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Marshall Clowfbd3e842018-07-24 03:01:02 +00001// -*- C++ -*-
2//===------------------------------ span ---------------------------------===//
3//
Chandler Carruth7c3769d2019-01-19 10:56:40 +00004// 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
Marshall Clowfbd3e842018-07-24 03:01:02 +00007//
8//===---------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_SPAN
11#define _LIBCPP_SPAN
12
13/*
14 span synopsis
15
16namespace std {
17
18// constants
Marshall Clowb3c66aa2019-02-27 00:32:16 +000019inline constexpr size_t dynamic_extent = numeric_limits<size_t>::max();
Marshall Clowfbd3e842018-07-24 03:01:02 +000020
21// [views.span], class template span
Marshall Clowb3c66aa2019-02-27 00:32:16 +000022template <class ElementType, size_t Extent = dynamic_extent>
Marshall Clowfbd3e842018-07-24 03:01:02 +000023 class span;
24
Marshall Clowfbd3e842018-07-24 03:01:02 +000025// [span.objectrep], views of object representation
Marshall Clowb3c66aa2019-02-27 00:32:16 +000026template <class ElementType, size_t Extent>
Louis Dionne2580fdb2018-08-03 22:36:53 +000027 span<const byte, ((Extent == dynamic_extent) ? dynamic_extent :
Marshall Clow526bce42019-03-06 03:59:44 +000028 (sizeof(ElementType) * Extent))> as_bytes(span<ElementType, Extent> s) noexcept;
Marshall Clowfbd3e842018-07-24 03:01:02 +000029
Marshall Clowb3c66aa2019-02-27 00:32:16 +000030template <class ElementType, size_t Extent>
Louis Dionne2580fdb2018-08-03 22:36:53 +000031 span< byte, ((Extent == dynamic_extent) ? dynamic_extent :
Marshall Clow526bce42019-03-06 03:59:44 +000032 (sizeof(ElementType) * Extent))> as_writable_bytes(span<ElementType, Extent> s) noexcept;
Marshall Clowfbd3e842018-07-24 03:01:02 +000033
34
35namespace std {
Marshall Clowb3c66aa2019-02-27 00:32:16 +000036template <class ElementType, size_t Extent = dynamic_extent>
Marshall Clowfbd3e842018-07-24 03:01:02 +000037class span {
38public:
39 // constants and types
40 using element_type = ElementType;
41 using value_type = remove_cv_t<ElementType>;
Marshall Clowb3c66aa2019-02-27 00:32:16 +000042 using index_type = size_t;
Marshall Clowfbd3e842018-07-24 03:01:02 +000043 using difference_type = ptrdiff_t;
44 using pointer = element_type*;
Marshall Clowc67930b2019-02-25 17:58:03 +000045 using const_pointer = const element_type*;
Marshall Clowfbd3e842018-07-24 03:01:02 +000046 using reference = element_type&;
Marshall Clowc67930b2019-02-25 17:58:03 +000047 using const_reference = const element_type&;
Marshall Clowb3c66aa2019-02-27 00:32:16 +000048 using iterator = implementation-defined;
Marshall Clowfbd3e842018-07-24 03:01:02 +000049 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 index_type extent = Extent;
53
54 // [span.cons], span constructors, copy, assignment, and destructor
55 constexpr span() noexcept;
56 constexpr span(pointer ptr, index_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;
Marshall Clowb3c66aa2019-02-27 00:32:16 +000069 template <class OtherElementType, size_t OtherExtent>
Marshall Clowfbd3e842018-07-24 03:01:02 +000070 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
Marshall Clowb3c66aa2019-02-27 00:32:16 +000075 template <size_t Count>
Marshall Clowfbd3e842018-07-24 03:01:02 +000076 constexpr span<element_type, Count> first() const;
Marshall Clowb3c66aa2019-02-27 00:32:16 +000077 template <size_t Count>
Marshall Clowfbd3e842018-07-24 03:01:02 +000078 constexpr span<element_type, Count> last() const;
Marshall Clowb3c66aa2019-02-27 00:32:16 +000079 template <size_t Offset, size_t Count = dynamic_extent>
Marshall Clowfbd3e842018-07-24 03:01:02 +000080 constexpr span<element_type, see below> subspan() const;
81
82 constexpr span<element_type, dynamic_extent> first(index_type count) const;
83 constexpr span<element_type, dynamic_extent> last(index_type count) const;
84 constexpr span<element_type, dynamic_extent> subspan(index_type offset, index_type count = dynamic_extent) const;
85
86 // [span.obs], span observers
87 constexpr index_type size() const noexcept;
88 constexpr index_type size_bytes() const noexcept;
89 constexpr bool empty() const noexcept;
90
91 // [span.elem], span element access
92 constexpr reference operator[](index_type idx) const;
Marshall Clowe5cb7442019-02-25 17:54:08 +000093 constexpr reference front() const;
94 constexpr reference back() const;
Marshall Clowfbd3e842018-07-24 03:01:02 +000095 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 index_type size_; // exposition only
110};
111
112template<class T, size_t N>
113 span(T (&)[N]) -> span<T, N>;
Louis Dionne2580fdb2018-08-03 22:36:53 +0000114
Marshall Clowfbd3e842018-07-24 03:01:02 +0000115template<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
Marshall Clow39bc5e72018-07-24 03:56:38 +0000131#include <__config>
Marshall Clowfbd3e842018-07-24 03:01:02 +0000132#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
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000146inline constexpr size_t dynamic_extent = numeric_limits<size_t>::max();
147template <typename _Tp, size_t _Extent = dynamic_extent> class span;
Marshall Clowfbd3e842018-07-24 03:01:02 +0000148
149
150template <class _Tp>
151struct __is_span_impl : public false_type {};
152
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000153template <class _Tp, size_t _Extent>
Marshall Clowfbd3e842018-07-24 03:01:02 +0000154struct __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<
Louis Dionne2580fdb2018-08-03 22:36:53 +0000185 is_convertible_v<remove_pointer_t<decltype(data(declval<_Tp &>()))>(*)[],
186 _ElementType(*)[]>,
Marshall Clowfbd3e842018-07-24 03:01:02 +0000187 nullptr_t>::type
188 >>
189 : public true_type {};
190
191
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000192template <typename _Tp, size_t _Extent>
Marshall Clowfbd3e842018-07-24 03:01:02 +0000193class _LIBCPP_TEMPLATE_VIS span {
194public:
195// constants and types
196 using element_type = _Tp;
197 using value_type = remove_cv_t<_Tp>;
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000198 using index_type = size_t;
Marshall Clowfbd3e842018-07-24 03:01:02 +0000199 using difference_type = ptrdiff_t;
200 using pointer = _Tp *;
Marshall Clowc67930b2019-02-25 17:58:03 +0000201 using const_pointer = const _Tp *;
Marshall Clowfbd3e842018-07-24 03:01:02 +0000202 using reference = _Tp &;
Marshall Clowc67930b2019-02-25 17:58:03 +0000203 using const_reference = const _Tp &;
Marshall Clowfbd3e842018-07-24 03:01:02 +0000204 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 index_type extent = _Extent;
Marshall Clowfbd3e842018-07-24 03:01:02 +0000210
Louis Dionne2580fdb2018-08-03 22:36:53 +0000211// [span.cons], span constructors, copy, assignment, and destructor
Marshall Clowfbd3e842018-07-24 03:01:02 +0000212 _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, index_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
Marshall Clowfbd3e842018-07-24 03:01:02 +0000227 template <class _OtherElementType>
Marshall Clow526bce42019-03-06 03:59:44 +0000228 _LIBCPP_INLINE_VISIBILITY
Marshall Clowfbd3e842018-07-24 03:01:02 +0000229 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>
Marshall Clow526bce42019-03-06 03:59:44 +0000236 _LIBCPP_INLINE_VISIBILITY
Marshall Clowfbd3e842018-07-24 03:01:02 +0000237 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
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000246 template <size_t _Count>
Marshall Clow526bce42019-03-06 03:59:44 +0000247 _LIBCPP_INLINE_VISIBILITY
248 constexpr span<element_type, _Count> first() const noexcept
Marshall Clowfbd3e842018-07-24 03:01:02 +0000249 {
Marshall Clowfbd3e842018-07-24 03:01:02 +0000250 static_assert(_Count <= _Extent, "Count out of range in span::first()");
251 return {data(), _Count};
252 }
253
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000254 template <size_t _Count>
Marshall Clow526bce42019-03-06 03:59:44 +0000255 _LIBCPP_INLINE_VISIBILITY
256 constexpr span<element_type, _Count> last() const noexcept
Marshall Clowfbd3e842018-07-24 03:01:02 +0000257 {
Marshall Clowfbd3e842018-07-24 03:01:02 +0000258 static_assert(_Count <= _Extent, "Count out of range in span::last()");
259 return {data() + size() - _Count, _Count};
260 }
Louis Dionne2580fdb2018-08-03 22:36:53 +0000261
Marshall Clowfbd3e842018-07-24 03:01:02 +0000262 _LIBCPP_INLINE_VISIBILITY
263 constexpr span<element_type, dynamic_extent> first(index_type __count) const noexcept
264 {
Marshall Clow526bce42019-03-06 03:59:44 +0000265 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::first(count)");
Marshall Clowfbd3e842018-07-24 03:01:02 +0000266 return {data(), __count};
267 }
268
269 _LIBCPP_INLINE_VISIBILITY
270 constexpr span<element_type, dynamic_extent> last(index_type __count) const noexcept
271 {
Marshall Clow526bce42019-03-06 03:59:44 +0000272 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::last(count)");
Marshall Clowfbd3e842018-07-24 03:01:02 +0000273 return {data() + size() - __count, __count};
274 }
275
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000276 template <size_t _Offset, size_t _Count = dynamic_extent>
Marshall Clow526bce42019-03-06 03:59:44 +0000277 _LIBCPP_INLINE_VISIBILITY
278 constexpr auto subspan() const noexcept
Marshall Clowfbd3e842018-07-24 03:01:02 +0000279 -> span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset>
280 {
Marshall Clow526bce42019-03-06 03:59:44 +0000281 static_assert(_Offset <= _Extent, "Offset out of range in span::subspan()");
Marshall Clowfbd3e842018-07-24 03:01:02 +0000282 return {data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count};
283 }
284
285
Marshall Clow526bce42019-03-06 03:59:44 +0000286 _LIBCPP_INLINE_VISIBILITY
Marshall Clowfbd3e842018-07-24 03:01:02 +0000287 constexpr span<element_type, dynamic_extent>
288 subspan(index_type __offset, index_type __count = dynamic_extent) const noexcept
Louis Dionne2580fdb2018-08-03 22:36:53 +0000289 {
Marshall Clow526bce42019-03-06 03:59:44 +0000290 _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)");
Marshall Clowfbd3e842018-07-24 03:01:02 +0000292 if (__count == dynamic_extent)
293 return {data() + __offset, size() - __offset};
Marshall Clow526bce42019-03-06 03:59:44 +0000294 _LIBCPP_ASSERT(__offset <= size() - __count, "count + offset out of range in span::subspan(offset, count)");
Marshall Clowfbd3e842018-07-24 03:01:02 +0000295 return {data() + __offset, __count};
296 }
297
298 _LIBCPP_INLINE_VISIBILITY constexpr index_type size() const noexcept { return _Extent; }
299 _LIBCPP_INLINE_VISIBILITY constexpr index_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[](index_type __idx) const noexcept
303 {
304 _LIBCPP_ASSERT(__idx >= 0 && __idx < size(), "span<T,N>[] index out of bounds");
Louis Dionne2580fdb2018-08-03 22:36:53 +0000305 return __data[__idx];
306 }
Marshall Clowfbd3e842018-07-24 03:01:02 +0000307
Marshall Clowe5cb7442019-02-25 17:54:08 +0000308 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept
Marshall Clowfbd3e842018-07-24 03:01:02 +0000309 {
Marshall Clowe5cb7442019-02-25 17:54:08 +0000310 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];
Louis Dionne2580fdb2018-08-03 22:36:53 +0000318 }
Marshall Clowfbd3e842018-07-24 03:01:02 +0000319
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 }
Louis Dionne2580fdb2018-08-03 22:36:53 +0000338
Marshall Clowfbd3e842018-07-24 03:01:02 +0000339 _LIBCPP_INLINE_VISIBILITY span<const byte, _Extent * sizeof(element_type)> __as_bytes() const noexcept
340 { return {reinterpret_cast<const byte *>(data()), size_bytes()}; }
341
Louis Dionnea9b10432019-03-28 01:27:52 +0000342 _LIBCPP_INLINE_VISIBILITY span<byte, _Extent * sizeof(element_type)> __as_writable_bytes() const noexcept
Marshall Clowfbd3e842018-07-24 03:01:02 +0000343 { 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>;
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000359 using index_type = size_t;
Marshall Clowfbd3e842018-07-24 03:01:02 +0000360 using difference_type = ptrdiff_t;
361 using pointer = _Tp *;
Marshall Clowc67930b2019-02-25 17:58:03 +0000362 using const_pointer = const _Tp *;
Marshall Clowfbd3e842018-07-24 03:01:02 +0000363 using reference = _Tp &;
Marshall Clowc67930b2019-02-25 17:58:03 +0000364 using const_reference = const _Tp &;
Marshall Clowfbd3e842018-07-24 03:01:02 +0000365 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 index_type extent = dynamic_extent;
371
Louis Dionne2580fdb2018-08-03 22:36:53 +0000372// [span.cons], span constructors, copy, assignment, and destructor
Marshall Clowfbd3e842018-07-24 03:01:02 +0000373 _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, index_type __count) : __data{__ptr}, __size{__count} {}
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000379 _LIBCPP_INLINE_VISIBILITY constexpr span(pointer __f, pointer __l) : __data{__f}, __size{static_cast<size_t>(distance(__f, __l))} {}
Marshall Clowfbd3e842018-07-24 03:01:02 +0000380
381 template <size_t _Sz>
Marshall Clow526bce42019-03-06 03:59:44 +0000382 _LIBCPP_INLINE_VISIBILITY
383 constexpr span(element_type (&__arr)[_Sz]) noexcept : __data{__arr}, __size{_Sz} {}
Marshall Clowfbd3e842018-07-24 03:01:02 +0000384
385 template <size_t _Sz>
Marshall Clow526bce42019-03-06 03:59:44 +0000386 _LIBCPP_INLINE_VISIBILITY
387 constexpr span(array<value_type, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {}
Louis Dionne2580fdb2018-08-03 22:36:53 +0000388
Marshall Clowfbd3e842018-07-24 03:01:02 +0000389 template <size_t _Sz>
Marshall Clow526bce42019-03-06 03:59:44 +0000390 _LIBCPP_INLINE_VISIBILITY
391 constexpr span(const array<value_type, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {}
Marshall Clowfbd3e842018-07-24 03:01:02 +0000392
393 template <class _Container>
Marshall Clow526bce42019-03-06 03:59:44 +0000394 _LIBCPP_INLINE_VISIBILITY
Marshall Clowfbd3e842018-07-24 03:01:02 +0000395 constexpr span( _Container& __c,
396 enable_if_t<__is_span_compatible_container<_Container, _Tp>::value, nullptr_t> = nullptr)
397 : __data{_VSTD::data(__c)}, __size{(index_type) _VSTD::size(__c)} {}
398
399 template <class _Container>
Marshall Clow526bce42019-03-06 03:59:44 +0000400 _LIBCPP_INLINE_VISIBILITY
Marshall Clowfbd3e842018-07-24 03:01:02 +0000401 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{(index_type) _VSTD::size(__c)} {}
404
405
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000406 template <class _OtherElementType, size_t _OtherExtent>
Marshall Clow526bce42019-03-06 03:59:44 +0000407 _LIBCPP_INLINE_VISIBILITY
Marshall Clowfbd3e842018-07-24 03:01:02 +0000408 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
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000416 template <size_t _Count>
Marshall Clow526bce42019-03-06 03:59:44 +0000417 _LIBCPP_INLINE_VISIBILITY
418 constexpr span<element_type, _Count> first() const noexcept
Marshall Clowfbd3e842018-07-24 03:01:02 +0000419 {
Marshall Clowfbd3e842018-07-24 03:01:02 +0000420 _LIBCPP_ASSERT(_Count <= size(), "Count out of range in span::first()");
421 return {data(), _Count};
422 }
423
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000424 template <size_t _Count>
Marshall Clow526bce42019-03-06 03:59:44 +0000425 _LIBCPP_INLINE_VISIBILITY
426 constexpr span<element_type, _Count> last() const noexcept
Marshall Clowfbd3e842018-07-24 03:01:02 +0000427 {
Marshall Clowfbd3e842018-07-24 03:01:02 +0000428 _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(index_type __count) const noexcept
434 {
Marshall Clow526bce42019-03-06 03:59:44 +0000435 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::first(count)");
Marshall Clowfbd3e842018-07-24 03:01:02 +0000436 return {data(), __count};
437 }
Louis Dionne2580fdb2018-08-03 22:36:53 +0000438
Marshall Clowfbd3e842018-07-24 03:01:02 +0000439 _LIBCPP_INLINE_VISIBILITY
440 constexpr span<element_type, dynamic_extent> last (index_type __count) const noexcept
441 {
Marshall Clow526bce42019-03-06 03:59:44 +0000442 _LIBCPP_ASSERT(__count <= size(), "Count out of range in span::last(count)");
Marshall Clowfbd3e842018-07-24 03:01:02 +0000443 return {data() + size() - __count, __count};
444 }
445
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000446 template <size_t _Offset, size_t _Count = dynamic_extent>
Marshall Clow526bce42019-03-06 03:59:44 +0000447 _LIBCPP_INLINE_VISIBILITY
448 constexpr span<_Tp, dynamic_extent> subspan() const noexcept
Marshall Clowfbd3e842018-07-24 03:01:02 +0000449 {
Marshall Clow526bce42019-03-06 03:59:44 +0000450 _LIBCPP_ASSERT(_Offset <= size(), "Offset out of range in span::subspan()");
Marshall Clowfbd3e842018-07-24 03:01:02 +0000451 _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>
Marshall Clow526bce42019-03-06 03:59:44 +0000456 _LIBCPP_INLINE_VISIBILITY
457 subspan(index_type __offset, index_type __count = dynamic_extent) const noexcept
Louis Dionne2580fdb2018-08-03 22:36:53 +0000458 {
Marshall Clow526bce42019-03-06 03:59:44 +0000459 _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)");
Marshall Clowfbd3e842018-07-24 03:01:02 +0000461 if (__count == dynamic_extent)
462 return {data() + __offset, size() - __offset};
Marshall Clow526bce42019-03-06 03:59:44 +0000463 _LIBCPP_ASSERT(__offset <= size() - __count, "Offset + count out of range in span::subspan(offset, count)");
Marshall Clowfbd3e842018-07-24 03:01:02 +0000464 return {data() + __offset, __count};
465 }
466
467 _LIBCPP_INLINE_VISIBILITY constexpr index_type size() const noexcept { return __size; }
468 _LIBCPP_INLINE_VISIBILITY constexpr index_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[](index_type __idx) const noexcept
472 {
473 _LIBCPP_ASSERT(__idx >= 0 && __idx < size(), "span<T>[] index out of bounds");
Louis Dionne2580fdb2018-08-03 22:36:53 +0000474 return __data[__idx];
475 }
Marshall Clowfbd3e842018-07-24 03:01:02 +0000476
Marshall Clowe5cb7442019-02-25 17:54:08 +0000477 _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept
Marshall Clowfbd3e842018-07-24 03:01:02 +0000478 {
Marshall Clowe5cb7442019-02-25 17:54:08 +0000479 _LIBCPP_ASSERT(!empty(), "span<T>[].front() on empty span");
480 return __data[0];
Louis Dionne2580fdb2018-08-03 22:36:53 +0000481 }
Marshall Clowfbd3e842018-07-24 03:01:02 +0000482
Marshall Clowe5cb7442019-02-25 17:54:08 +0000483 _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
Marshall Clowfbd3e842018-07-24 03:01:02 +0000490 _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 index_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
Louis Dionnea9b10432019-03-28 01:27:52 +0000516 _LIBCPP_INLINE_VISIBILITY span<byte, dynamic_extent> __as_writable_bytes() const noexcept
Marshall Clowfbd3e842018-07-24 03:01:02 +0000517 { return {reinterpret_cast<byte *>(data()), size_bytes()}; }
518
519private:
520 pointer __data;
521 index_type __size;
522};
523
Marshall Clowae4afd02019-02-27 15:41:37 +0000524// 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>
Louis Dionneb857e812019-04-01 16:39:34 +0000534struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, span<_Tp, _Size>>
Marshall Clowae4afd02019-02-27 15:41:37 +0000535{
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)");
Marshall Clowae4afd02019-02-27 15:41:37 +0000538 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
Louis Dionnea9b10432019-03-28 01:27:52 +0000552// as_bytes & as_writable_bytes
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000553template <class _Tp, size_t _Extent>
Marshall Clowae4afd02019-02-27 15:41:37 +0000554_LIBCPP_INLINE_VISIBILITY
555auto as_bytes(span<_Tp, _Extent> __s) noexcept
556-> decltype(__s.__as_bytes())
557{ return __s.__as_bytes(); }
Marshall Clowfbd3e842018-07-24 03:01:02 +0000558
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000559template <class _Tp, size_t _Extent>
Marshall Clowae4afd02019-02-27 15:41:37 +0000560_LIBCPP_INLINE_VISIBILITY
Louis Dionnea9b10432019-03-28 01:27:52 +0000561auto 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(); }
Marshall Clowfbd3e842018-07-24 03:01:02 +0000564
Marshall Clowb3c66aa2019-02-27 00:32:16 +0000565template <class _Tp, size_t _Extent>
Marshall Clowae4afd02019-02-27 15:41:37 +0000566_LIBCPP_INLINE_VISIBILITY
567constexpr void swap(span<_Tp, _Extent> &__lhs, span<_Tp, _Extent> &__rhs) noexcept
568{ __lhs.swap(__rhs); }
Marshall Clowfbd3e842018-07-24 03:01:02 +0000569
570
571// Deduction guides
572template<class _Tp, size_t _Sz>
573 span(_Tp (&)[_Sz]) -> span<_Tp, _Sz>;
Louis Dionne2580fdb2018-08-03 22:36:53 +0000574
Marshall Clowfbd3e842018-07-24 03:01:02 +0000575template<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
Marshall Clow39bc5e72018-07-24 03:56:38 +0000587#endif // _LIBCPP_STD_VER > 17
588
Marshall Clowfbd3e842018-07-24 03:01:02 +0000589_LIBCPP_END_NAMESPACE_STD
590
Marshall Clowfbd3e842018-07-24 03:01:02 +0000591#endif // _LIBCPP_SPAN