35 #define _GLIBCXX_SPAN 1
37 #pragma GCC system_header
39 #if __cplusplus > 201703L
46 #if __cpp_lib_concepts
47 namespace std _GLIBCXX_VISIBILITY(default)
49 _GLIBCXX_BEGIN_NAMESPACE_VERSION
51 #define __cpp_lib_span 202002L
53 inline constexpr
size_t dynamic_extent =
static_cast<size_t>(-1);
55 template<
typename _Type,
size_t _Extent>
60 template<
typename _Tp>
63 template<
typename _Tp,
size_t _Num>
64 struct __is_std_span<span<_Tp, _Num>> :
true_type { };
66 template<
typename _Tp>
69 template<
typename _Tp,
size_t _Num>
70 struct __is_std_array<std::array<_Tp, _Num>> :
true_type { };
72 template<
size_t _Extent>
73 class __extent_storage
77 __extent_storage(
size_t) noexcept
80 static constexpr
size_t
86 class __extent_storage<dynamic_extent>
90 __extent_storage(
size_t __extent) noexcept
91 : _M_extent_value(__extent)
95 _M_extent() const noexcept
96 {
return this->_M_extent_value; }
99 size_t _M_extent_value;
103 template<
typename _Type,
size_t _Extent = dynamic_extent>
106 template<
size_t _Offset,
size_t _Count>
107 static constexpr
size_t
110 if constexpr (_Count != dynamic_extent)
112 else if constexpr (extent != dynamic_extent)
113 return _Extent - _Offset;
115 return dynamic_extent;
120 template<typename _Tp,
size_t _ArrayExtent>
121 requires (_Extent == dynamic_extent || _ArrayExtent == _Extent)
122 using __is_compatible_array = __is_array_convertible<_Type, _Tp>;
124 template<typename _Ref>
125 using __is_compatible_ref
132 using size_type =
size_t;
133 using difference_type = ptrdiff_t;
134 using pointer = _Type*;
135 using const_pointer = const _Type*;
137 using const_reference = const element_type&;
138 using iterator = __gnu_cxx::__normal_iterator<pointer, span>;
139 using reverse_iterator = std::reverse_iterator<iterator>;
142 static constexpr
size_t extent = _Extent;
148 requires ((_Extent + 1u) <= 1u)
149 : _M_ptr(
nullptr), _M_extent(0)
152 template<contiguous_iterator _It>
153 requires __is_compatible_ref<iter_reference_t<_It>>::value
154 constexpr
explicit(extent != dynamic_extent)
155 span(_It __first, size_type __count)
157 : _M_ptr(std::to_address(__first)), _M_extent(__count)
159 if constexpr (_Extent != dynamic_extent)
161 __glibcxx_assert(__count == _Extent);
165 template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
166 requires __is_compatible_ref<iter_reference_t<_It>>::value
167 && (!is_convertible_v<_End, size_type>)
168 constexpr
explicit(extent != dynamic_extent)
169 span(_It __first, _End __last)
170 noexcept(noexcept(__last - __first))
171 : _M_ptr(std::to_address(__first)),
172 _M_extent(static_cast<size_type>(__last - __first))
174 if constexpr (_Extent != dynamic_extent)
176 __glibcxx_assert((__last - __first) == _Extent);
180 template<
size_t _ArrayExtent>
181 requires (_Extent == dynamic_extent || _ArrayExtent == _Extent)
183 span(type_identity_t<
element_type> (&__arr)[_ArrayExtent]) noexcept
184 : span(static_cast<pointer>(__arr), _ArrayExtent)
187 template<
typename _Tp,
size_t _ArrayExtent>
188 requires __is_compatible_array<_Tp, _ArrayExtent>::value
190 span(array<_Tp, _ArrayExtent>& __arr) noexcept
191 : span(static_cast<pointer>(__arr.data()), _ArrayExtent)
194 template<
typename _Tp,
size_t _ArrayExtent>
195 requires __is_compatible_array<const _Tp, _ArrayExtent>::value
197 span(
const array<_Tp, _ArrayExtent>& __arr) noexcept
198 : span(static_cast<pointer>(__arr.data()), _ArrayExtent)
201 template<
typename _Range>
202 requires ranges::contiguous_range<_Range> && ranges::sized_range<_Range>
203 && (ranges::borrowed_range<_Range> || is_const_v<element_type>)
204 && (!__detail::__is_std_span<remove_cvref_t<_Range>>::value)
205 && (!__detail::__is_std_array<remove_cvref_t<_Range>>::value)
206 && (!is_array_v<remove_cvref_t<_Range>>)
207 && __is_compatible_ref<ranges::range_reference_t<_Range>>::value
208 constexpr
explicit(extent != dynamic_extent)
209 span(_Range&& __range)
210 noexcept(noexcept(ranges::
data(__range))
211 && noexcept(ranges::
size(__range)))
212 : span(ranges::
data(__range), ranges::
size(__range))
214 if constexpr (extent != dynamic_extent)
221 span(
const span&) noexcept = default;
223 template<typename _OType,
size_t _OExtent>
224 requires (_Extent == dynamic_extent || _OExtent == dynamic_extent
225 || _Extent == _OExtent)
226 && (__is_array_convertible<_Type, _OType>::value)
228 explicit(extent != dynamic_extent && _OExtent == dynamic_extent)
229 span(const span<_OType, _OExtent>& __s) noexcept
230 : _M_extent(__s.
size()), _M_ptr(__s.
data())
232 if constexpr (extent != dynamic_extent)
234 __glibcxx_assert(__s.size() == extent);
238 ~span() noexcept = default;
241 operator=(const span&) noexcept = default;
246 size() const noexcept
247 {
return this->_M_extent._M_extent(); }
250 size_bytes() const noexcept
251 {
return this->_M_extent._M_extent() *
sizeof(
element_type); }
253 [[nodiscard]] constexpr
bool
254 empty() const noexcept
255 {
return size() == 0; }
260 front() const noexcept
262 __glibcxx_assert(!
empty());
263 return *this->_M_ptr;
267 back() const noexcept
269 __glibcxx_assert(!
empty());
270 return *(this->_M_ptr + (
size() - 1));
274 operator[](size_type __idx)
const noexcept
276 __glibcxx_assert(__idx <
size());
277 return *(this->_M_ptr + __idx);
281 data() const noexcept
282 {
return this->_M_ptr; }
287 begin() const noexcept
288 {
return iterator(this->_M_ptr); }
292 {
return iterator(this->_M_ptr + this->
size()); }
294 constexpr reverse_iterator
296 {
return reverse_iterator(this->
end()); }
298 constexpr reverse_iterator
299 rend() const noexcept
300 {
return reverse_iterator(this->
begin()); }
304 template<
size_t _Count>
305 constexpr span<element_type, _Count>
306 first() const noexcept
308 if constexpr (_Extent == dynamic_extent)
309 __glibcxx_assert(_Count <= size());
311 static_assert(_Count <= extent);
313 return _Sp{ this->
data(), _Count };
316 constexpr span<element_type, dynamic_extent>
317 first(size_type __count)
const noexcept
319 __glibcxx_assert(__count <=
size());
320 return { this->
data(), __count };
323 template<
size_t _Count>
324 constexpr span<element_type, _Count>
325 last() const noexcept
327 if constexpr (_Extent == dynamic_extent)
328 __glibcxx_assert(_Count <= size());
330 static_assert(_Count <= extent);
332 return _Sp{ this->
data() + (this->
size() - _Count), _Count };
335 constexpr span<element_type, dynamic_extent>
336 last(size_type __count)
const noexcept
338 __glibcxx_assert(__count <=
size());
339 return { this->
data() + (this->
size() - __count), __count };
342 template<
size_t _Offset,
size_t _Count = dynamic_extent>
344 subspan() const noexcept
345 -> span<
element_type, _S_subspan_extent<_Offset, _Count>()>
347 if constexpr (_Extent == dynamic_extent)
349 __glibcxx_assert(_Offset <=
size());
352 static_assert(_Offset <= extent);
354 using _Sp = span<element_type, _S_subspan_extent<_Offset, _Count>()>;
356 if constexpr (_Count == dynamic_extent)
357 return _Sp{ this->
data() + _Offset, this->
size() - _Offset };
360 if constexpr (_Extent == dynamic_extent)
362 __glibcxx_assert(_Count <=
size());
363 __glibcxx_assert(_Count <= (
size() - _Offset));
367 static_assert(_Count <= extent);
368 static_assert(_Count <= (extent - _Offset));
370 return _Sp{ this->
data() + _Offset, _Count };
374 constexpr span<element_type, dynamic_extent>
375 subspan(size_type __offset, size_type __count = dynamic_extent) const
378 __glibcxx_assert(__offset <=
size());
379 if (__count == dynamic_extent)
380 __count = this->
size() - __offset;
383 __glibcxx_assert(__count <=
size());
384 __glibcxx_assert(__offset + __count <=
size());
386 return {this->
data() + __offset, __count};
391 [[no_unique_address]] __detail::__extent_storage<extent> _M_extent;
396 template<
typename _Type,
size_t _ArrayExtent>
397 span(_Type(&)[_ArrayExtent]) -> span<_Type, _ArrayExtent>;
399 template<
typename _Type,
size_t _ArrayExtent>
400 span(array<_Type, _ArrayExtent>&) -> span<_Type, _ArrayExtent>;
402 template<
typename _Type,
size_t _ArrayExtent>
403 span(
const array<_Type, _ArrayExtent>&)
404 -> span<const _Type, _ArrayExtent>;
406 template<contiguous_iterator _Iter,
typename _End>
408 -> span<remove_reference_t<iter_reference_t<_Iter>>>;
410 template<
typename _Range>
412 -> span<remove_reference_t<ranges::range_reference_t<_Range&>>>;
414 template<
typename _Type,
size_t _Extent>
416 span<
const byte, _Extent == dynamic_extent
417 ? dynamic_extent : _Extent *
sizeof(_Type)>
418 as_bytes(span<_Type, _Extent> __sp) noexcept
420 auto data =
reinterpret_cast<const byte*
>(__sp.data());
421 auto size = __sp.size_bytes();
422 constexpr
auto extent = _Extent == dynamic_extent
423 ? dynamic_extent : _Extent *
sizeof(_Type);
424 return span<const byte, extent>{
data, size};
427 template<
typename _Type,
size_t _Extent>
428 requires (!is_const_v<_Type>)
430 span<byte, _Extent == dynamic_extent
431 ? dynamic_extent : _Extent * sizeof(_Type)>
432 as_writable_bytes(span<_Type, _Extent> __sp) noexcept
434 auto data =
reinterpret_cast<byte*
>(__sp.data());
435 auto size = __sp.size_bytes();
436 constexpr
auto extent = _Extent == dynamic_extent
437 ? dynamic_extent : _Extent *
sizeof(_Type);
438 return span<byte, extent>{
data, size};
444 template<
typename _ElementType,
size_t _Extent>
445 inline constexpr
bool
446 enable_borrowed_range<span<_ElementType, _Extent>> =
true;
449 template<
typename _ElementType,
size_t _Extent>
450 inline constexpr
bool
451 enable_view<span<_ElementType, _Extent>>
452 = _Extent == 0 || _Extent == dynamic_extent;
454 _GLIBCXX_END_NAMESPACE_VERSION
458 #endif // _GLIBCXX_SPAN
_Tp element_type
The pointed-to type.
constexpr auto rend(_Container &__cont) -> decltype(__cont.rend())
Return a reverse iterator pointing one past the first element of the container.
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
constexpr auto data(_Container &__cont) noexcept(noexcept(__cont.data())) -> decltype(__cont.data())
Return the data pointer of a container.
_Tp * begin(valarray< _Tp > &__va)
Return an iterator pointing to the first element of the valarray.
constexpr auto rbegin(_Container &__cont) -> decltype(__cont.rbegin())
Return a reverse iterator pointing to the last element of the container.
_Tp * end(valarray< _Tp > &__va)
Return an iterator pointing to one past the last element of the valarray.
typename remove_cv< _Tp >::type remove_cv_t
Alias template for remove_cv.
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
constexpr auto empty(const _Container &__cont) noexcept(noexcept(__cont.empty())) -> decltype(__cont.empty())
Return whether a container is empty.
typename remove_reference< _Tp >::type remove_reference_t
Alias template for remove_reference.
constexpr auto size(const _Container &__cont) noexcept(noexcept(__cont.size())) -> decltype(__cont.size())
Return the size of a container.