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 25// [span.objectrep], views of object representation 26template <class ElementType, size_t Extent> 27 span<const byte, ((Extent == dynamic_extent) ? dynamic_extent : 28 (sizeof(ElementType) * Extent))> as_bytes(span<ElementType, Extent> s) noexcept; 29 30template <class ElementType, size_t Extent> 31 span< byte, ((Extent == dynamic_extent) ? dynamic_extent : 32 (sizeof(ElementType) * Extent))> as_writable_bytes(span<ElementType, Extent> s) noexcept; 33 34 35namespace std { 36template <class ElementType, size_t Extent = dynamic_extent> 37class span { 38public: 39 // constants and types 40 using element_type = ElementType; 41 using value_type = remove_cv_t<ElementType>; 42 using size_type = size_t; 43 using difference_type = ptrdiff_t; 44 using pointer = element_type*; 45 using const_pointer = const element_type*; 46 using reference = element_type&; 47 using const_reference = const element_type&; 48 using iterator = implementation-defined; 49 using const_iterator = implementation-defined; 50 using reverse_iterator = std::reverse_iterator<iterator>; 51 using const_reverse_iterator = std::reverse_iterator<const_iterator>; 52 static constexpr size_type extent = Extent; 53 54 // [span.cons], span constructors, copy, assignment, and destructor 55 constexpr span() noexcept; 56 constexpr span(pointer ptr, size_type count); 57 constexpr 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 span(Container& cont); 66 template <class Container> 67 constexpr span(const Container& cont); 68 constexpr span(const span& other) noexcept = default; 69 template <class OtherElementType, size_t OtherExtent> 70 constexpr 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 const_iterator cbegin() const noexcept; 101 constexpr const_iterator cend() const noexcept; 102 constexpr reverse_iterator rbegin() const noexcept; 103 constexpr reverse_iterator rend() const noexcept; 104 constexpr const_reverse_iterator crbegin() const noexcept; 105 constexpr const_reverse_iterator crend() const noexcept; 106 107private: 108 pointer data_; // exposition only 109 size_type size_; // exposition only 110}; 111 112template<class T, size_t N> 113 span(T (&)[N]) -> span<T, N>; 114 115template<class T, size_t N> 116 span(array<T, N>&) -> span<T, N>; 117 118template<class T, size_t N> 119 span(const array<T, N>&) -> span<const T, N>; 120 121template<class Container> 122 span(Container&) -> span<typename Container::value_type>; 123 124template<class Container> 125 span(const Container&) -> span<const typename Container::value_type>; 126 127} // namespace std 128 129*/ 130 131#include <__config> 132#include <cstddef> // for ptrdiff_t 133#include <iterator> // for iterators 134#include <array> // for array 135#include <type_traits> // for remove_cv, etc 136#include <cstddef> // for byte 137 138#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 139#pragma GCC system_header 140#endif 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 using iterator = __wrap_iter<pointer>; 205 using const_iterator = __wrap_iter<const_pointer>; 206 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 207 using const_reverse_iterator = _VSTD::reverse_iterator<const_iterator>; 208 209 static constexpr size_type extent = _Extent; 210 211// [span.cons], span constructors, copy, assignment, and destructor 212 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data{nullptr} 213 { static_assert(_Extent == 0, "Can't default construct a statically sized span with size > 0"); } 214 215 constexpr span (const span&) noexcept = default; 216 constexpr span& operator=(const span&) noexcept = default; 217 218 _LIBCPP_INLINE_VISIBILITY constexpr span(pointer __ptr, size_type __count) : __data{__ptr} 219 { (void)__count; _LIBCPP_ASSERT(_Extent == __count, "size mismatch in span's constructor (ptr, len)"); } 220 _LIBCPP_INLINE_VISIBILITY constexpr span(pointer __f, pointer __l) : __data{__f} 221 { (void)__l; _LIBCPP_ASSERT(_Extent == distance(__f, __l), "size mismatch in span's constructor (ptr, ptr)"); } 222 223 _LIBCPP_INLINE_VISIBILITY constexpr span(element_type (&__arr)[_Extent]) noexcept : __data{__arr} {} 224 _LIBCPP_INLINE_VISIBILITY constexpr span( array<value_type, _Extent>& __arr) noexcept : __data{__arr.data()} {} 225 _LIBCPP_INLINE_VISIBILITY constexpr span(const array<value_type, _Extent>& __arr) noexcept : __data{__arr.data()} {} 226 227 template <class _OtherElementType> 228 _LIBCPP_INLINE_VISIBILITY 229 constexpr span(const span<_OtherElementType, _Extent>& __other, 230 enable_if_t< 231 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 232 nullptr_t> = nullptr) 233 : __data{__other.data()} {} 234 235 template <class _OtherElementType> 236 _LIBCPP_INLINE_VISIBILITY 237 constexpr span(const span<_OtherElementType, dynamic_extent>& __other, 238 enable_if_t< 239 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 240 nullptr_t> = nullptr) noexcept 241 : __data{__other.data()} { _LIBCPP_ASSERT(_Extent == __other.size(), "size mismatch in span's constructor (other span)"); } 242 243 244// ~span() noexcept = default; 245 246 template <size_t _Count> 247 _LIBCPP_INLINE_VISIBILITY 248 constexpr span<element_type, _Count> first() const noexcept 249 { 250 static_assert(_Count <= _Extent, "Count out of range in span::first()"); 251 return {data(), _Count}; 252 } 253 254 template <size_t _Count> 255 _LIBCPP_INLINE_VISIBILITY 256 constexpr span<element_type, _Count> last() const noexcept 257 { 258 static_assert(_Count <= _Extent, "Count out of range in span::last()"); 259 return {data() + size() - _Count, _Count}; 260 } 261 262 _LIBCPP_INLINE_VISIBILITY 263 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 264 { 265 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::first(count)"); 266 return {data(), __count}; 267 } 268 269 _LIBCPP_INLINE_VISIBILITY 270 constexpr span<element_type, dynamic_extent> last(size_type __count) const noexcept 271 { 272 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::last(count)"); 273 return {data() + size() - __count, __count}; 274 } 275 276 template <size_t _Offset, size_t _Count = dynamic_extent> 277 _LIBCPP_INLINE_VISIBILITY 278 constexpr auto subspan() const noexcept 279 -> span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset> 280 { 281 static_assert(_Offset <= _Extent, "Offset out of range in span::subspan()"); 282 return {data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 283 } 284 285 286 _LIBCPP_INLINE_VISIBILITY 287 constexpr span<element_type, dynamic_extent> 288 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 289 { 290 _LIBCPP_ASSERT(__offset <= size(), "Offset out of range in span::subspan(offset, count)"); 291 _LIBCPP_ASSERT(__count <= size() || __count == dynamic_extent, "Count out of range in span::subspan(offset, count)"); 292 if (__count == dynamic_extent) 293 return {data() + __offset, size() - __offset}; 294 _LIBCPP_ASSERT(__offset <= size() - __count, "count + offset out of range in span::subspan(offset, count)"); 295 return {data() + __offset, __count}; 296 } 297 298 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return _Extent; } 299 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return _Extent * sizeof(element_type); } 300 _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return _Extent == 0; } 301 302 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 303 { 304 _LIBCPP_ASSERT(__idx >= 0 && __idx < size(), "span<T,N>[] index out of bounds"); 305 return __data[__idx]; 306 } 307 308 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 309 { 310 static_assert(_Extent > 0, "span<T,N>[].front() on empty span"); 311 return __data[0]; 312 } 313 314 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 315 { 316 static_assert(_Extent > 0, "span<T,N>[].back() on empty span"); 317 return __data[size()-1]; 318 } 319 320 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; } 321 322// [span.iter], span iterator support 323 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { return iterator(data()); } 324 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { return iterator(data() + size()); } 325 _LIBCPP_INLINE_VISIBILITY constexpr const_iterator cbegin() const noexcept { return const_iterator(data()); } 326 _LIBCPP_INLINE_VISIBILITY constexpr const_iterator cend() const noexcept { return const_iterator(data() + size()); } 327 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 328 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 329 _LIBCPP_INLINE_VISIBILITY constexpr const_reverse_iterator crbegin() const noexcept { return const_reverse_iterator(cend()); } 330 _LIBCPP_INLINE_VISIBILITY constexpr const_reverse_iterator crend() const noexcept { return const_reverse_iterator(cbegin()); } 331 332 _LIBCPP_INLINE_VISIBILITY constexpr void swap(span &__other) noexcept 333 { 334 pointer __p = __data; 335 __data = __other.__data; 336 __other.__data = __p; 337 } 338 339 _LIBCPP_INLINE_VISIBILITY span<const byte, _Extent * sizeof(element_type)> __as_bytes() const noexcept 340 { return {reinterpret_cast<const byte *>(data()), size_bytes()}; } 341 342 _LIBCPP_INLINE_VISIBILITY span<byte, _Extent * sizeof(element_type)> __as_writable_bytes() const noexcept 343 { return {reinterpret_cast<byte *>(data()), size_bytes()}; } 344 345private: 346 pointer __data; 347 348}; 349 350 351template <typename _Tp> 352class _LIBCPP_TEMPLATE_VIS span<_Tp, dynamic_extent> { 353private: 354 355public: 356// constants and types 357 using element_type = _Tp; 358 using value_type = remove_cv_t<_Tp>; 359 using size_type = size_t; 360 using difference_type = ptrdiff_t; 361 using pointer = _Tp *; 362 using const_pointer = const _Tp *; 363 using reference = _Tp &; 364 using const_reference = const _Tp &; 365 using iterator = __wrap_iter<pointer>; 366 using const_iterator = __wrap_iter<const_pointer>; 367 using reverse_iterator = _VSTD::reverse_iterator<iterator>; 368 using const_reverse_iterator = _VSTD::reverse_iterator<const_iterator>; 369 370 static constexpr size_type extent = dynamic_extent; 371 372// [span.cons], span constructors, copy, assignment, and destructor 373 _LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data{nullptr}, __size{0} {} 374 375 constexpr span (const span&) noexcept = default; 376 constexpr span& operator=(const span&) noexcept = default; 377 378 _LIBCPP_INLINE_VISIBILITY constexpr span(pointer __ptr, size_type __count) : __data{__ptr}, __size{__count} {} 379 _LIBCPP_INLINE_VISIBILITY constexpr span(pointer __f, pointer __l) : __data{__f}, __size{static_cast<size_t>(distance(__f, __l))} {} 380 381 template <size_t _Sz> 382 _LIBCPP_INLINE_VISIBILITY 383 constexpr span(element_type (&__arr)[_Sz]) noexcept : __data{__arr}, __size{_Sz} {} 384 385 template <size_t _Sz> 386 _LIBCPP_INLINE_VISIBILITY 387 constexpr span(array<value_type, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {} 388 389 template <size_t _Sz> 390 _LIBCPP_INLINE_VISIBILITY 391 constexpr span(const array<value_type, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {} 392 393 template <class _Container> 394 _LIBCPP_INLINE_VISIBILITY 395 constexpr span( _Container& __c, 396 enable_if_t<__is_span_compatible_container<_Container, _Tp>::value, nullptr_t> = nullptr) 397 : __data{_VSTD::data(__c)}, __size{(size_type) _VSTD::size(__c)} {} 398 399 template <class _Container> 400 _LIBCPP_INLINE_VISIBILITY 401 constexpr span(const _Container& __c, 402 enable_if_t<__is_span_compatible_container<const _Container, _Tp>::value, nullptr_t> = nullptr) 403 : __data{_VSTD::data(__c)}, __size{(size_type) _VSTD::size(__c)} {} 404 405 406 template <class _OtherElementType, size_t _OtherExtent> 407 _LIBCPP_INLINE_VISIBILITY 408 constexpr span(const span<_OtherElementType, _OtherExtent>& __other, 409 enable_if_t< 410 is_convertible_v<_OtherElementType(*)[], element_type (*)[]>, 411 nullptr_t> = nullptr) noexcept 412 : __data{__other.data()}, __size{__other.size()} {} 413 414// ~span() noexcept = default; 415 416 template <size_t _Count> 417 _LIBCPP_INLINE_VISIBILITY 418 constexpr span<element_type, _Count> first() const noexcept 419 { 420 _LIBCPP_ASSERT(_Count <= size(), "Count out of range in span::first()"); 421 return {data(), _Count}; 422 } 423 424 template <size_t _Count> 425 _LIBCPP_INLINE_VISIBILITY 426 constexpr span<element_type, _Count> last() const noexcept 427 { 428 _LIBCPP_ASSERT(_Count <= size(), "Count out of range in span::last()"); 429 return {data() + size() - _Count, _Count}; 430 } 431 432 _LIBCPP_INLINE_VISIBILITY 433 constexpr span<element_type, dynamic_extent> first(size_type __count) const noexcept 434 { 435 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::first(count)"); 436 return {data(), __count}; 437 } 438 439 _LIBCPP_INLINE_VISIBILITY 440 constexpr span<element_type, dynamic_extent> last (size_type __count) const noexcept 441 { 442 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::last(count)"); 443 return {data() + size() - __count, __count}; 444 } 445 446 template <size_t _Offset, size_t _Count = dynamic_extent> 447 _LIBCPP_INLINE_VISIBILITY 448 constexpr span<_Tp, dynamic_extent> subspan() const noexcept 449 { 450 _LIBCPP_ASSERT(_Offset <= size(), "Offset out of range in span::subspan()"); 451 _LIBCPP_ASSERT(_Count == dynamic_extent || _Offset + _Count <= size(), "Count out of range in span::subspan()"); 452 return {data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count}; 453 } 454 455 constexpr span<element_type, dynamic_extent> 456 _LIBCPP_INLINE_VISIBILITY 457 subspan(size_type __offset, size_type __count = dynamic_extent) const noexcept 458 { 459 _LIBCPP_ASSERT(__offset <= size(), "Offset out of range in span::subspan(offset, count)"); 460 _LIBCPP_ASSERT(__count <= size() || __count == dynamic_extent, "count out of range in span::subspan(offset, count)"); 461 if (__count == dynamic_extent) 462 return {data() + __offset, size() - __offset}; 463 _LIBCPP_ASSERT(__offset <= size() - __count, "Offset + count out of range in span::subspan(offset, count)"); 464 return {data() + __offset, __count}; 465 } 466 467 _LIBCPP_INLINE_VISIBILITY constexpr size_type size() const noexcept { return __size; } 468 _LIBCPP_INLINE_VISIBILITY constexpr size_type size_bytes() const noexcept { return __size * sizeof(element_type); } 469 _LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return __size == 0; } 470 471 _LIBCPP_INLINE_VISIBILITY constexpr reference operator[](size_type __idx) const noexcept 472 { 473 _LIBCPP_ASSERT(__idx >= 0 && __idx < size(), "span<T>[] index out of bounds"); 474 return __data[__idx]; 475 } 476 477 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept 478 { 479 _LIBCPP_ASSERT(!empty(), "span<T>[].front() on empty span"); 480 return __data[0]; 481 } 482 483 _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept 484 { 485 _LIBCPP_ASSERT(!empty(), "span<T>[].back() on empty span"); 486 return __data[size()-1]; 487 } 488 489 490 _LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; } 491 492// [span.iter], span iterator support 493 _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { return iterator(data()); } 494 _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { return iterator(data() + size()); } 495 _LIBCPP_INLINE_VISIBILITY constexpr const_iterator cbegin() const noexcept { return const_iterator(data()); } 496 _LIBCPP_INLINE_VISIBILITY constexpr const_iterator cend() const noexcept { return const_iterator(data() + size()); } 497 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); } 498 _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); } 499 _LIBCPP_INLINE_VISIBILITY constexpr const_reverse_iterator crbegin() const noexcept { return const_reverse_iterator(cend()); } 500 _LIBCPP_INLINE_VISIBILITY constexpr const_reverse_iterator crend() const noexcept { return const_reverse_iterator(cbegin()); } 501 502 _LIBCPP_INLINE_VISIBILITY constexpr void swap(span &__other) noexcept 503 { 504 pointer __p = __data; 505 __data = __other.__data; 506 __other.__data = __p; 507 508 size_type __sz = __size; 509 __size = __other.__size; 510 __other.__size = __sz; 511 } 512 513 _LIBCPP_INLINE_VISIBILITY span<const byte, dynamic_extent> __as_bytes() const noexcept 514 { return {reinterpret_cast<const byte *>(data()), size_bytes()}; } 515 516 _LIBCPP_INLINE_VISIBILITY span<byte, dynamic_extent> __as_writable_bytes() const noexcept 517 { return {reinterpret_cast<byte *>(data()), size_bytes()}; } 518 519private: 520 pointer __data; 521 size_type __size; 522}; 523 524// tuple interface 525template <class _Tp, size_t _Size> 526struct _LIBCPP_TEMPLATE_VIS tuple_size<span<_Tp, _Size>> 527 : public integral_constant<size_t, _Size> {}; 528 529template <class _Tp> 530struct _LIBCPP_TEMPLATE_VIS tuple_size<span<_Tp, dynamic_extent>>; // declared but not defined 531 532 533template <size_t _Ip, class _Tp, size_t _Size> 534struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, span<_Tp, _Size>> 535{ 536 static_assert( dynamic_extent != _Size, "std::tuple_element<> not supported for std::span<T, dynamic_extent>"); 537 static_assert(_Ip < _Size, "Index out of bounds in std::tuple_element<> (std::span)"); 538 typedef _Tp type; 539}; 540 541template <size_t _Ip, class _Tp, size_t _Size> 542_LIBCPP_INLINE_VISIBILITY constexpr 543_Tp& 544get(span<_Tp, _Size> __s) noexcept 545{ 546 static_assert( dynamic_extent != _Size, "std::get<> not supported for std::span<T, dynamic_extent>"); 547 static_assert(_Ip < _Size, "Index out of bounds in std::get<> (std::span)"); 548 return __s[_Ip]; 549} 550 551 552// as_bytes & as_writable_bytes 553template <class _Tp, size_t _Extent> 554_LIBCPP_INLINE_VISIBILITY 555auto as_bytes(span<_Tp, _Extent> __s) noexcept 556-> decltype(__s.__as_bytes()) 557{ return __s.__as_bytes(); } 558 559template <class _Tp, size_t _Extent> 560_LIBCPP_INLINE_VISIBILITY 561auto as_writable_bytes(span<_Tp, _Extent> __s) noexcept 562-> enable_if_t<!is_const_v<_Tp>, decltype(__s.__as_writable_bytes())> 563{ return __s.__as_writable_bytes(); } 564 565template <class _Tp, size_t _Extent> 566_LIBCPP_INLINE_VISIBILITY 567constexpr void swap(span<_Tp, _Extent> &__lhs, span<_Tp, _Extent> &__rhs) noexcept 568{ __lhs.swap(__rhs); } 569 570 571// Deduction guides 572template<class _Tp, size_t _Sz> 573 span(_Tp (&)[_Sz]) -> span<_Tp, _Sz>; 574 575template<class _Tp, size_t _Sz> 576 span(array<_Tp, _Sz>&) -> span<_Tp, _Sz>; 577 578template<class _Tp, size_t _Sz> 579 span(const array<_Tp, _Sz>&) -> span<const _Tp, _Sz>; 580 581template<class _Container> 582 span(_Container&) -> span<typename _Container::value_type>; 583 584template<class _Container> 585 span(const _Container&) -> span<const typename _Container::value_type>; 586 587#endif // _LIBCPP_STD_VER > 17 588 589_LIBCPP_END_NAMESPACE_STD 590 591#endif // _LIBCPP_SPAN 592