP_ASSERT_VALID_INPUT_RANGE(__dist >= 0, "invalid range in span's constructor (iterator, sentinel)"); 246 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 247 __dist == _Extent, "invalid range in span's constructor (iterator, sentinel): last - first != extent"); 248 } 249 250 _LIBCPP_INLINE_VISIBILITY constexpr span(type_identity_t<element_type> (&__arr)[_Extent]) noexcept : __data_{__arr} {} 251 252 template <__span_array_convertible<element_type> _OtherElementType> 253 _LIBCPP_INLINE_VISIBILITY 254 constexpr span(array<_OtherElementType, _Extent>& __arr) noexcept : __data_{__arr.data()} {} 255 256 template <class _OtherElementType> 257 requires __span_array_convertible<const _OtherElementType, element_type> 258 _LIBCPP_INLINE_VISIBILITY 259 constexpr span(const array<_OtherElementType, _Extent>& __arr) noexcept : __data_{__arr.data()} {} 260 261 template <__span_compatible_range<element_type> _Range> 262 _LIBCPP_INLINE_VISIBILITY 263 constexpr explicit span(_Range&& __r) : __data_{ranges::data(__r)} { 264 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 265 ranges::size(__r) == _Extent, "size mismatch in span's constructor (range)"); 266 } 267 268 template <__span_array_convertible<element_type> _OtherElementType> 269 _LIBCPP_INLINE_VISIBILITY 270 constexpr span(const span<_OtherElementType, _Extent>& __other) 271 : __data_{__other.data()} {} 272 273 template <__span_array_convertible<element_type> _OtherElementType> 274 _LIBCPP_INLINE_VISIBILITY 275 constexpr explicit span(const span<_OtherElementType, dynamic_extent>& __other) noexcept 276 : __data_{__other.data()} { 277 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 278 _Extent == __other.size(), "size mismatch in span's constructor (other span)"); 279 } 280 281 template <size_t _Count> 282 _LIBCPP_INLINE_VISIBILITY 283 constexpr span<element_type, _Count> first() const noexcept 284 { 285 static_assert(_Count <= _Extent, "span<T, N>::first<Count>(): Count out of range"); 286 return span<element_type, _Count>{data(), _Count}; 287 } 288 289 template <size_t _Count> 290 _LIBCPP_INLINE_VISIBILITY 291 constexpr span<element_type, _Count> last() const noexcept 292 { 293 static_assert(_Count <= _Extent, "span<T, N>::last<Count>(): Count out of range"); 294 return span<element_type, _Count>{data() + size() - _Count, _Count}; 295 } 296 297 _LIBCPP_INLINE_VISIBILITY 298 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 299 { 300 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__count <= size(), "span<T, N>::first(count): count out of range"); 301 return {data(), __count}; 302 } 303 304 _LIBCPP_INLINE_VISIBILITY 305 constexpr span<element_type, dynamic_extent> last(size_type __count) const noexcept 306 { 307 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__count <= size(), "span<T, N>::last(count): count out of range"); 308 return {data() + size() - __count, __count}; 309 } 310 311 template <size_t _Offset, size_t _Count = dynamic_extent> 312 _LIBCPP_INLINE_VISIBILITY 313 constexpr auto subspan() const noexcept 314 -> span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset> 315 { 316 static_assert(_Offset <= _Extent, "span<T, N>::subspan<Offset, Count>(): Offset out of range"); 317 static_assert(_Count == dynamic_extent || _Count <= _Extent - _Offset, "span<T, N>::subspan<Offset, Count>(): Offset + Count out of range"); 318 319 using _ReturnType = span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset>; 320 return _ReturnType{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 321 } 322 323 324 _LIBCPP_INLINE_VISIBILITY 325 constexpr span<element_type, dynamic_extent> 326 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 327 { 328 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 329 __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_VALID_ELEMENT_ACCESS( 333 __count <= size() - __offset, "span<T, N>::subspan(offset, count): offset + count out of range"); 334 return {data() + __offset, __count}; 335 } 336 337 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return _Extent; } 338 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return _Extent * sizeof(element_type); } 339 [[nodiscard]] _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return _Extent == 0; } 340 341 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 342 { 343 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__idx < size(), "span<T, N>::operator[](index): index out of range"); 344 return __data_[__idx]; 345 } 346 347 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 348 { 349 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "span<T, N>::front() on empty span"); 350 return __data_[0]; 351 } 352 353 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 354 { 355 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "span<T, N>::back() on empty span"); 356 return __data_[size()-1]; 357 } 358 359 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data_; } 360 361// [span.iter], span iterator support 362 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { 363#ifdef _LIBCPP_ABI_BOUNDED_ITERATORS 364 return std::__make_bounded_iter(data(), data(), data() + size()); 365#else 366 return iterator(data()); 367#endif 368 } 369 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { 370#ifdef _LIBCPP_ABI_BOUNDED_ITERATORS 371 return std::__make_bounded_iter(data() + size(), data(), data() + size()); 372#else 373 return iterator(data() + size()); 374#endif 375 } 376 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 377 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 378 379 _LIBCPP_INLINE_VISIBILITY span<const byte, _Extent * sizeof(element_type)> __as_bytes() const noexcept 380 { return span<const byte, _Extent * sizeof(element_type)>{reinterpret_cast<const byte *>(data()), size_bytes()}; } 381 382 _LIBCPP_INLINE_VISIBILITY span<byte, _Extent * sizeof(element_type)> __as_writable_bytes() const noexcept 383 { return span<byte, _Extent * sizeof(element_type)>{reinterpret_cast<byte *>(data()), size_bytes()}; } 384 385private: 386 pointer __data_; 387}; 388 389 390template <typename _Tp> 391class _LIBCPP_TEMPLATE_VIS span<_Tp, dynamic_extent> { 392public: 393// constants and types 394 using element_type = _Tp; 395 using value_type = remove_cv_t<_Tp>; 396 using size_type = size_t; 397 using difference_type = ptrdiff_t; 398 using pointer = _Tp *; 399 using const_pointer = const _Tp *; 400 using reference = _Tp &; 401 using const_reference = const _Tp &; 402#ifdef _LIBCPP_ABI_BOUNDED_ITERATORS 403 using iterator = __bounded_iter<pointer>; 404#else 405 using iterator = __wrap_iter<pointer>; 406#endif 407 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 408 409 static constexpr size_type extent = dynamic_extent; 410 411// [span.cons], span constructors, copy, assignment, and destructor 412 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data_{nullptr}, __size_{0} {} 413 414 constexpr span (const span&) noexcept = default; 415 constexpr span& operator=(const span&) noexcept = default; 416 417 template <__span_compatible_iterator<element_type> _It> 418 _LIBCPP_INLINE_VISIBILITY 419 constexpr span(_It __first, size_type __count) 420 : __data_{_VSTD::to_address(__first)}, __size_{__count} {} 421 422 template <__span_compatible_iterator<element_type> _It, __span_compatible_sentinel_for<_It> _End> 423 _LIBCPP_INLINE_VISIBILITY constexpr span(_It __first, _End __last) 424 : __data_(_VSTD::to_address(__first)), __size_(__last - __first) { 425 _LIBCPP_ASSERT_VALID_INPUT_RANGE( 426 __last - __first >= 0, "invalid range in span's constructor (iterator, sentinel)"); 427 } 428 429 template <size_t _Sz> 430 _LIBCPP_INLINE_VISIBILITY 431 constexpr span(type_identity_t<element_type> (&__arr)[_Sz]) noexcept : __data_{__arr}, __size_{_Sz} {} 432 433 template <__span_array_convertible<element_type> _OtherElementType, size_t _Sz> 434 _LIBCPP_INLINE_VISIBILITY 435 constexpr span(array<_OtherElementType, _Sz>& __arr) noexcept : __data_{__arr.data()}, __size_{_Sz} {} 436 437 template <class _OtherElementType, size_t _Sz> 438 requires __span_array_convertible<const _OtherElementType, element_type> 439 _LIBCPP_INLINE_VISIBILITY 440 constexpr span(const array<_OtherElementType, _Sz>& __arr) noexcept : __data_{__arr.data()}, __size_{_Sz} {} 441 442 template <__span_compatible_range<element_type> _Range> 443 _LIBCPP_INLINE_VISIBILITY 444 constexpr span(_Range&& __r) : __data_(ranges::data(__r)), __size_{ranges::size(__r)} {} 445 446 template <__span_array_convertible<element_type> _OtherElementType, size_t _OtherExtent> 447 _LIBCPP_INLINE_VISIBILITY 448 constexpr span(const span<_OtherElementType, _OtherExtent>& __other) noexcept 449 : __data_{__other.data()}, __size_{__other.size()} {} 450 451 template <size_t _Count> 452 _LIBCPP_INLINE_VISIBILITY 453 constexpr span<element_type, _Count> first() const noexcept 454 { 455 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(_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_VALID_ELEMENT_ACCESS(_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_VALID_ELEMENT_ACCESS(__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_VALID_ELEMENT_ACCESS(__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_VALID_ELEMENT_ACCESS( 486 _Offset <= size(), "span<T>::subspan<Offset, Count>(): Offset out of range"); 487 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(_Count == dynamic_extent || _Count <= size() - _Offset, 488 "span<T>::subspan<Offset, Count>(): Offset + Count out of range"); 489 return span<element_type, _Count>{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 490 } 491 492 constexpr span<element_type, dynamic_extent> 493 _LIBCPP_INLINE_VISIBILITY 494 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 495 { 496 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__offset <= size(), "span<T>::subspan(offset, count): offset out of range"); 497 if (__count == dynamic_extent) 498 return {data() + __offset, size() - __offset}; 499 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 500 __count <= size() - __offset, "span<T>::subspan(offset, count): offset + count out of range"); 501 return {data() + __offset, __count}; 502 } 503 504 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return __size_; } 505 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return __size_ * sizeof(element_type); } 506 [[nodiscard]] _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return __size_ == 0; } 507 508 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 509 { 510 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__idx < size(), "span<T>::operator[](index): index out of range"); 511 return __data_[__idx]; 512 } 513 514 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 515 { 516 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "span<T>::front() on empty span"); 517 return __data_[0]; 518 } 519 520 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 521 { 522 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "span<T>::back() on empty span"); 523 return __data_[size()-1]; 524 } 525 526 527 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data_; } 528 529// [span.iter], span iterator support 530 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { 531#ifdef _LIBCPP_ABI_BOUNDED_ITERATORS 532 return std::__make_bounded_iter(data(), data(), data() + size()); 533#else 534 return iterator(data()); 535#endif 536 } 537 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { 538#ifdef _LIBCPP_ABI_BOUNDED_ITERATORS 539 return std::__make_bounded_iter(data() + size(), data(), data() + size()); 540#else 541 return iterator(data() + size()); 542#endif 543 } 544 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 545 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 546 547 _LIBCPP_INLINE_VISIBILITY span<const byte, dynamic_extent> __as_bytes() const noexcept 548 { return {reinterpret_cast<const byte *>(data()), size_bytes()}; } 549 550 _LIBCPP_INLINE_VISIBILITY span<byte, dynamic_extent> __as_writable_bytes() const noexcept 551 { return {reinterpret_cast<byte *>(data()), size_bytes()}; } 552 553private: 554 pointer __data_; 555 size_type __size_; 556}; 557 558template <class _Tp, size_t _Extent> 559inline constexpr bool ranges::enable_borrowed_range<span<_Tp, _Extent> > = true; 560 561template <class _ElementType, size_t _Extent> 562inline constexpr bool ranges::enable_view<span<_ElementType, _Extent>> = true; 563 564// as_bytes & as_writable_bytes 565template <class _Tp, size_t _Extent> 566_LIBCPP_INLINE_VISIBILITY 567auto as_bytes(span<_Tp, _Extent> __s) noexcept 568{ return __s.__as_bytes(); } 569 570template <class _Tp, size_t _Extent> requires(!is_const_v<_Tp>) 571_LIBCPP_INLINE_VISIBILITY 572auto as_writable_bytes(span<_Tp, _Extent> __s) noexcept 573{ return __s.__as_writable_bytes(); } 574 575#if _LIBCPP_STD_VER >= 20 576template<contiguous_iterator _It, class _EndOrSize> 577 span(_It, _EndOrSize) -> span<remove_reference_t<iter_reference_t<_It>>>; 578#endif // _LIBCPP_STD_VER >= 20 579 580template<class _Tp, size_t _Sz> 581 span(_Tp (&)[_Sz]) -> span<_Tp, _Sz>; 582 583template<class _Tp, size_t _Sz> 584 span(array<_Tp, _Sz>&) -> span<_Tp, _Sz>; 585 586template<class _Tp, size_t _Sz> 587 span(const array<_Tp, _Sz>&) -> span<const _Tp, _Sz>; 588 589template<ranges::contiguous_range _Range> 590 span(_Range&&) -> span<remove_reference_t<ranges::range_reference_t<_Range>>>; 591 592#endif // _LIBCPP_STD_VER >= 20 593 594_LIBCPP_END_NAMESPACE_STD 595 596_LIBCPP_POP_MACROS 597 598#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20 599# include <concepts> 600# include <functional> 601# include <iterator> 602# include <type_traits> 603#endif 604 605#endif // _LIBCPP_SPAN 606