master
1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
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// Kokkos v. 4.0
9// Copyright (2022) National Technology & Engineering
10// Solutions of Sandia, LLC (NTESS).
11//
12// Under the terms of Contract DE-NA0003525 with NTESS,
13// the U.S. Government retains certain rights in this software.
14//
15//===---------------------------------------------------------------------===//
16
17#ifndef _LIBCPP___MDSPAN_EXTENTS_H
18#define _LIBCPP___MDSPAN_EXTENTS_H
19
20#include <__assert>
21#include <__config>
22
23#include <__concepts/arithmetic.h>
24#include <__type_traits/common_type.h>
25#include <__type_traits/integer_traits.h>
26#include <__type_traits/is_convertible.h>
27#include <__type_traits/is_nothrow_constructible.h>
28#include <__type_traits/make_unsigned.h>
29#include <__utility/integer_sequence.h>
30#include <__utility/unreachable.h>
31#include <array>
32#include <concepts>
33#include <limits>
34#include <span>
35
36#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
37# pragma GCC system_header
38#endif
39
40_LIBCPP_PUSH_MACROS
41#include <__undef_macros>
42
43_LIBCPP_BEGIN_NAMESPACE_STD
44
45#if _LIBCPP_STD_VER >= 23
46
47namespace __mdspan_detail {
48
49// ------------------------------------------------------------------
50// ------------ __static_array --------------------------------------
51// ------------------------------------------------------------------
52// array like class which provides an array of static values with get
53template <class _Tp, _Tp... _Values>
54struct __static_array {
55 static constexpr array<_Tp, sizeof...(_Values)> __array = {_Values...};
56
57public:
58 _LIBCPP_HIDE_FROM_ABI static constexpr size_t __size() { return sizeof...(_Values); }
59 _LIBCPP_HIDE_FROM_ABI static constexpr _Tp __get(size_t __index) noexcept { return __array[__index]; }
60
61 template <size_t _Index>
62 _LIBCPP_HIDE_FROM_ABI static constexpr _Tp __get() {
63 return __get(_Index);
64 }
65};
66
67// ------------------------------------------------------------------
68// ------------ __possibly_empty_array -----------------------------
69// ------------------------------------------------------------------
70
71// array like class which provides get function and operator [], and
72// has a specialization for the size 0 case.
73// This is needed to make the __maybe_static_array be truly empty, for
74// all static values.
75
76template <class _Tp, size_t _Size>
77struct __possibly_empty_array {
78 _Tp __vals_[_Size];
79 _LIBCPP_HIDE_FROM_ABI constexpr _Tp& operator[](size_t __index) { return __vals_[__index]; }
80 _LIBCPP_HIDE_FROM_ABI constexpr const _Tp& operator[](size_t __index) const { return __vals_[__index]; }
81};
82
83template <class _Tp>
84struct __possibly_empty_array<_Tp, 0> {
85 _LIBCPP_HIDE_FROM_ABI constexpr _Tp& operator[](size_t) { __libcpp_unreachable(); }
86 _LIBCPP_HIDE_FROM_ABI constexpr const _Tp& operator[](size_t) const { __libcpp_unreachable(); }
87};
88
89// ------------------------------------------------------------------
90// ------------ static_partial_sums ---------------------------------
91// ------------------------------------------------------------------
92
93// Provides a compile time partial sum one can index into
94
95template <size_t... _Values>
96struct __static_partial_sums {
97 _LIBCPP_HIDE_FROM_ABI static constexpr array<size_t, sizeof...(_Values)> __static_partial_sums_impl() {
98 array<size_t, sizeof...(_Values)> __values{_Values...};
99 array<size_t, sizeof...(_Values)> __partial_sums{{}};
100 size_t __running_sum = 0;
101 for (int __i = 0; __i != sizeof...(_Values); ++__i) {
102 __partial_sums[__i] = __running_sum;
103 __running_sum += __values[__i];
104 }
105 return __partial_sums;
106 }
107 static constexpr array<size_t, sizeof...(_Values)> __result{__static_partial_sums_impl()};
108
109 _LIBCPP_HIDE_FROM_ABI static constexpr size_t __get(size_t __index) { return __result[__index]; }
110};
111
112// ------------------------------------------------------------------
113// ------------ __maybe_static_array --------------------------------
114// ------------------------------------------------------------------
115
116// array like class which has a mix of static and runtime values but
117// only stores the runtime values.
118// The type of the static and the runtime values can be different.
119// The position of a dynamic value is indicated through a tag value.
120template <class _TDynamic, class _TStatic, _TStatic _DynTag, _TStatic... _Values>
121struct __maybe_static_array {
122 static_assert(is_convertible<_TStatic, _TDynamic>::value,
123 "__maybe_static_array: _TStatic must be convertible to _TDynamic");
124 static_assert(is_convertible<_TDynamic, _TStatic>::value,
125 "__maybe_static_array: _TDynamic must be convertible to _TStatic");
126
127private:
128 // Static values member
129 static constexpr size_t __size_ = sizeof...(_Values);
130 static constexpr size_t __size_dynamic_ = ((_Values == _DynTag) + ... + 0);
131 using _StaticValues _LIBCPP_NODEBUG = __static_array<_TStatic, _Values...>;
132 using _DynamicValues _LIBCPP_NODEBUG = __possibly_empty_array<_TDynamic, __size_dynamic_>;
133
134 // Dynamic values member
135 _LIBCPP_NO_UNIQUE_ADDRESS _DynamicValues __dyn_vals_;
136
137 // static mapping of indices to the position in the dynamic values array
138 using _DynamicIdxMap _LIBCPP_NODEBUG = __static_partial_sums<static_cast<size_t>(_Values == _DynTag)...>;
139
140 template <size_t... _Indices>
141 _LIBCPP_HIDE_FROM_ABI static constexpr _DynamicValues __zeros(index_sequence<_Indices...>) noexcept {
142 return _DynamicValues{((void)_Indices, 0)...};
143 }
144
145public:
146 _LIBCPP_HIDE_FROM_ABI constexpr __maybe_static_array() noexcept
147 : __dyn_vals_{__zeros(make_index_sequence<__size_dynamic_>())} {}
148
149 // constructors from dynamic values only -- this covers the case for rank() == 0
150 template <class... _DynVals>
151 requires(sizeof...(_DynVals) == __size_dynamic_)
152 _LIBCPP_HIDE_FROM_ABI constexpr __maybe_static_array(_DynVals... __vals)
153 : __dyn_vals_{static_cast<_TDynamic>(__vals)...} {}
154
155 template <class _Tp, size_t _Size >
156 requires(_Size == __size_dynamic_)
157 _LIBCPP_HIDE_FROM_ABI constexpr __maybe_static_array([[maybe_unused]] const span<_Tp, _Size>& __vals) {
158 if constexpr (_Size > 0) {
159 for (size_t __i = 0; __i < _Size; __i++)
160 __dyn_vals_[__i] = static_cast<_TDynamic>(__vals[__i]);
161 }
162 }
163
164 // constructors from all values -- here rank will be greater than 0
165 template <class... _DynVals>
166 requires(sizeof...(_DynVals) != __size_dynamic_)
167 _LIBCPP_HIDE_FROM_ABI constexpr __maybe_static_array(_DynVals... __vals) {
168 static_assert(sizeof...(_DynVals) == __size_, "Invalid number of values.");
169 _TDynamic __values[__size_] = {static_cast<_TDynamic>(__vals)...};
170 for (size_t __i = 0; __i < __size_; __i++) {
171 _TStatic __static_val = _StaticValues::__get(__i);
172 if (__static_val == _DynTag) {
173 __dyn_vals_[_DynamicIdxMap::__get(__i)] = __values[__i];
174 } else
175 // Not catching this could lead to out of bounds errors later
176 // e.g. using my_mdspan_t = mdspan<int, extents<int, 10>>; my_mdspan_t = m(new int[5], 5);
177 // Right-hand-side construction looks ok with allocation and size matching,
178 // but since (potentially elsewhere defined) my_mdspan_t has static size m now thinks its range is 10 not 5
179 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
180 __values[__i] == static_cast<_TDynamic>(__static_val),
181 "extents construction: mismatch of provided arguments with static extents.");
182 }
183 }
184
185 template <class _Tp, size_t _Size>
186 requires(_Size != __size_dynamic_)
187 _LIBCPP_HIDE_FROM_ABI constexpr __maybe_static_array(const span<_Tp, _Size>& __vals) {
188 static_assert(_Size == __size_ || __size_ == dynamic_extent);
189 for (size_t __i = 0; __i < __size_; __i++) {
190 _TStatic __static_val = _StaticValues::__get(__i);
191 if (__static_val == _DynTag) {
192 __dyn_vals_[_DynamicIdxMap::__get(__i)] = static_cast<_TDynamic>(__vals[__i]);
193 } else
194 // Not catching this could lead to out of bounds errors later
195 // e.g. using my_mdspan_t = mdspan<int, extents<int, 10>>; my_mdspan_t = m(new int[N], span<int,1>(&N));
196 // Right-hand-side construction looks ok with allocation and size matching,
197 // but since (potentially elsewhere defined) my_mdspan_t has static size m now thinks its range is 10 not N
198 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
199 static_cast<_TDynamic>(__vals[__i]) == static_cast<_TDynamic>(__static_val),
200 "extents construction: mismatch of provided arguments with static extents.");
201 }
202 }
203
204 // access functions
205 _LIBCPP_HIDE_FROM_ABI static constexpr _TStatic __static_value(size_t __i) noexcept {
206 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__i < __size_, "extents access: index must be less than rank");
207 return _StaticValues::__get(__i);
208 }
209
210 _LIBCPP_HIDE_FROM_ABI constexpr _TDynamic __value(size_t __i) const {
211 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__i < __size_, "extents access: index must be less than rank");
212 _TStatic __static_val = _StaticValues::__get(__i);
213 return __static_val == _DynTag ? __dyn_vals_[_DynamicIdxMap::__get(__i)] : static_cast<_TDynamic>(__static_val);
214 }
215 _LIBCPP_HIDE_FROM_ABI constexpr _TDynamic operator[](size_t __i) const {
216 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__i < __size_, "extents access: index must be less than rank");
217 return __value(__i);
218 }
219
220 // observers
221 _LIBCPP_HIDE_FROM_ABI static constexpr size_t __size() { return __size_; }
222 _LIBCPP_HIDE_FROM_ABI static constexpr size_t __size_dynamic() { return __size_dynamic_; }
223};
224
225// Function to check whether a value is representable as another type
226// value must be a positive integer otherwise returns false
227// if _From is not an integral, we just check positivity
228template <integral _To, class _From>
229 requires(integral<_From>)
230_LIBCPP_HIDE_FROM_ABI constexpr bool __is_representable_as(_From __value) {
231 using _To_u = make_unsigned_t<_To>;
232 using _From_u = make_unsigned_t<_From>;
233 if constexpr (is_signed_v<_From>) {
234 if (__value < 0)
235 return false;
236 }
237 if constexpr (static_cast<_To_u>(numeric_limits<_To>::max()) >= static_cast<_From_u>(numeric_limits<_From>::max())) {
238 return true;
239 } else {
240 return static_cast<_To_u>(numeric_limits<_To>::max()) >= static_cast<_From_u>(__value);
241 }
242}
243
244template <integral _To, class _From>
245 requires(!integral<_From>)
246_LIBCPP_HIDE_FROM_ABI constexpr bool __is_representable_as(_From __value) {
247 if constexpr (is_signed_v<_To>) {
248 if (static_cast<_To>(__value) < 0)
249 return false;
250 }
251 return true;
252}
253
254template <integral _To, class... _From>
255_LIBCPP_HIDE_FROM_ABI constexpr bool __are_representable_as(_From... __values) {
256 return (__mdspan_detail::__is_representable_as<_To>(__values) && ... && true);
257}
258
259template <integral _To, class _From, size_t _Size>
260_LIBCPP_HIDE_FROM_ABI constexpr bool __are_representable_as(span<_From, _Size> __values) {
261 for (size_t __i = 0; __i < _Size; __i++)
262 if (!__mdspan_detail::__is_representable_as<_To>(__values[__i]))
263 return false;
264 return true;
265}
266
267} // namespace __mdspan_detail
268
269// ------------------------------------------------------------------
270// ------------ extents ---------------------------------------------
271// ------------------------------------------------------------------
272
273// Class to describe the extents of a multi dimensional array.
274// Used by mdspan, mdarray and layout mappings.
275// See ISO C++ standard [mdspan.extents]
276
277template <class _IndexType, size_t... _Extents>
278class extents {
279public:
280 // typedefs for integral types used
281 using index_type = _IndexType;
282 using size_type = make_unsigned_t<index_type>;
283 using rank_type = size_t;
284
285 static_assert(__signed_or_unsigned_integer<index_type>,
286 "extents::index_type must be a signed or unsigned integer type");
287 static_assert(((__mdspan_detail::__is_representable_as<index_type>(_Extents) || (_Extents == dynamic_extent)) && ...),
288 "extents ctor: arguments must be representable as index_type and nonnegative");
289
290private:
291 static constexpr rank_type __rank_ = sizeof...(_Extents);
292 static constexpr rank_type __rank_dynamic_ = ((_Extents == dynamic_extent) + ... + 0);
293
294 // internal storage type using __maybe_static_array
295 using _Values _LIBCPP_NODEBUG =
296 __mdspan_detail::__maybe_static_array<_IndexType, size_t, dynamic_extent, _Extents...>;
297 [[no_unique_address]] _Values __vals_;
298
299public:
300 // [mdspan.extents.obs], observers of multidimensional index space
301 _LIBCPP_HIDE_FROM_ABI static constexpr rank_type rank() noexcept { return __rank_; }
302 _LIBCPP_HIDE_FROM_ABI static constexpr rank_type rank_dynamic() noexcept { return __rank_dynamic_; }
303
304 _LIBCPP_HIDE_FROM_ABI constexpr index_type extent(rank_type __r) const noexcept { return __vals_.__value(__r); }
305 _LIBCPP_HIDE_FROM_ABI static constexpr size_t static_extent(rank_type __r) noexcept {
306 return _Values::__static_value(__r);
307 }
308
309 // [mdspan.extents.cons], constructors
310 _LIBCPP_HIDE_FROM_ABI constexpr extents() noexcept = default;
311
312 // Construction from just dynamic or all values.
313 // Precondition check is deferred to __maybe_static_array constructor
314 template <class... _OtherIndexTypes>
315 requires((is_convertible_v<_OtherIndexTypes, index_type> && ...) &&
316 (is_nothrow_constructible_v<index_type, _OtherIndexTypes> && ...) &&
317 (sizeof...(_OtherIndexTypes) == __rank_ || sizeof...(_OtherIndexTypes) == __rank_dynamic_))
318 _LIBCPP_HIDE_FROM_ABI constexpr explicit extents(_OtherIndexTypes... __dynvals) noexcept
319 : __vals_(static_cast<index_type>(__dynvals)...) {
320 // Not catching this could lead to out of bounds errors later
321 // e.g. mdspan m(ptr, dextents<char, 1>(200u)); leads to an extent of -56 on m
322 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__mdspan_detail::__are_representable_as<index_type>(__dynvals...),
323 "extents ctor: arguments must be representable as index_type and nonnegative");
324 }
325
326 template <class _OtherIndexType, size_t _Size>
327 requires(is_convertible_v<const _OtherIndexType&, index_type> &&
328 is_nothrow_constructible_v<index_type, const _OtherIndexType&> &&
329 (_Size == __rank_ || _Size == __rank_dynamic_))
330 explicit(_Size != __rank_dynamic_)
331 _LIBCPP_HIDE_FROM_ABI constexpr extents(const array<_OtherIndexType, _Size>& __exts) noexcept
332 : __vals_(span(__exts)) {
333 // Not catching this could lead to out of bounds errors later
334 // e.g. mdspan m(ptr, dextents<char, 1>(array<unsigned,1>(200))); leads to an extent of -56 on m
335 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__mdspan_detail::__are_representable_as<index_type>(span(__exts)),
336 "extents ctor: arguments must be representable as index_type and nonnegative");
337 }
338
339 template <class _OtherIndexType, size_t _Size>
340 requires(is_convertible_v<const _OtherIndexType&, index_type> &&
341 is_nothrow_constructible_v<index_type, const _OtherIndexType&> &&
342 (_Size == __rank_ || _Size == __rank_dynamic_))
343 explicit(_Size != __rank_dynamic_)
344 _LIBCPP_HIDE_FROM_ABI constexpr extents(const span<_OtherIndexType, _Size>& __exts) noexcept
345 : __vals_(__exts) {
346 // Not catching this could lead to out of bounds errors later
347 // e.g. array a{200u}; mdspan<int, dextents<char,1>> m(ptr, extents(span<unsigned,1>(a))); leads to an extent of -56
348 // on m
349 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__mdspan_detail::__are_representable_as<index_type>(__exts),
350 "extents ctor: arguments must be representable as index_type and nonnegative");
351 }
352
353private:
354 // Function to construct extents storage from other extents.
355 template <size_t _DynCount, size_t _Idx, class _OtherExtents, class... _DynamicValues>
356 requires(_Idx < __rank_)
357 _LIBCPP_HIDE_FROM_ABI constexpr _Values __construct_vals_from_extents(
358 integral_constant<size_t, _DynCount>,
359 integral_constant<size_t, _Idx>,
360 const _OtherExtents& __exts,
361 _DynamicValues... __dynamic_values) noexcept {
362 if constexpr (static_extent(_Idx) == dynamic_extent)
363 return __construct_vals_from_extents(
364 integral_constant<size_t, _DynCount + 1>(),
365 integral_constant<size_t, _Idx + 1>(),
366 __exts,
367 __dynamic_values...,
368 __exts.extent(_Idx));
369 else
370 return __construct_vals_from_extents(
371 integral_constant<size_t, _DynCount>(), integral_constant<size_t, _Idx + 1>(), __exts, __dynamic_values...);
372 }
373
374 template <size_t _DynCount, size_t _Idx, class _OtherExtents, class... _DynamicValues>
375 requires((_Idx == __rank_) && (_DynCount == __rank_dynamic_))
376 _LIBCPP_HIDE_FROM_ABI constexpr _Values __construct_vals_from_extents(
377 integral_constant<size_t, _DynCount>,
378 integral_constant<size_t, _Idx>,
379 const _OtherExtents&,
380 _DynamicValues... __dynamic_values) noexcept {
381 return _Values{static_cast<index_type>(__dynamic_values)...};
382 }
383
384public:
385 // Converting constructor from other extents specializations
386 template <class _OtherIndexType, size_t... _OtherExtents>
387 requires((sizeof...(_OtherExtents) == sizeof...(_Extents)) &&
388 ((_OtherExtents == dynamic_extent || _Extents == dynamic_extent || _OtherExtents == _Extents) && ...))
389 explicit((((_Extents != dynamic_extent) && (_OtherExtents == dynamic_extent)) || ...) ||
390 (static_cast<make_unsigned_t<index_type>>(numeric_limits<index_type>::max()) <
391 static_cast<make_unsigned_t<_OtherIndexType>>(numeric_limits<_OtherIndexType>::max())))
392 _LIBCPP_HIDE_FROM_ABI constexpr extents(const extents<_OtherIndexType, _OtherExtents...>& __other) noexcept
393 : __vals_(
394 __construct_vals_from_extents(integral_constant<size_t, 0>(), integral_constant<size_t, 0>(), __other)) {
395 if constexpr (rank() > 0) {
396 for (size_t __r = 0; __r < rank(); __r++) {
397 if constexpr (static_cast<make_unsigned_t<index_type>>(numeric_limits<index_type>::max()) <
398 static_cast<make_unsigned_t<_OtherIndexType>>(numeric_limits<_OtherIndexType>::max())) {
399 // Not catching this could lead to out of bounds errors later
400 // e.g. dextents<char,1>> e(dextents<unsigned,1>(200)) leads to an extent of -56 on e
401 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
402 __mdspan_detail::__is_representable_as<index_type>(__other.extent(__r)),
403 "extents ctor: arguments must be representable as index_type and nonnegative");
404 }
405 // Not catching this could lead to out of bounds errors later
406 // e.g. mdspan<int, extents<int, 10>> m = mdspan<int, dextents<int, 1>>(new int[5], 5);
407 // Right-hand-side construction was ok, but m now thinks its range is 10 not 5
408 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
409 (_Values::__static_value(__r) == dynamic_extent) ||
410 (static_cast<index_type>(__other.extent(__r)) == static_cast<index_type>(_Values::__static_value(__r))),
411 "extents construction: mismatch of provided arguments with static extents.");
412 }
413 }
414 }
415
416 // Comparison operator
417 template <class _OtherIndexType, size_t... _OtherExtents>
418 _LIBCPP_HIDE_FROM_ABI friend constexpr bool
419 operator==(const extents& __lhs, const extents<_OtherIndexType, _OtherExtents...>& __rhs) noexcept {
420 if constexpr (rank() != sizeof...(_OtherExtents)) {
421 return false;
422 } else {
423 for (rank_type __r = 0; __r < __rank_; __r++) {
424 // avoid warning when comparing signed and unsigner integers and pick the wider of two types
425 using _CommonType = common_type_t<index_type, _OtherIndexType>;
426 if (static_cast<_CommonType>(__lhs.extent(__r)) != static_cast<_CommonType>(__rhs.extent(__r))) {
427 return false;
428 }
429 }
430 }
431 return true;
432 }
433};
434
435// Recursive helper classes to implement dextents alias for extents
436namespace __mdspan_detail {
437
438template <class _IndexType, size_t _Rank, class _Extents = extents<_IndexType>>
439struct __make_dextents;
440
441template <class _IndexType, size_t _Rank, size_t... _ExtentsPack>
442struct __make_dextents< _IndexType, _Rank, extents<_IndexType, _ExtentsPack...>> {
443 using type _LIBCPP_NODEBUG =
444 typename __make_dextents< _IndexType, _Rank - 1, extents<_IndexType, dynamic_extent, _ExtentsPack...>>::type;
445};
446
447template <class _IndexType, size_t... _ExtentsPack>
448struct __make_dextents< _IndexType, 0, extents<_IndexType, _ExtentsPack...>> {
449 using type _LIBCPP_NODEBUG = extents<_IndexType, _ExtentsPack...>;
450};
451
452} // namespace __mdspan_detail
453
454// [mdspan.extents.dextents], alias template
455template <class _IndexType, size_t _Rank>
456using dextents = typename __mdspan_detail::__make_dextents<_IndexType, _Rank>::type;
457
458# if _LIBCPP_STD_VER >= 26
459// [mdspan.extents.dims], alias template `dims`
460template <size_t _Rank, class _IndexType = size_t>
461using dims = dextents<_IndexType, _Rank>;
462# endif
463
464// Deduction guide for extents
465# if _LIBCPP_STD_VER >= 26
466template <class... _IndexTypes>
467 requires(is_convertible_v<_IndexTypes, size_t> && ...)
468explicit extents(_IndexTypes...) -> extents<size_t, __maybe_static_ext<_IndexTypes>...>;
469# else
470template <class... _IndexTypes>
471 requires(is_convertible_v<_IndexTypes, size_t> && ...)
472explicit extents(_IndexTypes...) -> extents<size_t, size_t(((void)sizeof(_IndexTypes), dynamic_extent))...>;
473# endif
474
475namespace __mdspan_detail {
476
477// Helper type traits for identifying a class as extents.
478template <class _Tp>
479struct __is_extents : false_type {};
480
481template <class _IndexType, size_t... _ExtentsPack>
482struct __is_extents<extents<_IndexType, _ExtentsPack...>> : true_type {};
483
484template <class _Tp>
485inline constexpr bool __is_extents_v = __is_extents<_Tp>::value;
486
487// Function to check whether a set of indices are a multidimensional
488// index into extents. This is a word of power in the C++ standard
489// requiring that the indices are larger than 0 and smaller than
490// the respective extents.
491
492template <integral _IndexType, class _From>
493 requires(integral<_From>)
494_LIBCPP_HIDE_FROM_ABI constexpr bool __is_index_in_extent(_IndexType __extent, _From __value) {
495 if constexpr (is_signed_v<_From>) {
496 if (__value < 0)
497 return false;
498 }
499 using _Tp = common_type_t<_IndexType, _From>;
500 return static_cast<_Tp>(__value) < static_cast<_Tp>(__extent);
501}
502
503template <integral _IndexType, class _From>
504 requires(!integral<_From>)
505_LIBCPP_HIDE_FROM_ABI constexpr bool __is_index_in_extent(_IndexType __extent, _From __value) {
506 if constexpr (is_signed_v<_IndexType>) {
507 if (static_cast<_IndexType>(__value) < 0)
508 return false;
509 }
510 return static_cast<_IndexType>(__value) < __extent;
511}
512
513template <size_t... _Idxs, class _Extents, class... _From>
514_LIBCPP_HIDE_FROM_ABI constexpr bool
515__is_multidimensional_index_in_impl(index_sequence<_Idxs...>, const _Extents& __ext, _From... __values) {
516 return (__mdspan_detail::__is_index_in_extent(__ext.extent(_Idxs), __values) && ...);
517}
518
519template <class _Extents, class... _From>
520_LIBCPP_HIDE_FROM_ABI constexpr bool __is_multidimensional_index_in(const _Extents& __ext, _From... __values) {
521 return __mdspan_detail::__is_multidimensional_index_in_impl(
522 make_index_sequence<_Extents::rank()>(), __ext, __values...);
523}
524
525} // namespace __mdspan_detail
526
527#endif // _LIBCPP_STD_VER >= 23
528
529_LIBCPP_END_NAMESPACE_STD
530
531_LIBCPP_POP_MACROS
532
533#endif // _LIBCPP___MDSPAN_EXTENTS_H