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 <__debug> 129#include <__ranges/enable_borrowed_range.h> 130#include <array> // for array 131#include <cstddef> // for byte 132#include <iterator> // for iterators 133#include <type_traits> // for remove_cv, etc 134 135#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 136#pragma GCC system_header 137#endif 138 139_LIBCPP_PUSH_MACROS 140#include <__undef_macros> 141 142_LIBCPP_BEGIN_NAMESPACE_STD 143 144#if _LIBCPP_STD_VER > 17 145 146inline constexpr size_t dynamic_extent = numeric_limits<size_t>::max(); 147template <typename _Tp, size_t _Extent = dynamic_extent> class span; 148 149 150template <class _Tp> 151struct __is_span_impl : public false_type {}; 152 153template <class _Tp, size_t _Extent> 154struct __is_span_impl<span<_Tp, _Extent>> : public true_type {}; 155 156template <class _Tp> 157struct __is_span : public __is_span_impl<remove_cv_t<_Tp>> {}; 158 159template <class _Tp> 160struct __is_std_array_impl : public false_type {}; 161 162template <class _Tp, size_t _Sz> 163struct __is_std_array_impl<array<_Tp, _Sz>> : public true_type {}; 164 165template <class _Tp> 166struct __is_std_array : public __is_std_array_impl<remove_cv_t<_Tp>> {}; 167 168template <class _Tp, class _ElementType, class = void> 169struct __is_span_compatible_container : public false_type {}; 170 171template <class _Tp, class _ElementType> 172struct __is_span_compatible_container<_Tp, _ElementType, 173 void_t< 174 // is not a specialization of span 175 typename enable_if<!__is_span<_Tp>::value, nullptr_t>::type, 176 // is not a specialization of array 177 typename enable_if<!__is_std_array<_Tp>::value, nullptr_t>::type, 178 // is_array_v<Container> is false, 179 typename enable_if<!is_array_v<_Tp>, nullptr_t>::type, 180 // data(cont) and size(cont) are well formed 181 decltype(data(declval<_Tp>())), 182 decltype(size(declval<_Tp>())), 183 // remove_pointer_t<decltype(data(cont))>(*)[] is convertible to ElementType(*)[] 184 typename enable_if< 185 is_convertible_v<remove_pointer_t<decltype(data(declval<_Tp &>()))>(*)[], 186 _ElementType(*)[]>, 187 nullptr_t>::type 188 >> 189 : public true_type {}; 190 191 192template <typename _Tp, size_t _Extent> 193class _LIBCPP_TEMPLATE_VIS span { 194public: 195// constants and types 196 using element_type = _Tp; 197 using value_type = remove_cv_t<_Tp>; 198 using size_type = size_t; 199 using difference_type = ptrdiff_t; 200 using pointer = _Tp *; 201 using const_pointer = const _Tp *; 202 using reference = _Tp &; 203 using const_reference = const _Tp &; 204#if (_LIBCPP_DEBUG_LEVEL == 2) || defined(_LIBCPP_ABI_SPAN_POINTER_ITERATORS) 205 using iterator = pointer; 206#else 207 using iterator = __wrap_iter<pointer>; 208#endif 209 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 210 211 static constexpr size_type extent = _Extent; 212 213// [span.cons], span constructors, copy, assignment, and destructor 214 template <size_t _Sz = _Extent, enable_if_t<_Sz == 0, nullptr_t> = nullptr> 215 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data{nullptr} {} 216 217 constexpr span (const span&) noexcept = default; 218 constexpr span& operator=(const span&) noexcept = default; 219 220 _LIBCPP_INLINE_VISIBILITY constexpr explicit span(pointer __ptr, size_type __count) : __data{__ptr} 221 { (void)__count; _LIBCPP_ASSERT(_Extent == __count, "size mismatch in span's constructor (ptr, len)"); } 222 _LIBCPP_INLINE_VISIBILITY constexpr explicit span(pointer __f, pointer __l) : __data{__f} 223 { (void)__l; _LIBCPP_ASSERT(_Extent == distance(__f, __l), "size mismatch in span's constructor (ptr, ptr)"); } 224 225 _LIBCPP_INLINE_VISIBILITY constexpr span(element_type (&__arr)[_Extent]) noexcept : __data{__arr} {} 226 227 template <class _OtherElementType, 228 enable_if_t<is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 229 _LIBCPP_INLINE_VISIBILITY 230 constexpr span(array<_OtherElementType, _Extent>& __arr) noexcept : __data{__arr.data()} {} 231 232 template <class _OtherElementType, 233 enable_if_t<is_convertible_v<const _OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 234 _LIBCPP_INLINE_VISIBILITY 235 constexpr span(const array<_OtherElementType, _Extent>& __arr) noexcept : __data{__arr.data()} {} 236 237 template <class _Container> 238 _LIBCPP_INLINE_VISIBILITY 239 constexpr explicit span( _Container& __c, 240 enable_if_t<__is_span_compatible_container<_Container, _Tp>::value, nullptr_t> = nullptr) 241 : __data{_VSTD::data(__c)} { 242 _LIBCPP_ASSERT(_Extent == _VSTD::size(__c), "size mismatch in span's constructor (range)"); 243 } 244 245 template <class _Container> 246 _LIBCPP_INLINE_VISIBILITY 247 constexpr explicit span(const _Container& __c, 248 enable_if_t<__is_span_compatible_container<const _Container, _Tp>::value, nullptr_t> = nullptr) 249 : __data{_VSTD::data(__c)} { 250 _LIBCPP_ASSERT(_Extent == _VSTD::size(__c), "size mismatch in span's constructor (range)"); 251 } 252 253 template <class _OtherElementType> 254 _LIBCPP_INLINE_VISIBILITY 255 constexpr span(const span<_OtherElementType, _Extent>& __other, 256 enable_if_t< 257 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 258 nullptr_t> = nullptr) 259 : __data{__other.data()} {} 260 261 template <class _OtherElementType> 262 _LIBCPP_INLINE_VISIBILITY 263 constexpr explicit span(const span<_OtherElementType, dynamic_extent>& __other, 264 enable_if_t< 265 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 266 nullptr_t> = nullptr) noexcept 267 : __data{__other.data()} { _LIBCPP_ASSERT(_Extent == __other.size(), "size mismatch in span's constructor (other span)"); } 268 269 270// ~span() noexcept = default; 271 272 template <size_t _Count> 273 _LIBCPP_INLINE_VISIBILITY 274 constexpr span<element_type, _Count> first() const noexcept 275 { 276 static_assert(_Count <= _Extent, "Count out of range in span::first()"); 277 return span<element_type, _Count>{data(), _Count}; 278 } 279 280 template <size_t _Count> 281 _LIBCPP_INLINE_VISIBILITY 282 constexpr span<element_type, _Count> last() const noexcept 283 { 284 static_assert(_Count <= _Extent, "Count out of range in span::last()"); 285 return span<element_type, _Count>{data() + size() - _Count, _Count}; 286 } 287 288 _LIBCPP_INLINE_VISIBILITY 289 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 290 { 291 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::first(count)"); 292 return {data(), __count}; 293 } 294 295 _LIBCPP_INLINE_VISIBILITY 296 constexpr span<element_type, dynamic_extent> last(size_type __count) const noexcept 297 { 298 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::last(count)"); 299 return {data() + size() - __count, __count}; 300 } 301 302 template <size_t _Offset, size_t _Count = dynamic_extent> 303 _LIBCPP_INLINE_VISIBILITY 304 constexpr auto subspan() const noexcept 305 -> span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset> 306 { 307 static_assert(_Offset <= _Extent, "Offset out of range in span::subspan()"); 308 static_assert(_Count == dynamic_extent || _Count <= _Extent - _Offset, "Offset + count out of range in span::subspan()"); 309 310 using _ReturnType = span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset>; 311 return _ReturnType{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 312 } 313 314 315 _LIBCPP_INLINE_VISIBILITY 316 constexpr span<element_type, dynamic_extent> 317 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 318 { 319 _LIBCPP_ASSERT(__offset <= size(), "Offset out of range in span::subspan(offset, count)"); 320 _LIBCPP_ASSERT(__count <= size() || __count == dynamic_extent, "Count out of range in span::subspan(offset, count)"); 321 if (__count == dynamic_extent) 322 return {data() + __offset, size() - __offset}; 323 _LIBCPP_ASSERT(__count <= size() - __offset, "Offset + count out of range in span::subspan(offset, count)"); 324 return {data() + __offset, __count}; 325 } 326 327 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return _Extent; } 328 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return _Extent * sizeof(element_type); } 329 _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return _Extent == 0; } 330 331 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 332 { 333 _LIBCPP_ASSERT(__idx < size(), "span<T,N>[] index out of bounds"); 334 return __data[__idx]; 335 } 336 337 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 338 { 339 _LIBCPP_ASSERT(!empty(), "span<T, N>::front() on empty span"); 340 return __data[0]; 341 } 342 343 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 344 { 345 _LIBCPP_ASSERT(!empty(), "span<T, N>::back() on empty span"); 346 return __data[size()-1]; 347 } 348 349 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; } 350 351// [span.iter], span iterator support 352 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { return iterator(data()); } 353 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { return iterator(data() + size()); } 354 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 355 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 356 357 _LIBCPP_INLINE_VISIBILITY span<const byte, _Extent * sizeof(element_type)> __as_bytes() const noexcept 358 { return span<const byte, _Extent * sizeof(element_type)>{reinterpret_cast<const byte *>(data()), size_bytes()}; } 359 360 _LIBCPP_INLINE_VISIBILITY span<byte, _Extent * sizeof(element_type)> __as_writable_bytes() const noexcept 361 { return span<byte, _Extent * sizeof(element_type)>{reinterpret_cast<byte *>(data()), size_bytes()}; } 362 363private: 364 pointer __data; 365 366}; 367 368 369template <typename _Tp> 370class _LIBCPP_TEMPLATE_VIS span<_Tp, dynamic_extent> { 371private: 372 373public: 374// constants and types 375 using element_type = _Tp; 376 using value_type = remove_cv_t<_Tp>; 377 using size_type = size_t; 378 using difference_type = ptrdiff_t; 379 using pointer = _Tp *; 380 using const_pointer = const _Tp *; 381 using reference = _Tp &; 382 using const_reference = const _Tp &; 383#if (_LIBCPP_DEBUG_LEVEL == 2) || defined(_LIBCPP_ABI_SPAN_POINTER_ITERATORS) 384 using iterator = pointer; 385#else 386 using iterator = __wrap_iter<pointer>; 387#endif 388 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 389 390 static constexpr size_type extent = dynamic_extent; 391 392// [span.cons], span constructors, copy, assignment, and destructor 393 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data{nullptr}, __size{0} {} 394 395 constexpr span (const span&) noexcept = default; 396 constexpr span& operator=(const span&) noexcept = default; 397 398 _LIBCPP_INLINE_VISIBILITY constexpr span(pointer __ptr, size_type __count) : __data{__ptr}, __size{__count} {} 399 _LIBCPP_INLINE_VISIBILITY constexpr span(pointer __f, pointer __l) : __data{__f}, __size{static_cast<size_t>(distance(__f, __l))} {} 400 401 template <size_t _Sz> 402 _LIBCPP_INLINE_VISIBILITY 403 constexpr span(element_type (&__arr)[_Sz]) noexcept : __data{__arr}, __size{_Sz} {} 404 405 template <class _OtherElementType, size_t _Sz, 406 enable_if_t<is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 407 _LIBCPP_INLINE_VISIBILITY 408 constexpr span(array<_OtherElementType, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {} 409 410 template <class _OtherElementType, size_t _Sz, 411 enable_if_t<is_convertible_v<const _OtherElementType(*)[], element_type (*)[]>, nullptr_t> = nullptr> 412 _LIBCPP_INLINE_VISIBILITY 413 constexpr span(const array<_OtherElementType, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {} 414 415 template <class _Container> 416 _LIBCPP_INLINE_VISIBILITY 417 constexpr span( _Container& __c, 418 enable_if_t<__is_span_compatible_container<_Container, _Tp>::value, nullptr_t> = nullptr) 419 : __data{_VSTD::data(__c)}, __size{(size_type) _VSTD::size(__c)} {} 420 421 template <class _Container> 422 _LIBCPP_INLINE_VISIBILITY 423 constexpr span(const _Container& __c, 424 enable_if_t<__is_span_compatible_container<const _Container, _Tp>::value, nullptr_t> = nullptr) 425 : __data{_VSTD::data(__c)}, __size{(size_type) _VSTD::size(__c)} {} 426 427 428 template <class _OtherElementType, size_t _OtherExtent> 429 _LIBCPP_INLINE_VISIBILITY 430 constexpr span(const span<_OtherElementType, _OtherExtent>& __other, 431 enable_if_t< 432 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 433 nullptr_t> = nullptr) noexcept 434 : __data{__other.data()}, __size{__other.size()} {} 435 436// ~span() noexcept = default; 437 438 template <size_t _Count> 439 _LIBCPP_INLINE_VISIBILITY 440 constexpr span<element_type, _Count> first() const noexcept 441 { 442 _LIBCPP_ASSERT(_Count <= size(), "Count out of range in span::first()"); 443 return span<element_type, _Count>{data(), _Count}; 444 } 445 446 template <size_t _Count> 447 _LIBCPP_INLINE_VISIBILITY 448 constexpr span<element_type, _Count> last() const noexcept 449 { 450 _LIBCPP_ASSERT(_Count <= size(), "Count out of range in span::last()"); 451 return span<element_type, _Count>{data() + size() - _Count, _Count}; 452 } 453 454 _LIBCPP_INLINE_VISIBILITY 455 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 456 { 457 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::first(count)"); 458 return {data(), __count}; 459 } 460 461 _LIBCPP_INLINE_VISIBILITY 462 constexpr span<element_type, dynamic_extent> last (size_type __count) const noexcept 463 { 464 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::last(count)"); 465 return {data() + size() - __count, __count}; 466 } 467 468 template <size_t _Offset, size_t _Count = dynamic_extent> 469 _LIBCPP_INLINE_VISIBILITY 470 constexpr span<element_type, _Count> subspan() const noexcept 471 { 472 _LIBCPP_ASSERT(_Offset <= size(), "Offset out of range in span::subspan()"); 473 _LIBCPP_ASSERT(_Count == dynamic_extent || _Count <= size() - _Offset, "Offset + count out of range in span::subspan()"); 474 return span<element_type, _Count>{data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 475 } 476 477 constexpr span<element_type, dynamic_extent> 478 _LIBCPP_INLINE_VISIBILITY 479 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 480 { 481 _LIBCPP_ASSERT(__offset <= size(), "Offset out of range in span::subspan(offset, count)"); 482 _LIBCPP_ASSERT(__count <= size() || __count == dynamic_extent, "count out of range in span::subspan(offset, count)"); 483 if (__count == dynamic_extent) 484 return {data() + __offset, size() - __offset}; 485 _LIBCPP_ASSERT(__count <= size() - __offset, "Offset + count out of range in span::subspan(offset, count)"); 486 return {data() + __offset, __count}; 487 } 488 489 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return __size; } 490 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return __size * sizeof(element_type); } 491 _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return __size == 0; } 492 493 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 494 { 495 _LIBCPP_ASSERT(__idx < size(), "span<T>[] index out of bounds"); 496 return __data[__idx]; 497 } 498 499 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 500 { 501 _LIBCPP_ASSERT(!empty(), "span<T>[].front() on empty span"); 502 return __data[0]; 503 } 504 505 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 506 { 507 _LIBCPP_ASSERT(!empty(), "span<T>[].back() on empty span"); 508 return __data[size()-1]; 509 } 510 511 512 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; } 513 514// [span.iter], span iterator support 515 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { return iterator(data()); } 516 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { return iterator(data() + size()); } 517 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 518 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 519 520 _LIBCPP_INLINE_VISIBILITY span<const byte, dynamic_extent> __as_bytes() const noexcept 521 { return {reinterpret_cast<const byte *>(data()), size_bytes()}; } 522 523 _LIBCPP_INLINE_VISIBILITY span<byte, dynamic_extent> __as_writable_bytes() const noexcept 524 { return {reinterpret_cast<byte *>(data()), size_bytes()}; } 525 526private: 527 pointer __data; 528 size_type __size; 529}; 530 531#if !defined(_LIBCPP_HAS_NO_RANGES) 532template <class _Tp, size_t _Extent> 533inline constexpr bool ranges::enable_borrowed_range<span<_Tp, _Extent> > = true; 534#endif // !defined(_LIBCPP_HAS_NO_RANGES) 535 536// as_bytes & as_writable_bytes 537template <class _Tp, size_t _Extent> 538_LIBCPP_INLINE_VISIBILITY 539auto as_bytes(span<_Tp, _Extent> __s) noexcept 540-> decltype(__s.__as_bytes()) 541{ return __s.__as_bytes(); } 542 543template <class _Tp, size_t _Extent> 544_LIBCPP_INLINE_VISIBILITY 545auto as_writable_bytes(span<_Tp, _Extent> __s) noexcept 546-> enable_if_t<!is_const_v<_Tp>, decltype(__s.__as_writable_bytes())> 547{ return __s.__as_writable_bytes(); } 548 549// Deduction guides 550template<class _Tp, size_t _Sz> 551 span(_Tp (&)[_Sz]) -> span<_Tp, _Sz>; 552 553template<class _Tp, size_t _Sz> 554 span(array<_Tp, _Sz>&) -> span<_Tp, _Sz>; 555 556template<class _Tp, size_t _Sz> 557 span(const array<_Tp, _Sz>&) -> span<const _Tp, _Sz>; 558 559template<class _Container> 560 span(_Container&) -> span<typename _Container::value_type>; 561 562template<class _Container> 563 span(const _Container&) -> span<const typename _Container::value_type>; 564 565#endif // _LIBCPP_STD_VER > 17 566 567_LIBCPP_END_NAMESPACE_STD 568 569_LIBCPP_POP_MACROS 570 571#endif // _LIBCPP_SPAN 572