utility
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// <utility> -*- C++ -*-
// Copyright (C) 2001-2025 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/>.
/*
*
* Copyright (c) 1994
* Hewlett-Packard Company
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Hewlett-Packard Company makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
*
* Copyright (c) 1996,1997
* Silicon Graphics Computer Systems, Inc.
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Silicon Graphics makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*/
/** @file include/utility
* This is a Standard C++ Library header.
*/
#ifndef _GLIBCXX_UTILITY
#define _GLIBCXX_UTILITY 1
#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif
/**
* @defgroup utilities Utilities
*
* Basic function and class templates used with the rest of the library.
* Includes pair, swap, forward/move helpers, declval, integer_sequence.
*/
#include <bits/c++config.h>
#include <bits/stl_relops.h>
#include <bits/stl_pair.h>
#if __cplusplus >= 201103L
#include <initializer_list>
#include <type_traits>
#include <bits/move.h>
#include <bits/utility.h>
#if __cplusplus >= 202002L
#include <ext/numeric_traits.h> // __is_standard_integer, __int_traits
#endif
#if __cplusplus > 202302L
# include <bits/monostate.h>
#endif
#define __glibcxx_want_addressof_constexpr
#define __glibcxx_want_as_const
#define __glibcxx_want_constexpr_algorithms
#define __glibcxx_want_constexpr_utility
#define __glibcxx_want_exchange_function
#define __glibcxx_want_forward_like
#define __glibcxx_want_integer_comparison_functions
#define __glibcxx_want_integer_sequence
#define __glibcxx_want_ranges_zip
#define __glibcxx_want_to_underlying
#define __glibcxx_want_tuple_element_t
#define __glibcxx_want_tuples_by_type
#define __glibcxx_want_unreachable
#define __glibcxx_want_tuple_like
#define __glibcxx_want_constrained_equality
#include <bits/version.h>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
#ifdef __cpp_lib_exchange_function // C++ >= 14
/// Assign @p __new_val to @p __obj and return its previous value.
template <typename _Tp, typename _Up = _Tp>
_GLIBCXX20_CONSTEXPR
inline _Tp
exchange(_Tp& __obj, _Up&& __new_val)
noexcept(__and_<is_nothrow_move_constructible<_Tp>,
is_nothrow_assignable<_Tp&, _Up>>::value)
{ return std::__exchange(__obj, std::forward<_Up>(__new_val)); }
#endif
#ifdef __cpp_lib_as_const // C++ >= 17
template<typename _Tp>
[[nodiscard]]
constexpr add_const_t<_Tp>&
as_const(_Tp& __t) noexcept
{ return __t; }
template<typename _Tp>
void as_const(const _Tp&&) = delete;
#endif
#ifdef __cpp_lib_integer_comparison_functions // C++ >= 20
template<typename _Tp, typename _Up>
constexpr bool
cmp_equal(_Tp __t, _Up __u) noexcept
{
static_assert(__is_standard_integer<_Tp>::value);
static_assert(__is_standard_integer<_Up>::value);
if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
return __t == __u;
else if constexpr (is_signed_v<_Tp>)
return __t >= 0 && make_unsigned_t<_Tp>(__t) == __u;
else
return __u >= 0 && __t == make_unsigned_t<_Up>(__u);
}
template<typename _Tp, typename _Up>
constexpr bool
cmp_not_equal(_Tp __t, _Up __u) noexcept
{ return !std::cmp_equal(__t, __u); }
template<typename _Tp, typename _Up>
constexpr bool
cmp_less(_Tp __t, _Up __u) noexcept
{
static_assert(__is_standard_integer<_Tp>::value);
static_assert(__is_standard_integer<_Up>::value);
if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
return __t < __u;
else if constexpr (is_signed_v<_Tp>)
return __t < 0 || make_unsigned_t<_Tp>(__t) < __u;
else
return __u >= 0 && __t < make_unsigned_t<_Up>(__u);
}
template<typename _Tp, typename _Up>
constexpr bool
cmp_greater(_Tp __t, _Up __u) noexcept
{ return std::cmp_less(__u, __t); }
template<typename _Tp, typename _Up>
constexpr bool
cmp_less_equal(_Tp __t, _Up __u) noexcept
{ return !std::cmp_less(__u, __t); }
template<typename _Tp, typename _Up>
constexpr bool
cmp_greater_equal(_Tp __t, _Up __u) noexcept
{ return !std::cmp_less(__t, __u); }
template<typename _Res, typename _Tp>
constexpr bool
in_range(_Tp __t) noexcept
{
static_assert(__is_standard_integer<_Res>::value);
static_assert(__is_standard_integer<_Tp>::value);
using __gnu_cxx::__int_traits;
if constexpr (is_signed_v<_Tp> == is_signed_v<_Res>)
return __int_traits<_Res>::__min <= __t
&& __t <= __int_traits<_Res>::__max;
else if constexpr (is_signed_v<_Tp>)
return __t >= 0
&& make_unsigned_t<_Tp>(__t) <= __int_traits<_Res>::__max;
else
return __t <= make_unsigned_t<_Res>(__int_traits<_Res>::__max);
}
#endif // __cpp_lib_integer_comparison_functions
#ifdef __cpp_lib_to_underlying // C++ >= 23
/// Convert an object of enumeration type to its underlying type.
template<typename _Tp>
[[nodiscard]]
constexpr underlying_type_t<_Tp>
to_underlying(_Tp __value) noexcept
{ return static_cast<underlying_type_t<_Tp>>(__value); }
#endif
#ifdef __cpp_lib_unreachable // C++ >= 23
/// Informs the compiler that program control flow never reaches this point.
/**
* Evaluating a call to this function results in undefined behaviour.
* This can be used as an assertion informing the compiler that certain
* conditions are impossible, for when the compiler is unable to determine
* that by itself.
*
* For example, it can be used to prevent warnings about reaching the
* end of a non-void function without returning.
*
* @since C++23
*/
[[noreturn,__gnu__::__always_inline__]]
inline void
unreachable()
{
#ifdef _GLIBCXX_DEBUG
std::__glibcxx_assert_fail(nullptr, 0, "std::unreachable()", nullptr);
#elif defined _GLIBCXX_ASSERTIONS
__builtin_trap();
#else
__builtin_unreachable();
#endif
}
#endif
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif
#endif /* _GLIBCXX_UTILITY */
initializer_list
type_traits
move.h
monostate.h
stl_relops.h
stl_pair.h
utility.h
version.h
c++config.h
std::underlying_type_t
typename underlying_type< _Tp >::type underlying_type_t
Alias template for underlying_type.
Definition type_traits:2848
std::make_unsigned_t
typename make_unsigned< _Tp >::type make_unsigned_t
Alias template for make_unsigned.
Definition type_traits:2142
std::forward
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition move.h:72
std
ISO C++ entities toplevel namespace is std.
__gnu_cxx::__int_traits
__numeric_traits_integer< _Tp > __int_traits
Convenience alias for __numeric_traits<integer-type>.
Definition ext/numeric_traits.h:140
std::is_nothrow_assignable
is_nothrow_assignable
Definition type_traits:1311
numeric_traits.h