compare
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// -*- C++ -*- operator<=> three-way comparison support.
// Copyright (C) 2019-2021 Free Software Foundation, Inc.
//
// This file is part of GCC.
//
// GCC 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.
//
// GCC 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 compare
* This is a Standard C++ Library header.
*/
#ifndef _COMPARE
#define _COMPARE
#pragma GCC system_header
#if __cplusplus > 201703L && __cpp_impl_three_way_comparison >= 201907L
#pragma GCC visibility push(default)
#include <concepts>
#if __cpp_lib_concepts
# define __cpp_lib_three_way_comparison 201907L
#endif
namespace std
{
// [cmp.categories], comparison category types
namespace __cmp_cat
{
using type = signed char;
enum class _Ord : type { equivalent = 0, less = -1, greater = 1 };
enum class _Ncmp : type { _Unordered = 2 };
struct __unspec
{
constexpr __unspec(__unspec*) noexcept { }
};
}
class partial_ordering
{
// less=0xff, equiv=0x00, greater=0x01, unordered=0x02
__cmp_cat::type _M_value;
constexpr explicit
partial_ordering(__cmp_cat::_Ord __v) noexcept
: _M_value(__cmp_cat::type(__v))
{ }
constexpr explicit
partial_ordering(__cmp_cat::_Ncmp __v) noexcept
: _M_value(__cmp_cat::type(__v))
{ }
friend class weak_ordering;
friend class strong_ordering;
public:
// valid values
static const partial_ordering less;
static const partial_ordering equivalent;
static const partial_ordering greater;
static const partial_ordering unordered;
// comparisons
friend constexpr bool
operator==(partial_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value == 0; }
friend constexpr bool
operator==(partial_ordering, partial_ordering) noexcept = default;
friend constexpr bool
operator< (partial_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value == -1; }
friend constexpr bool
operator> (partial_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value == 1; }
friend constexpr bool
operator<=(partial_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value <= 0; }
friend constexpr bool
operator>=(partial_ordering __v, __cmp_cat::__unspec) noexcept
{ return __cmp_cat::type(__v._M_value & 1) == __v._M_value; }
friend constexpr bool
operator< (__cmp_cat::__unspec, partial_ordering __v) noexcept
{ return __v._M_value == 1; }
friend constexpr bool
operator> (__cmp_cat::__unspec, partial_ordering __v) noexcept
{ return __v._M_value == -1; }
friend constexpr bool
operator<=(__cmp_cat::__unspec, partial_ordering __v) noexcept
{ return __cmp_cat::type(__v._M_value & 1) == __v._M_value; }
friend constexpr bool
operator>=(__cmp_cat::__unspec, partial_ordering __v) noexcept
{ return 0 >= __v._M_value; }
friend constexpr partial_ordering
operator<=>(partial_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v; }
friend constexpr partial_ordering
operator<=>(__cmp_cat::__unspec, partial_ordering __v) noexcept
{
if (__v._M_value & 1)
return partial_ordering(__cmp_cat::_Ord(-__v._M_value));
else
return __v;
}
};
// valid values' definitions
inline constexpr partial_ordering
partial_ordering::less(__cmp_cat::_Ord::less);
inline constexpr partial_ordering
partial_ordering::equivalent(__cmp_cat::_Ord::equivalent);
inline constexpr partial_ordering
partial_ordering::greater(__cmp_cat::_Ord::greater);
inline constexpr partial_ordering
partial_ordering::unordered(__cmp_cat::_Ncmp::_Unordered);
class weak_ordering
{
__cmp_cat::type _M_value;
constexpr explicit
weak_ordering(__cmp_cat::_Ord __v) noexcept : _M_value(__cmp_cat::type(__v))
{ }
friend class strong_ordering;
public:
// valid values
static const weak_ordering less;
static const weak_ordering equivalent;
static const weak_ordering greater;
constexpr operator partial_ordering() const noexcept
{ return partial_ordering(__cmp_cat::_Ord(_M_value)); }
// comparisons
friend constexpr bool
operator==(weak_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value == 0; }
friend constexpr bool
operator==(weak_ordering, weak_ordering) noexcept = default;
friend constexpr bool
operator< (weak_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value < 0; }
friend constexpr bool
operator> (weak_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value > 0; }
friend constexpr bool
operator<=(weak_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value <= 0; }
friend constexpr bool
operator>=(weak_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value >= 0; }
friend constexpr bool
operator< (__cmp_cat::__unspec, weak_ordering __v) noexcept
{ return 0 < __v._M_value; }
friend constexpr bool
operator> (__cmp_cat::__unspec, weak_ordering __v) noexcept
{ return 0 > __v._M_value; }
friend constexpr bool
operator<=(__cmp_cat::__unspec, weak_ordering __v) noexcept
{ return 0 <= __v._M_value; }
friend constexpr bool
operator>=(__cmp_cat::__unspec, weak_ordering __v) noexcept
{ return 0 >= __v._M_value; }
friend constexpr weak_ordering
operator<=>(weak_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v; }
friend constexpr weak_ordering
operator<=>(__cmp_cat::__unspec, weak_ordering __v) noexcept
{ return weak_ordering(__cmp_cat::_Ord(-__v._M_value)); }
};
// valid values' definitions
inline constexpr weak_ordering
weak_ordering::less(__cmp_cat::_Ord::less);
inline constexpr weak_ordering
weak_ordering::equivalent(__cmp_cat::_Ord::equivalent);
inline constexpr weak_ordering
weak_ordering::greater(__cmp_cat::_Ord::greater);
class strong_ordering
{
__cmp_cat::type _M_value;
constexpr explicit
strong_ordering(__cmp_cat::_Ord __v) noexcept
: _M_value(__cmp_cat::type(__v))
{ }
public:
// valid values
static const strong_ordering less;
static const strong_ordering equal;
static const strong_ordering equivalent;
static const strong_ordering greater;
constexpr operator partial_ordering() const noexcept
{ return partial_ordering(__cmp_cat::_Ord(_M_value)); }
constexpr operator weak_ordering() const noexcept
{ return weak_ordering(__cmp_cat::_Ord(_M_value)); }
// comparisons
friend constexpr bool
operator==(strong_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value == 0; }
friend constexpr bool
operator==(strong_ordering, strong_ordering) noexcept = default;
friend constexpr bool
operator< (strong_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value < 0; }
friend constexpr bool
operator> (strong_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value > 0; }
friend constexpr bool
operator<=(strong_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value <= 0; }
friend constexpr bool
operator>=(strong_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value >= 0; }
friend constexpr bool
operator< (__cmp_cat::__unspec, strong_ordering __v) noexcept
{ return 0 < __v._M_value; }
friend constexpr bool
operator> (__cmp_cat::__unspec, strong_ordering __v) noexcept
{ return 0 > __v._M_value; }
friend constexpr bool
operator<=(__cmp_cat::__unspec, strong_ordering __v) noexcept
{ return 0 <= __v._M_value; }
friend constexpr bool
operator>=(__cmp_cat::__unspec, strong_ordering __v) noexcept
{ return 0 >= __v._M_value; }
friend constexpr strong_ordering
operator<=>(strong_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v; }
friend constexpr strong_ordering
operator<=>(__cmp_cat::__unspec, strong_ordering __v) noexcept
{ return strong_ordering(__cmp_cat::_Ord(-__v._M_value)); }
};
// valid values' definitions
inline constexpr strong_ordering
strong_ordering::less(__cmp_cat::_Ord::less);
inline constexpr strong_ordering
strong_ordering::equal(__cmp_cat::_Ord::equivalent);
inline constexpr strong_ordering
strong_ordering::equivalent(__cmp_cat::_Ord::equivalent);
inline constexpr strong_ordering
strong_ordering::greater(__cmp_cat::_Ord::greater);
// named comparison functions
constexpr bool
is_eq(partial_ordering __cmp) noexcept
{ return __cmp == 0; }
constexpr bool
is_neq(partial_ordering __cmp) noexcept
{ return __cmp != 0; }
constexpr bool
is_lt (partial_ordering __cmp) noexcept
{ return __cmp < 0; }
constexpr bool
is_lteq(partial_ordering __cmp) noexcept
{ return __cmp <= 0; }
constexpr bool
is_gt (partial_ordering __cmp) noexcept
{ return __cmp > 0; }
constexpr bool
is_gteq(partial_ordering __cmp) noexcept
{ return __cmp >= 0; }
namespace __detail
{
template<typename _Tp>
inline constexpr unsigned __cmp_cat_id = 1;
template<>
inline constexpr unsigned __cmp_cat_id<partial_ordering> = 2;
template<>
inline constexpr unsigned __cmp_cat_id<weak_ordering> = 4;
template<>
inline constexpr unsigned __cmp_cat_id<strong_ordering> = 8;
template<typename... _Ts>
constexpr auto __common_cmp_cat()
{
constexpr unsigned __cats = (__cmp_cat_id<_Ts> | ...);
// If any Ti is not a comparison category type, U is void.
if constexpr (__cats & 1)
return;
// Otherwise, if at least one Ti is std::partial_ordering,
// U is std::partial_ordering.
else if constexpr (bool(__cats & __cmp_cat_id<partial_ordering>))
return partial_ordering::equivalent;
// Otherwise, if at least one Ti is std::weak_ordering,
// U is std::weak_ordering.
else if constexpr (bool(__cats & __cmp_cat_id<weak_ordering>))
return weak_ordering::equivalent;
// Otherwise, U is std::strong_ordering.
else
return strong_ordering::equivalent;
}
} // namespace __detail
// [cmp.common], common comparison category type
template<typename... _Ts>
struct common_comparison_category
{
using type = decltype(__detail::__common_cmp_cat<_Ts...>());
};
// Partial specializations for one and zero argument cases.
template<typename _Tp>
struct common_comparison_category<_Tp>
{ using type = void; };
template<>
struct common_comparison_category<partial_ordering>
{ using type = partial_ordering; };
template<>
struct common_comparison_category<weak_ordering>
{ using type = weak_ordering; };
template<>
struct common_comparison_category<strong_ordering>
{ using type = strong_ordering; };
template<>
struct common_comparison_category<>
{ using type = strong_ordering; };
template<typename... _Ts>
using common_comparison_category_t
= typename common_comparison_category<_Ts...>::type;
#if __cpp_lib_concepts
namespace __detail
{
template<typename _Tp, typename _Cat>
concept __compares_as
= same_as<common_comparison_category_t<_Tp, _Cat>, _Cat>;
} // namespace __detail
// [cmp.concept], concept three_way_comparable
template<typename _Tp, typename _Cat = partial_ordering>
concept three_way_comparable
= __detail::__weakly_eq_cmp_with<_Tp, _Tp>
&& __detail::__partially_ordered_with<_Tp, _Tp>
&& requires(const remove_reference_t<_Tp>& __a,
const remove_reference_t<_Tp>& __b)
{
{ __a <=> __b } -> __detail::__compares_as<_Cat>;
};
template<typename _Tp, typename _Up, typename _Cat = partial_ordering>
concept three_way_comparable_with
= three_way_comparable<_Tp, _Cat>
&& three_way_comparable<_Up, _Cat>
&& common_reference_with<const remove_reference_t<_Tp>&,
const remove_reference_t<_Up>&>
&& three_way_comparable<
common_reference_t<const remove_reference_t<_Tp>&,
const remove_reference_t<_Up>&>, _Cat>
&& __detail::__weakly_eq_cmp_with<_Tp, _Up>
&& __detail::__partially_ordered_with<_Tp, _Up>
&& requires(const remove_reference_t<_Tp>& __t,
const remove_reference_t<_Up>& __u)
{
{ __t <=> __u } -> __detail::__compares_as<_Cat>;
{ __u <=> __t } -> __detail::__compares_as<_Cat>;
};
namespace __detail
{
template<typename _Tp, typename _Up>
using __cmp3way_res_t
= decltype(std::declval<_Tp>() <=> std::declval<_Up>());
// Implementation of std::compare_three_way_result.
// It is undefined for a program to add specializations of
// std::compare_three_way_result, so the std::compare_three_way_result_t
// alias ignores std::compare_three_way_result and uses
// __detail::__cmp3way_res_impl directly instead.
template<typename _Tp, typename _Up>
struct __cmp3way_res_impl
{ };
template<typename _Tp, typename _Up>
requires requires { typename __cmp3way_res_t<__cref<_Tp>, __cref<_Up>>; }
struct __cmp3way_res_impl<_Tp, _Up>
{
using type = __cmp3way_res_t<__cref<_Tp>, __cref<_Up>>;
};
} // namespace __detail
/// [cmp.result], result of three-way comparison
template<typename _Tp, typename _Up = _Tp>
struct compare_three_way_result
: __detail::__cmp3way_res_impl<_Tp, _Up>
{ };
/// [cmp.result], result of three-way comparison
template<typename _Tp, typename _Up = _Tp>
using compare_three_way_result_t
= typename __detail::__cmp3way_res_impl<_Tp, _Up>::type;
namespace __detail
{
// BUILTIN-PTR-THREE-WAY(T, U)
// This determines whether t <=> u results in a call to a built-in
// operator<=> comparing pointers. It doesn't work for function pointers
// (PR 93628).
template<typename _Tp, typename _Up>
concept __3way_builtin_ptr_cmp
= requires(_Tp&& __t, _Up&& __u)
{ static_cast<_Tp&&>(__t) <=> static_cast<_Up&&>(__u); }
&& convertible_to<_Tp, const volatile void*>
&& convertible_to<_Up, const volatile void*>
&& ! requires(_Tp&& __t, _Up&& __u)
{ operator<=>(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u)); }
&& ! requires(_Tp&& __t, _Up&& __u)
{ static_cast<_Tp&&>(__t).operator<=>(static_cast<_Up&&>(__u)); };
} // namespace __detail
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3530 BUILTIN-PTR-MEOW should not opt the type out of syntactic checks
// [cmp.object], typename compare_three_way
struct compare_three_way
{
template<typename _Tp, typename _Up>
requires three_way_comparable_with<_Tp, _Up>
constexpr auto
operator()(_Tp&& __t, _Up&& __u) const
noexcept(noexcept(std::declval<_Tp>() <=> std::declval<_Up>()))
{
if constexpr (__detail::__3way_builtin_ptr_cmp<_Tp, _Up>)
{
auto __pt = static_cast<const volatile void*>(__t);
auto __pu = static_cast<const volatile void*>(__u);
if (__builtin_is_constant_evaluated())
return __pt <=> __pu;
auto __it = reinterpret_cast<__UINTPTR_TYPE__>(__pt);
auto __iu = reinterpret_cast<__UINTPTR_TYPE__>(__pu);
return __it <=> __iu;
}
else
return static_cast<_Tp&&>(__t) <=> static_cast<_Up&&>(__u);
}
using is_transparent = void;
};
namespace __cmp_cust
{
template<floating_point _Tp>
constexpr weak_ordering
__fp_weak_ordering(_Tp __e, _Tp __f)
{
// Returns an integer with the same sign as the argument, and magnitude
// indicating the classification: zero=1 subnorm=2 norm=3 inf=4 nan=5
auto __cat = [](_Tp __fp) -> int {
const int __sign = __builtin_signbit(__fp) ? -1 : 1;
if (__builtin_isnormal(__fp))
return (__fp == 0 ? 1 : 3) * __sign;
if (__builtin_isnan(__fp))
return 5 * __sign;
if (int __inf = __builtin_isinf_sign(__fp))
return 4 * __inf;
return 2 * __sign;
};
auto __po = __e <=> __f;
if (is_lt(__po))
return weak_ordering::less;
else if (is_gt(__po))
return weak_ordering::greater;
else if (__po == partial_ordering::equivalent)
return weak_ordering::equivalent;
else // unordered, at least one argument is NaN
{
// return -1 for negative nan, +1 for positive nan, 0 otherwise.
auto __isnan_sign = [](_Tp __fp) -> int {
return __builtin_isnan(__fp)
? __builtin_signbit(__fp) ? -1 : 1
: 0;
};
auto __ord = __isnan_sign(__e) <=> __isnan_sign(__f);
if (is_eq(__ord))
return weak_ordering::equivalent;
else if (is_lt(__ord))
return weak_ordering::less;
else
return weak_ordering::greater;
}
}
template<typename _Tp, typename _Up>
concept __adl_strong = requires(_Tp&& __t, _Up&& __u)
{
strong_ordering(strong_order(static_cast<_Tp&&>(__t),
static_cast<_Up&&>(__u)));
};
template<typename _Tp, typename _Up>
concept __adl_weak = requires(_Tp&& __t, _Up&& __u)
{
weak_ordering(weak_order(static_cast<_Tp&&>(__t),
static_cast<_Up&&>(__u)));
};
template<typename _Tp, typename _Up>
concept __adl_partial = requires(_Tp&& __t, _Up&& __u)
{
partial_ordering(partial_order(static_cast<_Tp&&>(__t),
static_cast<_Up&&>(__u)));
};
template<typename _Ord, typename _Tp, typename _Up>
concept __cmp3way = requires(_Tp&& __t, _Up&& __u, compare_three_way __c)
{
_Ord(__c(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u)));
};
template<typename _Tp, typename _Up>
concept __strongly_ordered
= __adl_strong<_Tp, _Up>
// FIXME: || floating_point<remove_reference_t<_Tp>>
|| __cmp3way<strong_ordering, _Tp, _Up>;
template<typename _Tp, typename _Up>
concept __decayed_same_as = same_as<decay_t<_Tp>, decay_t<_Up>>;
class _Strong_order
{
template<typename _Tp, typename _Up>
static constexpr bool
_S_noexcept()
{
if constexpr (floating_point<decay_t<_Tp>>)
return true;
else if constexpr (__adl_strong<_Tp, _Up>)
return noexcept(strong_ordering(strong_order(std::declval<_Tp>(),
std::declval<_Up>())));
else if constexpr (__cmp3way<strong_ordering, _Tp, _Up>)
return noexcept(compare_three_way()(std::declval<_Tp>(),
std::declval<_Up>()));
}
friend class _Weak_order;
friend class _Strong_fallback;
public:
template<typename _Tp, __decayed_same_as<_Tp> _Up>
requires __strongly_ordered<_Tp, _Up>
constexpr strong_ordering
operator()(_Tp&& __e, _Up&& __f) const
noexcept(_S_noexcept<_Tp, _Up>())
{
/* FIXME:
if constexpr (floating_point<decay_t<_Tp>>)
return __cmp_cust::__fp_strong_order(__e, __f);
else */ if constexpr (__adl_strong<_Tp, _Up>)
return strong_ordering(strong_order(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f)));
else if constexpr (__cmp3way<strong_ordering, _Tp, _Up>)
return compare_three_way()(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
}
};
template<typename _Tp, typename _Up>
concept __weakly_ordered
= floating_point<remove_reference_t<_Tp>>
|| __adl_weak<_Tp, _Up>
|| __cmp3way<weak_ordering, _Tp, _Up>
|| __strongly_ordered<_Tp, _Up>;
class _Weak_order
{
template<typename _Tp, typename _Up>
static constexpr bool
_S_noexcept()
{
if constexpr (floating_point<decay_t<_Tp>>)
return true;
else if constexpr (__adl_weak<_Tp, _Up>)
return noexcept(weak_ordering(weak_order(std::declval<_Tp>(),
std::declval<_Up>())));
else if constexpr (__cmp3way<weak_ordering, _Tp, _Up>)
return noexcept(compare_three_way()(std::declval<_Tp>(),
std::declval<_Up>()));
else if constexpr (__strongly_ordered<_Tp, _Up>)
return _Strong_order::_S_noexcept<_Tp, _Up>();
}
friend class _Partial_order;
friend class _Weak_fallback;
public:
template<typename _Tp, __decayed_same_as<_Tp> _Up>
requires __weakly_ordered<_Tp, _Up>
constexpr weak_ordering
operator()(_Tp&& __e, _Up&& __f) const
noexcept(_S_noexcept<_Tp, _Up>())
{
if constexpr (floating_point<decay_t<_Tp>>)
return __cmp_cust::__fp_weak_ordering(__e, __f);
else if constexpr (__adl_weak<_Tp, _Up>)
return weak_ordering(weak_order(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f)));
else if constexpr (__cmp3way<weak_ordering, _Tp, _Up>)
return compare_three_way()(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
else if constexpr (__strongly_ordered<_Tp, _Up>)
return _Strong_order{}(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
}
};
template<typename _Tp, typename _Up>
concept __partially_ordered
= __adl_partial<_Tp, _Up>
|| __cmp3way<partial_ordering, _Tp, _Up>
|| __weakly_ordered<_Tp, _Up>;
class _Partial_order
{
template<typename _Tp, typename _Up>
static constexpr bool
_S_noexcept()
{
if constexpr (__adl_partial<_Tp, _Up>)
return noexcept(partial_ordering(partial_order(std::declval<_Tp>(),
std::declval<_Up>())));
else if constexpr (__cmp3way<partial_ordering, _Tp, _Up>)
return noexcept(compare_three_way()(std::declval<_Tp>(),
std::declval<_Up>()));
else if constexpr (__weakly_ordered<_Tp, _Up>)
return _Weak_order::_S_noexcept<_Tp, _Up>();
}
friend class _Partial_fallback;
public:
template<typename _Tp, __decayed_same_as<_Tp> _Up>
requires __partially_ordered<_Tp, _Up>
constexpr partial_ordering
operator()(_Tp&& __e, _Up&& __f) const
noexcept(_S_noexcept<_Tp, _Up>())
{
if constexpr (__adl_partial<_Tp, _Up>)
return partial_ordering(partial_order(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f)));
else if constexpr (__cmp3way<partial_ordering, _Tp, _Up>)
return compare_three_way()(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
else if constexpr (__weakly_ordered<_Tp, _Up>)
return _Weak_order{}(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
}
};
template<typename _Tp, typename _Up>
concept __op_eq_lt = requires(_Tp&& __t, _Up&& __u)
{
{ static_cast<_Tp&&>(__t) == static_cast<_Up&&>(__u) }
-> convertible_to<bool>;
{ static_cast<_Tp&&>(__t) < static_cast<_Up&&>(__u) }
-> convertible_to<bool>;
};
class _Strong_fallback
{
template<typename _Tp, typename _Up>
static constexpr bool
_S_noexcept()
{
if constexpr (__strongly_ordered<_Tp, _Up>)
return _Strong_order::_S_noexcept<_Tp, _Up>();
else
return noexcept(bool(std::declval<_Tp>() == std::declval<_Up>()))
&& noexcept(bool(std::declval<_Tp>() < std::declval<_Up>()));
}
public:
template<typename _Tp, __decayed_same_as<_Tp> _Up>
requires __strongly_ordered<_Tp, _Up> || __op_eq_lt<_Tp, _Up>
constexpr strong_ordering
operator()(_Tp&& __e, _Up&& __f) const
noexcept(_S_noexcept<_Tp, _Up>())
{
if constexpr (__strongly_ordered<_Tp, _Up>)
return _Strong_order{}(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
else // __op_eq_lt<_Tp, _Up>
return static_cast<_Tp&&>(__e) == static_cast<_Up&&>(__f)
? strong_ordering::equal
: static_cast<_Tp&&>(__e) < static_cast<_Up&&>(__f)
? strong_ordering::less
: strong_ordering::greater;
}
};
class _Weak_fallback
{
template<typename _Tp, typename _Up>
static constexpr bool
_S_noexcept()
{
if constexpr (__weakly_ordered<_Tp, _Up>)
return _Weak_order::_S_noexcept<_Tp, _Up>();
else
return noexcept(bool(std::declval<_Tp>() == std::declval<_Up>()))
&& noexcept(bool(std::declval<_Tp>() < std::declval<_Up>()));
}
public:
template<typename _Tp, __decayed_same_as<_Tp> _Up>
requires __weakly_ordered<_Tp, _Up> || __op_eq_lt<_Tp, _Up>
constexpr weak_ordering
operator()(_Tp&& __e, _Up&& __f) const
noexcept(_S_noexcept<_Tp, _Up>())
{
if constexpr (__weakly_ordered<_Tp, _Up>)
return _Weak_order{}(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
else // __op_eq_lt<_Tp, _Up>
return static_cast<_Tp&&>(__e) == static_cast<_Up&&>(__f)
? weak_ordering::equivalent
: static_cast<_Tp&&>(__e) < static_cast<_Up&&>(__f)
? weak_ordering::less
: weak_ordering::greater;
}
};
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3465. compare_partial_order_fallback requires F < E
template<typename _Tp, typename _Up>
concept __op_eq_lt_lt = __op_eq_lt<_Tp, _Up>
&& requires(_Tp&& __t, _Up&& __u)
{
{ static_cast<_Up&&>(__u) < static_cast<_Tp&&>(__t) }
-> convertible_to<bool>;
};
class _Partial_fallback
{
template<typename _Tp, typename _Up>
static constexpr bool
_S_noexcept()
{
if constexpr (__partially_ordered<_Tp, _Up>)
return _Partial_order::_S_noexcept<_Tp, _Up>();
else
return noexcept(bool(std::declval<_Tp>() == std::declval<_Up>()))
&& noexcept(bool(std::declval<_Tp>() < std::declval<_Up>()));
}
public:
template<typename _Tp, __decayed_same_as<_Tp> _Up>
requires __partially_ordered<_Tp, _Up> || __op_eq_lt_lt<_Tp, _Up>
constexpr partial_ordering
operator()(_Tp&& __e, _Up&& __f) const
noexcept(_S_noexcept<_Tp, _Up>())
{
if constexpr (__partially_ordered<_Tp, _Up>)
return _Partial_order{}(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
else // __op_eq_lt_lt<_Tp, _Up>
return static_cast<_Tp&&>(__e) == static_cast<_Up&&>(__f)
? partial_ordering::equivalent
: static_cast<_Tp&&>(__e) < static_cast<_Up&&>(__f)
? partial_ordering::less
: static_cast<_Up&&>(__f) < static_cast<_Tp&&>(__e)
? partial_ordering::greater
: partial_ordering::unordered;
}
};
} // namespace __cmp_cust
// [cmp.alg], comparison algorithms
inline namespace __cmp_alg
{
inline constexpr __cmp_cust::_Strong_order strong_order{};
inline constexpr __cmp_cust::_Weak_order weak_order{};
inline constexpr __cmp_cust::_Partial_order partial_order{};
inline constexpr __cmp_cust::_Strong_fallback
compare_strong_order_fallback{};
inline constexpr __cmp_cust::_Weak_fallback
compare_weak_order_fallback{};
inline constexpr __cmp_cust::_Partial_fallback
compare_partial_order_fallback{};
}
namespace __detail
{
// [expos.only.func] synth-three-way
inline constexpr struct _Synth3way
{
template<typename _Tp, typename _Up>
static constexpr bool
_S_noexcept(const _Tp* __t = nullptr, const _Up* __u = nullptr)
{
if constexpr (three_way_comparable_with<_Tp, _Up>)
return noexcept(*__t <=> *__u);
else
return noexcept(*__t < *__u) && noexcept(*__u < *__t);
}
template<typename _Tp, typename _Up>
constexpr auto
operator()(const _Tp& __t, const _Up& __u) const
noexcept(_S_noexcept<_Tp, _Up>())
requires requires
{
{ __t < __u } -> __boolean_testable;
{ __u < __t } -> __boolean_testable;
}
{
if constexpr (three_way_comparable_with<_Tp, _Up>)
return __t <=> __u;
else
{
if (__t < __u)
return weak_ordering::less;
else if (__u < __t)
return weak_ordering::greater;
else
return weak_ordering::equivalent;
}
}
} __synth3way = {};
// [expos.only.func] synth-three-way-result
template<typename _Tp, typename _Up = _Tp>
using __synth3way_t
= decltype(__detail::__synth3way(std::declval<_Tp&>(),
std::declval<_Up&>()));
} // namespace __detail
#endif // concepts
} // namespace std
#pragma GCC visibility pop
#endif // C++20
#endif // _COMPARE