1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
|
// Components for manipulating non-owning sequences of objects -*- C++ -*-
// Copyright (C) 2019 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file span
* This is a Standard C++ Library header.
*/
//
// P0122 span library
// Contributed by ThePhD
//
#ifndef _GLIBCXX_SPAN
#define _GLIBCXX_SPAN 1
#pragma GCC system_header
#if __cplusplus > 201703L
#include <type_traits>
#include <tuple>
#include <utility>
#include <array>
#include <bits/stl_iterator.h>
#include <bits/range_access.h>
#if __cpp_lib_concepts
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
#define __cpp_lib_span 201902L
inline constexpr size_t dynamic_extent = static_cast<size_t>(-1);
template<typename _Type, size_t _Extent>
class span;
namespace __detail
{
template<typename _Tp>
struct __is_std_span : false_type { };
template<typename _Tp, size_t _Num>
struct __is_std_span<span<_Tp, _Num>> : true_type { };
template<typename _Tp>
struct __is_std_array : false_type { };
template<typename _Tp, size_t _Num>
struct __is_std_array<_GLIBCXX_STD_C::array<_Tp, _Num>> : true_type { };
#ifdef _GLIBCXX_DEBUG
template<typename _Tp, size_t _Num>
struct __is_std_array<__debug::array<_Tp, _Num>> : true_type { };
#endif
template<size_t _Extent>
class __extent_storage
{
public:
constexpr
__extent_storage(size_t) noexcept
{ }
static constexpr size_t
_M_extent() noexcept
{ return _Extent; }
};
template<>
class __extent_storage<dynamic_extent>
{
public:
constexpr
__extent_storage(size_t __extent) noexcept
: _M_extent_value(__extent)
{ }
constexpr size_t
_M_extent() const noexcept
{ return this->_M_extent_value; }
private:
size_t _M_extent_value;
};
} // namespace __detail
template<typename _Type, size_t _Extent = dynamic_extent>
class span
{
template<size_t _Offset, size_t _Count>
static constexpr size_t
_S_subspan_extent()
{
if constexpr (_Count != dynamic_extent)
return _Count;
else if constexpr (extent != dynamic_extent)
return _Extent - _Offset;
else
return dynamic_extent;
}
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3255. span's array constructor is too strict
template<typename _Tp, size_t _ArrayExtent>
using __is_compatible_array = __and_<
bool_constant<(_Extent == dynamic_extent || _ArrayExtent == _Extent)>,
__is_array_convertible<_Type, _Tp>>;
template<typename _Iter, typename _Ref = iter_reference_t<_Iter>>
using __is_compatible_iterator = __and_<
bool_constant<contiguous_iterator<_Iter>>,
is_lvalue_reference<iter_reference_t<_Iter>>,
is_same<iter_value_t<_Iter>, remove_cvref_t<_Ref>>,
__is_array_convertible<_Type, remove_reference_t<_Ref>>>;
template<typename _Range>
using __is_compatible_range
= __is_compatible_iterator<ranges::iterator_t<_Range>>;
public:
// member types
using value_type = remove_cv_t<_Type>;
using element_type = _Type;
using size_type = size_t;
using reference = element_type&;
using const_reference = const element_type&;
using pointer = _Type*;
using const_pointer = const _Type*;
using iterator
= __gnu_cxx::__normal_iterator<pointer, span>;
using const_iterator
= __gnu_cxx::__normal_iterator<const_pointer, span>;
using reverse_iterator = std::reverse_iterator<iterator>;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
using difference_type = ptrdiff_t;
// member constants
static inline constexpr size_t extent = _Extent;
// constructors
constexpr
span() noexcept
requires ((_Extent + 1u) <= 1u)
: _M_extent(0), _M_ptr(nullptr)
{ }
constexpr
span(const span&) noexcept = default;
template<typename _Tp, size_t _ArrayExtent>
requires (__is_compatible_array<_Tp, _ArrayExtent>::value)
constexpr
span(_Tp (&__arr)[_ArrayExtent]) noexcept
: span(static_cast<pointer>(__arr), _ArrayExtent)
{ }
template<typename _Tp, size_t _ArrayExtent>
requires (__is_compatible_array<_Tp, _ArrayExtent>::value)
constexpr
span(array<_Tp, _ArrayExtent>& __arr) noexcept
: span(static_cast<pointer>(__arr.data()), _ArrayExtent)
{ }
template<typename _Tp, size_t _ArrayExtent>
requires (__is_compatible_array<const _Tp, _ArrayExtent>::value)
constexpr
span(const array<_Tp, _ArrayExtent>& __arr) noexcept
: span(static_cast<pointer>(__arr.data()), _ArrayExtent)
{ }
public:
template<ranges::contiguous_range _Range>
requires (_Extent == dynamic_extent)
&& (!__detail::__is_std_span<remove_cvref_t<_Range>>::value)
&& (!__detail::__is_std_array<remove_cvref_t<_Range>>::value)
&& (!is_array_v<remove_reference_t<_Range>>)
&& (__is_compatible_range<_Range>::value)
constexpr
span(_Range&& __range)
noexcept(noexcept(ranges::data(__range))
&& noexcept(ranges::size(__range)))
: span(ranges::data(__range), ranges::size(__range))
{ }
template<contiguous_iterator _ContiguousIterator,
sized_sentinel_for<_ContiguousIterator> _Sentinel>
requires (__is_compatible_iterator<_ContiguousIterator>::value)
&& (!is_convertible_v<_Sentinel, size_type>)
constexpr
span(_ContiguousIterator __first, _Sentinel __last)
: _M_extent(static_cast<size_type>(__last - __first)),
_M_ptr(std::to_address(__first))
{
if (_Extent != dynamic_extent)
__glibcxx_assert((__last - __first) == _Extent);
}
template<contiguous_iterator _ContiguousIterator>
requires (__is_compatible_iterator<_ContiguousIterator>::value)
constexpr
span(_ContiguousIterator __first, size_type __count)
noexcept(noexcept(std::to_address(__first)))
: _M_extent(__count), _M_ptr(std::to_address(__first))
{ __glibcxx_assert(_Extent == dynamic_extent || __count == _Extent); }
template<typename _OType, size_t _OExtent>
requires (_Extent == dynamic_extent || _Extent == _OExtent)
&& (__is_array_convertible<_Type, _OType>::value)
constexpr
span(const span<_OType, _OExtent>& __s) noexcept
: _M_extent(__s.size()), _M_ptr(__s.data())
{ }
// assignment
constexpr span&
operator=(const span&) noexcept = default;
// observers
constexpr size_type
size() const noexcept
{ return this->_M_extent._M_extent(); }
constexpr size_type
size_bytes() const noexcept
{ return this->_M_extent._M_extent() * sizeof(element_type); }
[[nodiscard]] constexpr bool
empty() const noexcept
{ return size() == 0; }
// element access
constexpr reference
front() const noexcept
{
static_assert(extent != 0);
__glibcxx_assert(!empty());
return *this->_M_ptr;
}
constexpr reference
back() const noexcept
{
static_assert(extent != 0);
__glibcxx_assert(!empty());
return *(this->_M_ptr + (size() - 1));
}
constexpr reference
operator[](size_type __idx) const noexcept
{
static_assert(extent != 0);
__glibcxx_assert(__idx < size());
return *(this->_M_ptr + __idx);
}
constexpr pointer
data() const noexcept
{ return this->_M_ptr; }
// iterator support
constexpr iterator
begin() const noexcept
{ return iterator(this->_M_ptr); }
constexpr const_iterator
cbegin() const noexcept
{ return const_iterator(this->_M_ptr); }
constexpr iterator
end() const noexcept
{ return iterator(this->_M_ptr + this->size()); }
constexpr const_iterator
cend() const noexcept
{ return const_iterator(this->_M_ptr + this->size()); }
constexpr reverse_iterator
rbegin() const noexcept
{ return reverse_iterator(this->end()); }
constexpr const_reverse_iterator
crbegin() const noexcept
{ return const_reverse_iterator(this->cend()); }
constexpr reverse_iterator
rend() const noexcept
{ return reverse_iterator(this->begin()); }
constexpr const_reverse_iterator
crend() const noexcept
{ return const_reverse_iterator(this->cbegin()); }
// subviews
template<size_t _Count>
constexpr span<element_type, _Count>
first() const noexcept
{
if constexpr (_Extent == dynamic_extent)
__glibcxx_assert(_Count <= size());
else
static_assert(_Count <= extent);
return { this->data(), _Count };
}
constexpr span<element_type, dynamic_extent>
first(size_type __count) const noexcept
{
__glibcxx_assert(__count <= size());
return { this->data(), __count };
}
template<size_t _Count>
constexpr span<element_type, _Count>
last() const noexcept
{
if constexpr (_Extent == dynamic_extent)
__glibcxx_assert(_Count <= size());
else
static_assert(_Count <= extent);
return { this->data() + (this->size() - _Count), _Count };
}
constexpr span<element_type, dynamic_extent>
last(size_type __count) const noexcept
{
__glibcxx_assert(__count <= size());
return { this->data() + (this->size() - __count), __count };
}
template<size_t _Offset, size_t _Count = dynamic_extent>
constexpr auto
subspan() const noexcept
-> span<element_type, _S_subspan_extent<_Offset, _Count>()>
{
if constexpr (_Extent == dynamic_extent)
__glibcxx_assert(_Offset <= size());
else
static_assert(_Offset <= extent);
if constexpr (_Count == dynamic_extent)
return { this->data() + _Offset, this->size() - _Offset };
else
{
if constexpr (_Extent == dynamic_extent)
{
__glibcxx_assert(_Count <= size());
__glibcxx_assert(_Count <= (size() - _Offset));
}
else
{
static_assert(_Count <= extent);
static_assert(_Count <= (extent - _Offset));
}
return { this->data() + _Offset, _Count };
}
}
constexpr span<element_type, dynamic_extent>
subspan(size_type __offset, size_type __count = dynamic_extent) const
noexcept
{
__glibcxx_assert(__offset <= size());
if (__count == dynamic_extent)
__count = this->size() - __offset;
else
{
__glibcxx_assert(__count <= size());
__glibcxx_assert(__offset + __count <= size());
}
return {this->data() + __offset, __count};
}
private:
[[no_unique_address]] __detail::__extent_storage<extent> _M_extent;
pointer _M_ptr;
};
// deduction guides
template<typename _Type, size_t _ArrayExtent>
span(_Type(&)[_ArrayExtent]) -> span<_Type, _ArrayExtent>;
template<typename _Type, size_t _ArrayExtent>
span(array<_Type, _ArrayExtent>&) -> span<_Type, _ArrayExtent>;
template<typename _Type, size_t _ArrayExtent>
span(const array<_Type, _ArrayExtent>&)
-> span<const _Type, _ArrayExtent>;
template<contiguous_iterator _Iter, typename _Sentinel>
span(_Iter, _Sentinel)
-> span<remove_reference_t<ranges::range_reference_t<_Iter>>>;
template<typename _Range>
span(_Range &&)
-> span<remove_reference_t<ranges::range_reference_t<_Range&>>>;
template<typename _Type, size_t _Extent>
inline
span<const byte, _Extent == dynamic_extent
? dynamic_extent : _Extent * sizeof(_Type)>
as_bytes(span<_Type, _Extent> __sp) noexcept
{
return {reinterpret_cast<const byte*>(__sp.data()), __sp.size_bytes()};
}
template<typename _Type, size_t _Extent>
inline
span<byte, _Extent == dynamic_extent
? dynamic_extent : _Extent * sizeof(_Type)>
as_writable_bytes(span<_Type, _Extent> __sp) noexcept
{
return {reinterpret_cast<byte*>(__sp.data()), __sp.size_bytes()};
}
// tuple helpers
template<size_t _Index, typename _Type, size_t _Extent>
constexpr _Type&
get(span<_Type, _Extent> __sp) noexcept
{
static_assert(_Extent != dynamic_extent && _Index < _Extent,
"get<I> can only be used with a span of non-dynamic (fixed) extent");
return __sp[_Index];
}
template<typename _Type, size_t _Extent>
struct tuple_size<span<_Type, _Extent>>
: public integral_constant<size_t, _Extent>
{
static_assert(_Extent != dynamic_extent, "tuple_size can only "
"be used with a span of non-dynamic (fixed) extent");
};
template<size_t _Index, typename _Type, size_t _Extent>
struct tuple_element<_Index, span<_Type, _Extent>>
{
static_assert(_Extent != dynamic_extent, "tuple_element can only "
"be used with a span of non-dynamic (fixed) extent");
static_assert(_Index < _Extent, "Index is less than Extent");
using type = _Type;
};
namespace ranges
{
template<typename> extern inline const bool enable_safe_range;
// Opt-in to safe_range concept
template<typename _ElementType, size_t _Extent>
inline constexpr bool
enable_safe_range<span<_ElementType, _Extent>> = true;
}
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // concepts
#endif // C++20
#endif // _GLIBCXX_SPAN
|