Files
clang-p2996/libcxx/include/span
Chandler Carruth 57b08b0944 Update more file headers across all of the LLVM projects in the monorepo
to reflect the new license. These used slightly different spellings that
defeated my regular expressions.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351648
2019-01-19 10:56:40 +00:00

564 lines
24 KiB
C++

// -*- C++ -*-
//===------------------------------ span ---------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===---------------------------------------------------------------------===//
#ifndef _LIBCPP_SPAN
#define _LIBCPP_SPAN
/*
span synopsis
namespace std {
// constants
inline constexpr ptrdiff_t dynamic_extent = -1;
// [views.span], class template span
template <class ElementType, ptrdiff_t Extent = dynamic_extent>
class span;
// [span.objectrep], views of object representation
template <class ElementType, ptrdiff_t Extent>
span<const byte, ((Extent == dynamic_extent) ? dynamic_extent :
(static_cast<ptrdiff_t>(sizeof(ElementType)) * Extent))> as_bytes(span<ElementType, Extent> s) noexcept;
template <class ElementType, ptrdiff_t Extent>
span< byte, ((Extent == dynamic_extent) ? dynamic_extent :
(static_cast<ptrdiff_t>(sizeof(ElementType)) * Extent))> as_writable_bytes(span<ElementType, Extent> s) noexcept;
namespace std {
template <class ElementType, ptrdiff_t Extent = dynamic_extent>
class span {
public:
// constants and types
using element_type = ElementType;
using value_type = remove_cv_t<ElementType>;
using index_type = ptrdiff_t;
using difference_type = ptrdiff_t;
using pointer = element_type*;
using reference = element_type&;
using iterator = implementation-defined;
using const_iterator = implementation-defined;
using reverse_iterator = std::reverse_iterator<iterator>;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
static constexpr index_type extent = Extent;
// [span.cons], span constructors, copy, assignment, and destructor
constexpr span() noexcept;
constexpr span(pointer ptr, index_type count);
constexpr span(pointer firstElem, pointer lastElem);
template <size_t N>
constexpr span(element_type (&arr)[N]) noexcept;
template <size_t N>
constexpr span(array<value_type, N>& arr) noexcept;
template <size_t N>
constexpr span(const array<value_type, N>& arr) noexcept;
template <class Container>
constexpr span(Container& cont);
template <class Container>
constexpr span(const Container& cont);
constexpr span(const span& other) noexcept = default;
template <class OtherElementType, ptrdiff_t OtherExtent>
constexpr span(const span<OtherElementType, OtherExtent>& s) noexcept;
~span() noexcept = default;
constexpr span& operator=(const span& other) noexcept = default;
// [span.sub], span subviews
template <ptrdiff_t Count>
constexpr span<element_type, Count> first() const;
template <ptrdiff_t Count>
constexpr span<element_type, Count> last() const;
template <ptrdiff_t Offset, ptrdiff_t Count = dynamic_extent>
constexpr span<element_type, see below> subspan() const;
constexpr span<element_type, dynamic_extent> first(index_type count) const;
constexpr span<element_type, dynamic_extent> last(index_type count) const;
constexpr span<element_type, dynamic_extent> subspan(index_type offset, index_type count = dynamic_extent) const;
// [span.obs], span observers
constexpr index_type size() const noexcept;
constexpr index_type size_bytes() const noexcept;
constexpr bool empty() const noexcept;
// [span.elem], span element access
constexpr reference operator[](index_type idx) const;
constexpr reference operator()(index_type idx) const;
constexpr pointer data() const noexcept;
// [span.iterators], span iterator support
constexpr iterator begin() const noexcept;
constexpr iterator end() const noexcept;
constexpr const_iterator cbegin() const noexcept;
constexpr const_iterator cend() const noexcept;
constexpr reverse_iterator rbegin() const noexcept;
constexpr reverse_iterator rend() const noexcept;
constexpr const_reverse_iterator crbegin() const noexcept;
constexpr const_reverse_iterator crend() const noexcept;
private:
pointer data_; // exposition only
index_type size_; // exposition only
};
template<class T, size_t N>
span(T (&)[N]) -> span<T, N>;
template<class T, size_t N>
span(array<T, N>&) -> span<T, N>;
template<class T, size_t N>
span(const array<T, N>&) -> span<const T, N>;
template<class Container>
span(Container&) -> span<typename Container::value_type>;
template<class Container>
span(const Container&) -> span<const typename Container::value_type>;
} // namespace std
*/
#include <__config>
#include <cstddef> // for ptrdiff_t
#include <iterator> // for iterators
#include <array> // for array
#include <type_traits> // for remove_cv, etc
#include <cstddef> // for byte
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER > 17
inline constexpr ptrdiff_t dynamic_extent = -1;
template <typename _Tp, ptrdiff_t _Extent = dynamic_extent> class span;
template <class _Tp>
struct __is_span_impl : public false_type {};
template <class _Tp, ptrdiff_t _Extent>
struct __is_span_impl<span<_Tp, _Extent>> : public true_type {};
template <class _Tp>
struct __is_span : public __is_span_impl<remove_cv_t<_Tp>> {};
template <class _Tp>
struct __is_std_array_impl : public false_type {};
template <class _Tp, size_t _Sz>
struct __is_std_array_impl<array<_Tp, _Sz>> : public true_type {};
template <class _Tp>
struct __is_std_array : public __is_std_array_impl<remove_cv_t<_Tp>> {};
template <class _Tp, class _ElementType, class = void>
struct __is_span_compatible_container : public false_type {};
template <class _Tp, class _ElementType>
struct __is_span_compatible_container<_Tp, _ElementType,
void_t<
// is not a specialization of span
typename enable_if<!__is_span<_Tp>::value, nullptr_t>::type,
// is not a specialization of array
typename enable_if<!__is_std_array<_Tp>::value, nullptr_t>::type,
// is_array_v<Container> is false,
typename enable_if<!is_array_v<_Tp>, nullptr_t>::type,
// data(cont) and size(cont) are well formed
decltype(data(declval<_Tp>())),
decltype(size(declval<_Tp>())),
// remove_pointer_t<decltype(data(cont))>(*)[] is convertible to ElementType(*)[]
typename enable_if<
is_convertible_v<remove_pointer_t<decltype(data(declval<_Tp &>()))>(*)[],
_ElementType(*)[]>,
nullptr_t>::type
>>
: public true_type {};
template <typename _Tp, ptrdiff_t _Extent>
class _LIBCPP_TEMPLATE_VIS span {
public:
// constants and types
using element_type = _Tp;
using value_type = remove_cv_t<_Tp>;
using index_type = ptrdiff_t;
using difference_type = ptrdiff_t;
using pointer = _Tp *;
using const_pointer = const _Tp *; // not in standard
using reference = _Tp &;
using const_reference = const _Tp &; // not in standard
using iterator = __wrap_iter<pointer>;
using const_iterator = __wrap_iter<const_pointer>;
using reverse_iterator = _VSTD::reverse_iterator<iterator>;
using const_reverse_iterator = _VSTD::reverse_iterator<const_iterator>;
static constexpr index_type extent = _Extent;
static_assert (_Extent >= 0, "Can't have a span with an extent < 0");
// [span.cons], span constructors, copy, assignment, and destructor
_LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data{nullptr}
{ static_assert(_Extent == 0, "Can't default construct a statically sized span with size > 0"); }
constexpr span (const span&) noexcept = default;
constexpr span& operator=(const span&) noexcept = default;
_LIBCPP_INLINE_VISIBILITY constexpr span(pointer __ptr, index_type __count) : __data{__ptr}
{ (void)__count; _LIBCPP_ASSERT(_Extent == __count, "size mismatch in span's constructor (ptr, len)"); }
_LIBCPP_INLINE_VISIBILITY constexpr span(pointer __f, pointer __l) : __data{__f}
{ (void)__l; _LIBCPP_ASSERT(_Extent == distance(__f, __l), "size mismatch in span's constructor (ptr, ptr)"); }
_LIBCPP_INLINE_VISIBILITY constexpr span(element_type (&__arr)[_Extent]) noexcept : __data{__arr} {}
_LIBCPP_INLINE_VISIBILITY constexpr span( array<value_type, _Extent>& __arr) noexcept : __data{__arr.data()} {}
_LIBCPP_INLINE_VISIBILITY constexpr span(const array<value_type, _Extent>& __arr) noexcept : __data{__arr.data()} {}
template <class _Container>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span( _Container& __c,
enable_if_t<__is_span_compatible_container<_Container, _Tp>::value, nullptr_t> = nullptr)
: __data{_VSTD::data(__c)}
{ _LIBCPP_ASSERT(_Extent == _VSTD::size(__c), "size mismatch in span's constructor (container)"); }
template <class _Container>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span(const _Container& __c,
enable_if_t<__is_span_compatible_container<const _Container, _Tp>::value, nullptr_t> = nullptr)
: __data{_VSTD::data(__c)}
{ _LIBCPP_ASSERT(_Extent == _VSTD::size(__c), "size mismatch in span's constructor (const container)"); }
template <class _OtherElementType>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span(const span<_OtherElementType, _Extent>& __other,
enable_if_t<
is_convertible_v<_OtherElementType(*)[], element_type (*)[]>,
nullptr_t> = nullptr)
: __data{__other.data()} {}
template <class _OtherElementType>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span(const span<_OtherElementType, dynamic_extent>& __other,
enable_if_t<
is_convertible_v<_OtherElementType(*)[], element_type (*)[]>,
nullptr_t> = nullptr) noexcept
: __data{__other.data()} { _LIBCPP_ASSERT(_Extent == __other.size(), "size mismatch in span's constructor (other span)"); }
// ~span() noexcept = default;
template <ptrdiff_t _Count>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span<element_type, _Count> first() const noexcept
{
static_assert(_Count >= 0, "Count must be >= 0 in span::first()");
static_assert(_Count <= _Extent, "Count out of range in span::first()");
return {data(), _Count};
}
template <ptrdiff_t _Count>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span<element_type, _Count> last() const noexcept
{
static_assert(_Count >= 0, "Count must be >= 0 in span::last()");
static_assert(_Count <= _Extent, "Count out of range in span::last()");
return {data() + size() - _Count, _Count};
}
_LIBCPP_INLINE_VISIBILITY
constexpr span<element_type, dynamic_extent> first(index_type __count) const noexcept
{
_LIBCPP_ASSERT(__count >= 0 && __count <= size(), "Count out of range in span::first(count)");
return {data(), __count};
}
_LIBCPP_INLINE_VISIBILITY
constexpr span<element_type, dynamic_extent> last(index_type __count) const noexcept
{
_LIBCPP_ASSERT(__count >= 0 && __count <= size(), "Count out of range in span::last(count)");
return {data() + size() - __count, __count};
}
template <ptrdiff_t _Offset, ptrdiff_t _Count = dynamic_extent>
inline _LIBCPP_INLINE_VISIBILITY
constexpr auto subspan() const noexcept
-> span<element_type, _Count != dynamic_extent ? _Count : _Extent - _Offset>
{
_LIBCPP_ASSERT(_Offset >= 0 && _Offset <= size(), "Offset out of range in span::subspan()");
return {data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count};
}
inline _LIBCPP_INLINE_VISIBILITY
constexpr span<element_type, dynamic_extent>
subspan(index_type __offset, index_type __count = dynamic_extent) const noexcept
{
_LIBCPP_ASSERT( __offset >= 0 && __offset <= size(), "Offset out of range in span::subspan(offset, count)");
_LIBCPP_ASSERT((__count >= 0 && __count <= size()) || __count == dynamic_extent, "Count out of range in span::subspan(offset, count)");
if (__count == dynamic_extent)
return {data() + __offset, size() - __offset};
_LIBCPP_ASSERT(__offset + __count <= size(), "count + offset out of range in span::subspan(offset, count)");
return {data() + __offset, __count};
}
_LIBCPP_INLINE_VISIBILITY constexpr index_type size() const noexcept { return _Extent; }
_LIBCPP_INLINE_VISIBILITY constexpr index_type size_bytes() const noexcept { return _Extent * sizeof(element_type); }
_LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return _Extent == 0; }
_LIBCPP_INLINE_VISIBILITY constexpr reference operator[](index_type __idx) const noexcept
{
_LIBCPP_ASSERT(__idx >= 0 && __idx < size(), "span<T,N>[] index out of bounds");
return __data[__idx];
}
_LIBCPP_INLINE_VISIBILITY constexpr reference operator()(index_type __idx) const noexcept
{
_LIBCPP_ASSERT(__idx >= 0 && __idx < size(), "span<T,N>() index out of bounds");
return __data[__idx];
}
_LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; }
// [span.iter], span iterator support
_LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { return iterator(data()); }
_LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { return iterator(data() + size()); }
_LIBCPP_INLINE_VISIBILITY constexpr const_iterator cbegin() const noexcept { return const_iterator(data()); }
_LIBCPP_INLINE_VISIBILITY constexpr const_iterator cend() const noexcept { return const_iterator(data() + size()); }
_LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); }
_LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); }
_LIBCPP_INLINE_VISIBILITY constexpr const_reverse_iterator crbegin() const noexcept { return const_reverse_iterator(cend()); }
_LIBCPP_INLINE_VISIBILITY constexpr const_reverse_iterator crend() const noexcept { return const_reverse_iterator(cbegin()); }
_LIBCPP_INLINE_VISIBILITY constexpr void swap(span &__other) noexcept
{
pointer __p = __data;
__data = __other.__data;
__other.__data = __p;
}
_LIBCPP_INLINE_VISIBILITY span<const byte, _Extent * sizeof(element_type)> __as_bytes() const noexcept
{ return {reinterpret_cast<const byte *>(data()), size_bytes()}; }
_LIBCPP_INLINE_VISIBILITY span<byte, _Extent * sizeof(element_type)> __as_writeable_bytes() const noexcept
{ return {reinterpret_cast<byte *>(data()), size_bytes()}; }
private:
pointer __data;
};
template <typename _Tp>
class _LIBCPP_TEMPLATE_VIS span<_Tp, dynamic_extent> {
private:
public:
// constants and types
using element_type = _Tp;
using value_type = remove_cv_t<_Tp>;
using index_type = ptrdiff_t;
using difference_type = ptrdiff_t;
using pointer = _Tp *;
using const_pointer = const _Tp *; // not in standard
using reference = _Tp &;
using const_reference = const _Tp &; // not in standard
using iterator = __wrap_iter<pointer>;
using const_iterator = __wrap_iter<const_pointer>;
using reverse_iterator = _VSTD::reverse_iterator<iterator>;
using const_reverse_iterator = _VSTD::reverse_iterator<const_iterator>;
static constexpr index_type extent = dynamic_extent;
// [span.cons], span constructors, copy, assignment, and destructor
_LIBCPP_INLINE_VISIBILITY constexpr span() noexcept : __data{nullptr}, __size{0} {}
constexpr span (const span&) noexcept = default;
constexpr span& operator=(const span&) noexcept = default;
_LIBCPP_INLINE_VISIBILITY constexpr span(pointer __ptr, index_type __count) : __data{__ptr}, __size{__count} {}
_LIBCPP_INLINE_VISIBILITY constexpr span(pointer __f, pointer __l) : __data{__f}, __size{distance(__f, __l)} {}
template <size_t _Sz>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span(element_type (&__arr)[_Sz]) noexcept : __data{__arr}, __size{_Sz} {}
template <size_t _Sz>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span(array<value_type, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {}
template <size_t _Sz>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span(const array<value_type, _Sz>& __arr) noexcept : __data{__arr.data()}, __size{_Sz} {}
template <class _Container>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span( _Container& __c,
enable_if_t<__is_span_compatible_container<_Container, _Tp>::value, nullptr_t> = nullptr)
: __data{_VSTD::data(__c)}, __size{(index_type) _VSTD::size(__c)} {}
template <class _Container>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span(const _Container& __c,
enable_if_t<__is_span_compatible_container<const _Container, _Tp>::value, nullptr_t> = nullptr)
: __data{_VSTD::data(__c)}, __size{(index_type) _VSTD::size(__c)} {}
template <class _OtherElementType, ptrdiff_t _OtherExtent>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span(const span<_OtherElementType, _OtherExtent>& __other,
enable_if_t<
is_convertible_v<_OtherElementType(*)[], element_type (*)[]>,
nullptr_t> = nullptr) noexcept
: __data{__other.data()}, __size{__other.size()} {}
// ~span() noexcept = default;
template <ptrdiff_t _Count>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span<element_type, _Count> first() const noexcept
{
static_assert(_Count >= 0, "Count must be >= 0 in span::first()");
_LIBCPP_ASSERT(_Count <= size(), "Count out of range in span::first()");
return {data(), _Count};
}
template <ptrdiff_t _Count>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span<element_type, _Count> last() const noexcept
{
static_assert(_Count >= 0, "Count must be >= 0 in span::last()");
_LIBCPP_ASSERT(_Count <= size(), "Count out of range in span::last()");
return {data() + size() - _Count, _Count};
}
_LIBCPP_INLINE_VISIBILITY
constexpr span<element_type, dynamic_extent> first(index_type __count) const noexcept
{
_LIBCPP_ASSERT(__count >= 0 && __count <= size(), "Count out of range in span::first(count)");
return {data(), __count};
}
_LIBCPP_INLINE_VISIBILITY
constexpr span<element_type, dynamic_extent> last (index_type __count) const noexcept
{
_LIBCPP_ASSERT(__count >= 0 && __count <= size(), "Count out of range in span::last(count)");
return {data() + size() - __count, __count};
}
template <ptrdiff_t _Offset, ptrdiff_t _Count = dynamic_extent>
inline _LIBCPP_INLINE_VISIBILITY
constexpr span<_Tp, dynamic_extent> subspan() const noexcept
{
_LIBCPP_ASSERT(_Offset >= 0 && _Offset <= size(), "Offset out of range in span::subspan()");
_LIBCPP_ASSERT(_Count == dynamic_extent || _Offset + _Count <= size(), "Count out of range in span::subspan()");
return {data() + _Offset, _Count == dynamic_extent ? size() - _Offset : _Count};
}
constexpr span<element_type, dynamic_extent>
inline _LIBCPP_INLINE_VISIBILITY
subspan(index_type __offset, index_type __count = dynamic_extent) const noexcept
{
_LIBCPP_ASSERT( __offset >= 0 && __offset <= size(), "Offset out of range in span::subspan(offset, count)");
_LIBCPP_ASSERT((__count >= 0 && __count <= size()) || __count == dynamic_extent, "count out of range in span::subspan(offset, count)");
if (__count == dynamic_extent)
return {data() + __offset, size() - __offset};
_LIBCPP_ASSERT(__offset + __count <= size(), "Offset + count out of range in span::subspan(offset, count)");
return {data() + __offset, __count};
}
_LIBCPP_INLINE_VISIBILITY constexpr index_type size() const noexcept { return __size; }
_LIBCPP_INLINE_VISIBILITY constexpr index_type size_bytes() const noexcept { return __size * sizeof(element_type); }
_LIBCPP_INLINE_VISIBILITY constexpr bool empty() const noexcept { return __size == 0; }
_LIBCPP_INLINE_VISIBILITY constexpr reference operator[](index_type __idx) const noexcept
{
_LIBCPP_ASSERT(__idx >= 0 && __idx < size(), "span<T>[] index out of bounds");
return __data[__idx];
}
_LIBCPP_INLINE_VISIBILITY constexpr reference operator()(index_type __idx) const noexcept
{
_LIBCPP_ASSERT(__idx >= 0 && __idx < size(), "span<T>() index out of bounds");
return __data[__idx];
}
_LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; }
// [span.iter], span iterator support
_LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept { return iterator(data()); }
_LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept { return iterator(data() + size()); }
_LIBCPP_INLINE_VISIBILITY constexpr const_iterator cbegin() const noexcept { return const_iterator(data()); }
_LIBCPP_INLINE_VISIBILITY constexpr const_iterator cend() const noexcept { return const_iterator(data() + size()); }
_LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); }
_LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator rend() const noexcept { return reverse_iterator(begin()); }
_LIBCPP_INLINE_VISIBILITY constexpr const_reverse_iterator crbegin() const noexcept { return const_reverse_iterator(cend()); }
_LIBCPP_INLINE_VISIBILITY constexpr const_reverse_iterator crend() const noexcept { return const_reverse_iterator(cbegin()); }
_LIBCPP_INLINE_VISIBILITY constexpr void swap(span &__other) noexcept
{
pointer __p = __data;
__data = __other.__data;
__other.__data = __p;
index_type __sz = __size;
__size = __other.__size;
__other.__size = __sz;
}
_LIBCPP_INLINE_VISIBILITY span<const byte, dynamic_extent> __as_bytes() const noexcept
{ return {reinterpret_cast<const byte *>(data()), size_bytes()}; }
_LIBCPP_INLINE_VISIBILITY span<byte, dynamic_extent> __as_writeable_bytes() const noexcept
{ return {reinterpret_cast<byte *>(data()), size_bytes()}; }
private:
pointer __data;
index_type __size;
};
// as_bytes & as_writeable_bytes
template <class _Tp, ptrdiff_t _Extent>
auto as_bytes(span<_Tp, _Extent> __s) noexcept
-> decltype(__s.__as_bytes())
{ return __s.__as_bytes(); }
template <class _Tp, ptrdiff_t _Extent>
auto as_writeable_bytes(span<_Tp, _Extent> __s) noexcept
-> typename enable_if<!is_const_v<_Tp>, decltype(__s.__as_writeable_bytes())>::type
{ return __s.__as_writeable_bytes(); }
template <class _Tp, ptrdiff_t _Extent>
constexpr void swap(span<_Tp, _Extent> &__lhs, span<_Tp, _Extent> &__rhs) noexcept
{ __lhs.swap(__rhs); }
// Deduction guides
template<class _Tp, size_t _Sz>
span(_Tp (&)[_Sz]) -> span<_Tp, _Sz>;
template<class _Tp, size_t _Sz>
span(array<_Tp, _Sz>&) -> span<_Tp, _Sz>;
template<class _Tp, size_t _Sz>
span(const array<_Tp, _Sz>&) -> span<const _Tp, _Sz>;
template<class _Container>
span(_Container&) -> span<typename _Container::value_type>;
template<class _Container>
span(const _Container&) -> span<const typename _Container::value_type>;
#endif // _LIBCPP_STD_VER > 17
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_SPAN