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