1// -*- C++ -*- 2//===------------------------------ span ---------------------------------===// 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_borrowed_range<span<ElementType, Extent>> = true; 27 28// [span.objectrep], views of object representation 29template <class ElementType, size_t Extent> 30 span<const byte, ((Extent == dynamic_extent) ? dynamic_extent : 31 (sizeof(ElementType) * Extent))> as_bytes(span<ElementType, Extent> s) noexcept; 32 33template <class ElementType, size_t Extent> 34 span< byte, ((Extent == dynamic_extent) ? dynamic_extent : 35 (sizeof(ElementType) * Extent))> as_writable_bytes(span<ElementType, Extent> s) noexcept; 36 37 38template <class ElementType, size_t Extent = dynamic_extent> 39class span { 40public: 41 // constants and types 42 using element_type = ElementType; 43 using value_type = remove_cv_t<ElementType>; 44 using size_type = size_t; 45 using difference_type = ptrdiff_t; 46 using pointer = element_type*; 47 using const_pointer = const element_type*; 48 using reference = element_type&; 49 using const_reference = const element_type&; 50 using iterator = implementation-defined; 51 using reverse_iterator = std::reverse_iterator<iterator>; 52 static constexpr size_type extent = Extent; 53 54 // [span.cons], span constructors, copy, assignment, and destructor 55 constexpr span() noexcept; 56 constexpr explicit(Extent != dynamic_extent) span(pointer ptr, size_type count); 57 constexpr explicit(Extent != dynamic_extent) span(pointer firstElem, pointer lastElem); 58 template <size_t N> 59 constexpr span(element_type (&arr)[N]) noexcept; 60 template <size_t N> 61 constexpr span(array<value_type, N>& arr) noexcept; 62 template <size_t N> 63 constexpr span(const array<value_type, N>& arr) noexcept; 64 template <class Container> 65 constexpr explicit(Extent != dynamic_extent) span(Container& cont); 66 template <class Container> 67 constexpr explicit(Extent != dynamic_extent) span(const Container& cont); 68 constexpr span(const span& other) noexcept = default; 69 template <class OtherElementType, size_t OtherExtent> 70 constexpr explicit(Extent != dynamic_extent) span(const span<OtherElementType, OtherExtent>& s) noexcept; 71 ~span() noexcept = default; 72 constexpr span& operator=(const span& other) noexcept = default; 73 74 // [span.sub], span subviews 75 template <size_t Count> 76 constexpr span<element_type, Count> first() const; 77 template <size_t Count> 78 constexpr span<element_type, Count> last() const; 79 template <size_t Offset, size_t Count = dynamic_extent> 80 constexpr span<element_type, see below> subspan() const; 81 82 constexpr span<element_type, dynamic_extent> first(size_type count) const; 83 constexpr span<element_type, dynamic_extent> last(size_type count) const; 84 constexpr span<element_type, dynamic_extent> subspan(size_type offset, size_type count = dynamic_extent) const; 85 86 // [span.obs], span observers 87 constexpr size_type size() const noexcept; 88 constexpr size_type size_bytes() const noexcept; 89 constexpr bool empty() const noexcept; 90 91 // [span.elem], span element access 92 constexpr reference operator[](size_type idx) const; 93 constexpr reference front() const; 94 constexpr reference back() const; 95 constexpr pointer data() const noexcept; 96 97 // [span.iterators], span iterator support 98 constexpr iterator begin() const noexcept; 99 constexpr iterator end() const noexcept; 100 constexpr reverse_iterator rbegin() const noexcept; 101 constexpr reverse_iterator rend() const noexcept; 102 103private: 104 pointer data_; // exposition only 105 size_type size_; // exposition only 106}; 107 108template<class T, size_t N> 109 span(T (&)[N]) -> span<T, N>; 110 111template<class T, size_t N> 112 span(array<T, N>&) -> span<T, N>; 113 114template<class T, size_t N> 115 span(const array<T, N>&) -> span<const T, N>; 116 117template<class Container> 118 span(Container&) -> span<typename Container::value_type>; 119 120template<class Container> 121 span(const Container&) -> span<const typename Container::value_type>; 122 123} // namespace std 124 125*/ 126 127#include <__config> 128#include <__ranges/enable_borrowed_range.h> 129#include <array> // for array 130#include <cstddef> // for byte 131#include <iterator> // for iterators 132#include <type_traits> // for remove_cv, etc 133 134#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 135#pragma GCC system_header 136#endif 137 138_LIBCPP_PUSH_MACROS 139#include <__undef_macros> 140 141_LIBCPP_BEGIN_NAMESPACE_STD 142 143#if _LIBCPP_STD_VER > 17 144 145inline constexpr size_t dynamic_extent = numeric_limits<size_t>::max(); 146template <typename _Tp, size_t _Extent = dynamic_extent> class span; 147 148 149template <class _Tp> 150struct __is_span_impl : public false_type {}; 151 152template <class _Tp, size_t _Extent> 153struct __is_span_impl<span<_Tp, _Extent>> : public true_type {}; 154 155template <class _Tp> 156struct __is_span : public __is_span_impl<remove_cv_t<_Tp>> {}; 157 158template <class _Tp> 159struct __is_std_array_impl : public false_type {}; 160 161template <class _Tp, size_t _Sz> 162struct __is_std_array_impl<array<_Tp, _Sz>> : public true_type {}; 163 164template <class _Tp> 165struct __is_std_array : public __is_std_array_impl<remove_cv_t<_Tp>> {}; 166 167template <class _Tp, class _ElementType, class = void> 168struct __is_span_compatible_container : public false_type {}; 169 170template <class _Tp, class _ElementType> 171struct __is_span_compatible_container<_Tp, _ElementType, 172 void_t< 173 // is not a specialization of span 174 typename enable_if<!__is_span<_Tp>::value, nullptr_t>::type, 175 // is not a specialization of array 176 typename enable_if<!__is_std_array<_Tp>::value, nullptr_t>::type, 177 // is_array_v<Container> is false, 178 typename enable_if<!is_array_v<_Tp>, nullptr_t>::type, 179 // data(cont) and size(cont) are well formed 180 decltype(data(declval<_Tp>())), 181 decltype(size(declval<_Tp>())), 182 // remove_pointer_t<decltype(data(cont))>(*)[] is convertible to ElementType(*)[] 183 typename enable_if< 184 is_convertible_v<remove_pointer_t<decltype(data(declval<_Tp &>()))>(*)[], 185 _ElementType(*)[]>, 186 nullptr_t>::type 187 >> 188 : public true_type {}; 189 190 191template <typename _Tp, size_t _Extent> 192class _LIBCPP_TEMPLATE_VIS span { 193public: 194// constants and types 195 using element_type = _Tp; 196 using value_type = remove_cv_t<_Tp>; 197 using size_type = size_t; 198 using difference_type = ptrdiff_t; 199 using pointer = _Tp *; 200 using const_pointer = const _Tp *; 201 using reference = _Tp &; 202 using const_reference = const _Tp &; 203 using iterator = __wrap_iter<pointer>; 204 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 205 206 static constexpr size_type extent = _Extent; 207 208// [span.cons], span constructors, copy, assignment, and destructor 209 template <size_t _Sz = _Extent, enable_if_t<_Sz == 0, nullptr_t> = nullptr> 210 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data{nullptr} {} 211 212 constexpr span (const span&) noexcept = default; 213 constexpr span& operator=(const span&) noexcept = default; 214 215 _LIBCPP_INLINE_VISIBILITY constexpr explicit span(pointer __ptr, size_type __count) : __data{__ptr} 216 { (void)__count; _LIBCPP_ASSERT(_Extent == __count, "size mismatch in span's constructor (ptr, len)"); } 217 _LIBCPP_INLINE_VISIBILITY constexpr explicit span(pointer __f, pointer __l) : __data{__f} 218 { (void)__l; _LIBCPP_ASSERT(_Extent == distance(__f, __l), "size mismatch in span's constructor (ptr, ptr)"); } 219 220 _LIBCPP_INLINE_VISIBILITY constexpr span(element_type (&__arr)[_Extent]) noexcept : __data{__arr} {} 221 222 template <class _OtherElementType, 223 enable_if_t<is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 224 _LIBCPP_INLINE_VISIBILITY 225 constexpr span(array<_OtherElementType, _Extent>& __arr) noexcept : __data{__arr.data()} {} 226 227 template <class _OtherElementType, 228 enable_if_t<is_convertible_v<const _OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 229 _LIBCPP_INLINE_VISIBILITY 230 constexpr span(const array<_OtherElementType, _Extent>& __arr) noexcept : __data{__arr.data()} {} 231 232 template <class _Container> 233 _LIBCPP_INLINE_VISIBILITY 234 constexpr explicit span( _Container& __c, 235 enable_if_t<__is_span_compatible_container<_Container, _Tp>::value, nullptr_t> = nullptr) 236 : __data{_VSTD::data(__c)} { 237 _LIBCPP_ASSERT(_Extent == _VSTD::size(__c), "size mismatch in span's constructor (range)"); 238 } 239 240 template <class _Container> 241 _LIBCPP_INLINE_VISIBILITY 242 constexpr explicit span(const _Container& __c, 243 enable_if_t<__is_span_compatible_container<const _Container, _Tp>::value, nullptr_t> = nullptr) 244 : __data{_VSTD::data(__c)} { 245 _LIBCPP_ASSERT(_Extent == _VSTD::size(__c), "size mismatch in span's constructor (range)"); 246 } 247 248 template <class _OtherElementType> 249 _LIBCPP_INLINE_VISIBILITY 250 constexpr span(const span<_OtherElementType, _Extent>& __other, 251 enable_if_t< 252 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 253 nullptr_t> = nullptr) 254 : __data{__other.data()} {} 255 256 template <class _OtherElementType> 257 _LIBCPP_INLINE_VISIBILITY 258 constexpr explicit span(const span<_OtherElementType, dynamic_extent>& __other, 259 enable_if_t< 260 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 261 nullptr_t> = nullptr) noexcept 262 : __data{__other.data()} { _LIBCPP_ASSERT(_Extent == __other.size(), "size mismatch in span's constructor (other span)"); } 263 264 265// ~span() noexcept = default; 266 267 template <size_t _Count> 268 _LIBCPP_INLINE_VISIBILITY 269 constexpr span<element_type, _Count> first() const noexcept 270 { 271 static_assert(_Count <= _Extent, "Count out of range in span::first()"); 272 return span<element_type, _Count>{data(), _Count}; 273 } 274 275 template <size_t _Count> 276 _LIBCPP_INLINE_VISIBILITY 277 constexpr span<element_type, _Count> last() const noexcept 278 { 279 static_assert(_Count <= _Extent, "Count out of range in span::last()"); 280 return span<element_type, _Count>{data() + size() - _Count, _Count}; 281 } 282 283 _LIBCPP_INLINE_VISIBILITY 284 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 285 { 286 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::first(count)"); 287 return {data(), __count}; 288 } 289 290 _LIBCPP_INLINE_VISIBILITY 291 constexpr span<element_type, dynamic_extent> last(size_type __count) const noexcept 292 { 293 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::last(count)"); 294 return {data() + size() - __count, __count}; 295 } 296 297 template <size_t _Offset, size_t _Count = dynamic_extent> 298 _LIBCPP_INLINE_VISIBILITY 299 constexpr auto subspan() const noexcept 300 -> span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset> 301 { 302 static_assert(_Offset <= _Extent, "Offset out of range in span::subspan()"); 303 static_assert(_Count == dynamic_extent || _Count <= _Extent - _Offset, "Offset + count out of range in span::subspan()"); 304 305 using _ReturnType = span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset>; 306 return _ReturnType{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 307 } 308 309 310 _LIBCPP_INLINE_VISIBILITY 311 constexpr span<element_type, dynamic_extent> 312 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 313 { 314 _LIBCPP_ASSERT(__offset <= size(), "Offset out of range in span::subspan(offset, count)"); 315 _LIBCPP_ASSERT(__count <= size() || __count == dynamic_extent, "Count out of range in span::subspan(offset, count)"); 316 if (__count == dynamic_extent) 317 return {data() + __offset, size() - __offset}; 318 _LIBCPP_ASSERT(__count <= size() - __offset, "Offset + count out of range in span::subspan(offset, count)"); 319 return {data() + __offset, __count}; 320 } 321 322 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return _Extent; } 323 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return _Extent * sizeof(element_type); } 324 _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return _Extent == 0; } 325 326 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 327 { 328 _LIBCPP_ASSERT(__idx < size(), "span<T,N>[] index out of bounds"); 329 return __data[__idx]; 330 } 331 332 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 333 { 334 _LIBCPP_ASSERT(!empty(), "span<T, N>::front() on empty span"); 335 return __data[0]; 336 } 337 338 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 339 { 340 _LIBCPP_ASSERT(!empty(), "span<T, N>::back() on empty span"); 341 return __data[size()-1]; 342 } 343 344 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; } 345 346// [span.iter], span iterator support 347 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { return iterator(data()); } 348 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { return iterator(data() + size()); } 349 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 350 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 351 352 _LIBCPP_INLINE_VISIBILITY span<const byte, _Extent * sizeof(element_type)> __as_bytes() const noexcept 353 { return span<const byte, _Extent * sizeof(element_type)>{reinterpret_cast<const byte *>(data()), size_bytes()}; } 354 355 _LIBCPP_INLINE_VISIBILITY span<byte, _Extent * sizeof(element_type)> __as_writable_bytes() const noexcept 356 { return span<byte, _Extent * sizeof(element_type)>{reinterpret_cast<byte *>(data()), size_bytes()}; } 357 358private: 359 pointer __data; 360 361}; 362 363 364template <typename _Tp> 365class _LIBCPP_TEMPLATE_VIS span<_Tp, dynamic_extent> { 366private: 367 368public: 369// constants and types 370 using element_type = _Tp; 371 using value_type = remove_cv_t<_Tp>; 372 using size_type = size_t; 373 using difference_type = ptrdiff_t; 374 using pointer = _Tp *; 375 using const_pointer = const _Tp *; 376 using reference = _Tp &; 377 using const_reference = const _Tp &; 378 using iterator = __wrap_iter<pointer>; 379 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 380 381 static constexpr size_type extent = dynamic_extent; 382 383// [span.cons], span constructors, copy, assignment, and destructor 384 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data{nullptr}, __size{0} {} 385 386 constexpr span (const span&) noexcept = default; 387 constexpr span& operator=(const span&) noexcept = default; 388 389 _LIBCPP_INLINE_VISIBILITY constexpr span(pointer __ptr, size_type __count) : __data{__ptr}, __size{__count} {} 390 _LIBCPP_INLINE_VISIBILITY constexpr span(pointer __f, pointer __l) : __data{__f}, __size{static_cast<size_t>(distance(__f, __l))} {} 391 392 template <size_t _Sz> 393 _LIBCPP_INLINE_VISIBILITY 394 constexpr span(element_type (&__arr)[_Sz]) noexcept : __data{__arr}, __size{_Sz} {} 395 396 template <class _OtherElementType, size_t _Sz, 397 enable_if_t<is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 398 _LIBCPP_INLINE_VISIBILITY 399 constexpr span(array<_OtherElementType, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {} 400 401 template <class _OtherElementType, size_t _Sz, 402 enable_if_t<is_convertible_v<const _OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 403 _LIBCPP_INLINE_VISIBILITY 404 constexpr span(const array<_OtherElementType, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {} 405 406 template <class _Container> 407 _LIBCPP_INLINE_VISIBILITY 408 constexpr span( _Container& __c, 409 enable_if_t<__is_span_compatible_container<_Container, _Tp>::value, nullptr_t> = nullptr) 410 : __data{_VSTD::data(__c)}, __size{(size_type) _VSTD::size(__c)} {} 411 412 template <class _Container> 413 _LIBCPP_INLINE_VISIBILITY 414 constexpr span(const _Container& __c, 415 enable_if_t<__is_span_compatible_container<const _Container, _Tp>::value, nullptr_t> = nullptr) 416 : __data{_VSTD::data(__c)}, __size{(size_type) _VSTD::size(__c)} {} 417 418 419 template <class _OtherElementType, size_t _OtherExtent> 420 _LIBCPP_INLINE_VISIBILITY 421 constexpr span(const span<_OtherElementType, _OtherExtent>& __other, 422 enable_if_t< 423 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 424 nullptr_t> = nullptr) noexcept 425 : __data{__other.data()}, __size{__other.size()} {} 426 427// ~span() noexcept = default; 428 429 template <size_t _Count> 430 _LIBCPP_INLINE_VISIBILITY 431 constexpr span<element_type, _Count> first() const noexcept 432 { 433 _LIBCPP_ASSERT(_Count <= size(), "Count out of range in span::first()"); 434 return span<element_type, _Count>{data(), _Count}; 435 } 436 437 template <size_t _Count> 438 _LIBCPP_INLINE_VISIBILITY 439 constexpr span<element_type, _Count> last() const noexcept 440 { 441 _LIBCPP_ASSERT(_Count <= size(), "Count out of range in span::last()"); 442 return span<element_type, _Count>{data() + size() - _Count, _Count}; 443 } 444 445 _LIBCPP_INLINE_VISIBILITY 446 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 447 { 448 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::first(count)"); 449 return {data(), __count}; 450 } 451 452 _LIBCPP_INLINE_VISIBILITY 453 constexpr span<element_type, dynamic_extent> last (size_type __count) const noexcept 454 { 455 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::last(count)"); 456 return {data() + size() - __count, __count}; 457 } 458 459 template <size_t _Offset, size_t _Count = dynamic_extent> 460 _LIBCPP_INLINE_VISIBILITY 461 constexpr span<element_type, _Count> subspan() const noexcept 462 { 463 _LIBCPP_ASSERT(_Offset <= size(), "Offset out of range in span::subspan()"); 464 _LIBCPP_ASSERT(_Count == dynamic_extent || _Count <= size() - _Offset, "Offset + count out of range in span::subspan()"); 465 return span<element_type, _Count>{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 466 } 467 468 constexpr span<element_type, dynamic_extent> 469 _LIBCPP_INLINE_VISIBILITY 470 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 471 { 472 _LIBCPP_ASSERT(__offset <= size(), "Offset out of range in span::subspan(offset, count)"); 473 _LIBCPP_ASSERT(__count <= size() || __count == dynamic_extent, "count out of range in span::subspan(offset, count)"); 474 if (__count == dynamic_extent) 475 return {data() + __offset, size() - __offset}; 476 _LIBCPP_ASSERT(__count <= size() - __offset, "Offset + count out of range in span::subspan(offset, count)"); 477 return {data() + __offset, __count}; 478 } 479 480 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return __size; } 481 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return __size * sizeof(element_type); } 482 _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return __size == 0; } 483 484 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 485 { 486 _LIBCPP_ASSERT(__idx < size(), "span<T>[] index out of bounds"); 487 return __data[__idx]; 488 } 489 490 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 491 { 492 _LIBCPP_ASSERT(!empty(), "span<T>[].front() on empty span"); 493 return __data[0]; 494 } 495 496 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 497 { 498 _LIBCPP_ASSERT(!empty(), "span<T>[].back() on empty span"); 499 return __data[size()-1]; 500 } 501 502 503 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; } 504 505// [span.iter], span iterator support 506 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { return iterator(data()); } 507 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { return iterator(data() + size()); } 508 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 509 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 510 511 _LIBCPP_INLINE_VISIBILITY span<const byte, dynamic_extent> __as_bytes() const noexcept 512 { return {reinterpret_cast<const byte *>(data()), size_bytes()}; } 513 514 _LIBCPP_INLINE_VISIBILITY span<byte, dynamic_extent> __as_writable_bytes() const noexcept 515 { return {reinterpret_cast<byte *>(data()), size_bytes()}; } 516 517private: 518 pointer __data; 519 size_type __size; 520}; 521 522#if !defined(_LIBCPP_HAS_NO_RANGES) 523template <class _Tp, size_t _Extent> 524inline constexpr bool ranges::enable_borrowed_range<span<_Tp, _Extent> > = true; 525#endif // !defined(_LIBCPP_HAS_NO_RANGES) 526 527// as_bytes & as_writable_bytes 528template <class _Tp, size_t _Extent> 529_LIBCPP_INLINE_VISIBILITY 530auto as_bytes(span<_Tp, _Extent> __s) noexcept 531-> decltype(__s.__as_bytes()) 532{ return __s.__as_bytes(); } 533 534template <class _Tp, size_t _Extent> 535_LIBCPP_INLINE_VISIBILITY 536auto as_writable_bytes(span<_Tp, _Extent> __s) noexcept 537-> enable_if_t<!is_const_v<_Tp>, decltype(__s.__as_writable_bytes())> 538{ return __s.__as_writable_bytes(); } 539 540// Deduction guides 541template<class _Tp, size_t _Sz> 542 span(_Tp (&)[_Sz]) -> span<_Tp, _Sz>; 543 544template<class _Tp, size_t _Sz> 545 span(array<_Tp, _Sz>&) -> span<_Tp, _Sz>; 546 547template<class _Tp, size_t _Sz> 548 span(const array<_Tp, _Sz>&) -> span<const _Tp, _Sz>; 549 550template<class _Container> 551 span(_Container&) -> span<typename _Container::value_type>; 552 553template<class _Container> 554 span(const _Container&) -> span<const typename _Container::value_type>; 555 556#endif // _LIBCPP_STD_VER > 17 557 558_LIBCPP_END_NAMESPACE_STD 559 560_LIBCPP_POP_MACROS 561 562#endif // _LIBCPP_SPAN 563