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gcc/libstdc++-v3/include/std/array

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// <array> -*- C++ -*-
// Copyright (C) 2007-2025 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 include/array
* This is a Standard C++ Library header.
*/
#ifndef _GLIBCXX_ARRAY
#define _GLIBCXX_ARRAY 1
#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif
#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#else
#include <compare>
#include <initializer_list>
#include <type_traits>
#include <bits/functexcept.h>
#include <bits/stl_algobase.h>
#include <bits/range_access.h> // std::begin, std::end etc.
#include <bits/utility.h> // std::index_sequence, std::tuple_size
#include <debug/assertions.h>
#define __glibcxx_want_array_constexpr
#define __glibcxx_want_freestanding_array
#define __glibcxx_want_nonmember_container_access
#define __glibcxx_want_to_array
#include <bits/version.h>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp, size_t _Nm>
struct __array_traits
{
using _Type = _Tp[_Nm];
using _Is_swappable = __is_swappable<_Tp>;
using _Is_nothrow_swappable = __is_nothrow_swappable<_Tp>;
};
template<typename _Tp>
struct __array_traits<_Tp, 0>
{
// Empty type used instead of _Tp[0] for std::array<_Tp, 0>.
struct _Type
{
// Indexing is undefined.
__attribute__((__always_inline__,__noreturn__))
_Tp& operator[](size_t) const noexcept { __builtin_trap(); }
// Conversion to a pointer produces a null pointer.
__attribute__((__always_inline__))
constexpr explicit operator _Tp*() const noexcept { return nullptr; }
};
using _Is_swappable = true_type;
using _Is_nothrow_swappable = true_type;
};
/**
* @brief A standard container for storing a fixed size sequence of elements.
*
* @ingroup sequences
*
* Meets the requirements of a <a href="tables.html#65">container</a>, a
* <a href="tables.html#66">reversible container</a>, and a
* <a href="tables.html#67">sequence</a>.
*
* Sets support random access iterators.
*
* @tparam Tp Type of element. Required to be a complete type.
* @tparam Nm Number of elements.
*/
template<typename _Tp, std::size_t _Nm>
struct array
{
typedef _Tp value_type;
typedef value_type* pointer;
typedef const value_type* const_pointer;
typedef value_type& reference;
typedef const value_type& const_reference;
typedef value_type* iterator;
typedef const value_type* const_iterator;
typedef std::size_t size_type;
typedef std::ptrdiff_t difference_type;
typedef std::reverse_iterator<iterator> reverse_iterator;
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
// Support for zero-sized arrays mandatory.
typename __array_traits<_Tp, _Nm>::_Type _M_elems;
// No explicit construct/copy/destroy for aggregate type.
// DR 776.
_GLIBCXX20_CONSTEXPR void
fill(const value_type& __u)
{ std::fill_n(begin(), size(), __u); }
_GLIBCXX20_CONSTEXPR void
swap(array& __other)
noexcept(__array_traits<_Tp, _Nm>::_Is_nothrow_swappable::value)
{ std::swap_ranges(begin(), end(), __other.begin()); }
// Iterators.
[[__gnu__::__const__, __nodiscard__]]
_GLIBCXX17_CONSTEXPR iterator
begin() noexcept
{ return iterator(data()); }
[[__nodiscard__]]
_GLIBCXX17_CONSTEXPR const_iterator
begin() const noexcept
{ return const_iterator(data()); }
[[__gnu__::__const__, __nodiscard__]]
_GLIBCXX17_CONSTEXPR iterator
end() noexcept
{ return iterator(data() + _Nm); }
[[__nodiscard__]]
_GLIBCXX17_CONSTEXPR const_iterator
end() const noexcept
{ return const_iterator(data() + _Nm); }
[[__gnu__::__const__, __nodiscard__]]
_GLIBCXX17_CONSTEXPR reverse_iterator
rbegin() noexcept
{ return reverse_iterator(end()); }
[[__nodiscard__]]
_GLIBCXX17_CONSTEXPR const_reverse_iterator
rbegin() const noexcept
{ return const_reverse_iterator(end()); }
[[__gnu__::__const__, __nodiscard__]]
_GLIBCXX17_CONSTEXPR reverse_iterator
rend() noexcept
{ return reverse_iterator(begin()); }
[[__nodiscard__]]
_GLIBCXX17_CONSTEXPR const_reverse_iterator
rend() const noexcept
{ return const_reverse_iterator(begin()); }
[[__nodiscard__]]
_GLIBCXX17_CONSTEXPR const_iterator
cbegin() const noexcept
{ return const_iterator(data()); }
[[__nodiscard__]]
_GLIBCXX17_CONSTEXPR const_iterator
cend() const noexcept
{ return const_iterator(data() + _Nm); }
[[__nodiscard__]]
_GLIBCXX17_CONSTEXPR const_reverse_iterator
crbegin() const noexcept
{ return const_reverse_iterator(end()); }
[[__nodiscard__]]
_GLIBCXX17_CONSTEXPR const_reverse_iterator
crend() const noexcept
{ return const_reverse_iterator(begin()); }
// Capacity.
[[__nodiscard__, __gnu__::__const__, __gnu__::__always_inline__]]
constexpr size_type
size() const noexcept { return _Nm; }
[[__nodiscard__, __gnu__::__const__, __gnu__::__always_inline__]]
constexpr size_type
max_size() const noexcept { return _Nm; }
[[__nodiscard__, __gnu__::__const__, __gnu__::__always_inline__]]
constexpr bool
empty() const noexcept { return size() == 0; }
// Element access.
[[__nodiscard__]]
_GLIBCXX17_CONSTEXPR reference
operator[](size_type __n) noexcept
{
__glibcxx_requires_subscript(__n);
return _M_elems[__n];
}
[[__nodiscard__]]
constexpr const_reference
operator[](size_type __n) const noexcept
{
#if __cplusplus >= 201402L
__glibcxx_requires_subscript(__n);
#endif
return _M_elems[__n];
}
_GLIBCXX17_CONSTEXPR reference
at(size_type __n)
{
if (__n >= _Nm)
std::__throw_out_of_range_fmt(__N("array::at: __n (which is %zu) "
">= _Nm (which is %zu)"),
__n, _Nm);
return _M_elems[__n];
}
constexpr const_reference
at(size_type __n) const
{
// Result of conditional expression must be an lvalue so use
// boolean ? lvalue : (throw-expr, lvalue)
return __n < _Nm ? _M_elems[__n]
: (std::__throw_out_of_range_fmt(__N("array::at: __n (which is %zu) "
">= _Nm (which is %zu)"),
__n, _Nm),
_M_elems[__n]);
}
[[__nodiscard__]]
_GLIBCXX17_CONSTEXPR reference
front() noexcept
{
__glibcxx_requires_nonempty();
return _M_elems[(size_type)0];
}
[[__nodiscard__]]
constexpr const_reference
front() const noexcept
{
#if __cplusplus >= 201402L
__glibcxx_requires_nonempty();
#endif
return _M_elems[(size_type)0];
}
[[__nodiscard__]]
_GLIBCXX17_CONSTEXPR reference
back() noexcept
{
__glibcxx_requires_nonempty();
return _M_elems[_Nm - 1];
}
[[__nodiscard__]]
constexpr const_reference
back() const noexcept
{
#if __cplusplus >= 201402L
__glibcxx_requires_nonempty();
#endif
return _M_elems[_Nm - 1];
}
[[__nodiscard__, __gnu__::__const__, __gnu__::__always_inline__]]
_GLIBCXX17_CONSTEXPR pointer
data() noexcept
{ return static_cast<pointer>(_M_elems); }
[[__nodiscard__]]
_GLIBCXX17_CONSTEXPR const_pointer
data() const noexcept
{ return static_cast<const_pointer>(_M_elems); }
};
#if __cpp_deduction_guides >= 201606
template<typename _Tp, typename... _Up>
array(_Tp, _Up...)
-> array<enable_if_t<(is_same_v<_Tp, _Up> && ...), _Tp>,
1 + sizeof...(_Up)>;
#endif
// Array comparisons.
template<typename _Tp, std::size_t _Nm>
[[__nodiscard__]]
_GLIBCXX20_CONSTEXPR
inline bool
operator==(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
{ return std::__equal_aux1(__one.begin(), __one.end(), __two.begin()); }
#if __cpp_lib_three_way_comparison // C++ >= 20 && lib_concepts
template<typename _Tp, size_t _Nm>
[[nodiscard]]
constexpr __detail::__synth3way_t<_Tp>
operator<=>(const array<_Tp, _Nm>& __a, const array<_Tp, _Nm>& __b)
{
if constexpr (_Nm && __is_memcmp_ordered<_Tp>::__value)
if (!std::__is_constant_evaluated())
{
constexpr size_t __n = _Nm * sizeof(_Tp);
return __builtin_memcmp(__a.data(), __b.data(), __n) <=> 0;
}
for (size_t __i = 0; __i < _Nm; ++__i)
{
auto __c = __detail::__synth3way(__a[__i], __b[__i]);
if (__c != 0)
return __c;
}
return strong_ordering::equal;
}
#else
template<typename _Tp, std::size_t _Nm>
[[__nodiscard__]]
_GLIBCXX20_CONSTEXPR
inline bool
operator!=(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
{ return !(__one == __two); }
template<typename _Tp, std::size_t _Nm>
[[__nodiscard__]]
_GLIBCXX20_CONSTEXPR
inline bool
operator<(const array<_Tp, _Nm>& __a, const array<_Tp, _Nm>& __b)
{
return std::lexicographical_compare(__a.begin(), __a.end(),
__b.begin(), __b.end());
}
template<typename _Tp, std::size_t _Nm>
[[__nodiscard__]]
_GLIBCXX20_CONSTEXPR
inline bool
operator>(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
{ return __two < __one; }
template<typename _Tp, std::size_t _Nm>
[[__nodiscard__]]
_GLIBCXX20_CONSTEXPR
inline bool
operator<=(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
{ return !(__one > __two); }
template<typename _Tp, std::size_t _Nm>
[[__nodiscard__]]
_GLIBCXX20_CONSTEXPR
inline bool
operator>=(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
{ return !(__one < __two); }
#endif // three_way_comparison && concepts
// Specialized algorithms.
template<typename _Tp, std::size_t _Nm>
_GLIBCXX20_CONSTEXPR
inline
#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
// Constrained free swap overload, see p0185r1
__enable_if_t<__array_traits<_Tp, _Nm>::_Is_swappable::value>
#else
void
#endif
swap(array<_Tp, _Nm>& __one, array<_Tp, _Nm>& __two)
noexcept(noexcept(__one.swap(__two)))
{ __one.swap(__two); }
#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2766. Swapping non-swappable types
template<typename _Tp, std::size_t _Nm>
__enable_if_t<!__array_traits<_Tp, _Nm>::_Is_swappable::value>
swap(array<_Tp, _Nm>&, array<_Tp, _Nm>&) = delete;
#endif
template<std::size_t _Int, typename _Tp, std::size_t _Nm>
[[__nodiscard__]]
constexpr _Tp&
get(array<_Tp, _Nm>& __arr) noexcept
{
static_assert(_Int < _Nm, "array index is within bounds");
return __arr._M_elems[_Int];
}
template<std::size_t _Int, typename _Tp, std::size_t _Nm>
[[__nodiscard__]]
constexpr _Tp&&
get(array<_Tp, _Nm>&& __arr) noexcept
{
static_assert(_Int < _Nm, "array index is within bounds");
return std::move(std::get<_Int>(__arr));
}
template<std::size_t _Int, typename _Tp, std::size_t _Nm>
[[__nodiscard__]]
constexpr const _Tp&
get(const array<_Tp, _Nm>& __arr) noexcept
{
static_assert(_Int < _Nm, "array index is within bounds");
return __arr._M_elems[_Int];
}
template<std::size_t _Int, typename _Tp, std::size_t _Nm>
[[__nodiscard__]]
constexpr const _Tp&&
get(const array<_Tp, _Nm>&& __arr) noexcept
{
static_assert(_Int < _Nm, "array index is within bounds");
return std::move(std::get<_Int>(__arr));
}
#ifdef __cpp_lib_to_array // C++ >= 20 && __cpp_generic_lambdas >= 201707L
template<typename _Tp, size_t _Nm>
[[nodiscard]]
constexpr array<remove_cv_t<_Tp>, _Nm>
to_array(_Tp (&__a)[_Nm])
noexcept(is_nothrow_constructible_v<_Tp, _Tp&>)
{
static_assert(!is_array_v<_Tp>);
static_assert(is_constructible_v<_Tp, _Tp&>);
if constexpr (is_constructible_v<_Tp, _Tp&>)
{
if constexpr (is_trivially_copyable_v<_Tp>
&& is_trivially_default_constructible_v<_Tp>
&& is_copy_assignable_v<_Tp>)
{
array<remove_cv_t<_Tp>, _Nm> __arr;
if (!__is_constant_evaluated() && _Nm != 0)
__builtin_memcpy((void*)__arr.data(), (void*)__a, sizeof(__a));
else
for (size_t __i = 0; __i < _Nm; ++__i)
__arr._M_elems[__i] = __a[__i];
return __arr;
}
else
return [&__a]<size_t... _Idx>(index_sequence<_Idx...>) {
return array<remove_cv_t<_Tp>, _Nm>{{ __a[_Idx]... }};
}(make_index_sequence<_Nm>{});
}
else
__builtin_unreachable(); // FIXME: see PR c++/91388
}
template<typename _Tp, size_t _Nm>
[[nodiscard]]
constexpr array<remove_cv_t<_Tp>, _Nm>
to_array(_Tp (&&__a)[_Nm])
noexcept(is_nothrow_move_constructible_v<_Tp>)
{
static_assert(!is_array_v<_Tp>);
static_assert(is_move_constructible_v<_Tp>);
if constexpr (is_move_constructible_v<_Tp>)
{
if constexpr (is_trivially_copyable_v<_Tp>
&& is_trivially_default_constructible_v<_Tp>
&& is_copy_assignable_v<_Tp>)
{
array<remove_cv_t<_Tp>, _Nm> __arr;
if (!__is_constant_evaluated() && _Nm != 0)
__builtin_memcpy((void*)__arr.data(), (void*)__a, sizeof(__a));
else
for (size_t __i = 0; __i < _Nm; ++__i)
__arr._M_elems[__i] = __a[__i];
return __arr;
}
else
return [&__a]<size_t... _Idx>(index_sequence<_Idx...>) {
return array<remove_cv_t<_Tp>, _Nm>{{ std::move(__a[_Idx])... }};
}(make_index_sequence<_Nm>{});
}
else
__builtin_unreachable(); // FIXME: see PR c++/91388
}
#endif // __cpp_lib_to_array
// Tuple interface to class template array.
/// Partial specialization for std::array
template<typename _Tp, size_t _Nm>
struct tuple_size<array<_Tp, _Nm>>
: public integral_constant<size_t, _Nm> { };
/// Partial specialization for std::array
template<size_t _Ind, typename _Tp, size_t _Nm>
struct tuple_element<_Ind, array<_Tp, _Nm>>
{
static_assert(_Ind < _Nm, "array index is in range");
using type = _Tp;
};
#if __cplusplus >= 201703L
template<typename _Tp, size_t _Nm>
inline constexpr size_t tuple_size_v<array<_Tp, _Nm>> = _Nm;
template<typename _Tp, size_t _Nm>
inline constexpr size_t tuple_size_v<const array<_Tp, _Nm>> = _Nm;
#endif
template<typename _Tp, size_t _Nm>
struct __is_tuple_like_impl<array<_Tp, _Nm>> : true_type
{ };
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // C++11
#endif // _GLIBCXX_ARRAY
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